Science.gov

Sample records for double hydroxide ldh

  1. Delamination of layered double hydroxides in polar monomers: new LDH-acrylate nanocomposites.

    PubMed

    O'Leary, Shane; O'Hare, Dermot; Seeley, Gordon

    2002-07-21

    The layered double hydroxide Mg2Al(OH)6(C12H25SO4) was delaminated to give high levels of inclusion in acrylate monomers; subsequent polymerisation of the monomers containing the LDH dispersion gave polyacrylates with the inorganic component still in the delaminated form. PMID:12189866

  2. A pH-responsive layered double hydroxide (LDH)-phthalocyanine nanohybrid for efficient photodynamic therapy.

    PubMed

    Li, Xing-Shu; Ke, Mei-Rong; Huang, Wei; Ye, Chun-Hong; Huang, Jian-Dong

    2015-02-16

    A pH-responsive nanohybrid (LDH-ZnPcPS4 ), in which a highly hydrophilic zinc(II) phthalocyanine tetra-α-substituted with 4-sulfonatophenoxy groups (ZnPcPS4 ) is incorporated with a cationic layered double hydroxide (LDH) based on electrostatic interaction, has been specially designed and prepared through a facile co-precipitation approach. ZnPcPS4 is an excellent singlet-oxygen generator with strong absorption at the near-infrared region (692 nm) in cellular culture media, whereas the photoactivities of ZnPcPS4 were remarkably inhibited after incorporation with the LDH. The nanohybrid is essentially stable in aqueous media at pH 7.4; nevertheless, in slightly acidic media of pH 6.5 or 5.0, ZnPcPS4 can be efficiently released from the LDH matrix, thus leading to restoration of the photoactivities. The nanohybrid shows a high photocytotoxicity against HepG2 cells as a result of much more efficient cellular uptake and preferential accumulation in lysosomes, whereby the acidic environment leads to the release of ZnPcPS4 . The IC50 value of LDH-ZnPcPS4 is as low as 0.053 μM, which is 24-fold lower than that of ZnPcPS4 . This work provides a facile approach for the fabrication of photosensitizers with high photocytotoxicity, potential tumor selectivity, and rapid clearance character. PMID:25639348

  3. Layered double hydroxide/polyethylene terephthalate nanocomposites. Influence of the intercalated LDH anion and the type of polymerization heating method

    SciTech Connect

    Herrero, M.; Martinez-Gallegos, S.; Labajos, F.M.; Rives, V.

    2011-11-15

    Conventional and microwave heating routes have been used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate had been previously intercalated in the LDH. PXRD and TEM were used to detect the degree of dispersion of the filler and the type of the polymeric composites obtained, and FTIR spectroscopy confirmed that the polymerization process had taken place. The thermal stability of these composites, as studied by thermogravimetric analysis, was enhanced when the microwave heating method was applied. Dodecyl sulphate was more effective than terephthalate to exfoliate the samples, which only occurred for the terephthalate ones under microwave irradiation. - Graphical abstract: Conventional and microwave heating routes were used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate was previously intercalated into the LDH. The microwave process improves the dispersion and the thermal stability of nanocomposites due to the interaction of the microwave radiation and the dipolar properties of EG and the homogeneous heating. Highlights: > LDH-PET compatibility is enhanced by preintercalation of organic anions. > Dodecylsulphate performance is much better than that of terephthalate. > Microwave heating improves the thermal stability of the composites. > Microwave heating improves as well the dispersion of the inorganic phase.

  4. Insights into the synthesis of layered double hydroxide (LDH) nanoparticles: Part 1. Optimization and controlled synthesis of chloride-intercalated LDH.

    PubMed

    Sun, Xiaodi; Neuperger, Erica; Dey, Sandwip K

    2015-12-01

    Layered double hydroxide (LDH) nanoparticles have excellent anion-intercalating property, and their potential as theranostic nanovectors is high. However, understanding of the control of the mean particle size (MPS) and achievement of monodispersed particle size distribution (PSD) remains elusive. Herein, with the aid of statistical design of experiments on a model system of Cl(-)-intercalated (Zn, Al)-LDH, controlled synthesis of single crystalline nanoparticles using the coprecipitation method followed by hydrothermal treatment (HT) was achieved in three steps. First, a 2(4-1) design enabled the identification of influential parameters for MPS (i.e., salt concentration, molar ratio of carbonate to aluminum, solution addition rate, and interaction between salt concentration and stirring rate) and PSD (i.e., salt concentration and stirring rate), as well as the optimum coprecipitation conditions that result in a monodispersed PSD (i.e., low salt concentration and high stirring rate). Second, a preliminary explanation of the HT was suggested and the optimum HT conditions for obtaining ideal Gaussian PSD with chi-squared (χ(2))<3 were found to be 85°C for 5 h. Third, using a central composite design, a quantitative MPS model, expressed in terms of the significant factors, was developed and experimentally verified to synthesize nearly monodispersed LDH nanoparticles with MPS ∼200-500 nm. PMID:26301838

  5. Highly efficient and selective adsorption of In3+ on pristine Zn/Al layered double hydroxide (Zn/Al-LDH) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Barnabas, Mary Jenisha; Parambadath, Surendran; Mathew, Aneesh; Park, Sung Soo; Vinu, Ajayan; Ha, Chang-Sik

    2016-01-01

    A pristine Zn/Al-layered double hydroxide (Zn/Al-LDH) showed excellent adsorption ability and selectivity towards In3+ ions from aqueous solutions. The adsorption behaviour as a function of the contact time, solution pH, ionic strength, and amount of adsorbent under ambient conditions revealed a strong dependency on the pH and ionic strength over In3+ intake. The structure and properties of Zn/Al-LDH and In3+ adsorbed Zn/Al-LDH (In-Zn/Al-LDH) were examined carefully by X-ray diffraction, Fourier transform infrared spectroscopy, N2-sorption/desorption, UV-vis spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent had a sufficient number of active sites that were responsible for the In3+ adsorption and quite stable even after the adsorption process. The selective adsorption of In3+ on Zn/Al-LDH was also observed even from a mixture containing competing ions, such as Mn2+, Co2+, Ni2+, Cd2+, Pb2+, and Cu2+. The adsorption experiments showed that Zn/Al-LDH is a promising material for the pre-concentration and selective removal of In3+ from large volumes of aqueous solutions.

  6. Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit ® S 100 covering

    NASA Astrophysics Data System (ADS)

    del Arco, M.; Fernández, A.; Martín, C.; Rives, V.

    2010-12-01

    Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+, Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 Å. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit ® S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7.

  7. Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering

    SciTech Connect

    Arco, M. del; Fernandez, A.; Martin, C.; Rives, V.

    2010-12-15

    Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg{sup 2+} and Al{sup 3+} or Mg{sup 2+}, Al{sup 3+} and Fe{sup 3+} in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

  8. Layered double hydroxide stability. 1. Relative stabilities of layered double hydroxides and their simple counterparts

    NASA Technical Reports Server (NTRS)

    Boclair, J. W.; Braterman, P. S.

    1999-01-01

    Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant titration curves yields nominal solubility constants for the LDH. The corresponding LDH stabilities are in the order Mg < Mn < Co approximately Ni < Zn for M(II) and Al < Fe for M(III). The stability of LDH relative to the separate metal hydroxides/hydrous oxides is discussed.

  9. Methotrexate intercalated ZnAl-layered double hydroxide

    SciTech Connect

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-15

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate ({approx}34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: > ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. > XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. > TG and CHN analyses showed {approx}34 wt% of methotrexate loading into the nanohybrid. > Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

  10. Biological evaluation of layered double hydroxides as efficient drug vehicles.

    PubMed

    Li, Yan; Liu, Dan; Ai, Hanhua; Chang, Qing; Liu, Dandan; Xia, Ying; Liu, Shuwen; Peng, Nanfang; Xi, Zhuge; Yang, Xu

    2010-03-12

    Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration. PMID:20154371

  11. Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor

    SciTech Connect

    Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming; Hou, Wanguo

    2014-02-15

    The synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1–2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials. - Graphical abstract: Layered double hydroxide (LDH) nanosheets were synthesized by coprecipitation using a T-type microchannel reactor, and could be used as basic building blocks for LDH-based functional materials. Display Omitted - Highlights: • LDH nanosheets were synthesized by coprecipitation using a T-type microchannel reactor. • Naked LDH nanosheets were dispersed in aqueous media. • LDH nanosheets can be used as building blocks for functional materials.

  12. Methotrexate intercalated ZnAl-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  13. Subcellular compartment targeting of layered double hydroxide nanoparticles.

    PubMed

    Xu, Zhi Ping; Niebert, Marcus; Porazik, Katharina; Walker, Tara L; Cooper, Helen M; Middelberg, Anton P J; Gray, Peter P; Bartlett, Perry F; Lu, Gao Qing Max

    2008-08-25

    Current investigations show that layered double hydroxide (LDH) nanoparticles have high potential as effective non-viral agents for cellular drug delivery due to their low cytotoxicity, good biocompatibility, high drug loading, control of particle size and shape, targeted delivery and drug release control. Two types of Mg(2)Al-LDH nanoparticles with fluorescein isothiocyanate (FITC) were controllably prepared. One is morphologically featured as typical hexagonal sheets (50-150 nm laterally wide and 10-20 nm thick), while the other as typical rods (30-60 nm wide and 100-200 nm long). These LDH(FTIC) nanoparticles are observed to immediately transfect into different mammalian cell lines. We found that internalized LDH(FITC) nanorods are quickly translocated into the nucleus while internalized LDH(FITC) nanosheets are retained in the cytoplasm. Inhibition experiments show that the cellular uptake is a clathrin-mediated time- and concentration-dependent endocytosis. Endosomal escape of LDH(FITC) nanoparticles is suggested to occur through the deacidification of LDH nanoparticles. Since quick nuclear targeting of LDH(FITC) nanorods requires an active process, and although the exact mechanism is yet to be fully understood, it probably involves an active transport via microtubule-mediated trafficking processes. Targeted addressing of two major subcellular compartments by simply controlling the particle morphology/size could find a number of applications in cellular biomedicine. PMID:18614254

  14. Tunable Electronic Transport Properties of 2D Layered Double Hydroxide Crystalline Microsheets with Varied Chemical Compositions.

    PubMed

    Zhao, Yibing; Hu, Hai; Yang, Xiaoxia; Yan, Dongpeng; Dai, Qing

    2016-09-01

    Transistors based on layered double hydroxides (LDH) single microcrystal are fabricated, whose conductivity of LDH can be tuned by varying metal cations or interlayer anions, but weakly affected by external electric field. The carrier mobility can reach about 1 × 10(-5) cm(2) V(-1) s(-1) , a value comparable to that of organic C60-based transistors. This work paves a way for future electrical applications of LDH. PMID:27416544

  15. New antimony substituted Mg-Al layered double hydroxides.

    PubMed

    Kim, Jin A; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-10-01

    No antimony hydroxide has been previously reported not only in solid state but also in aqueous solution, surely due to the fact that the formation of antimony oxide, Sb2O3, is thermodynamically more favorable than that of the hydroxide phase, Sb(OH)3. According to the pH dependent solubility diagram of Sb2O3, antimony (III) hydroxide may not exist as a definite compound but be proposed as a hydrated monomeric molecular species, Sb(OH)3(aq), which is in equilibrium with Sb2O3, under a condition of very small ionic strength. This is probably the reason why no Sb(3+)-containing layered double hydroxide, LDH, has been reported as yet. In the present study, an attempt has been made to prepare new Sb(3+)-LDH by substituting the Al3+ in octahedral site partially with Sb3+ up to approximately 10%. From the X-ray diffraction analysis, we found that the lattice constants (a = 3.075 angstroms, c = 23.788 angstroms) of the pristine, Mg-Al LDH, increased gradually upto those (a = 3.087 angstroms, c = 24.167 angstroms) of Sb-LDH (8%-substituted). Beyond 10%, the Sb substitution does not lead to any further increases of lattice constants but the impurity Sb2O3 phase is formed. It is, therefore, concluded that the solubility limit of Sb3+ in LDH would be around 10%. In addition, we were able to determine the chemical formula of Sb-substituted LDHs as follows, Mg4Al(1-x)Sb(x)OH10(CO3)(1/2) x H2O (x = 0 approximately 0.08) on the basis of energy dispersive X-ray spectroscopy. PMID:19198414

  16. Facile synthesis of deoxycholate intercalated layered double hydroxide nanohybrids via a coassembly process

    SciTech Connect

    Wu, Xiaowen; Wang, Shuang; Du, Na; Zhang, Renjie; Hou, Wanguo

    2013-07-15

    In this paper, we describe a synthesis strategy of deoxycholate (DC) intercalated layered double hydroxide (LDH) nanohybrids via a coassembly method at room temperature. For this strategy, LDH particles were delaminated to well-dispersed 2D nanosheets in formamide, and the resulting LDH nanosheets were then coassembled with DC anions into the DC intercalated LDH (DC-LDH) nanohybrids. The so-synthesized nanohybrids were characterized by XRD, TEM, FT-IR, elemental analyses and TG-DSC. It was found that the loading amount of DC in the nanohybrids could be easily controlled by changing the ratio of DC to LDH. In addition, the nanohybrids have similar characteristics with the DC-LDH nanohybrids synthesized by the hydrothermal method, including their DC loading, crystal structure, morphology and thermal gravimetric behavior. However, this strategy exhibited the advantages of short reaction time and mild experimental conditions compared with the hydrothermal method. - Graphical abstract: Deoxycholate intercalated layered double hydroxide nanohybrids were successfully synthesized via a coassembly strategy. In this strategy, the interlayer spaces of LDHs can be efficiently used for the intercalation of guest species. - Highlights: • Deoxycholate intercalated layered double hydroxide nanohybrids were synthesized via a coassembly strategy. • This strategy exhibited the advantages of short time and mild conditions. • This strategy can enable organic species to be readily intercalated into the LDH galleries.

  17. Magnetic alginate-layered double hydroxide composites for phosphate removal.

    PubMed

    Lee, Chang-Gu; Kim, Song-Bae

    2013-01-01

    The objective of this study was to investigate phosphate removal using magnetic alginate-layered double hydroxide (LDH) composites. The magnetic composites were prepared by entrapping synthetic magnetic iron oxide and calcined Mg-Al LDH in polymer matrix (alginate). Results showed that the magnetic composites (2% magnetic iron oxide and 6% calcined Mg-Al LDH) were effective in the removal of phosphate with the sorption capacity of 5.0 +/- 0.1 mgP/g under given experimental conditions (adsorbent dose = 0.05 g in 30 ml solution; initial phosphate concentration = 10 mgP/l; reaction time = 24 h). Both magnetic iron oxide and calcined Mg-Al LDH have the ability to adsorb phosphate, with the latter having much higher sorption capacity. In the magnetic composites, calcined Mg-Al LDH functions as a phosphate adsorbent while magnetic iron oxide provides both magnetic and sorption properties. Results also demonstrated that phosphate sorption to the magnetic composites reached equilibrium at 24 h. The maximum phosphate sorption capacity was determined to be 39.1 mgP/g. In addition, phosphate removal was not sensitive to initial solution pH between 4.1 and 10.2. Only 9% of the phosphate sorption capacity was reduced as the solution pH increased from 4.1 to 10.2. This study demonstrated that magnetic alginate-LDH composites could be used for phosphate removal in combination with magnetic separation. PMID:24527638

  18. Sugar-anionic clay composite materials: intercalation of pentoses in layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Aisawa, Sumio; Hirahara, Hidetoshi; Ishiyama, Kayoko; Ogasawara, Wataru; Umetsu, Yoshio; Narita, Eiichi

    2003-09-01

    The intercalation of non-ionized guest pentoses (ribose and 2-deoxyribose) into the Mg-Al and Zn-Al layered double hydroxides (LDHs) was carried out at 298 K by the calcination-rehydration reaction using the Mg-Al and Zn-Al oxide precursors calcined at 773 K. The resulting solid products reconstructed the LDH structure with incorporating pentoses, and the maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 20 times that by the Zn-Al oxide precursor. The ribose/Mg-Al LDH was observed to have the expanded LDH structure with a broad (003) spacing of 0.85 nm. As the thickness of the LDH hydroxide basal layer is 0.48 nm, the interlayer distance of the ribose/Mg-Al LDH is 0.37 nm. This value corresponds to molecular size of ribose in thickness (0.36 nm), supporting that ribose is horizontally oriented in the interlayer space of LDH. The maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 5 times that of 2-deoxyribose. Ribose is substituted only by the hydroxyl group at C-2 position for 2-deoxyribose. Therefore, the number of hydroxyl group of sugar is essentially important for the intercalation of sugar molecule into the LDH, suggesting that the intercalation behavior of sugar for the LDH was greatly influenced by hydrogen bond between hydroxyl group of the intercalated pentose and the LDH hydroxide basal layers.

  19. Polymer Coated CaAl-Layered Double Hydroxide Nanomaterials for Potential Calcium Supplement

    PubMed Central

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-01-01

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement. PMID:25490138

  20. Double-Shelled Nanocages with Cobalt Hydroxide Inner Shell and Layered Double Hydroxides Outer Shell as High-Efficiency Polysulfide Mediator for Lithium-Sulfur Batteries.

    PubMed

    Zhang, Jintao; Hu, Han; Li, Zhen; Lou, Xiong Wen David

    2016-03-14

    Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li-S batteries. Here, we have designed and synthesized double-shelled nanocages with two shells of cobalt hydroxide and layered double hydroxides (CH@LDH) as a conceptually new sulfur host for Li-S batteries. Specifically, the hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur (75 wt %), but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. When evaluated as cathode material for Li-S batteries, the CH@LDH/S composite shows a significantly improved electrochemical performance. PMID:26894940

  1. Preparation of the poly(vinyl alcohol)/layered double hydroxide nanocomposite

    SciTech Connect

    Li Baoguang; Hu Yuan; Zhang Rui; Chen Zuyao; Fan Weicheng

    2003-10-01

    Intercalated nanocomposite based on Mg, Al layered double hydroxide (LDH) and poly(vinyl alcohol) (PVA) was prepared using exfoliation-adsorption technique, and characterized by X-ray diffraction and thermal gravimetric analysis. The results suggest that the intercalated species are formed via the re-aggregation of the delaminated LDH lamellar with the interlayer spacing 14.5 A, and the thermal stability of the nanocomposite improved compared with the original PVA.

  2. Functionalized layered double hydroxide nanoparticles conjugated with disulfide-linked polycation brushes for advanced gene delivery.

    PubMed

    Hu, H; Xiu, K M; Xu, S L; Yang, W T; Xu, F J

    2013-06-19

    Layered double hydroxides (LDHs) have aroused great attention as potential nanosized drug delivery carriers, but independent inorganic LDH wrapped with DNA shows very low transfection efficiency. To manipulate and control the surface properties of LDH nanoparticles is of crucial importance in the designing of LDH-based drug carriers. In this work, surface-initiated atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) is employed to tailor the functionality of LDH surfaces in a well-controlled manner and produce a series of well-defined novel gene delivery vectors (termed as LDH-PDs), where a flexible three-step method was first developed to introduce the ATRP initiation sites containing disulfide bonds onto LDH surfaces. In comparison the pristine LDH particles, the resultant LDH-PDs exhibited better ability to condense plasmid DNA (pDNA) and much higher levels to delivery genes in different cell lines including COS7 and HepG2 cell lines. Moreover, the LDH-PDs also could largely enhance cellular uptake. This present study demonstrates that functionalization of bioinorganic LDH with flexible polycation brushes is an effective means to produce new LDH-based gene delivery systems. PMID:23682934

  3. One-step direct synthesis of layered double hydroxide single-layer nanosheets

    NASA Astrophysics Data System (ADS)

    Yu, Jingfang; Martin, Benjamin R.; Clearfield, Abraham; Luo, Zhiping; Sun, Luyi

    2015-05-01

    Layered double hydroxide (LDH) single-layer nanosheets were traditionally prepared through a multi-step exfoliation process which is very time-consuming and of low efficiency. Herein we report the preparation of LDH single-layer nanosheets through a facile direct synthesis method. By introducing a layer growth inhibitor, one can directly synthesize LDH single-layer nanosheets instead of LDH layered compounds. The inhibitor weakens the interactions between neighboring layers, thus preventing the interlayer growth. This investigation on blocking interlayer growth by weakening interlayer interactions to obtain inorganic single-layer nanosheets opens a new route for the synthesis of 2-dimensional materials.Layered double hydroxide (LDH) single-layer nanosheets were traditionally prepared through a multi-step exfoliation process which is very time-consuming and of low efficiency. Herein we report the preparation of LDH single-layer nanosheets through a facile direct synthesis method. By introducing a layer growth inhibitor, one can directly synthesize LDH single-layer nanosheets instead of LDH layered compounds. The inhibitor weakens the interactions between neighboring layers, thus preventing the interlayer growth. This investigation on blocking interlayer growth by weakening interlayer interactions to obtain inorganic single-layer nanosheets opens a new route for the synthesis of 2-dimensional materials. Electronic supplementary information (ESI) available: Synthesis methods and SEM, EDX, XRD and scheme. See DOI: 10.1039/c5nr01077b

  4. Intercalation of Anionic Oxalato Complexes into Layered Double Hydroxides

    NASA Astrophysics Data System (ADS)

    Prevot, V.; Forano, C.; Besse, J. P.

    2000-09-01

    Intercalation compounds of layered double hydroxide (LDH), MII1-xMIIIx(OH)2Ax/y·nH2O (with MII=Zn, Cu and MIII=Al, Cr, Ga), with oxalato complexes of aluminium, gallium, chromium, copper, and beryllium, were obtained via anion-exchange processes. Powder X-ray diffraction indicated that the intercalation reactions were successful. The basal spacings measured after intercalation are near 0.98±0.02 nm, whatever the host matrix composition. Studies by FTIR spectroscopy confirmed the intercalation of the oxalato complex, too. In order to study the thermal decomposition of the exchanged products, TGA-coupled mass spectrometry was performed.

  5. Biopolymer immobilization during the crystalline growth of layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Leroux, Fabrice; Gachon, Julien; Besse, Jean-Pierre

    2004-01-01

    Alginic acid, a biopolymer produced by brown seaweed, is incorporated between the sheets of a layered double hydroxide (LDH) via direct coprecipitation. The growth of the inorganic crystalline seeds over the polymer gives rise to a lamellar structure. The obtained nanocomposite presents a basal spacing in agreement with the ideal picture of the polymer lying perpendicularly to the inorganic sheets. A study using FTIR and 13C CP-MAS spectroscopies suggests that the interaction between the organic guest and the inorganic framework is weak. However, the polymer has a stabilizing effect in temperature, since ZnO is observed at 350°C, whereas it appears at 200°C for the chloride LDH pristine material.

  6. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    PubMed Central

    Bi, Xue; Zhang, Hui; Dou, Liguang

    2014-01-01

    Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS). In this article, we review developments in the use of layered double hydroxides (LDHs) for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i) DDS with cardiovascular drugs as guests; (ii) DDS with anti-inflammatory drugs as guests; and (iii) DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed. PMID:24940733

  7. Structural characterisation of a layered double hydroxide nanosheet

    NASA Astrophysics Data System (ADS)

    Funnell, Nicholas P.; Wang, Qiang; Connor, Leigh; Tucker, Matthew G.; O'Hare, Dermot; Goodwin, Andrew L.

    2014-06-01

    We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves.We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01265h

  8. Treatment with coated layer double hydroxide clays decreases the toxicity of copper-contaminated water.

    PubMed

    Blake, Deanne; Nar, Mangesh; D'Souza, Nandika Anne; Glenn, J Brad; Klaine, Stephen J; Roberts, Aaron P

    2014-05-01

    Copper is a common pollutant found in watersheds that exerts toxic effects on both invertebrates and vertebrates. Layer double hydroxide (LDH) clays are able to adsorb a wide range of contaminants through ion-exchange mechanisms. Coating LDH clays with various materials alters the aggregation of clay particles into the nano-size range, thus increasing relative surface area and offering great potential for contaminant remediation. The goal of this study was to determine if treatment with coated LDH clays decreases the toxicity of copper-containing solutions to Daphnia magna. Four LDH clays with different coatings used to alter hydrophobicity were as follows: used: Na(+) montmorillonite, Zn-Al LDH-nitrate, Zn-Al LDH-stearate, and Zn-Al LDH-carbonate. It was determined that coated LDH clays decreased copper toxicity by decreasing bioavailability and that smaller aggregate sizes decreased bioavailability the most. 96 h LC50 values increased by as much as 4.2 times with the treatment of the solutions with 100 mg/L LDH clay. Copper analysis of the clay and solutions indicated that the clays work by decreasing copper bioavailability by way of a binding mechanism. Coated LDH clays hold promise as a small-scale remediation tool or as an innovative tool for toxicity identification and evaluation characterization of metals. PMID:24442186

  9. High-Density Protein Loading on Hierarchically Porous Layered Double Hydroxide Composites with a Rational Mesostructure.

    PubMed

    Tokudome, Yasuaki; Fukui, Megu; Tarutani, Naoki; Nishimura, Sari; Prevot, Vanessa; Forano, Claude; Poologasundarampillai, Gowsihan; Lee, Peter D; Takahashi, Masahide

    2016-09-01

    Hierarchically porous biocompatible Mg-Al-Cl-type layered double hydroxide (LDH) composites containing aluminum hydroxide (Alhy) have been prepared using a phase-separation process. The sol-gel synthesis allows for the hierarchical pores of the LDH-Alhy composites to be tuned, leading to a high specific solid surface area per unit volume available for high-molecular-weight protein adsorptions. A linear relationship between the effective surface area, SEFF, and loading capacity of a model protein, bovine serum albumin (BSA), is established following successful control of the structure of the LDH-Alhy composite. The threshold of the mean pore diameter, Dpm, above which BSA is effectively adsorbed on the surface of LDH-Alhy composites, is deduced as 20 nm. In particular, LDH-Alhy composite aerogels obtained via supercritical drying exhibit an extremely high capacity for protein loading (996 mg/g) as a result of a large mean mesopore diameter (>30 nm). The protein loading on LDH-Alhy is >14 times that of a reference LDH material (70 mg/g) prepared via a standard procedure. Importantly, BSA molecules pre-adsorbed on porous composites were successfully released on soaking in ionic solutions (HPO4(2-) and Cl(-) aqueous). The superior capability of the biocompatible LDH materials for loading, encapsulation, and releasing large quantities of proteins was clearly demonstrated. PMID:27501777

  10. Ternary NiFeMn layered double hydroxides as highly-efficient oxygen evolution catalysts.

    PubMed

    Lu, Zhiyi; Qian, Li; Tian, Yang; Li, Yaping; Sun, Xiaoming; Duan, Xue

    2016-01-18

    Layered double hydroxides (LDHs) are a family of layer materials that receive heightened attention. Herein a ternary NiFeMn-LDH is investigated with superior oxygen evolution activity, which is attributed to the Mn(4+) doping in the intralayer, which modifies the electronic structure and improves the conductivity of the electrocatalyst. PMID:26579843

  11. Efficient drug delivery using SiO2-layered double hydroxide nanocomposites.

    PubMed

    Li, Li; Gu, Zi; Gu, Wenyi; Liu, Jian; Xu, Zhi Ping

    2016-05-15

    MgAl-layered double hydroxide (MgAl-LDH) nanoparticles have great potentials in drug and siRNA delivery. In this work, we used a nanodot-coating strategy to prepare SiO2 dot-coated layered double hydroxide (SiO2@MgAl-LDH) nanocomposites with good dispersibility and controllable size for drug delivery. The optimal SiO2@MgAl-LDH nanocomposite was obtained by adjusting synthetic parameters including the mass ratio of MgAl-LDH to SiO2, the mixing temperature and time. The optimal SiO2@MgAl-LDH nanocomposite was shown to have SiO2 nanodots (10-15nm in diameter) evenly deposited on the surface of MgAl-LDHs (110nm in diameter) with the plate-like morphology and the average hydrodynamic diameter of 170nm. We further employed SiO2@MgAl-LDH nanocomposite as a nanocarrier to deliver methotrexate (MTX), a chemotherapy drug, to the human osteosarcoma cell (U2OS) and found that MTX delivered by SiO2@MgAl-LDH nanocomposite apparently inhibited the U2OS cell growth. PMID:26930539

  12. APPLICATIONS OF LAYERED DOUBLE HYDROXIDES IN REMOVING OXYANIONS FROM OIL REFINING AND COAL MINING WASTEWATER

    SciTech Connect

    Song Jin; Paul Fallgren

    2006-03-01

    Western Research Institute (WRI), in conjunction with the U.S. Department of Energy (DOE), conducted a study of using the layered double hydroxides (LDH) as filter material to remove microorganisms, large biological molecules, certain anions and toxic oxyanions from various waste streams, including wastewater from refineries. Results demonstrate that LDH has a high adsorbing capability to those compounds with negative surface charge. Constituents studied include model bacteria, viruses, arsenic, selenium, vanadium, diesel range hydrocarbons, methyl tert-butyl ether (MTBE), mixed petroleum constituents, humic materials and anions. This project also attempted to modify the physical structure of LDH for the application as a filtration material. Flow characterizations of the modified LDH materials were also investigated. Results to date indicate that LDH is a cost-effective new material to be used for wastewater treatment, especially for the treatment of anions and oxyanions.

  13. A novel nanocomposite material prepared by intercalating photoresponsive dendrimers into a layered double hydroxide

    SciTech Connect

    Tanaka, Toshiyuki; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Matsukawa, Junpei; Fujita, Yasuhiko; Takaguchi, Yutaka; Matsuda, Motohide; Miyake, Michihiro

    2010-02-15

    A novel combination for an inorganic-organic nanocomposite material was demonstrated. Anthryl dendron, i.e., poly(amidoamine) dendron with an anthracene chromophore group at the focal point, was incorporated in the interlayer space of ZnAl-NO{sub 3} type layered double hydroxide (LDH) through an anion-exchange reaction. The photoabsorption and fluorescence properties of the resulting material were different from those of the bare anthryl dendron molecule. It was suggested that the change in photochemical properties was due to the organization and pi-pi interaction of anthracene chromophores within the interlayer of the LDH. - Graphical abstract: A novel inorganic-organic nanocomposite material, a layered double hydroxide (LDH) containing photoresponsive dendrimers in the interlayer space, was successfully prepared through an ion-exchange reaction. The resulting material exhibited unique photochemical properties, compared to those of the bare photoresponsive dendrimer molecule.

  14. Efficient uranium capture by polysulfide/layered double hydroxide composites.

    PubMed

    Ma, Shulan; Huang, Lu; Ma, Lijiao; Shim, Yurina; Islam, Saiful M; Wang, Pengli; Zhao, Li-Dong; Wang, Shichao; Sun, Genban; Yang, Xiaojing; Kanatzidis, Mercouri G

    2015-03-18

    There is a need to develop highly selective and efficient materials for capturing uranium (normally as UO2(2+)) from nuclear waste and from seawater. We demonstrate the promising adsorption performance of S(x)-LDH composites (LDH is Mg/Al layered double hydroxide, [S(x)](2-) is polysulfide with x = 2, 4) for uranyl ions from a variety of aqueous solutions including seawater. We report high removal capacities (q(m) = 330 mg/g), large K(d)(U) values (10(4)-10(6) mL/g at 1-300 ppm U concentration), and high % removals (>95% at 1-100 ppm, or ∼80% for ppb level seawater) for UO2(2+) species. The S(x)-LDHs are exceptionally efficient for selectively and rapidly capturing UO2(2+) both at high (ppm) and trace (ppb) quantities from the U-containing water including seawater. The maximum adsorption coeffcient value K(d)(U) of 3.4 × 10(6) mL/g (using a V/m ratio of 1000 mL/g) observed is among the highest reported for U adsorbents. In the presence of very high concentrations of competitive ions such as Ca(2+)/Na(+), S(x)-LDH exhibits superior selectivity for UO2(2+), over previously reported sorbents. Under low U concentrations, (S4)(2-) coordinates to UO2(2+) forming anionic complexes retaining in the LDH gallery. At high U concentrations, (S4)(2-) binds to UO2(2+) to generate neutral UO2S4 salts outside the gallery, with NO3(-) entering the interlayer to form NO3-LDH. In the presence of high Cl(-) concentration, Cl(-) preferentially replaces [S4](2-) and intercalates into LDH. Detailed comparison of U removal efficiency of S(x)-LDH with various known sorbents is reported. The excellent uranium adsorption ability along with the environmentally safe, low-cost constituents points to the high potential of S(x)-LDH materials for selective uranium capture. PMID:25714654

  15. Layered double hydroxide nanoparticles as cellular delivery vectors of supercoiled plasmid DNA.

    PubMed

    Xu, Zhi Ping; Walker, Tara L; Liu, Kerh-lin; Cooper, Helen M; Lu, G Q Max; Bartlett, Perry F

    2007-01-01

    We prepared stable homogeneous suspensions with layered double hydroxide (LDH) nanoparticles for in vitro gene delivery tests. The viability of HEK 293T cells in the presence of LDH nanoparticles at different concentrations was investigated. This revealed 50% cell viability at 500 microg/mL of LDH nanoparticles that is much higher than 50-100 microg/mL used for the delivery tests. The supercoiled pEF-eGFP plasmid (ca. 6100 base pairs) was mixed with LDH nanoparticle suspensions for anion exchange at a weight ratio of DNA/LDH between 1:25 and 1:100. In vitro experiments show that GFP expression in HEK 293T cells starts in the first day, reaches the maximum levels by the second day and continues in the third day. The GFP expression generally increases with the increase in DNA loading in DNA-LDH nanohybrids. However, the delivery efficiency with LDH nanoparticles as the agent is low. For example, the relative efficiency is 7%-15% of that of the commercial agent FuGENE 6. Three to 6% of total cells expressed GFP in an amount detectable by the FACS cytometry 2 days after transfection at 1 microg/mL of plasmid DNA with 25 microg/mL of LDH nanomaterial. The lower delivery efficiency could be attributed to the aggregation of LDH nanoparticles caused by the long-chain plasmid DNA. PMID:17722544

  16. Bionanocomposites based on layered double hydroxides as drug delivery systems

    NASA Astrophysics Data System (ADS)

    Aranda, Pilar; Alcântara, Ana C. S.; Ribeiro, Ligia N. M.; Darder, Margarita; Ruiz-Hitzky, Eduardo

    2012-10-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biopolymers to produce bionanocomposites, able to act as effective drug delivery systems (DDS). Ibuprofen (IBU) and 5-aminosalicylic acid (5-ASA) have been chosen as model drugs, being intercalated in a Mg-Al LDH matrix. On the one side, the LDHIBU intercalation compound prepared by ion-exchange reaction was blended with the biopolymers zein, a highly hydrophobic protein, and alginate, a polysaccharide widely applied for encapsulating drugs. On the other side, the LDH- 5-ASA intercalation compound prepared by co-precipitation was assembled to the polysaccharides chitosan and pectin, which show mucoadhesive properties and resistance to acid pH values, respectively. Characterization of the intercalation compounds and the resulting bionanocomposites was carried out by means of different experimental techniques: X-ray diffraction, infrared spectroscopy, chemical and thermal analysis, as well as optical and scanning electron microscopies. Data on the swelling behavior and drug release under different pH conditions are also reported.

  17. Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2 Reduction.

    PubMed

    Saliba, Daniel; Ezzeddine, Alaa; Sougrat, Rachid; Khashab, Niveen M; Hmadeh, Mohamad; Al-Ghoul, Mazen

    2016-04-21

    We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure. The internal and external morphologies of the particles are studied by electron microscopy and tomography revealing interconnected channels and a high surface area. This material is shown to exhibit a promising performance in the photoreduction of carbon dioxide using solar light. Moreover, the palladium-decorated version shows a significant improvement in its reduction potential at room temperature. PMID:27028104

  18. Chelator-Free Labeling of Layered Double Hydroxide Nanoparticles for in Vivo PET Imaging

    NASA Astrophysics Data System (ADS)

    Shi, Sixiang; Fliss, Brianne C.; Gu, Zi; Zhu, Yian; Hong, Hao; Valdovinos, Hector F.; Hernandez, Reinier; Goel, Shreya; Luo, Haiming; Chen, Feng; Barnhart, Todd E.; Nickles, Robert J.; Xu, Zhi Ping; Cai, Weibo

    2015-11-01

    Layered double hydroxide (LDH) nanomaterial has emerged as a novel delivery agent for biomedical applications due to its unique structure and properties. However, in vivo positron emission tomography (PET) imaging with LDH nanoparticles has not been achieved. The aim of this study is to explore chelator-free labeling of LDH nanoparticles with radioisotopes for in vivo PET imaging. Bivalent cation 64Cu2+ and trivalent cation 44Sc3+ were found to readily label LDH nanoparticles with excellent labeling efficiency and stability, whereas tetravalent cation 89Zr4+ could not label LDH since it does not fit into the LDH crystal structure. PET imaging shows that prominent tumor uptake was achieved in 4T1 breast cancer with 64Cu-LDH-BSA via passive targeting alone (7.7 ± 0.1%ID/g at 16 h post-injection; n = 3). These results support that LDH is a versatile platform that can be labeled with various bivalent and trivalent radiometals without comprising the native properties, highly desirable for PET image-guided drug delivery.

  19. Chelator-Free Labeling of Layered Double Hydroxide Nanoparticles for in Vivo PET Imaging

    PubMed Central

    Shi, Sixiang; Fliss, Brianne C.; Gu, Zi; Zhu, Yian; Hong, Hao; Valdovinos, Hector F.; Hernandez, Reinier; Goel, Shreya; Luo, Haiming; Chen, Feng; Barnhart, Todd E.; Nickles, Robert J.; Xu, Zhi Ping; Cai, Weibo

    2015-01-01

    Layered double hydroxide (LDH) nanomaterial has emerged as a novel delivery agent for biomedical applications due to its unique structure and properties. However, in vivo positron emission tomography (PET) imaging with LDH nanoparticles has not been achieved. The aim of this study is to explore chelator-free labeling of LDH nanoparticles with radioisotopes for in vivo PET imaging. Bivalent cation 64Cu2+ and trivalent cation 44Sc3+ were found to readily label LDH nanoparticles with excellent labeling efficiency and stability, whereas tetravalent cation 89Zr4+ could not label LDH since it does not fit into the LDH crystal structure. PET imaging shows that prominent tumor uptake was achieved in 4T1 breast cancer with 64Cu-LDH-BSA via passive targeting alone (7.7 ± 0.1%ID/g at 16 h post-injection; n = 3). These results support that LDH is a versatile platform that can be labeled with various bivalent and trivalent radiometals without comprising the native properties, highly desirable for PET image-guided drug delivery. PMID:26585551

  20. Micrometer-Thick Graphene Oxide-Layered Double Hydroxide Nacre-Inspired Coatings and Their Properties.

    PubMed

    Yan, You-Xian; Yao, Hong-Bin; Mao, Li-Bo; Asiri, Abdullah M; Alamry, Khalid A; Marwani, Hadi M; Yu, Shu-Hong

    2016-02-10

    Robust, functional, and flame retardant coatings are attractive in various fields such as building construction, food packaging, electronics encapsulation, and so on. Here, strong, colorful, and fire-retardant micrometer-thick hybrid coatings are reported, which can be constructed via an enhanced layer-by-layer assembly of graphene oxide (GO) nanosheets and layered double hydroxide (LDH) nanoplatelets. The fabricated GO-LDH hybrid coatings show uniform nacre-like layered structures that endow them good mechanic properties with Young's modulus of ≈ 18 GPa and hardness of ≈ 0.68 GPa. In addition, the GO-LDH hybrid coatings exhibit nacre-like iridescence and attractive flame retardancy as well due to their well-defined 2D microstructures. This kind of nacre-inspired GO-LDH hybrid thick coatings will be applied in various fields in future due to their high strength and multifunctionalities. PMID:26682698

  1. Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

    PubMed

    Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

    2016-05-24

    Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems. PMID:27124717

  2. Nanohybrids of Mg/Al layered double hydroxide and long-chain (C18) unsaturated fatty acid anions: Structure and sorptive properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-chain (C18) unsaturated fatty acid anions, elaidate (ELA), oleate (OLE), linoleate (LINO), and linolenate (LINOLEN), were intercalated into Mg/Al (3:1) layered double hydroxide (LDH) and the resultant organo-LDH nanohybrid materials were characterized and subsequently evaluated as sorbents of s...

  3. Enhanced thermal- and photo-stability of acid yellow 17 by incorporation into layered double hydroxides

    SciTech Connect

    Wang Qian; Feng Yongjun; Feng Junting; Li Dianqing

    2011-06-15

    2,5-dichloro-4-(5-hydroxy-3-methyl-4-(sulphophenylazo) pyrazol-1-yl) benzenesulphonate (DHSB) anions, namely acid yellow 17 anions, have been successfully intercalated into Zn-Al layered double hydroxides (LDH) to produce a novel organic-inorganic pigment by a simple method involving separate nucleation and aging steps (SNAS), and the dye-intercalated LDH was analyzed by various techniques, e.g., XRD, SEM, FT-IR, TG-DTA and ICP. The d-spacing of the prepared LDH is 2.09 nm. Furthermore, the incorporation of the DHSB aims to enhance the thermal- and photo-stability of the guest dye molecule, for example, the less color change after accelerated thermal- and photo-aging test. - Graphical abstract: Acid yellow anions were successfully assembled into ZnAl layered double hydroxides (LDH) to produce a novel organic-inorganic composite pigment by a simple method involving separate nucleation and aging steps (SNAS). Highlights: > Acid yellow 17 was directly intercalated into ZnAl-LDH to form a novel pigment. > The pigment was prepared by a method involving separate nucleation and aging steps. > The intercalation of dye anions enhances its thermal- and photo-stability.

  4. Crosslinking to enhance colloidal stability and redispersity of layered double hydroxide nanoparticles.

    PubMed

    Zuo, Huali; Gu, Zi; Cooper, Helen; Xu, Zhi Ping

    2015-12-01

    This article introduces a strategy for stabilizing and redispersing layered double hydroxide (LDH) nanoparticles by crosslinking bovine serum albumin (BSA) coated onto the surface. The strategy involves optimization of the amount of the crosslinking agent glutaraldehyde (GTA) to achieve minimal aggregation and ready redispersion. LDH nanoparticles were prepared by co-precipitation and hydrothermal treatment, with subsequent BSA coating at the BSA/LDH mass ratio of 5:2. BSA coated onto LDH nanoparticles was crosslinked with different amounts of GTA. Aggregation studies using dilution assays, dynamic light scattering, and zeta potential analysis indicated that severe aggregation at lower LDH nanoparticle concentrations can be prevented by proper crosslinking of BSA with GTA. The GTA-crosslinked BSA-coated nanoparticles showed excellent redispersity compared to the non-crosslinked nanoparticles. In vitro cytotoxicity and cell uptake were found to be minimally affected by GTA-crosslinking. The new strategy therefore provides a much more effective method for the prevention of LDH nanoparticle aggregation and improved LDH nanoparticle redispersion for use in a wide variety of bio-applications in vitro and in vivo. PMID:26254867

  5. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    SciTech Connect

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-05-15

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g{sup −1}. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  6. Tuneable ultra high specific surface area Mg/Al-CO3 layered double hydroxides.

    PubMed

    Chen, Chunping; Wangriya, Aunchana; Buffet, Jean-Charles; O'Hare, Dermot

    2015-10-01

    We report the synthesis of tuneable ultra high specific surface area Aqueous Miscible Organic solvent-Layered Double Hydroxides (AMO-LDHs). We have investigated the effects of different solvent dispersion volumes, dispersion times and the number of re-dispersion cycles specific surface area of AMO-LDHs. In particular, the effects of acetone dispersion on two different morphology AMO-LDHs (Mg3Al-CO3 AMO-LDH flowers and Mg3Al-CO3 AMO-LDH plates) was investigated. It was found that the amount of acetone used in the dispersion step process can significantly affect the specific surface area of Mg3Al-CO3 AMO-LDH flowers while the dispersion time in acetone is critical factor to obtain high specific surface area Mg3Al-CO3 AMO-LDH plates. Optimisation of the acetone washing steps enables Mg3Al-CO3 AMO-LDH to have high specific surface area up to 365 m(2) g(-1) for LDH flowers and 263 m(2) g(-1) for LDH plates. In addition, spray drying was found to be an effective and practical drying method to increase the specific surface area by a factor of 1.75. Our findings now form the basis of an effective general strategy to obtain ultrahigh specific surface area LDHs. PMID:26308729

  7. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    NASA Astrophysics Data System (ADS)

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-05-01

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g-1. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  8. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    SciTech Connect

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-15

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed. - Graphical abstract: Dependence of ZnAl LDH Morphology on SDS concentration. Highlights: Black-Right-Pointing-Pointer In-situ intercalation of SDS in ZnAl LDH was achieved via urea hydrolysis method. Black-Right-Pointing-Pointer Morphology of ZnAl LDH intercalated with SDS depended on the SDS concentration. Black-Right-Pointing-Pointer Ring like morphology for SDS intercalated ZnAl LDH was obtained for the first time. Black-Right-Pointing-Pointer Growth mechanism was discussed. Black-Right-Pointing-Pointer Template assisted growth of ZnAl LDH was proposed.

  9. Rearrangement of layered double hydroxide nanoplatelets during hollow colloidosome preparation.

    PubMed

    Liu, Guopeng; Liu, Shangying; Dong, Xiaoqiang; Yang, Fei; Sun, Dejun

    2010-05-15

    Hollow colloidosomes consisting of plate-like Mg/Al layered double hydroxide (LDH) nanoparticles have been prepared by a facile route from a Pickering emulsion. The particles are first adsorbed onto the surface of paraffin oil-in-water emulsion droplets. After the core oil is dissolved in the surrounding bulk liquid, using solvents that are miscible with both the internal and external phases of the droplets, colloidosomes are formed. In this process, we find that the diameters of the colloidosomes are significantly reduced compared to those of the emulsion droplets. The reduction in the diameter is caused by rearrangement of the LDH platelets. That is, the platelets change their orientation from lying flat on the emulsion droplet surface to standing erect in a dense, face-to-face connecting pattern in the colloidosome shell. The main reason for the particle rearrangement is the increase of the attractive forces among the particles due to the reduced polarity of the solvents used during colloidosome preparation. PMID:20219203

  10. Large-scale synthesis of highly dispersed layered double hydroxide powders containing delaminated single layer nanosheets.

    PubMed

    Wang, Qiang; O'Hare, Dermot

    2013-07-18

    A facile method for the synthesis of Zn2Al-borate and Mg3Al-borate layered double hydroxides (LDHs) with extremely high specific surface areas of 458.6 and 263 m(2) g(-1) and containing delaminated nanosheets is reported. To the best of our knowledge, this is the first report of LDH powders that still remain exfoliated on drying. PMID:23739826

  11. The use of layered double hydroxides as DNA vaccine delivery vector for enhancement of anti-melanoma immune response.

    PubMed

    Li, Ang; Qin, Lili; Wang, Wenrui; Zhu, Rongrong; Yu, Yongchun; Liu, Hui; Wang, Shilong

    2011-01-01

    Our previous studies have shown that Mg:Al 1:1 layered double hydroxides (LDH(R1)) nanoparticles could be taken up by the MDDCs effectively and had an adjuvant activity for DC maturation. Furthermore, these LDH(R1) nanoparticles could up-regulate the expression of CCR7 and augment the migration of DCs in response to CCL21. In current study, we have evaluated whether LDH(R1) as DNA vaccine delivery carrier can augment the efficacy of DNA vaccine immunization in vivo. Firstly, we found that LDH(R1) was efficient in combining DNA and formed LDH(R1)/DNA complex with an average diameter of about 80-120 nm. Its high transfection efficiency in vivo delivered with a GFP expression plasmid was also observed. After delivery of pcDNA(3)-OVA/LDH(R1) complex by intradermal immunization in C57BL/6 mice, the LDH(R1) induced an enhanced serum antibody response much greater than naked DNA vaccine. Using B16-OVA melanoma as tumor model, we demonstrated that pcDNA(3)-OVA/LDH(R1) complex enhanced immune priming and protection from tumor challenge in vivo. Furthermore, we showed that LDH(R1) induced dramatically more effective CTL activation and skewed T helper polarization to Th1. Collectively, these findings demonstrate that this LDH(R1)/DNA plasmid complex should be a new and promising way in vaccination against tumor. PMID:20934217

  12. Hierarchical construction of an ultrathin layered double hydroxide nanoarray for highly-efficient oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Yang, Qiu; Li, Tian; Lu, Zhiyi; Sun, Xiaoming; Liu, Junfeng

    2014-09-01

    Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (η) of 257 mV is needed for a current density of 80 mA cm-2 with a Tafel slope of 53 mV per decade. The hierarchical LDH nanoarray also shows excellent structural stability in alkaline media. After continuous testing under a high OER current density (~300 mA cm-2) for 10 h, the sample maintains the ordered hierarchical structure with no significant deactivation of the catalytic properties.Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (η) of 257 mV is needed for a current density of 80 mA cm-2 with a

  13. Enhancement of the coercivity in Co-Ni layered double hydroxides by increasing basal spacing.

    PubMed

    Zhang, Cuijuan; Tsuboi, Tomoya; Namba, Hiroaki; Einaga, Yasuaki; Yamamoto, Takashi

    2016-09-14

    The magnetic properties of layered double hydroxides (LDH) containing transition metal ions can still develop, compared with layered metal hydroxide salts which exhibit structure-dependent magnetism. In this article, we report the preparation of a hybrid magnet composed of Co-Ni LDH and n-alkylsulfonate anions (Co-Ni-CnSO3 LDH). As Co-Ni LDH is anion-exchangeable, we can systematically control the interlayer spacing by intercalating n-alkylsulfonates with different carbon numbers. The magnetic properties were examined with temperature- and field-dependent magnetization measurements. As a result, we have revealed that the coercive field depends on the basal spacing. It is suggested that increasing the basal spacing varies the competition between the in-plane superexchange interactions and long-range out-of-plane dipolar interactions. Moreover, a jump in the coercive field at around 20 Å of the basal spacing is assumed to be the modification of the magnetic ordering in Co-Ni-CnSO3 LDH. PMID:27381282

  14. Reversible color changes in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide nanosheets.

    PubMed

    Itoh, Toshio; Shichi, Tetsuya; Yui, Tatsuto; Takahashi, Hiroki; Inui, Yoshihisa; Takagi, Katsuhiko

    2005-03-01

    The present study is an investigation of a reversible thermal color change induced in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide (LDH) nanosheets. These poly-[m,n]/LDH hybrids prepared by the photo- or gamma-ray-induced polymerization of diacetylenecarboxylates, i.e., CH(3)(CH(2))(m)()(-)(1)CC-CC(CH(2))(n)()(-)(1)CO(2)(-) (mono-[m,n]), and intercalated in LDH lamella sheets, were observed to develop colors ranging from yellow to blue. The change in color was found to depend greatly on the alkyl carbon numbers of the mono-[m,n] (m,n = 10,11; 5,11; 10,5; 16,1) values. Moreover, the conformational alignment of the mono-[m,n] within the LDH was observed to be a crucial factor in color development, which was greatly affected by the intercalation degrees and extent of poly(ene-yne) linkage elongation of the polymers. For the poly-[m,n]/LDH hybrids investigated, a reversible color change was found to occur repeatedly and remarkably for the poly-[10,11]/LDH hybrid. This color change occurred at temperatures between ca. 20 and 80 degrees C back and forth from purple red to bright orange, in stark contrast to the irreversible color change for poly-[10,11] without LDH. Moreover, DSC and Raman spectroscopic studies of the LDH hybrids showed that the thermochromic temperature corresponded to the phase transition temperature of 80 degrees C. XRD analysis also indicated that the poly-[m,n]/LDH hybrid could retain its lamella structure during such thermochromic color changes, enabling conformational recovery in the polymer chains by a cooling down of the hybrids to temperatures lower than the transition temperature, while the nonhybrid poly-[10,11] powders exhibited an irreversible color change at 60 degrees C, above which the polymer powder turned amorphous. PMID:16851341

  15. Eu-doped Mg-Al layered double hydroxide as a responsive fluorescent material and its interaction with glutamic acid

    NASA Astrophysics Data System (ADS)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Wei, Junchao

    2012-10-01

    The paper describes a study on the fluorescence of a Eu-doped Mg-Al layered double hydroxide (Eu-doped LDH) response to glutamic acid (Glu). Various characterizations (UV-Vis transmittance, TG-DTA and IR-spectrum) indicated that there is an interaction between the Eu-doped LDH and Glu. Fluorescent study was found that the red emissions resulted from 5D0-7FJ transition (J = 1, 2) of Eu3+ markedly decreased, while the blue emission at 440 nm contributed to Glu shifted to low energy after the addition of Glu to the Eu-doped LDH. The fluorescent changes may be relevant to the hydrogen-bond interaction between the Eu-doped LDH and Glu, and the mechanism of the interaction between Eu-doped LDH and Glu was discussed.

  16. Enhanced catalytic oxidation ability of ternary layered double hydroxides for organic pollutants degradation.

    PubMed

    Fahel, Jean; Kim, Sanghoon; Durand, Pierrick; André, Erwan; Carteret, Cédric

    2016-05-10

    Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants. PMID:27097543

  17. Tungstocobaltate-pillared layered double hydroxides: Preparation, characterization, magnetic and catalytic properties

    SciTech Connect

    Wei Xiaocui; Fu Youzhi; Xu Lin Li Fengyan; Bi Bo; Liu Xizheng

    2008-06-15

    A new polyoxometalate anion-pillared layered double hydroxide (LDH) was prepared by aqueous ion exchange of a Mg-Al LDH precursor in nitrate form with the tungstocobaltate anions [CoW{sub 12}O{sub 40}]{sup 5-}. The physicochemical properties of the product were characterized by the methods of powder X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry. It was confirmed that [CoW{sub 12}O{sub 40}]{sup 5-} was intercalated between the brucite-type layers of the LDHs without a change in the structure. Magnetic measurement shows the occurrence of antiferromagnetic interactions between the magnetic centers. The investigation of catalytic performance for this sample exhibits high activity for the oxidation of benzaldehyde by hydrogen peroxide. - Graphical abstract: A tungstocobaltate anion [CoW{sub 12}O{sub 40}]{sup 5-} pillared layered double hydroxide (LDH) was prepared by aqueous ion exchange with a Mg-Al LDH precursor in nitrate form, demonstrating that [CoW{sub 12}O{sub 40}]{sup 5-} was intercalated between the brucite-type layers of the LDHs without change in structure. Magnetic measurement shows the occurrence of antiferromagnetic interactions between the magnetic centers. The investigation of catalytic performance for this sample exhibits high activity for the oxidation of benzaldehyde by hydrogen peroxide.

  18. First insight into catalytic activity of anionic iron porphyrins immobilized on exfoliated layered double hydroxides.

    PubMed

    Nakagaki, Shirley; Halma, Matilte; Bail, Alesandro; Arízaga, Gregório Guadalupe Carbajal; Wypych, Fernando

    2005-01-15

    Mg-Al layered double hydroxide (LDH) intercalated with glycinate anions was synthesized through co-precipitation and exfoliated in formamide and the single-layer suspension was reacted with aqueous iron porphyrin solutions (Fe(TDFSPP) and Fe(TCFSPP)). The obtained materials were characterized by X-ray powder diffraction, UV-vis, and electron paramagnetic resonance and investigated in the oxidation reaction of cyclooctene and cyclohexane using iodosylbenzene as oxidant. The iron porphyrin seems to be immobilized at the surface of the glycinate intercalated LDH. The catalytic activities obtained in heterogeneous media for iron porphyrin, Fe(TDFSPP), was superior to the results obtained under homogeneous conditions, but the opposite effect was observed on the Fe(TCFSPP), indicating that, instead of the structural similarity of both iron porphyrins (second-generation porphyrins), the immobilization of each one produced different catalysts. The best catalytic activity of the Fe(TDFSPP)/Gly-LDH, compared to Fe(TCFSPP)/Gly-LDH, can be explained by the easy access of the oxidant and the substrate to the catalytic sites in the former, probably located at the surface of the layered double hydroxide pillared with glycinate anions. A model for the immobilization and a mechanism for the oxidation reaction will be discussed. PMID:15571697

  19. High pseudocapacitive cobalt carbonate hydroxide films derived from CoAl layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Lu, Zhiyi; Zhu, Wei; Lei, Xiaodong; Williams, Gareth R.; O'Hare, Dermot; Chang, Zheng; Sun, Xiaoming; Duan, Xue

    2012-05-01

    A thin nanosheet of mesoporous cobalt carbonate hydroxide (MPCCH) has been fabricated from a CoAl-LDH nanosheet following removal of the Al cations by alkali etching. The basic etched electrode exhibits enhanced specific capacitance (1075 F g-1 at 5 mA cm-2) and higher rate capability and cycling stability (92% maintained after 2000 cycles).A thin nanosheet of mesoporous cobalt carbonate hydroxide (MPCCH) has been fabricated from a CoAl-LDH nanosheet following removal of the Al cations by alkali etching. The basic etched electrode exhibits enhanced specific capacitance (1075 F g-1 at 5 mA cm-2) and higher rate capability and cycling stability (92% maintained after 2000 cycles). Electronic supplementary information (ESI) available: Detailed experimental procedure, specific capacitance calculation, EDS and FTIR results, electrochemical results of CoAl-LDH and SEM image. See DOI: 10.1039/c2nr30617d

  20. Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

    NASA Technical Reports Server (NTRS)

    Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

    1999-01-01

    Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

  1. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  2. Layered Double Hydroxide as a Vehicle to Increase Toxicity of Gallate Ions against Adenocarcinoma Cells.

    PubMed

    Arratia-Quijada, Jenny; Rivas-Fuentes, Selma; Saavedra, Karina J Parra; Lamas, Adriana M Macías; Carbajal Arízaga, Gregorio Guadalupe

    2016-01-01

    The antineoplasic activity of gallic acid has been reported. This compound induces apoptosis and inhibits the growth of several neoplasic cells. However, this molecule is easily oxidized and degraded in the body. The aim of this work was to intercalate gallate ions into layered double hydroxide (LDH) nanoparticles under controlled conditions to reduce oxidation of gallate and to evaluate its toxicity against the A549 adenocarcinoma cell line. An isopropanol medium under nitrogen atmosphere was adequate to intercalate gallate ions with a lesser oxidation degree as detected by electron spin resonance spectroscopy. Concentrations of the hybrid LDH-gallate nanoparticles between 0.39 and 25 µg/mL reduced the cell viability to 67%, while the value reached with the pure gallic acid and LDH was 90% and 78%, respectively, thus proving that the combination of gallate ions with the inorganic nanoparticles increases the toxicity potential within this dose range. PMID:27438820

  3. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor.

    PubMed

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g(-1) at 0.5 A g(-1) and 1181 F g(-1) even at current density as high as 10 A g(-1), which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg(-1) (at power density of 551 W kg(-1)) with a 1.5 V operating voltage. PMID:26754281

  4. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor

    NASA Astrophysics Data System (ADS)

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g-1 at 0.5 A g-1 and 1181 F g-1 even at current density as high as 10 A g-1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg-1 (at power density of 551 W kg-1) with a 1.5 V operating voltage.

  5. Synthesis and photoluminescence of red emitting phosphors of europium complex intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Gao, Zhen; Yin, Xiaoru; Xie, Juan

    2015-12-01

    An inorganic-organic red emitting phosphor, europium ethylenediaminetetraacetate complex ([Eu(EDTA)]-) anions intercalated Mg/Al and Zn/Al layered double hydroxides (LDHs) were synthesized through an ion exchange method. X-ray powder diffraction (XRD) results exhibit that a nearly vertical arrangement of [Eu(EDTA)]- anions with the maximal dimension in the gallery is adopted. Measurement of the excitation and emission spectra show that the two materials display high red luminescence from Eu3+ ions. Furthermore, Mg/Al LDH containing europium complex has higher luminescence intensity than Zn/Al LDH, which probably was related with more inversion asymmetry sites of Eu3+ occurring in the Mg/Al LDH.

  6. Thin bacteria/Layered Double Hydroxide films using a layer-by-layer approach.

    PubMed

    Halma, Matilte; Khenifi, Aicha; Sancelme, Martine; Besse-Hoggan, Pascale; Bussière, Pierre-Olivier; Prévot, Vanessa; Mousty, Christine

    2016-07-15

    This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bacterial cells of Pseudomonas sp. strain ADP were assembled alternatively with Mg2Al-NO3 LDH nanosheets by a layer-by-layer deposition method. The UV-Vis spectroscopy was used to monitor the assembly process, showing a progressive increase in immobilized bacteria amount upon deposited cycles. The {ADP/LDH}n film was characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and atomic force microscopy. The metabolic activity of immobilized bacteria was determined using chronoamperometry by measuring the biochemical oxygen demand in presence of glucose using an artificial electron acceptor (Fe(CN)6(3-)) at 0.5V/Ag-AgCl. A steady current of 0.250μAcm(-2) was reached in about 30s after the addition of 5mM glucose. PMID:27124809

  7. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor

    PubMed Central

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g−1 at 0.5 A g−1 and 1181 F g−1 even at current density as high as 10 A g−1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg−1 (at power density of 551 W kg−1) with a 1.5 V operating voltage. PMID:26754281

  8. The construction and characterization of layered double hydroxides as delivery vehicles for podophyllotoxins.

    PubMed

    Xue, Yan Hua; Zhang, Rui; Sun, Xiao Yu; Wang, Shi Long

    2008-03-01

    The aim of this study was to construct PPT-LDH nanohybrids and compare their tumor inhibition effects with that of free PPT. Anticancer drug podophyllotoxin (PPT) was encapsulated in the galleries of Mg-Al layered double hydroxides (LDHs) by a two-step approach. Tyrosine (Tyr) was first incorporated into the interlayer space by co-precipitation with LDH, prop-opening the layers of Mg-Al/LDH and creating an interlayer environment inviting drug molecules. PPT was subsequently intercalated into the resulting material lamella by an ion exchange process. The intermediate and final products, which can be termed drug-inorganic nanocomposites, have been characterized by powder X-ray diffraction (XRD), UV-VIS spectrophotometer, transmission electron microscopy (TEM) and in cell culture. Our results demonstrate that the interlayer spacing distance of the PPT-LDH nanohybrids (34% w/w of drug/material) is 18.2 A. LDHs do not harm normal cells (293T) based on toxicity tests. Ex-vivo anticancer experiments reveal that the PPT-LDH nanohybrids have higher tumor suppression effects than intercalated PPT. We conclude that the higher tumor inhibition effects of PPT-LDH hybrids result from the inorganic drug delivery vehicle, LDHs. PMID:17701296

  9. The in vitro sustained release profile and antitumor effect of etoposide-layered double hydroxide nanohybrids.

    PubMed

    Qin, Lili; Wang, Mei; Zhu, Rongrong; You, Songhui; Zhou, Ping; Wang, Shilong

    2013-01-01

    Magnesium-aluminum layered double hydroxides intercalated with antitumor drug etoposide (VP16) were prepared for the first time using a two-step procedure. The X-ray powder diffraction data suggested the intercalation of VP16 into layers with the increased basal spacing from 0.84-1.18 nm was successful. Then, it was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, and transmission electron microscopy. The prepared nanoparticles, VP16-LDH, showed an average diameter of 62.5 nm with a zeta potential of 20.5 mV. Evaluation of the buffering effect of VP16-LDH indicated that the nanohybrids were ideal for administration of the drugs that treat human stomach irritation. The loading amount of intercalated VP16 was 21.94% and possessed a profile of sustained release. The mechanism of VP16-LDH release in the phosphate buffered saline solution at pH 7.4 is likely controlled by the diffusion of VP16 anions from inside to the surface of LDH particles. The in vitro cytotoxicity and antitumor assays indicated that VP16-LDH hybrids were less toxic to GES-1 cells while exhibiting better antitumor efficacy on MKN45 and SGC-7901 cells. These results imply that VP16-LDH is a potential antitumor drug for a broad range of gastric cancer therapeutic applications. PMID:23737669

  10. The in vitro sustained release profile and antitumor effect of etoposide-layered double hydroxide nanohybrids

    PubMed Central

    Qin, Lili; Wang, Mei; Zhu, Rongrong; You, Songhui; Zhou, Ping; Wang, Shilong

    2013-01-01

    Magnesium-aluminum layered double hydroxides intercalated with antitumor drug etoposide (VP16) were prepared for the first time using a two-step procedure. The X-ray powder diffraction data suggested the intercalation of VP16 into layers with the increased basal spacing from 0.84–1.18 nm was successful. Then, it was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, and transmission electron microscopy. The prepared nanoparticles, VP16-LDH, showed an average diameter of 62.5 nm with a zeta potential of 20.5 mV. Evaluation of the buffering effect of VP16-LDH indicated that the nanohybrids were ideal for administration of the drugs that treat human stomach irritation. The loading amount of intercalated VP16 was 21.94% and possessed a profile of sustained release. The mechanism of VP16-LDH release in the phosphate buffered saline solution at pH 7.4 is likely controlled by the diffusion of VP16 anions from inside to the surface of LDH particles. The in vitro cytotoxicity and antitumor assays indicated that VP16-LDH hybrids were less toxic to GES-1 cells while exhibiting better antitumor efficacy on MKN45 and SGC-7901 cells. These results imply that VP16-LDH is a potential antitumor drug for a broad range of gastric cancer therapeutic applications. PMID:23737669

  11. Mg-Al layered double hydroxide-methotrexate nanohybrid drug delivery system: evaluation of efficacy.

    PubMed

    Chakraborty, Jui; Roychowdhury, Susanta; Sengupta, Somoshree; Ghosh, Swapankumar

    2013-05-01

    Mg-Al layered double hydroxide nanoparticles were synthesized by one-pot co-precipitation method and anticancerous drug methotrexate was incorporated into it by in-situ ion exchange. The LDH-MTX nanohybrid produced moderately stable suspension in water, as predicted by zeta potential measurement. X-ray diffraction revealed that the basal spacing increased to nearly twice the same for pristine LDH on MTX intercalation. Thermogravimetric analyses confirmed an increase in thermal stability of the intercalated drug in the LDH framework. A striking enhancement in efficacy/sensitivity of MTX on the HCT-116 cells was obtained when intercalated within the LDH layers, as revealed by the attainment of half maximal inhibitory concentration of LDH-MTX nanohybrid by 48 h, whereas, bare MTX required 72 h for the same. The MTX release from MgAl-LDH-MTX hybrids in phosphate buffer saline at pH7.4 followed a relatively slow, first order kinetics and was complete within 8 days following diffusion and crystal dissolution mechanism. PMID:23498245

  12. Three-dimensional porous MXene/layered double hydroxide composite for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Dou, Hui; Wang, Jie; Ding, Bing; Xu, Yunling; Chang, Zhi; Hao, Xiaodong

    2016-09-01

    In this work, an exfoliated MXene (e-MXene) nanosheets/nickel-aluminum layered double hydroxide (MXene/LDH) composite as supercapacitor electrode material is fabricated by in situ growth of LDH on e-MXene substrate. The LDH platelets homogeneously grown on the surface of the e-MXene sheets construct a three-dimensional (3D) porous structure, which not only leads to high active sites exposure of LDH and facile liquid electrolyte penetration, but also alleviates the volume change of LDH during the charge/discharge process. Meanwhile, the e -MXene substrate forms a conductive network to facilitate the electron transport of active material. The optimized MXene/LDH composite exhibits a high specific capacitance of 1061 F g-1 at a current density of 1 A g-1, excellent capacitance retention of 70% after 4000 cycle tests at a current density of 4 A g-1 and a good rate capability with 556 F g-1 retention at 10 A g-1.

  13. Intracrystalline structure of DNA molecules stabilized in the layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Oh, Jae-Min; Kwak, Seo-Young; Choy, Jin-Ho

    2006-05-01

    DNA was successfully intercalated into layered double hydroxide (LDH), Mg2Al(OH)6NO3·0.1H2O, through ion exchange reaction to form DNA LDH nanohybrid. Powder X-ray diffraction (PXRD) and fourier-transform infrared (FT-IR) spectroscopic results demonstrate that the DNA molecules are stabilized between the hydroxide layers. According to the circular dichroism (CD) spectroscopic studies, the B-form DNA molecules are electrostatically bound in the interlayer space of LDHs upon satisfying the charge neutralization condition. However, the intercalated DNA molecules are supposed to be more or less twisted due to the charge mismatch between anionic DNA and cationic LDH. To verify the size of DNA strands in the LDH lattice, the DNA molecules with different length of 0.2 5 kbps were intercalated into the LDHs with various particle size. Three kinds of LDHs with discrete particle size were synthesized through both coprecipitation and hydrothermal methods. From the scanning electron microscopy (SEM), the particle sizes were determined as ˜80, 150, and 300 nm, respectively. Thus prepared DNA LDH nanohybrids with various particle size were treated with DNA destroying enzyme such as DNase I. Since the LDHs (80, 150, 300 nm) are smaller in size than the DNA molecules, some parts of the intercalated DNA chains are eventually dangling outside of the host LDH layer. Therefore, the dangling part of DNA chains and the surface adsorbed DNA were decomposed quickly by DNase I treatment. The DNA strands protected by LDH layers could intentionally be recovered by treating with an acidic solution. The length of DNA strands thus recovered were confirmed by electrophoresis, and determined to be ˜200 bps irrespective of the particle size of LDHs.

  14. Ni3+ doped monolayer layered double hydroxide nanosheets as efficient electrodes for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhao, Yufei; Wang, Qing; Bian, Tong; Yu, Huijun; Fan, Hua; Zhou, Chao; Wu, Li-Zhu; Tung, Chen-Ho; O'Hare, Dermot; Zhang, Tierui

    2015-04-01

    Ni3+ doped NiTi layered double hydroxide (NiTi-LDH) monolayer nanosheets with a particle size of ~20 nm and a thickness of ~0.9 nm have been successfully prepared through a facile bottom-up approach. These NiTi-LDH monolayer nanosheets exhibit excellent supercapacitor performance, including a high specific pseudocapacitance (2310 F g-1 at 1.5 A g-1) and long durability compared with bulk LDH, owing to highly exposed conductive Ni3+ species (NiOOH) which lead to the increased mobility rate of surface charge and electrolyte-transfer. Therefore, this work is expected to take a significant step towards exploring novel 2D monolayer electrode materials with unique physical and chemical properties for applications in energy storage and conversion.Ni3+ doped NiTi layered double hydroxide (NiTi-LDH) monolayer nanosheets with a particle size of ~20 nm and a thickness of ~0.9 nm have been successfully prepared through a facile bottom-up approach. These NiTi-LDH monolayer nanosheets exhibit excellent supercapacitor performance, including a high specific pseudocapacitance (2310 F g-1 at 1.5 A g-1) and long durability compared with bulk LDH, owing to highly exposed conductive Ni3+ species (NiOOH) which lead to the increased mobility rate of surface charge and electrolyte-transfer. Therefore, this work is expected to take a significant step towards exploring novel 2D monolayer electrode materials with unique physical and chemical properties for applications in energy storage and conversion. Electronic supplementary information (ESI) available: Experimental details and additional characterization data. See DOI: 10.1039/c5nr01320h

  15. Coagulation Behavior of Graphene Oxide on Nanocrystallined Mg/Al Layered Double Hydroxides: Batch Experimental and Theoretical Calculation Study.

    PubMed

    Zou, Yidong; Wang, Xiangxue; Ai, Yuejie; Liu, Yunhai; Li, Jiaxing; Ji, Yongfei; Wang, Xiangke

    2016-04-01

    Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH-Cl) and nanocrystallined Mg/Al LDHs (LDH-CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH-Cl and LDH-CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH-Cl and LDH-CO3 occupying the binding sites of GO. The coagulation of GO by LDH-Cl and LDH-CO3 was strongly dependent on pH and ionic strength. Results of theoretical DFT calculations indicated that the coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH-Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment. PMID:26978487

  16. Interlayer interaction in Ca-Fe layered double hydroxides intercalated with nitrate and chloride species

    NASA Astrophysics Data System (ADS)

    Al-Jaberi, Muayad; Naille, Sébastien; Dossot, Manuel; Ruby, Christian

    2015-12-01

    Ca-Fe layered double hydroxide (LDH) intercalated with chloride and nitrate ions has been synthesized with varying CaII:FeIII molar ratios of the initial solution. Phase pure LDH is observed with CaII:FeIII molar ratio of 2:1 and a mixture of LDH and Ca(OH)2 is formed for CaII:FeIII molar ratios higher than 2:1. Vibrational spectroscopies (Raman and IR) were used successfully to understand the interaction between the cationic and anionic sheets. The Raman bands positions at lower frequencies (150-600 cm-1) are intimately correlated to the nature of the divalent and trivalent ions but also to the nature of the anions. Indeed, a shift of ˜9 cm-1 is observed for the Raman double bands situated in the 300-400 cm-1 region when comparing Raman spectra of CaFe-LDH containing either nitrate or chloride ions. Two types of nitrate environments are observed namely free (non-hydrogen bonded) nitrate and nitrate hydrogen bonded to the interlayer water or to the 'brucite-like' hydroxyl surface. Multiple types of water structure are observed and would result from different hydrogen bond structures. Water bending modes are identified at 1645 cm-1 greater than the one observed for LDH intercalated with chloride anions (1618 cm-1), indicating that the water is strongly hydrogen bonded to the nitrate anions.

  17. Epigallocatechin Gallate/Layered Double Hydroxide Nanohybrids: Preparation, Characterization, and In Vitro Anti-Tumor Study

    PubMed Central

    Shafiei, Seyedeh Sara; Solati-Hashjin, Mehran; Samadikuchaksaraei, Ali; Kalantarinejad, Reza; Asadi-Eydivand, Mitra; Abu Osman, Noor Azuan

    2015-01-01

    In recent years, nanotechnology in merging with biotechnology has been employed in the area of cancer management to overcome the challenges of chemopreventive strategies in order to gain promising results. Since most biological processes occur in nano scale, nanoparticles can act as carriers of certain drugs or agents to deliver it to specific cells or targets. In this study, we intercalated Epigallocatechin-3-Gallate (EGCG), the most abundant polyphenol in green tea, into Ca/Al-NO3 Layered double hydroxide (LDH) nanoparticles, and evaluated its efficacy compared to EGCG alone on PC3 cell line. The EGCG loaded LDH nanohybrids were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) and nanosizer analyses. The anticancer activity of the EGCG-loaded LDH was investigated in prostate cancer cell line (PC3) while the release behavior of EGCG from LDH was observed at pH 7.45 and 4.25. Besides enhancing of apoptotic activity of EGCG, the results showed that intercalation of EGCG into LDH can improve the anti- tumor activity of EGCG over 5-fold dose advantages in in-vitro system. Subsequently, the in-vitro release data showed that EGCG-loaded LDH had longer release duration compared to physical mixture, and the mechanism of diffusion through the particle was rate-limiting step. Acidic attack was responsible for faster release of EGCG molecules from LDH at pH of 4.25 compared to pH of 7.4. The results showed that Ca/Al-LDH nanoparticles could be considered as an effective inorganic host matrix for the delivery of EGCG to PC3 cells with controlled release properties. PMID:26317853

  18. Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Tsukanov, A. A.; Psakhie, S. G.

    2016-01-01

    The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered.

  19. Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study

    PubMed Central

    Tsukanov, A.A.; Psakhie, S.G.

    2016-01-01

    The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered. PMID:26817816

  20. Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study.

    PubMed

    Tsukanov, A A; Psakhie, S G

    2016-01-01

    The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered. PMID:26817816

  1. Layered double hydroxide as an efficient drug reservoir for folate derivatives.

    PubMed

    Choy, Jin-Ho; Jung, Ji-Sun; Oh, Jae-Min; Park, Man; Jeong, Jinyoung; Kang, Young-Koo; Han, Ok-Jin

    2004-07-01

    Folic acid derivatives such as folinic acid and methotrexate (MTX) have been successfully hybridized with layered double hydroxide (LDH) by ion-exchange reaction. The X-ray diffraction patterns and spectroscopic analyses indicate that these molecules intercalated into the hydroxide interlayer space are stabilized in the tilted longitudinal monolayer mode by electrostatic interaction. No significant changes in their structural and functional properties are found in the hybrids. The cellular uptake test of MTX-LDH hybrid is carried out in the fibroblast (human tendon) and SaOS-2 cell line (Osteosarcoma, human) by in vitro MTT (3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide) assay. The initial proliferation of SaOS-2 cell is more strongly suppressed by treatment with MTX-LDH hybrid than with MTX alone. This study clearly shows that LDH not only plays a role as a biocompatible-delivery matrix for drugs but also facilitates a significant increase in the delivery efficiency. PMID:14967539

  2. MgAl- Layered Double Hydroxide Nanoparticles for controlled release of Salicylate.

    PubMed

    Mondal, Soumini; Dasgupta, Sudip; Maji, Kanchan

    2016-11-01

    Layered double hydroxides (LDHs), have been known for many decades as catalyst and ceramic precursors, traps for anionic pollutants, and additives for polymers. Recently, their successful synthesis on the nanometer scale opened up a whole new field for their application in nanomedicine. Here we report the efficacy of Mg1-xAlx (NO3)x (OH)2 LDH nanoparticles as a carrier and for controlled release of one of the non-steroidal anti-inflammatory drugs (NSAID), sodium salicylate. Mg1-xAlx (NO3)x (OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Salicylate was intercalated in the interlayer space of Mg-Al LDH after suspending nanoparticles in 0.0025(M) HNO3 and 0.75 (M) NaNO3 solution and using anion exchange method under N2 atmosphere. The shift in the basal planes like (003) and (006) to lower 2θ value in the XRD plot of intercalated sample confirmed the increase in basal spacing in LDH because of intercalation of salicylate into the interlayer space of LDH. FTIR spectroscopy of SA-LDH nano hybrid revealed a red shift in the frequency band of carboxylate group in salicylate indicating an electrostatic interaction between cationic LDH sheet and anionic drug. Differential thermal analysis of LDH-SA nanohybrid indicated higher thermal stability of salicylate in the intercalated form into LDH as compared to its free state. DLS studies showed a particle size distribution between 30-60 nm for pristine LDH whereas salicylate intercalated LDH exhibited a particle size distribution between 40-80nm which is ideal for its efficacy as a superior carrier for drugs and biomolecules. The cumulative release kinetic of salicylate from MgAl-LDH-SA hybrids in phosphate buffer saline (PBS) at pH7.4 showed a sustained release of salicylate up to 72h that closely resembled first order release kinetics through a combination of drug diffusion and dissolution of LDH under physiological conditions. Also the

  3. Layered double hydroxides as supports for the slow release of acid herbicides.

    PubMed

    Cardoso, Lucelena P; Celis, Rafael; Cornejo, Juan; Valim, João B

    2006-08-01

    A Mg/Al layered double hydroxide (LDH) was intercalated with the anionic herbicides 2,4-D, MCPA, and picloram by using three different methodologies: (i) direct synthesis (DS), (ii) regeneration (RE), and (iii) ion exchange (IE). The resulting complexes were characterized and assayed by batch release and column leaching tests, aiming at the controlled release of these herbicides. All the tested LDH-herbicide complexes displayed similar slow herbicide release properties in water, although the IE method seemed to result in complexes with a greater fraction of herbicide in a readily available form. Apparently, the LDH-herbicide complexes released most of the active ingredient present in the complexes at the end of the batch release experiment. This was attributed to the replacement of the intercalated herbicide by carbonate and hydroxyl anions from the aqueous solution. Compared to the free herbicides, the application of the three LDH-herbicide complexes (RE) to soil columns resulted in reduction in the maximum herbicide concentration in leachates and led to the retardation of herbicide leaching through the soil. All LDH-herbicide complexes presented an herbicidal efficacy similar to that of the free (technical) herbicides. Our results indicated the potential applicability of LDHs as supports for the preparation of slow release formulations of acid herbicides such as 2,4-D, MCPA, or picloram. PMID:16881703

  4. Polarized immune responses modulated by layered double hydroxides nanoparticle conjugated with CpG.

    PubMed

    Yan, Shiyu; Rolfe, Barbara E; Zhang, Bing; Mohammed, Yousuf H; Gu, Wenyi; Xu, Zhi P

    2014-11-01

    Modulation of the immune response is an important step in the induction of protective humoral and cellular immunity against pathogens. In this study, we investigated the possibility of using a nanomaterial conjugated with the toll-like receptor (TLR) ligand CpG to modulate the immune response towards the preferred polarity. MgAl-layered double hydroxide (LDH) nanomaterial has a very similar chemical composition to Alum, an FDA approved adjuvant for human vaccination. We used a model antigen, ovalbumin (OVA) to demonstrate that MgAl-LDH had comparable adjuvant activity to Alum, but much weaker inflammation. Conjugation of TLR9 ligand CpG to LDH nanoparticles significantly enhanced the antibody response and promoted a switch from Th2 toward Th1 response, demonstrated by a change in the IgG2a:IgG1 ratio. Moreover, immunization of mice with CpG-OVA-conjugated LDH before challenge with OVA-expressing B16/F10 tumor cells retarded tumor growth. Together, these data indicate that LDH nanomaterial can be used as an immune adjuvant to promote Th1 or Th2 dominant immune responses suitable for vaccination purposes. PMID:25145853

  5. Antibacterial carboxymethyl cellulose/Ag nanocomposite hydrogels cross-linked with layered double hydroxides.

    PubMed

    Yadollahi, Mehdi; Namazi, Hassan; Aghazadeh, Mohammad

    2015-08-01

    This paper deals with the preparation of antibacterial nanocomposite hydrogels through the combination of carboxy methyl cellulose (CMC), layered double hydroxides (LDH), and silver nanoparticles (AgNPs). CMC-LDH hydrogels were prepared by intercalating CMC into different LDHs. Then, Ag/CMC-LDH nanocomposite hydrogels were prepared through in situ formation of AgNPs within the CMC-LDHs. XRD analysis confirmed the intercalating CMC into the LDH sheets and formation of intercalated structures, as well as formation of AgNPs within the CMC-LDHs. SEM and TEM micrographs indicated well distribution of AgNPs within the Ag/CMC-LDHs. The prepared hydrogels showed a pH sensitive swelling behavior. The Ag/CMC-LDH nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with CMC-LDHs. The antibacterial activity of CMC-LDHs increased considerably after formation of AgNPs and was stable for more than one month. PMID:25964179

  6. Synthesis and characterization of 10-hydroxycamptothecin - sebacate - layered double hydroxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Pang, Xiujiang; Ma, Xiuming; Li, Dongxiang; Hou, Wanguo

    2013-02-01

    10-Hydroxycamptothecin (HCPT) as a hydrophobic anticancer drug brings many challenges in the clinical applications due to its poor water solubility and the presence of a chemically unstable lactone ring. In this work, the nanocomposites of HCPT intercalated layered double hydroxide (LDH) were prepared by a secondary intercalation method, and the encapsulated HCPT could keep the biologically active lactone form. A Zn-Al-NO3 LDH was pillared with sebacate anions by a co-precipitation method in an aqueous medium, and then HCPT was intercalated into the LDH's gallery via hydrophobic interaction in an ethanol medium. The parallel alkyl chains of perpendicularly arranged sebacate anions in the LDH gallery provide a hydrophobic space for the drug intercalation. The in vitro release kinetics of HCPT from the nanocomposites could be fitted with the pseudo-second-order kinetic model, and the diffusion of HCPT through the LDH particles played an important role in controlling the drug release. The nanocomposites can be considered as a potential drug delivery system.

  7. Starch Biocatalyst Based on α-Amylase-Mg/Al-Layered Double Hydroxide Nanohybrids.

    PubMed

    Bruna, Felipe; Pereira, Marita G; Polizeli, Maria de Lourdes T M; Valim, João B

    2015-08-26

    The design of new biocatalysts through the immobilization of enzymes, improving their stability and reuse, plays a major role in the development of sustainable methodologies toward the so-called green chemistry. In this work, α-amylase (AAM) biocatalyst based on Mg3Al-layered double-hydroxide (LDH) matrix was successfully developed with the adsorption method. The adsorption process was studied and optimized as a function of time and enzyme concentration. The biocatalyst was characterized, and the mechanism of interaction between AAM and LDH, as well as the immobilization effects on the catalytic activity, was elucidated. The adsorption process was fast and irreversible, thus yielding a stable biohybrid material. The immobilized AAM partially retained its enzymatic activity, and the biocatalyst rapidly hydrolyzed starch in an aqueous solution with enhanced efficiency at intermediate loading values of ca. 50 mg/g of AAM/LDH. Multiple attachments through electrostatic interactions affected the conformation of the immobilized enzyme on the LDH surface. The biocatalyst was successfully stored in its dry form, retaining 100% of its catalytic activity. The results reveal the potential usefulness of a LDH compound as a support of α-amylase for the hydrolysis of starch that may be applied in industrial and pharmaceutical processes as a simple, environmentally friendly, and low-cost biocatalyst. PMID:26259168

  8. Efficient delivery of siRNA to cortical neurons using layered double hydroxide nanoparticles.

    PubMed

    Wong, Yunyi; Markham, Kathryn; Xu, Zhi Ping; Chen, Min; Max Lu, Gao Qing; Bartlett, Perry F; Cooper, Helen M

    2010-11-01

    Small interfering RNAs (siRNAs) are capable of targeting and destroying specific mRNAs, making them particularly suited to the treatment of neurodegenerative conditions such as Huntington's Disease where the production of abnormal proteins results in a gain-of-function phenotype. Although a variety of nanoparticle formulations are currently under development as siRNA delivery systems, application of these technologies has been limited by their high cytotoxicity, low drug loading capacity and release, and inability to penetrate cell membranes. Layered double hydroxide (LDH) nanoparticles are now emerging as a potential new drug delivery system as they exhibit low cytotoxicity and are highly biocompatible. Here we present the first study investigating LDH delivery of siRNAs to primary cultured neurons. We show that internalization by neurons is rapid, dose-dependent and saturable, and markedly more efficient than in other cell types. We demonstrate that siRNA-LDH complexes are internalized by clathrin-dependent endocytosis at the cell body and in neurites, with subsequent retrograde transport to the cell body followed by efficient release into the cytoplasm. Finally we show that LDH mediated siRNA delivery effectively silences neuronal gene expression. This study therefore confirms the potential of LDH nanoparticles as a drug delivery system for patients suffering from neurodegenerative disease. PMID:20709387

  9. Anticancer Drug-Incorporated Layered Double Hydroxide Nanohybrids and Their Enhanced Anticancer Therapeutic Efficacy in Combination Cancer Treatment

    PubMed Central

    Lee, Gyeong Jin; Kang, Joo-Hee

    2014-01-01

    Objective. Layered double hydroxide (LDH) nanoparticles have been studied as cellular delivery carriers for anionic anticancer agents. As MTX and 5-FU are clinically utilized anticancer drugs in combination therapy, we aimed to enhance the therapeutic performance with the help of LDH nanoparticles. Method. Anticancer drugs, MTX and 5-FU, and their combination, were incorporated into LDH by reconstruction method. Simply, LDHs were thermally pretreated at 400°C, and then reacted with drug solution to simultaneously form drug-incorporated LDH. Thus prepared MTX/LDH (ML), 5-FU/LDH (FL), and (MTX + 5-FU)/LDH (MFL) nanohybrids were characterized by X-ray diffractometer, scanning electron microscopy, infrared spectroscopy, thermal analysis, zeta potential measurement, dynamic light scattering, and so forth. The nanohybrids were administrated to the human cervical adenocarcinoma, HeLa cells, in concentration-dependent manner, comparing with drug itself to verify the enhanced therapeutic efficacy. Conclusion. All the nanohybrids successfully accommodated intended drug molecules in their house-of-card-like structures during reconstruction reaction. It was found that the anticancer efficacy of MFL nanohybrid was higher than other nanohybrids, free drugs, or their mixtures, which means the multidrug-incorporated LDH nanohybrids could be potential drug delivery carriers for efficient cancer treatment via combination therapy. PMID:24860812

  10. Direct observation of grafting interlayer phosphate in Mg/Al layered double hydroxides

    SciTech Connect

    Shimamura, Akihiro; Kanezaki, Eiji; Jones, Mark I.; Metson, James B.

    2012-02-15

    The grafting of interlayer phosphate in synthetic Mg/Al layered double hydroxides with interlayer hydrogen phosphate (LDH-HPO{sub 4}) has been studied by XRD, TG/DTA, FT-IR, XPS and XANES. The basal spacing of crystalline LDH-HPO{sub 4} decreases in two stages with increasing temperature, from 1.06 nm to 0.82 nm at 333 K in the first transition, and to 0.722 nm at 453 K in the second. The first stage occurs due to the loss of interlayer water and rearrangement of the interlayer HPO{sub 4}{sup 2-}. In the second transition, the interlayer phosphate is grafted to the layer by the formation of direct bonding to metal cations in the layer, accompanied by a change in polytype of the crystalline structure. The grafted phosphate becomes immobilized and cannot be removed by anion-exchange with 1-octanesulfonate. The LDH is amorphous at 743 K but decomposes to Mg{sub 3}(PO{sub 4}){sub 2}, AlPO{sub 4}, MgO and MgAl{sub 2}O{sub 4} after heated to 1273 K. - Graphical abstract: The cross section of the synthetic Mg, Al layered double hydroxides in Phase 1, with interlayer hydrogen phosphate Phase 2, and with grafted phosphate, Phase 3. Highlights: Black-Right-Pointing-Pointer The grafting of hydrogen phosphate intercalated Mg/Al-LDH has been studied. Black-Right-Pointing-Pointer The basal spacing of crystalline LDH-HPO{sub 4} decreases in two stages with increasing temperature. Black-Right-Pointing-Pointer The first decrease is due to loss of interlayer water, the second is attributed to phosphate grafting. Black-Right-Pointing-Pointer The grafted interlayer phosphate becomes immobilized and cannot be removed by anion-exchange.

  11. Double layered hydroxides as potential anti-cancer drug delivery agents.

    PubMed

    Riaz, Ufana; Ashraf, S M

    2013-04-01

    The emergence of nanotechnology has changed the scenario of the medical world by revolutionizing the diagnosis, monitoring and treatment of cancer. This nanotechnology has been proved miraculous in detecting cancer cells, delivering chemotherapeutic agents and monitoring treatment from non-specific to highly targeted killing of tumor cells. In the past few decades, a number of inorganic materials have been investigated such as calcium phosphate, gold, carbon materials, silicon oxide, iron oxide, and layered double hydroxide (LDH) for examining their efficacy in targeting drug delivery. The reason behind the selection of these inorganic materials was their versatile and unique features efficient in drug delivery, such as wide availability, rich surface functionality, good biocompatibility, potential for target delivery, and controlled release of the drug from these inorganic nanomaterials. Although, the drug-LDH hybrids are found to be quite instrumental because of their application as advanced anti-cancer drug delivery systems, there has not been much research on them. This mini review is set to highlight the advancement made in the use of layered double hydroxides (LDHs) as anti-cancer drug delivery agents. Along with the advantages of LDHs as anti-cancer drug delivery agents, the process of interaction of some of the common anti-cancer drugs with LDH has also been discussed. PMID:23170959

  12. A facile method for the construction of covalently cross-linked layered double hydroxides layer-by-layer films: Enhanced stability and delayed release of guests

    NASA Astrophysics Data System (ADS)

    Li, Yulong; An, Qi; Hu, Yingmo; Luan, Xinglong; Zhang, Qian; Zhang, Tianhang; Zhang, Yihe

    2015-07-01

    Stable composite films that contain layered double hydroxide (LDH) are appealing materials but are also difficult to prepare. We report here a facile strategy for the fabrication of covalently cross-linked layer-by-layer multilayers that incorporate LDH. The films were first prepared using the traditional LbL method based on non-covalent interactions, followed by infiltration of a photoactive small molecule DAS. UV light was then used to cross-link the multilayers. The stability of the cross-linked film was remarkably enhanced. Furthermore, the release profile of incorporated molecules from layered double hydroxide was significantly delayed.

  13. Ultrafast switching of an electrochromic device based on layered double hydroxide/Prussian blue multilayered films

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoxi; Zhou, Awu; Dou, Yibo; Pan, Ting; Shao, Mingfei; Han, Jingbin; Wei, Min

    2015-10-01

    Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K+ ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH/PB)n-ITO/0.1 M KCl electrolyte/ITO sandwich structure displays superior response properties (0.91/1.21 s for coloration/bleaching), a comparable coloration efficiency (68 cm2 C-1) and satisfactory optical contrast (45% at 700 nm), in comparison with other inorganic material-based ECDs reported previously. Therefore, this work presents a facile and cost-effective strategy to immobilize electrochemically active nanoparticles in a 2D inorganic matrix for potential application in displays, smart windows and optoelectronic devices.Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K+ ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH

  14. Antimycobacterial, antimicrobial, and biocompatibility properties of para-aminosalicylic acid with zinc layered hydroxide and Zn/Al layered double hydroxide nanocomposites

    PubMed Central

    Saifullah, Bullo; El Zowalaty, Mohamed E; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin M; Hussein, Mohd Zobir

    2014-01-01

    The treatment of tuberculosis by chemotherapy is complicated due to multiple drug prescriptions, long treatment duration, and adverse side effects. We report here for the first time an in vitro therapeutic effect of nanocomposites based on para-aminosalicylic acid with zinc layered hydroxide (PAS-ZLH) and zinc-aluminum layered double hydroxides (PAS-Zn/Al LDH), against mycobacteria, Gram-positive bacteria, and Gram-negative bacteria. The nanocomposites demonstrated good antimycobacterial activity and were found to be effective in killing Gram-positive and Gram-negative bacteria. A biocompatibility study revealed good biocompatibility of the PAS-ZLH nanocomposites against normal human MRC-5 lung cells. The para-aminosalicylic acid loading was quantified with high-performance liquid chromatography analysis. In summary, the present preliminary in vitro studies are highly encouraging for further in vivo studies of PAS-ZLH and PAS-Zn/Al LDH nanocomposites to treat tuberculosis. PMID:25114509

  15. In vitro controlled release of vitamin C from Ca/Al layered double hydroxide drug delivery system.

    PubMed

    Gao, Xiaorui; Chen, Le; Xie, Juan; Yin, Yaobing; Chang, Tao; Duan, Yancong; Jiang, Nan

    2014-06-01

    A new drug delivery system for vitamin C (VC), Ca/Al layered double hydroxide (LDH), is demonstrated in this work. VC anions were intercalated successfully in the Ca/Al LDH gallery by a coprecipitation method. The interlayer space of 9.8Å suggests that VC anions are vertical to the LDH layers in the form of interdigitated bilayer. The loading of VC in LDH is 36.4wt.%. The thermal stability of VC is significantly enhanced after intercalation. In vitro VC release results show that the release time of VC in a phosphate buffer at pH7.4 was significantly extended, and the maximal percentage of VC released is 80% of the total. The Avrami-Erofe'ev equation most satisfactorily explains the release kinetics of VC, which is that the release of VC is mainly dominated by the ion-exchange reaction. PMID:24863197

  16. Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites

    NASA Astrophysics Data System (ADS)

    Nedim Ay, Ahmet; Konuk, Deniz; Zümreoglu-Karan, Birgul

    2011-12-01

    A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

  17. Recyclable Mg-Al layered double hydroxides for fluoride removal: Kinetic and equilibrium studies.

    PubMed

    Kameda, Tomohito; Oba, Jumpei; Yoshioka, Toshiaki

    2015-12-30

    Mg-Al layered double hydroxides (LDHs) intercalated with NO3(-) (NO3 · Mg-Al LDH) and Cl(-) (Cl · Mg-Al LDH) were found to adsorb fluoride from aqueous solutions. Fluoride is removed by anion exchange in solution with NO3(-) and Cl(-) intercalated in the LDH interlayer. In both cases, the residual F concentration is lower than the effluent standards for F in Japan (8 mg/L). The rate-determining step in the removal of F using NO3 · Mg-Al and Cl · Mg-Al LDH is chemical adsorption involving F(-) anion exchange with intercalated NO3(-) and Cl(-) ions. The removal of F is described by pseudo-second-order reaction kinetics, with Langmuir-type adsorption. The values obtained for the maximum adsorption and the equilibrium adsorption constant are respectively 3.3 mmol g(-1) and 2.8 with NO3 · Mg-Al LDH, and 3.2 mmol g(-1) and 1.5 with Cl · Mg-Al LDH. The F in the F · Mg-Al LDH produced in these reactions was found to exchange with NO3(-) and Cl(-) ions in solution. The regenerated NO3 · Mg-Al and Cl · Mg-Al LDHs thus obtained can be used once more to capture aqueous F. This suggests that NO3 · Mg-Al and Cl · Mg-Al LDHs can be recycled and used repeatedly for F removal. PMID:26223022

  18. Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

    PubMed

    Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

    2014-10-22

    The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation. PMID:25275963

  19. Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate

    NASA Astrophysics Data System (ADS)

    Woo, Myong A.; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho; Hwang, Seong-Ju

    2011-01-01

    The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO 3- compound and its H 2PO 4--intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO 42- caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO 42- and H 2PO 4-. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

  20. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    NASA Astrophysics Data System (ADS)

    Li, Shuo; Bhushan, Bharat

    2016-08-01

    Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  1. Binder-free Co3O4@NiCoAl-layered double hydroxide core-shell hybrid architectural nanowire arrays with enhanced electrochemical performance

    NASA Astrophysics Data System (ADS)

    Li, Xuan; Yang, Zhengchun; Qi, Wen; Li, Yutao; Wu, Ying; Zhou, Shaoxiong; Huang, Shengming; Wei, Jun; Li, Huijun; Yao, Pei

    2016-02-01

    Herein, binder-free Co3O4@NiCoAl-layered double hydroxide (Co3O4@LDH) core-shell hybrid architectural nanowire arrays were prepared via a two-step hydrothermal synthesis route. LDH nanosheets possessing a large electroactive surface area uniformly dispersed on the surface of Co3O4 nanowires were successfully fabricated allowing for fast electron transport that enhances the electrochemical performance of LDH nanosheets. Co3O4@LDH nanowire arrays of 2 to 1.5 molar ratio (Co3O4:LDH) exhibit high specific capacitance (1104 F g-1 at 1 A g-1), adequate rate capability and cycling stability (87.3% after 5000 cycles), attributed to the synergistic effect between the robust Co3O4 nanowire arrays and LDH nanosheets.

  2. Detection of copper ions from aqueous solutions using layered double hydroxides thin films deposited by PLD

    NASA Astrophysics Data System (ADS)

    Vlad, A.; Birjega, R.; Matei, A.; Luculescu, C.; Nedelcea, A.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2015-10-01

    Layered double hydroxides (LDHs) thin films with Mg-Al were deposited using pulsed laser deposition (PLD) technique. We studied the ability of our films to detect copper ions in aqueous solutions. Copper is known to be a common pollutant in water, originating from urban and industrial waste. Clay minerals, including layered double hydroxides (LDHs), can reduce the toxicity of such wastes by adsorbing copper. We report on the uptake of copper ions from aqueous solution on LDH thin films obtained via PLD. The obtained thin films were characterized using X-ray Diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The results in this study indicate that LDHs thin films obtained by PLD have potential as an efficient adsorbent for removing copper from aqueous solution.

  3. Facile one-step synthesis of nanocomposite based on carbon nanotubes and Nickel-Aluminum layered double hydroxides with high cycling stability for supercapacitors.

    PubMed

    Bai, Caihui; Sun, Shiguo; Xu, Yongqian; Yu, Ruijin; Li, Hongjuan

    2016-10-15

    Nickel-Aluminum Layered Double Hydroxide (NiAl-LDH) and nanocomposite of Carbon Nanotubes (CNTs) and NiAl-LDH (CNTs/NiAl-LDH) were prepared by using a facile one-step homogeneous precipitation approach. The morphology, structure and electrochemical properties of the as-prepared CNTs/NiAl-LDH nanocomposite were then systematically studied. According to the galvanostatic charge-discharge curves, the CNTs/NiAl-LDH nanocomposite exhibited a high specific capacitance of 694Fg(-1) at the 1Ag(-1). Furthermore, the specific capacitance of the CNTs/NiAl-LDH nanocomposite still retained 87% when the current density was increased from 1 to 10Ag(-1). These results indicated that the CNTs/NiAl-LDH nanocomposite displayed a higher specific capacitance and rate capability than pure NiAl-LDH. And the participation of CNTs in the NiAl-LDH composite improved the electrochemical properties. Additionally, the capacitance of the CNTs/NiAl-LDH nanocomposite kept at least 92% after 3000cycles at 20Ag(-1), suggesting that the nanocomposite exhibited excellent cycling durability. This strategy provided a facile and effective approach for the synthesis of nanocomposite based on CNTs and NiAl-LDH with enhanced supercapacitor behaviors, which can be potentially applied in energy storage conversion devices. PMID:27405071

  4. Large-scale simulations of layered double hydroxide nanocomposite materials

    NASA Astrophysics Data System (ADS)

    Thyveetil, Mary-Ann

    Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up

  5. Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

    SciTech Connect

    Wang Lijing; Xu Xiangyu; Evans, David G.; Duan Xue; Li Dianqing

    2010-05-15

    An MgAl-NO{sub 3}-layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filled with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO{sub 3}-LDH in the 7-25 {mu}m range, particularly in the key 9-11 {mu}m range required for application in agricultural plastic films. - Graphical abstract: Intercalation of iminodiacetic acid (IDA) anions in a MgAl-NO{sub 3}-layered double hydroxide host leads to an enhancement of its infrared absorbing ability for application in agricultural plastic films.

  6. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    SciTech Connect

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  7. A photochromic thin film based on salicylideneaniline derivatives intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Wang, Xin Rui; Lu, Jun; Yan, Dongpeng; Wei, Min; Evans, David G.; Duan, Xue

    2010-06-01

    Optically transparent thin films with photochromic properties have been fabricated by means of co-intercalation of azomethine-H anions (AMH) and 1-pentanesulfonate (PS) with different molar ratios into the galleries of a ZnAl layered double hydroxide (LDH). The photochromism of AMH occurred in a 2D confined inorganic matrix has been studied by steady state and transient UV-vis spectroscopy. The AMH anion undergoes an excited-state intramolecular proton transfer from the enol tautomer to trans-keto tautomer after UV excitation, and the relaxed back-isomerization to the ground state of enol tautomer was investigated by transient UV-vis spectroscopy.

  8. Layered double hydroxide nanoparticles promote self-renewal of mouse embryonic stem cells through the PI3K signaling pathway

    NASA Astrophysics Data System (ADS)

    Wu, Youjun; Zhu, Rongrong; Zhou, Yang; Zhang, Jun; Wang, Wenrui; Sun, Xiaoyu; Wu, Xianzheng; Cheng, Liming; Zhang, Jing; Wang, Shilong

    2015-06-01

    Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles have shown promising applications in directing the stem cell fate. Herein, we investigated the cellular effects of layered double hydroxide nanoparticles (LDH NPs) on mouse ESCs (mESCs) and the associated molecular mechanisms. Mg-Al-LDH NPs with an average diameter of ~100 nm were prepared by hydrothermal methods. To determine the influences of LDH NPs on mESCs, cellular cytotoxicity, self-renewal, differentiation potential, and the possible signaling pathways were explored. Evaluation of cell viability, lactate dehydrogenase release, ROS generation and apoptosis demonstrated the low cytotoxicity of LDH NPs. The alkaline phosphatase activity and the expression of pluripotency genes in mESCs were examined, which indicated that exposure to LDH NPs could support self-renewal and inhibit spontaneous differentiation of mESCs under feeder-free culture conditions. The self-renewal promotion was further proved to be independent of the leukemia inhibitory factor (LIF). Furthermore, cells treated with LDH NPs maintained the potential to differentiate into all three germ layers both in vitro and in vivo through formation of embryoid bodies and teratomas. In addition, we observed that LDH NPs initiated the activation of the PI3K/Akt pathway, while treatment with the PI3K inhibitor LY294002 could block the effects of LDH NPs on mESCs. The results confirmed that the promotion of self-renewal by LDH NPs was associated with activation of the PI3K/Akt signaling pathway. Altogether, our studies identified a new role of LDH NPs in maintaining self-renewal of mouse ES cells which could potentially be applied in stem cell research.Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles

  9. Layered double hydroxides toward electrochemical energy storage and conversion: design, synthesis and applications.

    PubMed

    Shao, Mingfei; Zhang, Ruikang; Li, Zhenhua; Wei, Min; Evans, David G; Duan, Xue

    2015-11-14

    Two-dimensional (2D) materials have attracted increasing interest in electrochemical energy storage and conversion. As typical 2D materials, layered double hydroxides (LDHs) display large potential in this area due to the facile tunability of their composition, structure and morphology. Various preparation strategies, including in situ growth, electrodeposition and layer-by-layer (LBL) assembly, have been developed to directly modify electrodes by using LDH materials. Moreover, several composite materials based on LDHs and conductive matrices have also been rationally designed and employed in supercapacitors, batteries and electrocatalysis with largely enhanced performances. This feature article summarizes the latest developments in the design, preparation and evaluation of LDH materials toward electrochemical energy storage and conversion. PMID:26459951

  10. Zn-Co layered double hydroxide modified hematite photoanode for enhanced photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Xu, Dongyu; Rui, Yichuan; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

    2015-12-01

    Zinc-cobalt layered double hydroxide (LDH) was electrodeposited on Ti-doped hematite photoanodes for the first time, and a significant enhanced performance for photoelectrochemical water splitting was demonstrated over the composite photoanodes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS) were characterized with the resulted photoanodes. With the electrodepositing treatment, the photocurrent density increased from 1.27 mA/cm2 for pristine hematite to 1.73 mA/cm2 for modified materials at 1.23 V vs. RHE (i.e. 36% improvement). The photocurrent improvement is mainly attributed to a suppression of electron-hole recombination and reduced overpotential for water oxidation at the hematite-electrolyte interface due to the formation of Zn-Co LDH layer on hematite.

  11. Photostability enhancement of azoic dyes adsorbed and intercalated into Mg-Al-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Liu, Pengfei; Liu, Pei; Zhao, Kongcao; Li, Lei

    2015-11-01

    Two azoic dyes 4-aminoazobenzene-4-sulfonic (AS) and ethyl orange (EO) were adsorbed on or intercalated into Mg-Al-CO3 layered double hydroxide (LDH) for photostability enhancement. Fluorescence analysis results showed that the photostability of two dyes could be greatly improved after being adsorbed on the surface of Mg-Al-CO3-LDH matrix. Furthermore, photostability of adsorbed dyes was superior to that of intercalated dyes. It was suggested that AS or EO was adsorbed on LDHs surface through a strong chemisorption interaction, resulting in the enhancement of photostability. After the UV irradiation under N2 atmosphere, the absorbed dyes not only show great increase of fluorescence intensity but also exhibited high stability against UV irradiation. This work provides a feasible approach to enhance the photostability of azoic dye confined in an inorganic two-dimensional (2D) matrix via changing the microenvironment, which may be considered to be a promising method of improving photostability of solid fluorescent materials.

  12. Wetting behavior and drag reduction of superhydrophobic layered double hydroxides films on aluminum

    NASA Astrophysics Data System (ADS)

    Zhang, Haifeng; Yin, Liang; Liu, Xiaowei; Weng, Rui; Wang, Yang; Wu, Zhiwen

    2016-09-01

    We present a novel method to fabricate Zn-Al LDH (layered double hydroxides) film with 3D flower-like micro-and nanostructure on the aluminum foil. The wettability of the Zn-Al LDH film can be easily changed from superhydrophilic to superhydrophobic with a simple chemical modification. The as-prepared superhydrophobic surfaces have water CAs (contact angles) of 165 ± 2°. In order to estimate the drag reduction property of the surface with different adhesion properties, the experimental setup of the liquid/solid friction drag is proposed. The drag reduction ratio for the as-prepared superhydrophobic sample is 20-30% at low velocity. Bearing this in mind, we construct superhydrophobic surfaces that have numerous technical applications in drag reduction field.

  13. Intercalation of p-methycinnamic acid anion into Zn-Al layered double hydroxide to improve UV aging resistance of asphalt

    NASA Astrophysics Data System (ADS)

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-02-01

    A UV absorber, p-methycinnamic acid (PMCA), was intercalated into Zn-Al layered double hydroxide (LDH) by calcination recovery. Fourier transform infrared spectroscopy showed that the PMCA anions completely replaced the CO32- anions in the interlayer galleries of Zn-Al-LDH containing PMCA anions (Zn-Al-PMCA-LDH). X-ray diffraction and transmission electron microscopy showed that the interlayer distance increased from 0.78 nm to 1.82 nm after the substitution of PMCA anions for CO32- anions. The similar diffraction angles of the CO32- anion-containing Zn-Al-LDH (Zn-Al-CO32--LDH) and the Zn-Al-CO32--LDH/styrene-butadiene-styrene (SBS) modified asphalt implied that the asphalt molecules do not enter into the LDH interlayer galleries to form separated-phase structures. The different diffraction angles of Zn-Al-PMCA-LDH and Zn-Al-PMCA-LDH/SBS modified asphalt indicated that the asphalt molecules penetrated into the LDH interlayer galleries to form an expanded-phase structure. UV-Vis absorbance analyses showed that Zn-Al-PMCA-LDH was better able to block UV light due to the synergistic effects of PMCA and Zn-Al-LDH. Conventional physical tests and atomic force microscopy images of the SBS modified asphalt, Zn-Al-CO32--LDH/SBS modified asphalt and Zn-Al-PMCA-LDH/SBS modified asphalt before and after UV aging indicated that Zn-Al-PMCA-LDH improved the UV aging resistance of SBS modified asphalts.

  14. Intercalation of p-methycinnamic acid anion into Zn-Al layered double hydroxide to improve UV aging resistance of asphalt

    SciTech Connect

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-02-15

    A UV absorber, p-methycinnamic acid (PMCA), was intercalated into Zn-Al layered double hydroxide (LDH) by calcination recovery. Fourier transform infrared spectroscopy showed that the PMCA anions completely replaced the CO{sub 3}{sup 2−} anions in the interlayer galleries of Zn-Al-LDH containing PMCA anions (Zn-Al-PMCA-LDH). X-ray diffraction and transmission electron microscopy showed that the interlayer distance increased from 0.78 nm to 1.82 nm after the substitution of PMCA anions for CO{sub 3}{sup 2−} anions. The similar diffraction angles of the CO{sub 3}{sup 2−} anion-containing Zn-Al-LDH (Zn-Al-CO{sub 3}{sup 2−}-LDH) and the Zn-Al-CO{sub 3}{sup 2−}-LDH/styrene–butadiene–styrene (SBS) modified asphalt implied that the asphalt molecules do not enter into the LDH interlayer galleries to form separated-phase structures. The different diffraction angles of Zn-Al-PMCA-LDH and Zn-Al-PMCA-LDH/SBS modified asphalt indicated that the asphalt molecules penetrated into the LDH interlayer galleries to form an expanded-phase structure. UV-Vis absorbance analyses showed that Zn-Al-PMCA-LDH was better able to block UV light due to the synergistic effects of PMCA and Zn-Al-LDH. Conventional physical tests and atomic force microscopy images of the SBS modified asphalt, Zn-Al-CO{sub 3}{sup 2−}-LDH/SBS modified asphalt and Zn-Al-PMCA-LDH/SBS modified asphalt before and after UV aging indicated that Zn-Al-PMCA-LDH improved the UV aging resistance of SBS modified asphalts.

  15. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives

    PubMed Central

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-01-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application. PMID:26951794

  16. Preparation of Nickel-Aluminum-Containing Layered Double Hydroxide Films by Secondary (Seeded) Growth Method and Their Electrochemical Properties.

    PubMed

    Zhang, Fazhi; Guo, Li; Xu, Sailong; Zhang, Rong

    2015-06-23

    Thin films of nickel-aluminum-containing layered double hydroxide (NiAl-LDH) have been prepared on nickel foil and nickel foam substrates by secondary (seeded) growth of NiAl-LDH seed layer. The preparation procedure consists of deposition of LDH seeds from a colloidal suspension on the substrate by dip coating, followed by hydrothermal treatment of the nanocrystals to form the LDH film. The secondary grown film is found to provide a higher crystallinity and more uniform composition of metal cations in the film layer than the in situ grown film on seed-free substrate under identical hydrothermal conditions. A systematic investigation of the film evolution process reveals that the crystallite growth rate is relatively fast for the secondary grown film because of the presence of LDH nanocrystal seeds. Electrochemical performance of the resulting NiAl-LDH films as positive electrode material was further assessed as an example of their practical applications. The secondary grown film electrode delivers improved recharge-discharge capacity and cycling stability compared with that of the in situ grown film, which can be explained by the existence of a unique microstructure of the former. Our findings show an example for the effective fabrication of LDH film with controllable microstructure and enhanced application performance through a secondary (seeded) growth procedure. PMID:26033419

  17. The in vitro and in vivo anti-tumor effect of layered double hydroxides nanoparticles as delivery for podophyllotoxin.

    PubMed

    Qin, Lili; Xue, Meng; Wang, Wenrui; Zhu, Rongrong; Wang, Shilong; Sun, Jing; Zhang, Rui; Sun, Xiaoyu

    2010-03-30

    In this research, we intercalated anti-tumor drug podophyllotoxin (PPT) into layered double hydroxides (LDHs) and investigated the in vitro cytotoxicity to tumor cells, the cellular uptake and in vivo anti-tumor inhibition of PPT-LDH. The nanohybrids were prepared by a two-step method with the size of 80-90nm and the zeta potential of 20.3mV. The in vitro cytotoxicity experiment indicated that PPT-LDH nanoparticles show better anti-tumor efficacy than PPT and are more readily taken up by Hela cells. PPT-LDH shows a long-term suppression effect on the tumor growth, and enhances the apoptotic process of tumor cells. The in vivo tests reveal that delivery of PPT via LDH nanoparticles is more efficient, but the mice toxicity of PPT in PPT-LDH hybrids is reduced in comparison with PPT alone. Pharmacokinetics study displays a prolonged circulation time and an increased bioavailability of PPT-LDH than PPT. These observations imply that LDH nanoparticles are the potential carrier of anti-tumor drugs in a range of new therapeutic applications. PMID:20045452

  18. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives.

    PubMed

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-01-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application. PMID:26951794

  19. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives

    NASA Astrophysics Data System (ADS)

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-03-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application.

  20. Hierarchical Ni-Co layered double hydroxide nanosheets entrapped on conductive textile fibers: a cost-effective and flexible electrode for high-performance pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Nagaraju, Goli; Raju, G. Seeta Rama; Ko, Yeong Hwan; Yu, Jae Su

    2015-12-01

    Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high specific capacitance of 2105 F g-1 at a current density of 2 A g-1 as well as an excellent cyclic stability as a pseudocapacitive electrode due to the advantageous properties of 3D interconnected porous frameworks of Ni10Co5 LDH NSs/CTs. This facile fabrication of bimetallic hydroxide nanostructures on CTs can provide a promising electrode for low-cost energy storage device applications.Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high

  1. New synthetic route to Mg–Al–CO{sub 3} layered double hydroxide using magnesite

    SciTech Connect

    Wang, Xiaobo; Bai, Zhimin; Zhao, Dong; Chai, Yupu; Guo, Man; Zhang, Jingyu

    2013-03-15

    Highlights: ► The use of magnesite to prepare Mg–Al–CO{sub 3} LDH is novel. ► The result sample is systematically studied. ► Furthermore, the cost of preparing Mg–Al–CO{sub 3} LDH may be reduced through this synthetic route. ► In the synthesis process, there is no CO{sub 2} released. That is significant to environmental protection. - Abstract: A novel synthesis of Mg–Al–CO{sub 3} layered double hydroxide (LDH) through chemical precipitation and hydrothermal methods has been investigated in this paper. The advantages of this method are using magnesite as magnesium source and no CO{sub 2} released in the process of preparation. Mg–Al–CO{sub 3} LDH (ZY) prepared under the optimized condition (the molar ratio of magnesite and Al(NO{sub 3}){sub 3}·9H{sub 2}O was 2.5:1; the aging time and temperature were 16 h and 100 °C, respectively) was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analyser (TG–DTA) and scanning electron microscope (SEM). The crystal morphology of the prepared LDH displays platelet-like structure with a hexagonal shape, which is agreed with the LDH produced by industrial chemicals. Through elemental analysis and inductively coupled plasma-atomic emission spectrometry (ICP-AES), the chemical formula of ZY is determined as Mg{sub 0.70}Al{sub 0.30}(OH){sub 2}(CO{sub 3}){sub 0.15}·0.6H{sub 2}O.

  2. A thermochromic thin film based on host-guest interactions in a layered double hydroxide.

    PubMed

    Wang, Xinrui; Lu, Jun; Shi, Wenying; Li, Feng; Wei, Min; Evans, David G; Duan, Xue

    2010-01-19

    Optically transparent thin films with thermochromic properties have been fabricated by means of cointercalation of different molar ratios of 4-(4-anilinophenylazo)benzenesulfonate (AO5) and sodium dodecylbenzene sulfonate (SDS) into the galleries of a ZnAl layered double hydroxide (LDH). The X-ray diffraction (XRD) patterns of these thin films show that they are assembled in a highly c-oriented manner, and the basal spacing ranges from 2.95 to 2.63 nm with varying AO5/SDS molar ratio. The preferential orientation of AO5 in the galleries of 10% AO5-LDH (AO5/SDS = 10:90, molar percentage) was evaluated by the fluorescence polarization technique; the results show that AO5 anions are accommodated between sheets of ZnAl-LDH as monomeric units with a tilt angle Psi (defined as the angle between the transition dipole moment of the AO5 anion with respect to the normal to the LDH layer) of 74 degrees. It was found that the composite film exhibits marked thermochromic behavior (light yellow <==> reddish-orange) in the temperature range of 35-65 degrees C, which is reversible over a number of heating-cooling cycles. It has been demonstrated that the thermochromic behavior results from tautomerism of interlayer AO5 and furthermore that both the host-guest and guest-guest interactions are key factors, since pristine AO5 shows no thermochromic performance. The 10% AO5-LDH film shows the highest thermochromic efficiency of all the films examined. Furthermore, a reversible contraction and expansion of the LDH basal spacing was also observed for this thin film over the same temperature range. PMID:19761228

  3. Natural curcuminoids encapsulated in layered double hydroxides: a novel antimicrobial nanohybrid.

    PubMed

    Megalathan, Ajona; Kumarage, Sajeewani; Dilhari, Ayomi; Weerasekera, Manjula M; Samarasinghe, Siromi; Kottegoda, Nilwala

    2016-01-01

    Currently, there is an increased scientific interest to discover plant based drug formulations with improved therapeutic potential. Among the cornucopia of traditional medicinal plants, Curcuma longa rhizomes have been used as a powerful antibacterial and antifungal agent. However, its practical applications are limited due to its instability under thermal and UV radiation and its low bioavailability and the extensive procedures needed for isolation. This study focuses on exploring the potential of nanotechnology-based approaches to stabilize the natural curcuminoids, the major active components in turmeric without the need for its isolation, and to evaluate the release characteristics, stability and antimicrobial activity of the resulting nanohybrids. Natural curcuminoids were selectively encapsulated into nanolayers present in Mg-Al-layered double hydroxides (LDHs) using a method that avoids any isolation of the curcuminoids. The products were characterized using solid state techniques, while thermal and photo-stability were studied using thermogravimetric analysis (TGA) and UV exposure data. The morphological features were studied using scanning electron microscope (SEM) and transmission electron microscope (TEM). Drug release characteristics of the nanohybrid were quantitatively monitored under pH 3 and 5, and therapeutic potentials were assessed by using distinctive kinetic models. Finally, the antimicrobial activity of curcuminoids-LDH was tested against three bacterial and two fungal species. Powder X-ray diffraction, Fourier transform infra-red spectroscopy, SEM and TEM data confirmed the successful and selective encapsulation of curcuminoids in the LDH, while the TGA and UV exposure data suggested the stabilization of curcuminoids within the LDH matrix. The LDH demonstrated a slow and a sustained release of the curcuminoids in an acidic medium, while it was active against the three bacteria and two fungal species used in this study, suggesting its

  4. Layered Double Hydroxide Nanotransporter for Molecule Delivery to Intact Plant Cells.

    PubMed

    Bao, Wenlong; Wang, Junya; Wang, Qiang; O'Hare, Dermot; Wan, Yinglang

    2016-01-01

    Here we report a powerful method that facilitates the transport of biologically active materials across the cell wall barrier in plant cells. Positively charged delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) with a 0.5‒2 nm thickness and 30‒60 nm diameter exhibit a high adsorptive capacity for negatively charged biomolecules, including fluorescent dyes such as tetramethyl rhodamine isothiocyanate (TRITC), fluorescein isothiocyanate isomer I(FITC) and DNA molecules, forming neutral LDH-nanosheet conjugates. These neutral conjugates can shuttle the bound fluorescent dye into the cytosol of intact plant cell very efficiently. Furthermore, typical inhibitors of endocytosis and low temperature incubation did not prevent LDH-lactate-NS internalization, suggesting that LDH-lactate-NS penetrated the plasma membrane via non-endocytic pathways, which will widen the applicability to a variety of plant cells. Moreover, the absence of unwanted side effects in our cytological studies, and the nuclear localization of ssDNA-FITC suggest that nano-LDHs have potential application as a novel gene carrier to plants. PMID:27221055

  5. Layered Double Hydroxide Nanotransporter for Molecule Delivery to Intact Plant Cells

    PubMed Central

    Bao, Wenlong; Wang, Junya; Wang, Qiang; O’Hare, Dermot; Wan, Yinglang

    2016-01-01

    Here we report a powerful method that facilitates the transport of biologically active materials across the cell wall barrier in plant cells. Positively charged delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) with a 0.5‒2 nm thickness and 30‒60 nm diameter exhibit a high adsorptive capacity for negatively charged biomolecules, including fluorescent dyes such as tetramethyl rhodamine isothiocyanate (TRITC), fluorescein isothiocyanate isomer I(FITC) and DNA molecules, forming neutral LDH-nanosheet conjugates. These neutral conjugates can shuttle the bound fluorescent dye into the cytosol of intact plant cell very efficiently. Furthermore, typical inhibitors of endocytosis and low temperature incubation did not prevent LDH-lactate-NS internalization, suggesting that LDH-lactate-NS penetrated the plasma membrane via non-endocytic pathways, which will widen the applicability to a variety of plant cells. Moreover, the absence of unwanted side effects in our cytological studies, and the nuclear localization of ssDNA-FITC suggest that nano-LDHs have potential application as a novel gene carrier to plants. PMID:27221055

  6. Fe-Al layered double hydroxides in bromate reduction: Synthesis and reactivity.

    PubMed

    Chitrakar, Ramesh; Makita, Yoji; Sonoda, Akinari; Hirotsu, Takahiro

    2011-02-15

    This study presents a rare use of layered double hydroxides of Fe(II) and Al(III) (Fe-Al LDH), as reported for the first time for bromate removal from aqueous solutions. The Fe-Al LDH samples were prepared with Fe/Al molar ratios of 1-4 using a co-precipitation method at pH 7, with subsequent hydrothermal treatment at 120°C. The Fe-Al LDH (molar ratio of Fe/Al=1, 2) with a layered structure exhibited nearly complete removal of bromate from initial concentration of 100μmol/dm(3) at a wide pH range of 4.0-10.5 over a 2h reaction period; the residual bromate concentration in the solution was lower than the detection limit of 0.07μmol/dm(3) (9μg-BrO(3)(-)/dm(3)). During the reaction period, bromide was released into the solution via a reduction process. Reactivity of Fe-Al LDH with a Fe/Al molar ratio of 2 did not decrease the bromate reduction efficiency during 30days. PMID:21126742

  7. Novel biohybrids of layered double hydroxide and lactate dehydrogenase enzyme: Synthesis, characterization and catalytic activity studies

    NASA Astrophysics Data System (ADS)

    Djebbi, Mohamed Amine; Braiek, Mohamed; Hidouri, Slah; Namour, Philippe; Jaffrezic-Renault, Nicole; Ben Haj Amara, Abdesslem

    2016-02-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biomolecule such as enzyme to produce bioinorganic system. Lactate dehydrogenase (Lac Deh) has been chosen as a model enzyme, being immobilized onto MgAl and ZnAl LDH materials via direct ion-exchange (adsorption) and co-precipitation methods. The immobilization efficiency was largely dependent upon the immobilization methods. A comparative study shows that the co-precipitation method favors the immobilization of great and tunable amount of enzyme. The structural behavior, chemical bonding composition and morphology of the resulting biohybrids were determined by X-ray diffraction (XRD) study, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM), respectively. The free and immobilized enzyme activity and kinetic parameters were also reported using UV-Visible spectroscopy. However, the modified LDH materials showed a decrease in crystallinity as compared to the unmodified LDH. The change in activity of the immobilized lactate dehydrogenase was considered to be due, to the reduced accessibility of substrate molecules to the active sites of the enzyme and the partial conformational change of the Lac Deh molecules as a result of the immobilization way. Finally, it was proven that there is a correlation between structure/microstructure and enzyme activity dependent on the immobilization process.

  8. Fire and thermal properties of layered double hydroxides and polyurea nanocomposites

    NASA Astrophysics Data System (ADS)

    Nyambo, Calistor

    Layered double hydroxide (LDH) intercalated with linear alkyl carboxylates (CH3(CH2)n COO-, n = 8, 10, 12, 14, 16, 20), borate and benzyl anions were prepared. The effect on fire and thermal properties of the mode of preparation for LDHs (i.e. ion exchange, coprecipitation and rehydration of the calcined LDH methods) has been studied. After characterization, the LDHs were used to prepare nanocomposites with a range of polar and non-polar polymers. Characterization of the LDHs and the nanocomposites was performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry analysis (TGA), transmission electron microscopy (TEM) and cone calorimetry. FTIR and XRD analyses confirmed the presence of the charge balancing anions in the galleries of the LDHs. Improvements in fire and thermal properties of the nanocomposites were observed. The cone calorimeter revealed that the addition of LDHs reduces the peak heat release rate significantly. LDHs were combined with commercial fire retardants. Synergistic effects were observed in both TGA and cone calorimetry for formulations containing both LDH and ammonium polyphosphate (APP). Physical and chemical interactions between LDH and APP are responsible for the observed synergy in thermal stability and fire performance.

  9. Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hyun; Oh, Jae-Min

    2016-01-01

    Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, a few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV-vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca1.30Al(OH)4.6FA0.74·3.33H2O and Ca1.53Fe(OH)5.06FA2.24·9.94H2O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca.

  10. Thermal, solution and reductive decomposition of Cu-Al layered double hydroxides into oxide products

    SciTech Connect

    Britto, Sylvia; Vishnu Kamath, P.

    2009-05-15

    Cu-Al layered double hydroxides (LDHs) with [Cu]/[Al] ratio 2 adopt a structure with monoclinic symmetry while that with the ratio 0.25 adopt a structure with orthorhombic symmetry. The poor thermodynamic stability of the Cu-Al LDHs is due in part to the low enthalpies of formation of Cu(OH){sub 2} and CuCO{sub 3} and in part to the higher solubility of the LDH. Consequently, the Cu-Al LDH can be decomposed thermally (150 deg. C), hydrothermally (150 deg. C) and reductively (ascorbic acid, ambient temperature) to yield a variety of oxide products. Thermal decomposition at low (400 deg. C) temperature yields an X-ray amorphous residue, which reconstructs back to the LDH on soaking in water or standing in the ambient. Solution decomposition under hydrothermal conditions yields tenorite at 150 deg. C itself. Reductive decomposition yields a composite of Cu{sub 2}O and Al(OH){sub 3}, which on alkali-leaching of the latter, leads to the formation of fine particles of Cu{sub 2}O (<1 {mu}m). - Graphical abstract: SEM image of (a) the Cu{sub 2}O-Al(OH){sub 3} composite obtained on reductive decomposition of CuAl{sub 4}-LDH and (b) Cu{sub 2}O obtained on leaching of Al(OH){sub 3} from (a).

  11. Two steps in situ structure fabrication of Ni-Al layered double hydroxide on Ni foam and its electrochemical performance for supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Liu, Qi; Qian, Zhongyu; Zhang, Xiaofei; Wang, Jun; Li, Zhanshuang; Yan, Huijun; Gao, Zan; Zhao, Fangbo; Liu, Lianhe

    2014-01-01

    In this paper, two steps in situ growth method has been used to solve the accumulation of layered double hydroxide (LDH) in oriented growth. Moreover, the petal-like Ni-Al LDH displays excellent pseudocapacitance performance: a specific capacitance of 795 F g-1, a long cycle life with 80% performance remains after 1000 cycles and good charge/discharge stability, owing to the improvement of pseudocapacitive reaction by the large sheet structure of Ni-Al LDH on Ni foam. And the comparison results of different electrode preparation process and different growth process reflect the great advantages of our synthesis method.

  12. Mechano-hydrothermal synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxides

    SciTech Connect

    Zhang, Fengrong; Du, Na; Song, Shue; Liu, Jianqiang; Hou, Wanguo

    2013-10-15

    A mechano-hydrothermal method was developed to synthesize Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) from MgO, Al{sub 2}O{sub 3} and NaNO{sub 3} as starting materials. A two-step synthesis was conducted, that is, a mixture of MgO and Al{sub 2}O{sub 3} was milled for 1 h, followed by hydrothermal treatment with NaNO{sub 3} solution. The resulting LDHs were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared and elemental analyses. Pre-milling played a key role in the LDH formation during subsequent hydrothermal treatment. The process is advantageous in terms of low reaction temperature and short reaction time compared with the conventional hydrothermal method, and the target products are of high crystallinity, good dispersion and regular shape compared with the conventional mechanochemical method. - Graphical abstract: The novel mechano-hydrothermal route to synthesize LDH has advantages in low reaction temperature and short reaction time, and the target product was of high crystallinity, good dispersion and regular shape. Display Omitted - Highlights: • A mechano-hydrothermal route was developed for layered double hydroxide synthesis. • Synthesis could be achieved at low temperature and in a short time. • Resulting layered double hydroxide samples were well dispersed and of regular shape. • A dissolution–recrystallization mechanism was proposed for the formation process.

  13. Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate

    SciTech Connect

    Woo, Myong A.; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho; Hwang, Seong-Ju

    2011-01-15

    The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO{sub 3}{sup -} compound and its H{sub 2}PO{sub 4}{sup -}-intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO{sub 4}{sup 2-} caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil. -- Graphical abstract: We synthesized phosphate-intercalated Ca-Fe-LDH materials that can act as bifunctional inorganic vectors for the slow release of phosphate fertilizer and also the neutralization of acid soil. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. Display Omitted Research Highlights: {yields} The phosphate forms of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) were synthesized via co-precipitation method. The crystal structure, bonding character, and release kinetics of phosphate of the phosphate-intercalates were investigated. These Ca-Fe-LDH materials are applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

  14. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

    PubMed Central

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  15. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation.

    PubMed

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type-III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  16. Synthesis and release behavior of composites of camptothecin and layered double hydroxide

    SciTech Connect

    Dong Lun; Yan Li; Hou Wanguo; Liu Shaojie

    2010-08-15

    A simple method, reconstruction of calcinated layered double hydroxides (CLDH) in an organic (ethanol)-water mixed solvent medium containing drug, was developed to intercalate partially a non-ionic and poorly water-soluble drug (camptothecin) into the gallery of layered double hydroxides (LDHs) to form the drug-LDH composites. The purpose of choosing organic-water mixed solvent is to increase remarkably the solubility of camptothecin (CPT) in the reconstruction medium. A probable morphology of CPT molecules in the gallery of LDHs is that CPT molecules arrange as monolayer with the long axis parallel to the LDH layers. The in vitro drug release from the composites was remarkably lower than that from the corresponding physical mixture, which shows these drug-inorganic composites can be used as a potential drug delivery system. - Graphical abstract: A simple method, reconstruction of calcinated LDHs in an organic-water medium containing drug, was developed to intercalate non-ionic and poorly water-soluble camptothecin into the gallery of LDHs.

  17. Facile synthesis of novel two-dimensional silver-coated layered double hydroxide nanosheets as advanced anode material for Ni-Zn secondary batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Yang, Zhanhong; Wang, Ruijuan

    2014-04-01

    Silver-coated layered double hydroxide (Ag-coated LDH) nanosheets are successfully prepared by a facile silver mirror reaction and their electrochemical performance has been evaluated as anode materials for Ni-Zn secondary batteries. The microstructure and morphology of as-prepared Ag-coated Zn/Al-LDH are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). As anode material for Ni-Zn secondary batteries, Ag-coated Zn/Al-LDH exhibits high specific capacity (400 mAh g-1), good charge-discharge properties and excellent cycling performance, which is attributed to the effect of the electron conductivity improvement by the Ag coating on the surface of Zn/Al-LDH nanosheet. This newly designed Ag-coated Zn/Al-LDH may offer a promising anode candidate for high-performance Ni-Zn secondary batteries.

  18. Intercalation of biomolecules into NiAl-NO 3 layered double hydroxide films synthesized in situ on anodic alumina/aluminium support

    NASA Astrophysics Data System (ADS)

    Zhao, Hua-Zhang; Chang, Ying-Yue; Yang, Jing; Yang, Qin-Zheng

    2013-03-01

    Layered double hydroxide (LDH) films were synthesized in situ on anodic alumina/aluminium (AAO/Al). Glucose oxidase (GOD) and L-ascorbic acid (vitamin C, VC) were intercalated respectively into the in-situ grown LDH films by anion-exchange in aqueous solutions. Dodecylsulfate (SDS) was used to expand the lamellar structure before GOD intercalation into the LDH film. The resulting products were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). The results showed that VC and GOD were successfully intercalated into the in-situ synthesized LDH film. These biomolecules loaded LDH films could have potential applications in electrode modification, safe storage and effective delivery of bioactive compounds.

  19. Chemisorption Mechanism of DNA on Mg/Fe Layered Double Hydroxide Nanoparticles: Insights into Engineering Effective SiRNA Delivery Systems.

    PubMed

    Lu, Mingsheng; Shan, Zhi; Andrea, Kori; MacDonald, Bruce; Beale, Stefanie; Curry, Dennis E; Wang, Li; Wang, Shujun; Oakes, Ken D; Bennett, Craig; Wu, Wenhui; Zhang, Xu

    2016-03-22

    Layered double hydroxide nanoparticles (LDH NPs) have attracted interest as an effective gene delivery vehicle in biomedicine. Recent advances in clinic trials have demonstrated the efficacy of Mg/Fe LDHs for hyperphosphatemia treatment, but their feasibility for gene delivery has not been systematically evaluated. As a starting point, we aimed to study the interaction between oligo-DNA and Mg/Fe LDH NPs. Our investigation revealed the chemisorption mechanism of DNA on Mg/Fe LDH surfaces, wherein the phosphate backbone of the DNA polymer coordinates with the metal cations of the LDH lattice via the ligand-exchange process. This mechanistic insight may facilitate future gene delivery applications using Mg/Fe LDH NPs. PMID:26919981

  20. Improvement of pharmacokinetic and antitumor activity of layered double hydroxide nanoparticles by coating with PEGylated phospholipid membrane

    PubMed Central

    Yan, Mina; Zhang, Zhaoguo; Cui, Shengmiao; Lei, Ming; Zeng, Ke; Liao, Yunhui; Chu, Weijing; Deng, Yihui; Zhao, Chunshun

    2014-01-01

    Layered double hydroxide (LDH) has attracted considerable attention as a drug carrier. However, because of its poor in vivo behavior, polyethylene glycolylated (PEGylated) phospholipid must be used as a coformer to produce self-assembled core–shell nanoparticles. In the present study, we prepared a PEGylated phospholipid-coated LDH (PLDH) (PEG-PLDH) delivery system. The PEG-PLDH nanoparticles had an average size of 133.2 nm. Their core–shell structure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. In vitro liposome-cell-association and cytotoxicity experiments demonstrated its ability to be internalized by cells. In vivo studies showed that PEGylated phospholipid membranes greatly reduced the blood clearance rate of LDH nanoparticles. PEG-PLDH nanoparticles demonstrated a good control of tumor growth and increased the survival rate of mice. These results suggest that PEG-PLDH nanoparticles can be a useful drug delivery system for cancer therapy. PMID:25364245

  1. Gold Nanoparticles Supported on a Layered Double Hydroxide as Efficient Catalysts for the One-Pot Synthesis of Flavones.

    PubMed

    Yatabe, Takafumi; Jin, Xiongjie; Yamaguchi, Kazuya; Mizuno, Noritaka

    2015-11-01

    Flavones are a class of natural products with diverse biological activities and have frequently been synthesized by step-by-step procedures using stoichiometric amounts of reagents. Herein, a catalytic one-pot procedure for the synthesis of flavone and its derivatives is developed. In the presence of gold nanoparticles supported on a Mg-Al layered double hydroxide (Au/LDH), various kinds of flavones can be synthesized starting from 2'-hydroxyacetophenones and benzaldehydes (or benzyl alcohols). The present one-pot procedure consists of a sequence of several reactions, and Au/LDH can catalyze all these different types of reactions. The catalysis is shown to be truly heterogeneous, and Au/LDH can be readily recovered and reused. PMID:26367015

  2. Phosphorus-containing flame retardant modified layered double hydroxides and their applications on polylactide film with good transparency.

    PubMed

    Ding, Peng; Kang, Bai; Zhang, Jin; Yang, Jingwen; Song, Na; Tang, Shengfu; Shi, Liyi

    2015-02-15

    Polylactide (PLA)/layered double hydroxide (LDH) films with good flame retardant property and transparency were synthesized by solution exfoliation and film casting method. The organic-inorganic interfacial interaction between PLA and NiAl-LDH was carefully modified by 2-carboxylethyl-phenyl-phosphinic acid (CEPPA) to well solve the dispersion problem of NiAl-LDH nanolayers and get enhanced flame retardancy of PLA composites. The results showed the NiAl-LDH/CEPPA (LC) nanolayers had exfoliated structures and were homogenously dispersed in PLA matrixes. All the PLA/LDH films had good transparency even LC content was up to 10 wt%. The PLA/LDH films absorbed the ultraviolet light, which alleviates the embrittlement of PLA films in the using procedure. The flame retardant effect characterized by microscale combustion calorimeter was observed when LC contents increased. The total heat release value of the sample with 10 wt% LC decreased to 9.7 kJ/g from 12.0 kJ/g of virgin PLA. PMID:25460688

  3. Study of the structure and luminescent properties of terbium complex intercalated Zn/Al layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Xie, Juan; Yin, Yaobing; Hao, Yongjing; Lian, Yiwei

    2016-01-01

    Terbium complex of ethylenediaminetetraacetate ([Tb(EDTA)]-) intercalated Zn/Al layered double hydroxide (LDH), as an inorganic-organic green-emitting phosphor, was synthesized through an ion exchange method. X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) spectra exhibit a successful intercalation of [Tb(EDTA)]- anions between the hydroxide sheets of the LDH. The basal spacing of 14.5 Å indicate a vertical arrangement of [Tb(EDTA)]- anions with the maximal dimension in the gallery is adopted. The luminescent properties of this material were studied by excitation and emission spectra. The results show that the strongest emission peak of Tb3+ ion occurs at 544 nm. This material may supply a candidate of green light emitting phosphor.

  4. Effect of reaction time and (Ca+Mg)/Al molar ratios on crystallinity of Ca-Mg-Al layered double Hydroxide

    NASA Astrophysics Data System (ADS)

    Heraldy, E.; Nugrahaningtyas, K. D.; Sanjaya, F. B.; Darojat, A. A.; Handayani, D. S.; Hidayat, Y.

    2016-02-01

    Ca-Mg-Al Layered Double Hydroxides (Ca-Mg-Al-LDH) compounds were successfully synthesized from brine water and AlCl3.6H2O as the starting materials by coprecipitation method. The product result was characterized by X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR). The effects of the reaction time and the molar ratios of the raw material on the crystallinity of Ca-Mg-Al-LDH were examining. Results show that increasing reaction time (30; 60 and 90 min.) could improve the crystallinity and monodispersity of layered double hydroxide compounds particles. The well-defined Ca-Mg- Al-LDH could be prepared with (Ca+Mg)/Al molar ratios 0.5.

  5. Facile synthesis of methotrexate intercalated layered double hydroxides: particle control, structure and bioassay explore.

    PubMed

    Tian, De-Ying; Liu, Zhen-Lei; Li, Shu-Ping; Li, Xiao-Dong

    2014-12-01

    To study the influence of particle size on drug efficacy and other properties, a series of methotrexate intercalated layered double hydroxides (MTX/LDHs) were synthesized through the traditional coprecipitation method, using a mixture of water and polyethylene glycol (PEG-400) as the solvent. To adjust the particle size of MTX/LDHs, the dropping way, the volume ratio of water to PEG-400 and different hydrothermal treatment time changed accordingly, and the results indicate that the particle size can be controlled between 90 and 140 nm. Elemental C/H/N and inductive coupled plasma (ICP) analysis indicated that different synthesis conditions almost have no effect on the compositions of the nanohybrids. X-ray diffraction (XRD) patterns manifested the successful intercalation of MTX anions into the LDH interlayers, and it's also found out that different volume ratios of water to PEG-400 and variable dropping way can affect the crystallinity of the final samples, i.e., the volume ratio of 3:1 and pH decreasing are proved to be optimum conditions. Furthermore, both antiparallel monolayer and bilayers adopting different orientations are suggested for four samples from XRD results. Fourier transform infrared spectroscopy (FTIR) investigations proved the coexistence of CO3(2-) and MTX anions in the interlayer of the nanohybrids. MTX/LDH particles exhibited hexagonal platelet morphology with round corner and different dropping ways can affect the morphology greatly. Moreover, a DSC study indicated that longer time treatment can weaken the bond between the MTX anions and LDH layers. The kinetic release profiles told us that larger MTX/LDH particles have enhanced the ability of LDH layers to protect interlayer molecules. At last, the bioassay study indicated that the nanohybrids with larger diameters have higher tumor suppression efficiency. PMID:25491832

  6. Enhanced sequestration of Cr(VI) by nanoscale zero-valent iron supported on layered double hydroxide by batch and XAFS study.

    PubMed

    Sheng, Guodong; Hu, Jun; Li, Hui; Li, Jiaxing; Huang, Yuying

    2016-04-01

    Herein, the reduction of nanoscale zero-valent iron (NZVI) and adsorption of layered double hydroxides (LDH) to sequester Cr(VI) were well combined by the immobilization of NZVI onto LDH surface (NZVI/LDH). The characterization results revealed that LDH decreased NZVI aggregation and thus increased Cr(VI) sequestration. The batch results indicated that Cr(VI) sequestration by NZVI/LDH was higher than that of NZVI, and superior to the sum of reduction and adsorption. The LDH with good anion exchange property allowed the adsorption of Cr(VI), facilitating interfacial reaction by increasing the local concentration of Cr(VI) in the NZVI vicinity. X-ray absorption near edge structure (XANES) results indicated that Cr(VI) was almost completely reduced to Cr(III) by NZVI/LDH, but Cr(VI) was partly reduced to Cr(III) by NZVI with a trace of Cr(VI) adsorbed on corrosion products. The coordination environment of Cr from extended X-ray absorption fine structure (EXAFS) analysis revealed that LDH could be a good scavenger for the insoluble products produced during reaction. So, the insoluble products on NZVI could be reduced, and its reactivity could be maintained. These results demonstrated that NZVI/LDH exhibits multiple functionalities relevant to the remediation of Cr(VI)-contaminated sites. PMID:26807943

  7. Hybridization Between Natural Extract of Angelica gigas Nakai and Inorganic Nanomaterial of Layered Double Hydroxide via Reconstruction Reaction.

    PubMed

    Kim, Tae-Hyun; Kim, Hyoung-Jun; Choi, Ae-Jin; Choi, Hyun-Jin; Oh, Jae-Min

    2016-01-01

    We have hybridized layered double hydroxide (LDH) with Angelica gigas Nakai root extract (AGNR) through reversible dehydration-rehydration reaction which is known as reconstruction. LDHs having well-ordered hydrotalcite-like crystal structure and average size 250 ± 20 nm were prepared by hydrothermal method. The root of Angelica gigas Nakai, which has been utilized in the treatment of female disorders as herbal medicine, was treated with methanol to obtain extract. Pristine LDHs were calcined at 400 °C for 8 hours to obtain layered double oxide (LDO), which was further dispersed into extract solution with various AGNR/LDO weight ratios, 0.11, 0.21 and 0.43. The extract content in each hybrid increased in proportion to initial AGNR/LDO ratio, showing the highest content of ~12%. The zeta potential of LDH shifted from +44 mV to +20 mV upon hybridization with extract, which was attributed to the adsorption of negatively charged organic moieties in AGNR on LDH surface. The scanning electron microscopic (SEM) results exhibited that the random stacking of LDH nanolayers resulted in LDH-AGNR hybrid with house-of-cards structure, of which inter-particle cavity serves nano-reservoir for natural extract. According to quantitative analyses, it was revealed that the content of active components in AGNR increased when they were hybridized with LDHs compared with those in AGNR alone. PMID:27398576

  8. Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS)

    SciTech Connect

    Y. Wang; H. Gao

    2006-03-16

    Layered double hydroxides (LDHs) have shown great promise as anion getters. In this paper, we demonstrate that the sorption capability of a LDH for a specific oxyanion can be greatly increased by appropriately manipulating material composition and structure. A large set of LDH materials have been synthesized with various combinations of metal cations, interlayer anions, and the molar ratios of divalent cation M(II) to trivalent cation M(III). The synthesized materials have then been tested systematically for their sorption capabilities for pertechnetate (TcO{sub 4}{sup -}). It is discovered that for a given interlayer anion (either CO{sub 3}{sup 2-} or NO{sub 3}{sup -}) the Ni-Al LDH with a Ni/Al ratio of 3:1 exhibits the highest sorption capability among all the materials tested. The distribution coefficient (K{sub d}) is determined to be as high as 307 mL/g for Ni{sub 6}Al{sub 2}(0H){sub 16}CO{sub 3}nH{sub 2}O and 1390 mL/g for Ni{sub 6}Al{sub 2}(OH){sub 16}NO{sub 3}nH{sub 2}O at a pH of 8. The sorption of TcO{sub 4}{sup -} on M(II)-M(III)-CO{sub 3} LDHs is dominated by the edge sites of LDH layers and strongly correlated with the basal spacing d{sub 003} of the materials, which increases with the decreasing radii of both divalent and trivalent cations. The sorption reaches its maximum when the layer spacing is just large enough for a pertechnetate anion to fit into a cage space between two neighboring octahedra of metal hydroxides at the edge. Furthermore, the sorption is found to increase with the crystallinity of the materials. For a given combination of metal cations and an interlayer anion, a best crystalline LDH material is obtained generally with a M(II)/M(III) ratio of 3:1. Replacement of interlayer carbonate with readily exchangeable nitrate greatly increases the sorption capability of a LDH material for pertechnetate, due to the enhanced adsorption on edge sites and the possible contribution from interlayer anion exchanges. The work reported here will

  9. Synthesis, characterization, and controlled release anticorrosion behavior of benzoate intercalated Zn-Al layered double hydroxides

    SciTech Connect

    Wang, Yi; Zhang, Dun

    2011-11-15

    Graphical abstract: The benzoate anion released from Zn-Al LDHs provides a more effective long-term protection against corrosion of Q235 carbon steel in 3.5% NaCl solution. Highlights: {yields} A benzoate anion corrosion inhibitor intercalated Zn-Al layered double hydroxides (LDHs) has been assembled by coprecipitation method. {yields} The kinetic simulation indicates that the ion-exchange one is responsible for the release process and the diffusion through particle is the rate limiting step. {yields} A significant reduction of the corrosion rate is observed when the LDH nanohybrid is present in the corrosive media. -- Abstract: Corrosion inhibitor-inorganic clay composite including benzoate anion intercalated Zn-Al layered double hydroxides (LDHs) are assembled by coprecipitation. Powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectrum analyses indicate that the benzoate anion is successfully intercalated into the LDH interlayer and the benzene planes are vertically bilayer-positioned as a quasi-guest ion-pair form in the gallery space. Kinetic simulation for the release data, XRD and FT-IR analyses of samples recovered from the release medium indicate that ion-exchange is responsible for the release process and diffusion through the particle is also indicated to be the rate-limiting step. The anticorrosion capabilities of LDHs loaded with corrosion inhibitor toward Q235 carbon steel are analyzed by polarization curve and electrochemical impedance spectroscopy methods. Significant reduction of corrosion rate is observed when the LDH nanohybrid is present in the corrosive medium. This hybrid material may potentially be applied as a nanocontainer in self-healing coatings.

  10. Hierarchical Ni-Co layered double hydroxide nanosheets entrapped on conductive textile fibers: a cost-effective and flexible electrode for high-performance pseudocapacitors.

    PubMed

    Nagaraju, Goli; Raju, G Seeta Rama; Ko, Yeong Hwan; Yu, Jae Su

    2016-01-14

    Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high specific capacitance of 2105 F g(-1) at a current density of 2 A g(-1) as well as an excellent cyclic stability as a pseudocapacitive electrode due to the advantageous properties of 3D interconnected porous frameworks of Ni10Co5 LDH NSs/CTs. This facile fabrication of bimetallic hydroxide nanostructures on CTs can provide a promising electrode for low-cost energy storage device applications. PMID:26450829

  11. Interlayer intercalation and arrangement of 2-mercaptobenzothiazolate and 1,2,3-benzotriazolate anions in layered double hydroxides: In situ X-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Serdechnova, Maria; Salak, Andrei N.; Barbosa, Filipe S.; Vieira, Daniel E. L.; Tedim, João; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2016-01-01

    2-mercaptobenzothiazole (MBT) and 1,2,3-benzotriazole (BTA) are very promising inhibitors for the corrosion protection of aluminum alloys. These inhibitors can be incorporated in protective coatings in the form of anions intercalated into interlayers of layered double hydroxides (LDHs). Capacity and performance of such LDH-nanocontainers depend on the arrangement of the anions in their interlayers. In this work, intercalation of MBT- and BTA- into Mg-Al-NO3 and Zn-Al-NO3 LDHs were studied in detail using X-ray diffraction (XRD) methods including in situ XRD. The nitrate-to-MBT(BTA) anion exchange is much faster than considered previously. Well-formed Mg-Al-MBT, Zn-Al-MBT, Mg-Al-BTA LDHs were obtained after a 20-min exchange reaction at pH 11.5 at room temperature. It was demonstrated that Zn-Al-BTA LDH cannot be obtained under the same conditions due to the reaction between BTA and the Zn-Al hydroxide layers. Substitution of nitrates by organic anions occurs with the participation of hydroxide anions. Although no intermediate LDH phase intercalated with the combination of NO3 - and OH- appears, formation of the LDH-MBT and LDH-BTA phases results also in appearance of an LDH phase intercalated with OH- at the final stage of the anion exchange. In the LDH interlayer, MBT- and BTA- form a double layer in which these species have a tilted orientation against the layer plane (herringbone-like arrangement). Such an arrangement meets the LDH layer-interlayer electroneutrality and matches well with the observed values of the layer-interlayer distance.

  12. Thermal decomposition behavior of Cu–Al layered double hydroxide, and ethylenediaminetetraacetate-intercalated Cu–Al layered double hydroxide reconstructed from Cu–Al oxide for uptake of Y{sup 3+} from aqueous solution

    SciTech Connect

    Kameda, Tomohito; Hoshi, Kazuaki; Yoshioka, Toshiaki

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. ► The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. ► The edta·Cu–Al LDH could selectively take up rare earth ions from a mixed solution. -- Abstract: CO{sub 3}{sup 2−}-intercalated Cu–Al layered double hydroxide (CO{sub 3}·Cu–Al LDH) was calcined to yield Cu–Al oxide, and then ethylenediaminetetraacetate-intercalated Cu–Al LDH (edta·Cu–Al LDH) was prepared by reconstructing Cu–Al oxide in edta solution. Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. The production of Cu–Al oxide was caused by the thermal decomposition of CO{sub 3}·Cu–Al LDH until the third stage. The first stage was the elimination of adsorbed surface water and interlayer water in CO{sub 3}·Cu–Al LDH. The second and third stages were the dehydroxylation of the brucite-like octahedral layers and the elimination of CO{sub 3}{sup 2−} intercalated in the interlayers. The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. The uptake of Y{sup 3+} was caused not only by the chelating function of Hedta{sup 3−} in the interlayer but also by the chemical behavior of Cu–Al LDH itself. The edta·Cu–Al LDH was found to selectively take up rare earth ions from a mixed solution. The degree of uptake was high, in the order Sc{sup 3+} > Y{sup 3+} > La{sup 3+} for all time durations, which was attributable to differences among the stabilities of Sc(edta){sup −}, Y(edta){sup −} and La(edta){sup −}.

  13. Bone cement/layered double hydroxide nanocomposites as potential biomaterials for joint implant.

    PubMed

    Kapusetti, Govinda; Misra, Nira; Singh, Vakil; Kushwaha, R K; Maiti, Pralay

    2012-12-01

    Poly(methyl methacrylate)-based bone cement and layered double hydroxide (LDH) nanocomposites have been used as a grouting material for total joint arthroplasty. Few weight percentage of nanoLDH was uniformly dispersed in the bone cement matrix to have adequate interaction with matrix polymer. Mechanical strength, stiffness, toughness, and fatigue resistance of the nanocomposites are found to be higher than that of pure bone cement. Nanocomposites are thermally stable as compared to pristine bone cement. Direct mixing of the nanoLDH without any organic solvent makes these nanocomposites biocompatible. Biocompatibility was evaluated and compared with that of commercial bone cement by measuring hydrophilic nature, hemolysis assay, thrombosis assay, and deposition of apatite in simulated body fluid immersion. Finally, the viability of human osteoblast cells on the above developed nanocomposites was testified for actual biocompatibility. The experiment showed better cell growth in nanocomposites as compared to pure bone cement. Thus, these nanocomposites are found to be better grouting material than bone cement. PMID:22733710

  14. Dependence of bonding interactions in Layered Double Hydroxides on metal cation chemistry

    NASA Astrophysics Data System (ADS)

    Shamim, Mostofa; Dana, Kausik

    2016-12-01

    The evolution of various Infrared bands of Layered Double Hydroxides (LDH) with variable Zn:Al ratio was analyzed to correlate it with the changes in octahedral metal cation chemistry, interlayer carbonate anion and hydroxyl content of LDH. The synthesized phase-pure LDHs were crystallized as hexagonal 2H polytype with a Manasseite structure. The broad and asymmetric hydroxyl stretching region (2400-4000 cm-1) can be deconvoluted into four different bands. With increase in Zn2+:Al3+ metal ratio, the peak position of stretching frequencies of Al3+sbnd OH and carbonate-bridged hydroxyl (water) decrease almost linearly. Individual band's peak position and area under the curve have been successfully correlated with the carbonate and hydroxyl content of LDH. Due to lowering of symmetry of the carbonate anion, the IR-inactive peak νCsbnd O, symm at 1064 cm-1 becomes IR active. The peak position of metal-oxygen bands and carbonate bending modes are practically unaffected by the Zn2+:Al3+ ratio but the area under the individual M-O bands shows a direct correlation.

  15. Methotrexatum intercalated layered double hydroxides: statistical design, mechanism explore and bioassay study.

    PubMed

    Wang, Xiao-Feng; Liu, Su-Qing; Li, Shu-Ping

    2015-04-01

    A series of methotrexatum intercalated layered double hydroxide (MTX/LDH for short) hybrids have been synthesized by a mechanochemical-hydrothermal method, the statistical experiments are planned and conducted to find out the critical factor influencing the physicochemical properties. Four variables, i.e., addition of NaOH solution, grinding duration, hydrothermal temperature and time, are chosen to play as the examined factors in the orthogonal design. Furthermore, three respective levels, i.e., high, medium and low levels, are conducted in the design. The resulting hybrids are then characterized by X-ray diffraction (XRD) patterns, transmission electron microscope (TEM) graphs and Zeta potentials. XRD diffractions indicate that MTX anions have been successfully intercalated into LDH interlayers and the amount of NaOH solution can change the gallery height greatly. The information from TEM graphs and Zeta potentials state that the increase of alkali solution gives rise to regular morphology and the increase of Zeta potentials. As a result of the statistical analysis, addition of alkali solution is the major factor affecting the morphology and drug-loading capacity. At last, the mechanism of particle growth is explored emphatically, and the anticancer efficacy of some MTX/LDH hybrids is estimated by MTT assay on A549 cells as well. PMID:25686957

  16. Layered double hydroxides as supports for intercalation and sustained release of antihypertensive drugs

    NASA Astrophysics Data System (ADS)

    Xia, Sheng-Jie; Ni, Zhe-Ming; Xu, Qian; Hu, Bao-Xiang; Hu, Jun

    2008-10-01

    Zn/Al layered double hydroxides (LDHs) were intercalated with the anionic antihypertensive drugs Enalpril, Lisinopril, Captopril and Ramipril by using coprecipitation or ion-exchange technique. TG-MS analyses suggested that the thermal stability of Ena -, Lis - (arranged with monolayer, resulted from X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) analysis was enhanced much more than Cap - and Ram - (arranged with bilayer). The release studies show that the release rate of all samples markedly decreased in both pH 4.25 and 7.45. However, the release time of Ena -, Lis - were much longer compared with Cap -, Ram - in both pH 4.25 and 7.45, it is possible that the intercalated guests, arranged with monolayer in the interlayer, show lesser repulsive force and strong affinity with the LDH layers. And the release data followed both the Higuchi-square-root law and the first-order equation well. Based on the analysis of batch release, intercalated structural models as well as the TG-DTA results, we conclude that for drug-LDH, stronger the affinity between intercalated anions and the layers is, better the thermal property and the stability to the acid attack of drug-LDH, and the intercalated anions are easier apt to monolayer arrangement within the interlayer, were presented.

  17. Nickel-cobalt layered double hydroxide nanosheets as high-performance electrocatalyst for oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Jiang, Jing; Zhang, Ailing; Li, Lili; Ai, Lunhong

    2015-03-01

    Developing the first-row transition-metal-based oxygen evolution reaction (OER) catalysts with highly efficient electrocatalytic activity to replace precious catalysts, such as RuO2 and IrO2 have recently attracted considerable attention because of their earth abundant nature, low cost, environmentally friendly, multiple valence state and high theoretical activity. In this work, an advanced integrated electrode for high-performance electrochemical water oxidation has been designed and fabricated by directly growing binary nickel-cobalt layered double hydroxide (NiCo-LDH) nanosheet arrays on nickel foam. Such economical, earth abundant NiCo-LDH nanosheets show excellent OER activity in alkaline medium with an onset overpotential as low as 290 mV, large anodic current density and excellent durability, which makes them comparable to the most active RuO2 catalyst and better than the Pt/C catalyst. The outstanding OER activity of the NiCo-LDH nanosheets can be attributed to their intrinsic layered structure, interconnected nanoarray configuration and unique redox characteristics.

  18. Photocatalytic property and structural stability of CuAl-based layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Lv, Ming; Liu, Haiqiang

    2015-07-01

    Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV-Vis diffuse reflectance spectrum (UV-vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO2 reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M2+ on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials.

  19. Optimized immobilization of transketolase from E. coli in MgAl-layered double hydroxides.

    PubMed

    Touisni, Nadia; Charmantray, Franck; Helaine, Virgil; Forano, Claude; Hecquet, Laurence; Mousty, Christine

    2013-12-01

    Immobilization of TK from Escherichia coli (TKec) on MgAl-NO3 layered double hydroxides (LDH) was carried out by two processes: adsorption and coprecipitation. As a comparison, the adsorption method was realized either at pH 7.5 in buffered solutions (MOPS and Gly-Gly) or in pure water. For the coprecipitation method, the formation of the inorganic LDH support was realized directly in the presence of TKec solubilized in Gly-Gly. The prepared biohybrids, called respectively TKec@LDHads and TKec@LDHcop, were characterized by powder X-ray diffraction, FTIR spectroscopy in comparison with TKec free reference products, i.e. MgAl-NO3, MgAl-Gly-Gly. The enzymatic activities of the various TKec@LDH biohybrids as well as their stabilities over time were investigated by UV-vis assay. A maximum of activity (12 U/mg of solid) was reached for TKec@MgAl-Gly-Gly biohybrid prepared by coprecipitation. Finally, thin films were prepared through a one-step deposition on a polished support. The enzymatic activity of the resulting TKec@MgAl-Gly-Glycop film was tested over four recycling processes with a reproducible activity of 2.7 U/mg cm(2). PMID:24055860

  20. Optimization of UV absorptivity of layered double hydroxide by intercalating organic UV-absorbent molecules.

    PubMed

    Mohsin, Sumaiyah Megat Nabil; Hussein, Mohd Zobir; Sarijo, Siti Halimah; Fakurazi, Sharida; Arulselvan, Palanisamy; Taufiq-Yap, Yun Hin

    2014-08-01

    Intercalation of Zn/Al layered double hydroxide (LDH) with benzophenone 9 (B9), a strong ultraviolet (UV) absorber, had been carried out by two different routes; co-precipitation and ion exchange method. Powder X-ray diffraction (PXRD) patterns of co-precipitated (ZB9C) and ion exchanged product (ZB91) showed basal spacing of 15.9 angstrom and 16.6 angstrom, respectively, as a result of the intercalation of B9 anions into the lamellae spaces of LDH. Intercalation was further confirmed by Fourier transform infrared spectra (FTIR), carbon, hydrogen, nitrogen and sulfur (CHNS) and thermogravimetric and differential thermogravimetric (TGA/DTG) studies. UV-vis absorption properties of the nanocomposite was investigated with diffuse reflectance UV-visible spectrometer and showed broader UV absorption range. Furthermore, stability of sunscreen molecules in LDH interlayer space was tested in deionized water, artificial sea water and skin pH condition to show slow deintercalation and high retention in host. Cytotoxicity study of the synthesized nanocomposites on human dermal fibroblast (HDF) cells shows no significant cytotoxicity after 24 h exposure for test concentrations up to 25 microg/mL. PMID:25016649

  1. Evidences for decarbonation and exfoliation of layered double hydroxide in N,N-dimethylformamide-ethanol solvent mixture

    SciTech Connect

    Gordijo, Claudia R.; Leopoldo Constantino, Vera R.; Oliveira Silva, Denise de

    2007-07-15

    The behavior of a Hydrotalcite-like material (carbonate-containing Mg,Al-layered double hydroxide) in N,N-dimethylformamide (DMF)-ethanol mixture, at ambient temperature, has been investigated. The releasing of CO{sub 2} and production of a formate-containing material occurred mainly for 1:1 (v/v) solvent mixture. Decarbonation of Hydrotalcite is promoted by DMF hydrolysis followed by neutralization of brucite-like layers through HCOO{sup -} intercalation. Translucent colloidal dispersion of LDH nanoparticles from the formate-containing phase was characterized by transmission electron (TEM) and atomic force (AFM) microscopies. The absence of (00l) reflection at X-ray diffraction (XRD) pattern for dried colloidal dispersion indicated delamination of Hydrotalcite. The restacked sample exhibited broad reflections and typical hydroxide ordered layers non-basal (110) diffraction peaks. A LDH-HCOO{sup -} material was also prepared and characterized by FTIR and FT-Raman spectroscopies. Decarbonation and exfoliation of Hydrotalcite in N,N-dimethylformamide-ethanol mixed solvent provide an interesting method for preparation of new intercalated LDH materials. - Graphical abstract: Hydrotalcite suspended in 1:1 (v/v) N,N-dimethylformamide-ethanol solvent mixture, at ambient temperature, undergoes decarbonation and exfoliation. The process is promoted by DMF hydrolysis. Restacking of LDH layers is achieved by evaporating the solvent.

  2. Magnesium-containing layered double hydroxides as orthopaedic implant coating materials--An in vitro and in vivo study.

    PubMed

    Weizbauer, Andreas; Kieke, Marc; Rahim, Muhammad Imran; Angrisani, Gian Luigi; Willbold, Elmar; Diekmann, Julia; Flörkemeier, Thilo; Windhagen, Henning; Müller, Peter Paul; Behrens, Peter; Budde, Stefan

    2016-04-01

    The total hip arthroplasty is one of the most common artificial joint replacement procedures. Several different surface coatings have been shown to improve implant fixation by facilitating bone ingrowth and consequently enhancing the longevity of uncemented orthopaedic hip prostheses. In the present study, two different layered double hydroxides (LDHs), Mg-Fe- and Mg-Al-LDH, were investigated as potential magnesium (Mg)-containing coating materials for orthopaedic applications in comparison to Mg hydroxide (Mg(OH)2). In vitro direct cell compatibility tests were carried out using the murine fibroblast cell line NIH 3T3 and the mouse osteosarcoma cell line MG 63. The host response of bone tissue was evaluated in in vivo experiments with nine rabbits. Two cylindrical pellets (3 × 3 mm) were implanted into each femoral condyle of the left hind leg. The samples were analyzed histologically and with μ-computed tomography (μ-CT) 6 weeks after surgery. An in vitro cytotoxicity test determined that more cells grew on the LDH pellets than on the Mg(OH)2-pellets. The pH value and the Mg(2+) content of the cell culture media were increased after incubation of the cells on the degradable samples. The in vivo tests demonstrated the formation of fibrous capsules around Mg(OH)2 and Mg-Fe-LDH. In contrast, the host response of the Mg-Al-LDH samples indicated that this Mg-containing biomaterial is a potential candidate for implant coating. PMID:25939995

  3. Synthesis and characterization of metal (Core) - layered double hydroxide (Shell) nanostructures

    NASA Astrophysics Data System (ADS)

    Noh, Woo C.

    Layered double hydroxides (LDH) which belong to a class of inorganic ceramic layered materials have been studied since the mid-19th century for a variety of applications including catalysis, anion exchange, adsorbents and antacid, but more recently as a potential drug and gene delivery platform. Drug delivery platforms based on nano-sized geometries are nanovectors which promise a revolutionary impact on the therapy and imaging of various types of cancers and diseases. To date, various polymeric platforms have been the focus of intense research, but the development of inorganic, bio-hybrid nanoparticles for therapeutics and molecular imaging are at a stage of infancy. The hybridization of LDH with bioactive agents or the fabrication of metal (Core)---LDH (Shell) nanostructures could have many beneficial effects including multimodality, active targetability, and efficacy. For example, Core---Shell nanostructures may be designed to have a high scattering optical cross-section for imaging, but may also be tailored to strongly absorb near infrared (NIR) light for hyperthermic ablation. The central theme of this thesis was to demonstrate proof-of-concept of spherical silver and gold metal (Core)---LDH (Shell) nanostructures that have uniform size distribution and are agglomeration free. The effects of processing parameters on the characteristics of LDH as well as LDH-coated spherical metal (Ag, Au) nanoparticles have been evaluated using X-ray Diffraction, Dynamic Light Scattering, Scanning Electron Microscopy, Transmission Electron Microscopy, Rutherford Backscattering Spectrometry, and Inductively Coupled Plasma Emission Spectrometry to arrive at appropriate process windows. The core---shell nanostructures were also characterized for their optical properties in the ultra---violet---visible region, and the data were compared with simulated data, computed by using a quasi static model from Mie scattering theory. Moreover, in order to achieve a strong plasmon resonance

  4. 13C nuclear magnetic resonance analysis of glucose and citrate end products in an ldhL-ldhD double-knockout strain of Lactobacillus plantarum.

    PubMed Central

    Ferain, T; Schanck, A N; Delcour, J

    1996-01-01

    We have examined the metabolic consequences of knocking out the two ldh genes in Lactobacillus plantarum using 13C nuclear magnetic resonance. Unlike its wild-type isogenic progenitor, which produced lactate as the major metabolite under all conditions tested, ldh null strain TF103 mainly produced acetoin. A variety of secondary end products were also found, including organic acids (acetate, succinate, pyruvate, and lactate), ethanol, 2,3-butanediol, and mannitol. PMID:8955418

  5. 3D-architectured nickel-cobalt-manganese layered double hydroxide/reduced graphene oxide composite for high-performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Li, M.; Cheng, J. P.; Liu, F.; Zhang, X. B.

    2015-11-01

    Pure flower-like NiCoMn layered double hydroxide (LDH) and 3D-architectured NiCoMn LDH/reduced graphene oxide (rGO) composite are fabricated by a solution method. The NiCoMn hydroxide nanoflakes are tightly deposited on the surface of rGO. Electrochemical measurements prove that rGO can greatly improve its capacitive performances, compared with the pure counterpart. A high-specific capacitance of 912 F g-1, high-rate capability and long cycle life are achieved for the composite. A NiCoMn LDH/rGO//activated carbon hybrid capacitor is also fabricated. It possesses a high-specific capacitance of 206 F g-1 and an energy density of 92.8 W h kg-1 in 1.8 V.

  6. Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Wang, Lijing; Xu, Xiangyu; Evans, David G.; Duan, Xue; Li, Dianqing

    2010-05-01

    An MgAl-NO 3-layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filled with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO 3-LDH in the 7-25 μm range, particularly in the key 9-11 μm range required for application in agricultural plastic films.

  7. Electrochemical sensor for bisphenol A based on ionic liquid functionalized Zn-Al layered double hydroxide modified electrode.

    PubMed

    Zhan, Tianrong; Song, Yang; Li, Xianjun; Hou, Wanguo

    2016-07-01

    The plate-like Zn-Al layered double hydroxide modified with 1-aminopropyl-3-methylimidzaolium tetrafluoroborate (named as ILs-LDH) was synthesized by coprecipitation method. Several techniques confirmed the layered structure of ILs-LDH with a disk-like morphology. A novel electrochemical sensor based on ILs-LDH modified glass carbon electrode (GCE) was developed for bisphenol A (BPA) determination. Experimental factors including modified content, pH, scan rate, accumulation time and potential had been carefully optimized. ILs-LDH/GCE performed the excellent electro-oxidation ability toward BPA with the more negative oxidation overpotential and larger peak current than bare GCE or LDH/GCE. Differential pulse voltammetry determination of BPA afforded a wider linear range from 0.02 to 3μM with the detection limit of 4.6nM (S/N=3). The fabricated sensor demonstrated an acceptable reproducibility, good stability and high sensitivity. The proposed method was successfully used to detect BPA in real water samples with satisfactory recovery ranging from 94.9% to 102.0%. PMID:27127064

  8. Layered double hydroxides as effective carrier for anticancer drugs and tailoring of release rate through interlayer anions.

    PubMed

    Senapati, Sudipta; Thakur, Ravi; Verma, Shiv Prakash; Duggal, Shivali; Mishra, Durga Prasad; Das, Parimal; Shripathi, T; Kumar, Mohan; Rana, Dipak; Maiti, Pralay

    2016-02-28

    Hydrophobic anticancer drug, raloxifene hydrochloride (RH) is intercalated into a series of magnesium aluminum layered double hydroxides (LDHs) with various charge density anions through ion exchange technique for controlled drug delivery. The particle nature of the LDH in presence of drug is determined through electron microscopy and surface morphology. The release of drug from the RH intercalated LDHs was made very fast or sustained by altering the exchangeable anions followed by the modified Freundlich and parabolic diffusion models. The drug release rate is explained from the interactions between the drug and LDHs along with order-disorder structure of drug intercalated LDHs. Nitrate bound LDH exhibits greater interaction with drug and sustained drug delivery against the loosely interacted phosphate bound LDH-drug, which shows fast release. Cell viability through MTT assay suggests drug intercalated LDHs as better drug delivery vehicle for cancer cell line against poor bioavailability of the pure drug. In vivo study with mice indicates the differential tumor healing which becomes fast for greater drug release system but the body weight index clearly hints at damaged organ in the case of fast release system. Histopathological experiment confirms the damaged liver of the mice treated either with pure drug or phosphate bound LDH-drug, fast release system, vis-à-vis normal liver cell morphology for sluggish drug release system with steady healing rate of tumor. These observations clearly demonstrate that nitrate bound LDH nanoparticle is a potential drug delivery vehicle for anticancer drugs without any side effect. PMID:26774219

  9. In vitro antioxidant activity and in vivo antifatigue effect of layered double hydroxide nanoparticles as delivery vehicles for folic acid

    PubMed Central

    Qin, Lili; Wang, Wenrui; You, Songhui; Dong, Jingmei; Zhou, Yunhe; Wang, Jibing

    2014-01-01

    Folic acid antioxidants were successfully intercalated into layered double hydroxides (LDH) nanoparticles according to a previous method with minor modification. The resultant folic acid-LDH constructs were then characterized by X-ray powder diffraction and transmission electron microscopy. The in vitro antioxidant activities, cytotoxicity effect, and in vivo antifatigue were examined by a series of assays. The results showed that folic acid-LDH antioxidant system can scavenge 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radicals and chelate pro-oxidative Cu2+. The in vitro cytotoxicity assays indicated that folic acid-LDH antioxidant system had no significant cytotoxic effect or obvious toxicity to normal cells. It also prolonged the forced swimming time of the mice by 32% and 51% compared to folic acid and control groups, respectively. It had an obvious effect on decreasing the blood urea nitrogen and blood lactic acid, while increasing muscle and hepatic glycogen levels. Therefore, folic acid-LDH might be used as a novel antioxidant and antifatigue nutritional supplement. PMID:25506219

  10. Mg-Al and Zn-Fe layered double hydroxides used for organic species storage and controlled release.

    PubMed

    Seftel, E M; Cool, P; Lutic, D

    2013-12-01

    Layered double hydroxides (LDH) containing (Mg and Al) or (Zn and Fe) were prepared by coprecipitation at constant pH, using NaOH and urea as precipitation agents. The most pure LDH phase in the Zn/Fe system was obtained with urea and in Mg/Al system when using NaOH. The incorporation of phenyl-alanine (Phe) anions in the interlayer of the LDH was performed by direct coprecipitation, ionic exchange and structure reconstruction of the mixed oxide obtained by the calcination of the coprecipitated product at 400°C. The reconstruction method and the direct coprecipitation in a medium containing Phe in the initial mixture were less successful in terms of high yields of organic-mineral composite than the ionic exchange method. A spectacular change in sample morphology and yield in exchanged solid was noticed for the Zn3Fe sample obtained by ionic exchange for 6h with Phe solution. A delivery test in PBS of pH=7.4 showed the release of the Phe in several steps up to 25 h indicating different host-guest interactions between the Phe and the LDH matrix. This behavior makes the preparation useful to obtain late delivery drugs, by the incorporation of the anion inside the LDH layer. PMID:24094226

  11. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  12. Nanometric dispersion of a Mg/Al layered double hydroxide into a chemically modified polycaprolactone.

    PubMed

    Mangiacapra, Pasqualina; Raimondo, Marialuigia; Tammaro, Loredana; Vittoria, Vittoria; Malinconico, Mario; Laurienzo, Paola

    2007-03-01

    Polycaprolactone (PCL) was chemically modified by grafting maleic anhydride on it, through a radical reaction induced by benzoyl peroxide as initiator. To improve the grafting degree, a second unsaturated comonomer such as glycidyl methacrylate (GMA) has been added, demonstrating a good reactivity in melt grafting without leading to long grafted chains. The quantitative determination of grafted maleic anhydride, performed by FTIR analysis, revealed a grafting weight percentage of 9.5 +/- 0.9, and the NMR characterization made it possible to propose a structure for the grafted polymer (PCLgMA). The modified polymer was analyzed by DSC and X-ray diffraction, showing a structural organization even better than that of the pristine polymer. An exchange reaction with a layered double hydroxide (LDH), hydrotalcite-like solid in the nitrate form, led to the disappearance of the crystalline basal peak of LDH in the X-ray diffractograms, suggesting a possible exfoliation of the inorganic sample. An oxidative etching on the composite surface followed by atomic force microscopy analysis made it possible to enlighten the lamellar structure in the pristine sample. In the composite sample, the well identifiable narrow fissures homogeneously distributed on the surface demonstrate that nanometer stacks of LDH sheets, embedded in a highly textured PCLgMA matrix, are present in the composite sample. The comparison of X-ray diffractograms and AFM analysis suggests either a partial exfoliation or an intercalation of the polymer in a lamellar texture with a basal spacing higher than 5 nm. In any case, the process of ionic exchange between nitrate LDH and PCLgMA led to the formation of nanocomposites, in which no large hydrotalcite aggregates are present. This is an interesting method to obtain a direct intercalation of the modified polymer into the inorganic solid with a simple ionic exchange reaction. PMID:17319719

  13. Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

    DOE PAGESBeta

    Abellán, Gonzalo; Jordá, Jose Luis; Atienzar, Pedro; Varela, María; Jaafar, Miriam; Gómez-Herrero, Julio; Zamora, Félix; Ribera, Antonio; García, Hermenegildo; Coronado, Eugenio

    2014-12-04

    In this study, a hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl–LDH ferromagnetic layers intercalated with thermoresponsive 4-(4 anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In situ variable temperature XRD of these thin hybrids shows thatmore » the reversible change into the two tautomers is reflected in a shift of the position of the diffraction peaks at high temperatures towards lower interlayer spacing for the hydrazone form, as well as a broadening of the peaks reflecting lower crystallinity and ordering due to non-uniform spacing between the layers. These structural variations between room temperature (basal spacing (BS) = 25.91 Å) and 100 °C (BS = 25.05 Å) are also reflected in the magnetic properties of the layered double hydroxide (LDH) due to the variation of the magnetic coupling between the layers. Finally and in conclusion, our study constitutes one of the few examples showing fully reversible thermo-responsive breathing in a 2D hybrid material. In addition, the magnetic response of the hybrid can be modulated due to the thermotropism of the organic component that, by influencing the distance and in-plane correlation of the inorganic LDH, modulates the magnetism of the CoAl–LDH sheets in a certain range.« less

  14. Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

    SciTech Connect

    Abellán, Gonzalo; Jordá, Jose Luis; Atienzar, Pedro; Varela, María; Jaafar, Miriam; Gómez-Herrero, Julio; Zamora, Félix; Ribera, Antonio; García, Hermenegildo; Coronado, Eugenio

    2014-12-04

    In this study, a hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl–LDH ferromagnetic layers intercalated with thermoresponsive 4-(4 anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In situ variable temperature XRD of these thin hybrids shows that the reversible change into the two tautomers is reflected in a shift of the position of the diffraction peaks at high temperatures towards lower interlayer spacing for the hydrazone form, as well as a broadening of the peaks reflecting lower crystallinity and ordering due to non-uniform spacing between the layers. These structural variations between room temperature (basal spacing (BS) = 25.91 Å) and 100 °C (BS = 25.05 Å) are also reflected in the magnetic properties of the layered double hydroxide (LDH) due to the variation of the magnetic coupling between the layers. Finally and in conclusion, our study constitutes one of the few examples showing fully reversible thermo-responsive breathing in a 2D hybrid material. In addition, the magnetic response of the hybrid can be modulated due to the thermotropism of the organic component that, by influencing the distance and in-plane correlation of the inorganic LDH, modulates the magnetism of the CoAl–LDH sheets in a certain range.

  15. Synthesis and Characterization of Chitosan-Coated Near-Infrared (NIR) Layered Double Hydroxide-Indocyanine Green Nanocomposites for Potential Applications in Photodynamic Therapy.

    PubMed

    Wei, Pei-Ru; Kuthati, Yaswanth; Kankala, Ranjith Kumar; Lee, Chia-Hung

    2015-01-01

    We designed a study for photodynamic therapy (PDT) using chitosan coated Mg-Al layered double hydroxide (LDH) nanoparticles as the delivery system. A Food and Drug Administration (FDA) approved near-infrared (NIR) fluorescent dye, indocyanine green (ICG) with photoactive properties was intercalated into amine modified LDH interlayers by ion-exchange. The efficient positively charged polymer (chitosan (CS)) coating was achieved by the cross linkage using surface amine groups modified on the LDH nanoparticle surface with glutaraldehyde as a spacer. The unique hybridization of organic-inorganic nanocomposites rendered more effective and successful photodynamic therapy due to the photosensitizer stabilization in the interlayer of LDH, which prevents the leaching and metabolization of the photosensitizer in the physiological conditions. The results indicated that the polymer coating and the number of polymer coats have a significant impact on the photo-toxicity of the nano-composites. The double layer chitosan coated LDH-NH₂-ICG nanoparticles exhibited enhanced photo therapeutic effect compared with uncoated LDH-NH₂-ICG and single layer chitosan-coated LDH-NH₂-ICG due to the enhanced protection to photosensitizers against photo and thermal degradations. This new class of organic-inorganic hybrid nanocomposites can potentially serve as a platform for future non-invasive cancer diagnosis and therapy. PMID:26340627

  16. Utilization of Active Ni to Fabricate Pt-Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation.

    PubMed

    Ren, Fumin; Wang, Zheng; Luo, Liangfeng; Lu, Haiyuan; Zhou, Gang; Huang, Weixin; Hong, Xun; Wu, Yuen; Li, Yadong

    2015-09-14

    Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel-aluminum layered double hydroxide (NiAl-LDH) onto a Pt-Ni alloy surface. The incorporation of chemical etching of Pt-Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni-rich Pt-Ni octahedra transform by interior erosion into Pt3 Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt3 Ni, the resulting Pt-Ni nanoframe/NiAl-LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural. PMID:26241390

  17. Reduced graphene oxide/Ni(1-x)Co(x)Al-layered double hydroxide composites: preparation and high supercapacitor performance.

    PubMed

    Xu, Jie; Gai, Shili; He, Fei; Niu, Na; Gao, Peng; Chen, Yujin; Yang, Piaoping

    2014-08-14

    Reduced graphene oxide (rGO) sheet and ternary-component Ni(1-x)Co(x)Al-layered double hydroxide (Ni(1-x)Co(x)Al-LDH) hybrid composites with an interesting sandwich structure have been fabricated by an in situ growth route. The as-obtained composite displays a sandwich architecture constructed by the self-assembly of sheet-like LDH crystals on both sides of the rGO sheets. It was found that the Co content doped in Ni(1-x)Co(x)Al-LDH plays an important role in the shape and structure of the final products. When the Co doped content is 17%, the rGO/Ni(0.83)Co(0.17)Al-LDH has a high surface area (171.5 m(2) g(-1)) and exhibits a perfect sandwich structure. In addition, this structure and morphology is favorable for a supercapacitor electrode material with a high performance. The influence of cobalt content on the electrochemical behavior of rGO/Ni(1-x)Co(x)Al-LDH has been systematically studied. The results indicate that the rGO/Ni(0.83)Co(0.17)Al-LDH composite exhibits the highest electrochemical performance, with a specific capacitance of 1902 F g(-1) at 1 A g(-1), and an excellent cycling stability. The markedly improved electrochemical performance is superior to undoped rGO/NiAl-LDH and can be attributed to the enhanced conductivity achieved through cobalt doping. Such composites could be used as a type of potential energy storage/conversion material for supercapacitors. PMID:24950435

  18. Intercalation of methotrexatum into layered double hydroxides via exfoliation-reassembly process

    NASA Astrophysics Data System (ADS)

    Liu, Su-Qing; Li, Shu-Ping; Li, Xiao-Dong

    2015-03-01

    In this paper, the intercalation of methotrexatum (MTX) into layered double hydroxides (LDHs) via an exfoliation-reassembly process was reported and the resulting hybrids were then characterized by X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) patterns etc. In the synthesis procedure, LDHs particles were firstly delaminated into well-dispersed 2D nanosheets in formamide by ultrasonic treatment at room temperature, and then the resulting LDH nanosheets were reassembled in MTX solution to form MTX intercalated LDH (MTX/LDHs) hybrids. AFM images showed that during the exfoliation process a large part of LDHs particles were delaminated into single and double brucite layers. XRD patterns and FTIR investigations manifested the successful intercalation of MTX anions into LDHs interlayers for the final samples. It was also found out that the drug-loading capacity of the hybrids increased with the concentrations of MTX solutions, while the morphology became even aggregated. At last, the cell cytotoxicity of the hybrids was estimated by MTT assays on the human lung cancer cells (A549), and the results stated that MTX/LDHs hybrids had effective suppress role on the proliferation of cancer cells.

  19. Novel inorganic host layered double hydroxides intercalated with guest organic inhibitors for anticorrosion applications.

    PubMed

    Poznyak, S K; Tedim, J; Rodrigues, L M; Salak, A N; Zheludkevich, M L; Dick, L F P; Ferreira, M G S

    2009-10-01

    Zn-Al and Mg-Al layered double hydroxides (LDHs) loaded with quinaldate and 2-mercaptobenzothiazolate anions were synthesized via anion-exchange reaction. The resulting compounds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy. Spectrophotometric measurements demonstrated that the release of organic anions from these LDHs into the bulk solution is triggered by the presence of chloride anions, evidencing the anion-exchange nature of this process. The anticorrosion capabilities of LDHs loaded with organic inhibitors toward the AA2024 aluminum alloy were analyzed by electrochemical impedance spectroscopy. A significant reduction of the corrosion rate is observed when the LDH nanopigments are present in the corrosive media. The mechanism by which the inhibiting anions can be released from the LDHs underlines the versatility of these environmentally friendly structures and their potential application as nanocontainers in self-healing coatings. PMID:20355873

  20. Structure and photoluminescence of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides

    SciTech Connect

    Chen Yufeng; Li Fei; Zhou Songhua; Wei Junchao; Dai Yanfeng; Chen Yiwang

    2010-09-15

    A series of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides (LDHs), with Eu/Al atomic ratios of {approx}0.06 and Mg/(Al+Eu) atomic ratios ranging from 1.3 to 4.0, were synthesized by a coprecipitation method. The Mg-Al-Eu ternary LDHs were investigated by various techniques. X-ray diffraction (XRD) results indicated that the crystallinity of the ternary LDHs was gradually improved with the increase of Mg{sup 2+}/(Al{sup 3+}+Eu{sup 3+}) molar ratio from 1.3/1 to 4/1, and all the samples were a single phase corresponding to LDH. The photoluminescent (PL) spectra of the ternary Mg-Al-Eu LDHs were described by the well-known {sup 5}D{sub 0}-{sup 7}F{sub J} transition (J=1, 2, 3, 4) of Eu{sup 3+} ions with the strongest emission for J=2, suggesting that the host LDH was favorable to the emissions of Eu{sup 3+} ions. The asymmetry parameter (R) relevant to {sup 5}D{sub 0}-{sup 7}F{sub J} transition (J=1, 2) dependant of the atomic ratios of Mg{sup 2+}/(Al{sup 3+}+Eu{sup 3+}) was discussed, and was consistent with the result of XRD. - Graphical abstract: A series of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides (LDHs), with Mg/(Al+Eu) atomic ratios ranging from 1.3/1, 2/1 3/1 to 4/1, were synthesized by a coprecipitation method. The photoluminescent spectra of the Mg-Al-Eu ternary LDHs are described by the well-known {sup 5}D{sub 0}-{sup 7}F{sub J} transition (J=1, 2, 3, 4) of Eu{sup 3+} ions with the strongest emission for J=2.

  1. Synthesis of Cd/(Al+Fe) layered double hydroxides and characterization of the calcination products

    SciTech Connect

    Perez, M.R.; Barriga, C.; Fernandez, J.M.; Rives, V.; Ulibarri, M.A.

    2007-12-15

    Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method at a constant pH value of 8. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange at pH 9. The samples have been characterized by elemental chemical analysis, powder X-ray diffraction (PXRD), and FT-IR spectroscopy. Their thermal stability has been assessed by thermogravimetric and differential thermal analyses (TG-DTA) and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 deg. C show diffraction lines corresponding to Cd(Al)O and spinel-type materials, which precise nature (CdAl{sub 2}O{sub 4}, Cd{sub 1-x}Fe{sub 2+x}O{sub 4}, or Cd{sub x}Fe{sub 2.66}O{sub 4}) depends on location and concentration of iron in the parent material or precursor. - Graphical abstract: Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange. Calcination at 800 deg. C shows diffraction lines corresponding to CdO and to spinel-type materials. SEM micrograph of sample CdAlFe-N-0.

  2. Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

    SciTech Connect

    Tao, Qi; He, Hongping; Li, Tian; Frost, Ray L.; Zhang, Dan; He, Zisen

    2014-05-01

    Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and {sup 29}Si MAS nuclear magnetic resonance spectra ({sup 29}Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and {sup 29}Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (S{sub BET}) and total pore volumes (V{sub p}) of the products. - Graphical abstract: The replacement of water by ethanol in the tactoids and aggregations of LDHs, and the polysiloxane oligomers formed during silylation process can dramatically increase the BET surface area (S{sub BET}) and the total pore volume (V{sub p}) of the silylated products. - Highlights: • Silanes with multifunctional groups were grafted onto LDH surface in C{sub 2}H{sub 5}OH medium. • The number of hydrolysable groups in silanes affects the structure of grafted LDH. • Replacement of H{sub 2}O by C{sub 2}H{sub 5}OH in aggregations increases S{sub BET} and V{sub p} of grafted LDH. • Polysiloxane oligomers contribute to the increase of S{sub BET} and V{sub p} of grafted LDH.

  3. In situ oligomerization of 2-(thiophen-3-yl)acetate intercalated into Zn{sub 2}Al layered double hydroxide

    SciTech Connect

    Tronto, Jairo; Pinto, Frederico G.; Costa, Liovando M. da; Leroux, Fabrice; Dubois, Marc; Valim, João B.

    2015-01-15

    A layered double hydroxide (LDH) with cation composition Zn{sub 2}Al was intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers. To achieve in situ polymerization and/or oligomerization of the intercalated monomers, soft thermal treatments were carried out, and subsequent hybrid LDH materials were analyzed by means of several characterization techniques using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), {sup 13}C CP–MAS nuclear magnetic resonance (NMR), electron spin resonance (EPR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP–OES), and elemental analysis. PXRD analysis suggested that the intercalated monomers formed a bilayer. Thermal treatment of the hybrid LDH assembly above 120 °C provokes partially the breakdown of the layered structure, generating the phase zincite. EPR results indicated that vicinal monomers (oligomerization) were bound to each other after hydrothermal or thermal treatment, leading to a polaron response characteristic of electron conductivity localized on a restricted number of thiophene-based monomer segments. Localized unpaired electrons exist in the material and interact with the {sup 27}Al nuclei of the LDH layers by superhyperfine coupling. These unpaired electrons also interact with the surface of ZnO (O{sup 2−} vacancies), formed during the thermal treatments. - Graphical abstract: We synthesized a layered double hydroxide (LDH) with cation composition Zn{sub 2}Al, intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers, by coprecipitation at constant pH. We thermally treated the material, to achieve in situ polymerization and/or oligomerization of the intercalated monomers. - Highlights: • A Zn{sub 2}Al–LDH was intercalated with 2-(thiophen-3-yl)acetate monomers. • To achieve in situ oligomerization of the monomers, thermal treatments were made.

  4. Mixed metal oxides for dye-sensitized solar cell using zinc titanium layered double hydroxide as precursor

    NASA Astrophysics Data System (ADS)

    Liu, Jianqiang; Qin, Yaowei; Zhang, Liangji; Xiao, Hongdi; Song, Jianye; Liu, Dehe; Leng, Mingzhe; Hou, Wanguo; Du, Na

    2013-12-01

    Mixed metal oxides (MMO) are always obtained from layered double hydroxide (LDH) by thermal decomposition. In the present work, a zinc titanium LDH with the zinc titanium molar ratio of 4.25 was prepared by urea method and ZnO-based mixed oxides were obtained by calcining at or over 500°C. The MMO was used as electrodes for dye sensitized solar cell (DSSC). The cells constructed by films of prepared composite materials using a N719 as dye were prepared. The efficiency values of these cells are 0.691%, 0.572% and 0.302% with MMO prepared at 500, 600 and 700°C, respectively.

  5. Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides.

    PubMed

    Caporale, A G; Pigna, M; Dynes, J J; Cozzolino, V; Zhu, J; Violante, A

    2011-12-30

    This paper describes the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides as affected by pH and varying concentrations of inorganic and organic ligands, and the effect of residence time on the desorption of arsenate by ligands. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrateLDH and nitrateLDH. The inhibition of arsenate sorption increased by increasing the initial ligand concentration and was greater on Al-Mg-LDH than on Fe-Mg-LDH. The longer the arsenate residence time on the LDH surfaces the less effective the competing ligands were in desorbing arsenate from sorbents. A greater percentage of arsenate was removed by phosphate from Al-Mg-LDH than from Fe-Mg-LDH, due to the higher affinity of arsenate for iron than aluminum. PMID:22071258

  6. Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies.

    PubMed

    Liu, Zhaoping; Ma, Renzhi; Osada, Minoru; Iyi, Nobuo; Ebina, Yasuo; Takada, Kazunori; Sasaki, Takayoshi

    2006-04-12

    This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-CO3 LDH hexagonal platelets of 4 mum in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared CO3(2-)-LDH was converted to Cl- -LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl- -LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3- -LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 microm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response. PMID:16594724

  7. A novel injectable thermoresponsive and cytocompatible gel of poly(N-isopropylacrylamide) with layered double hydroxides facilitates siRNA delivery into chondrocytes in 3D culture.

    PubMed

    Yang, Hsiao-yin; van Ee, Renz J; Timmer, Klaas; Craenmehr, Eric G M; Huang, Julie H; Öner, F Cumhur; Dhert, Wouter J A; Kragten, Angela H M; Willems, Nicole; Grinwis, Guy C M; Tryfonidou, Marianna A; Papen-Botterhuis, Nicole E; Creemers, Laura B

    2015-09-01

    Hybrid hydrogels composed of poly(N-isopropylacrylamide) (pNIPAAM) and layered double hydroxides (LDHs) are presented in this study as novel injectable and thermoresponsive materials for siRNA delivery, which could specifically target several negative regulators of tissue homeostasis in cartilaginous tissues. Effectiveness of siRNA transfection using pNIPAAM formulated with either MgAl-LDH or MgFe-LDH platelets was investigated using osteoarthritic chondrocytes. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an endogenous model gene to evaluate the extent of silencing. No significant adverse effects of pNIPAAM/LDH hydrogels on cell viability were noticed. Cellular uptake of fluorescently labeled siRNA was greatly enhanced (>75%) in pNIPAAM/LDH hydrogel constructs compared to alginate, hyaluronan and fibrin gels, and was absent in pNIPAAM hydrogel without LDH platelets. When using siRNA against GAPDH, 82-98% reduction of gene expression was found in both types of pNIPAAM/LDH hydrogel constructs after 6 days of culturing. In the pNIPAAM/MgAl-LDH hybrid hydrogel, 80-95% of GAPDH enzyme activity was reduced in parallel with gene. Our findings show that the combination of a cytocompatible hydrogel and therapeutic RNA oligonucleotides is feasible. Thus it might hold promise in treating degeneration of cartilaginous tissues by providing supporting scaffolds for cells and interference with locally produced degenerative factors. PMID:26022968

  8. High-performance hybrid supercapacitor with 3D hierarchical porous flower-like layered double hydroxide grown on nickel foam as binder-free electrode

    NASA Astrophysics Data System (ADS)

    Zhang, Luojiang; Hui, Kwun Nam; San Hui, Kwan; Lee, Haiwon

    2016-06-01

    The synthesis of layered double hydroxide (LDH) as electroactive material has been well reported; however, fabricating an LDH electrode with excellent electrochemical performance at high current density remains a challenge. In this paper, we report a 3D hierarchical porous flower-like NiAl-LDH grown on nickel foam (NF) through a liquid-phase deposition method as a high-performance binder-free electrode for energy storage. With large ion-accessible surface area as well as efficient electron and ion transport pathways, the prepared LDH-NF electrode achieves high specific capacity (1250 C g-1 at 2 A g-1 and 401 C g-1 at 50 A g-1) after 5000 cycles of activation at 20 A g-1 and high cycling stability (76.7% retention after another 5000 cycles at 50 A g-1), which is higher than those of most previously reported NiAl-LDH-based materials. Moreover, a hybrid supercapacitor with LDH-NF as the positive electrode and porous graphene nanosheet coated on NF (GNS-NF) as the negative electrode, delivers high energy density (30.2 Wh kg-1 at a power density of 800 W kg-1) and long cycle life, which outperforms the other devices reported in the literature. This study shows that the prepared LDH-NF electrode offers great potential in energy storage device applications.

  9. Bioactive Nanocomposite Poly (Ethylene Glycol) Hydrogels Crosslinked by Multifunctional Layered Double Hydroxides Nanocrosslinkers.

    PubMed

    Huang, Heqin; Xu, Jianbin; Wei, Kongchang; Xu, Yang J; Choi, Chun Kit K; Zhu, Meiling; Bian, Liming

    2016-07-01

    Poly (ethylene glycol) (PEG) based hydrogels have been widely used in many biomedical applications such as regenerative medicine due to their good biocompatibility and negligible immunogenicity. However, bioactivation of PEG hydrogels, such as conjugation of bioactive biomolecules, is usually necessary for cell-related applications. Such biofunctionalization of PEG hydrogels generally involves complicated and time-consuming bioconjugation procedures. Herein, we describe the facile preparation of bioactive nanocomposite PEG hydrogel crosslinked by the novel multifunctional nanocrosslinkers, namely polydopamine-coated layered double hydroxides (PD-LDHs). The catechol-rich PD-LDH nanosheets not only act as effective nanocrosslinkers reinforcing the mechanical strength of the hydrogel, but also afford the hydrogels with robust bioactivity and bioadhesion via the cortical-mediated couplings. The obtained nanocomposite PEG hydrogels with the multifunctional PD-LDH crosslinking domains show tunable mechanical properties, self-healing ability, and bioadhesion to biological tissues. Furthermore, these hydrogels also promote the sequestration of proteins and support the osteogenic differentiation of human mesenchymal stem cells without any further bio-functionalization. Such facile preparation of bioactive and bioadhesive PEG hydrogels have rarely been achieved and may open up a new avenue for the design of nanocomposite PEG hydrogels for biomedical applications. PMID:27061462

  10. Removal of Remazol Blue 19 from wastewater by zinc-aluminium-chloride-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Elkhattabi, El Hassan; Lakraimi, Mohamed; Badreddine, Mohamed; Legrouri, Ahmed; Cherkaoui, Omar; Berraho, Moha

    2013-06-01

    Layered double hydroxides (LDHs), also called anionic clays, consist of cationic brucite-like layers and exchangeable interlayer anions. These hydrotalcite-like compounds, with Zn and Al in the layers and chloride in the interlayer space, were prepared following the coprecipitation method at constant pH. The affinity of this material for Remazol Blue 19, RB19 [ 2- (3- (4- Amino- 9,10- dihydro- 3- sulpho- 9,10- dioxoanthracen- 4- yl) aminobenzenesulphonyl) vinyl) disodiumsulphate], was studied as a function of contact time, pH of the solutions LDH dose and the RB19/[Zn-Al-Cl] mass ratio. It was found that 48 h is enough time for the equilibrium state to be reached with maximum RB19 retention at pH of 9 for an LDH dose equal to 100 mg and with an RB19/[Zn-Al-Cl] mass ratio higher than 3. The adsorption isotherm, described by the Langmuir model, is of L-type. The results demonstrate that RB19 retention on LDHs occurs by adsorption on external surface when RB19/[Zn-Al-Cl] mass ratio is equal or <3 and by both adsorption and interlayer ion exchange for ratios higher than 3. A mechanism for removal of RB19 anion has been confirmed by X-ray diffraction, IR spectroscopy and TG analysis (TG and DTG curves).

  11. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Benito, P.; Labajos, F. M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-01

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), 27Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al 3+ and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M 2+/M 3+ ratio and consequent modification of the cell parameters.

  12. Potential for Layered Double Hydroxides-Based, Innovative Drug Delivery Systems

    PubMed Central

    Zhang, Kai; Xu, Zhi Ping; Lu, Ji; Tang, Zhi Yong; Zhao, Hui Jun; Good, David A.; Wei, Ming Qian

    2014-01-01

    Layered Double Hydroxides (LDHs)-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications. PMID:24786098

  13. From spent Mg/Al layered double hydroxide to porous carbon materials.

    PubMed

    Laipan, Minwang; Zhu, Runliang; Chen, Qingze; Zhu, Jianxi; Xi, Yunfei; Ayoko, Godwin A; He, Hongping

    2015-12-30

    Adsorption has been considered as an efficient method for the treatment of dye effluents, but proper disposal of the spent adsorbents is still a challenge. This work attempts to provide a facile method to reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II (OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washed with acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that the carbonization could be well achieved above 600°C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000°C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption-desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m(2)/g and 1.67 cm(3)/g for the sample carbonized at 800°C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH. PMID:26257095

  14. Synthesis and reversible hydration behavior of the thiosulfate intercalated layered double hydroxide of Zn and Al

    SciTech Connect

    Radha, S.; Milius, Wolfgang; Breu, Josef; Kamath, P. Vishnu

    2013-08-15

    The thiosulfate-intercalated layered double hydroxide of Zn and Al undergoes reversible hydration with a variation in the relative humidity of the ambient. The hydrated and dehydrated phases, which represent the end members of the hydration cycle, both adopt the structure of the 3R{sub 1} polytype. In the intermediate range of relative humidity values (40–60%), the hydrated and dehydrated phases coexist. The end members of the hydration cycle adopt the structure of the same polytype, and vary only in their basal spacings. This points to the possibility that all the intermediate phases have a kinetic origin. - Graphical abstract: Basal spacing evolution of the thiosulfate ion intercalated [Zn–Al] LDH during one complete hydration–dehydration cycle as a function of relative humidity. Display Omitted - Highlights: • Thiosulfate intercalated [Zn–Al] LDHs were synthesized by co-precipitation. • The LDH exhibits reversible hydration with variation in humidity. • Both the end members of the hydration cycle adopt the same polytype structure. • The interstratified intermediates observed are kinetic in origin.

  15. Synthesis, characterization, and controlled release antibacterial behavior of antibiotic intercalated Mg–Al layered double hydroxides

    SciTech Connect

    Wang, Yi; Zhang, Dun

    2012-11-15

    Graphical abstract: The antibiotic anion released from Mg–Al LDHs provides a controlled release antibacterial activity against the growth of Micrococcus lysodeikticus in 3.5% NaCl solution. Highlights: ► Antibiotic anion intercalated LDHs were synthesized and characterized. ► The ion-exchange one is responsible for the release process. ► The diffusion through particle is the release rate limiting step. ► LDHs loaded with antibiotic anion have high antibacterial capabilities. -- Abstract: Antibiotic–inorganic clay composites including four antibiotic anions, namely, benzoate (BZ), succinate (SU), benzylpenicillin (BP), and ticarcillin (TC) anions, intercalated Mg–Al layered double hydroxides (LDHs) were synthesized via ion-exchange. Powder X-ray diffraction and Fourier transform infrared spectrum analyses showed the successful intercalation of antibiotic anion into the LDH interlayer. BZ and BP anions were accommodated in the interlayer region as a bilayer, whereas SU and TC anions were intercalated in a monolayer arrangement. Kinetic simulation of the release data indicated that ion-exchange was responsible for the release process, and the diffusion through the particles was the rate-limiting step. The antibacterial capabilities of LDHs loaded with antibiotic anion toward Micrococcus lysodeikticus growth were analyzed using a turbidimetric method. Significant high inhibition rate was observed when LDH nanohybrid was introduced in 3.5% NaCl solution. Therefore, this hybrid material may be applied as nanocontainer in active antifouling coating for marine equipment.

  16. Simultaneous photooxidation and sorptive removal of As(III) by TiO2 supported layered double hydroxide.

    PubMed

    Lee, Sang-Ho; Kim, Kyoung-Woong; Choi, Heechul; Takahashi, Yoshio

    2015-09-15

    The present study focused on the enhanced removal of As(III) by the simultaneous photooxidation and removal process using TiO2 nanoparticles supported layered double hydroxide (TiO2/LDH). The TiO2/LDH nanocomposites were synthesized using a flocculation method, and nanosized (30-50 nm) TiO2 particles were well-distributed on the LDH surface. The XPS and DLS data revealed that the TiO2/LDH nanocomposites were both chemically and physically stable in the aquatic system. The optimum ratio of TiO2 was 20 wt.% and the calcination process of LDH enhanced the removal capacity of As(III) by the reconstruction process. In the kinetic removal experiment, UV irradiation improved the removal rate of As(III), based on the continuous conversion of As(III) to As(V), and that the removal rate was faster under alkaline conditions than acidic and neutral conditions due to the abundance of oxidants and negative charged As(III) species (pKa: 9.2). The main mechanism of As(III) photooxidation is the direct oxidation by [Formula: see text] , which is generated by supported TiO2 nanoparticles. X-ray near edge structure results also confirmed that the As(III) was completely oxidized to As(V). Consequently, the simultaneous photooxidation and removal process of As(III) by TiO2/LDH nanocomposites may be the effective removal option in As(III) contaminated water. PMID:26186550

  17. Strong interfacial attrition developed by oleate/layered double hydroxide nanoplatelets dispersed into poly(butylene succinate).

    PubMed

    Zhou, Qian; Verney, Vincent; Commereuc, Sophie; Chin, In-Joo; Leroux, Fabrice

    2010-09-01

    Poly(butylene succinate) (PBS) nanocomposite structure was studied as a function of the filler percentage loading. The resulting state of dispersion was evaluated by XRD and TEM, and the interfacial attrition between PBS chain and lamellar platelets by the melt rheological properties. Hybrid organic inorganic (O/I) layered double hydroxide (LDH) organo-modified by oleate anions was used as filler. It was found that the confinement supplied by the LDH framework forces the interleaved organic molecule to be more distant from each other than in the case of oleate salt, this having as an effect to decrease strongly the homonuclear intermolecular (1)H(1)H dipolar interaction. An additional consequence of this relatively free molecular rotation, affecting the (13)C CPMAS response as well, is to facilitate the delamination of the 2D-stacked layers during extrusion since an quasi-exfoliated PBS:Mg(2)Al/oleate structure is observed for filler loading lower than 5% w/w. This is in association to a non-linear viscoelasticity in the low-omega region and the observed shear-thinning tendency compares better than other PBS:silicate nanocomposite derivatives and is here explained by the presence of a percolated LDH nanoparticle network. Indeed the plastic deformation in the low-omega region is found to be restricted by well-dispersed LDH tactoids in association with a rather strong attrition phenomenon between tethered oleate anions and PBS chains. PMID:20605578

  18. Development of efficient electrocatalysts via molecular hybridization of NiMn layered double hydroxide nanosheets and graphene.

    PubMed

    Ma, Wei; Ma, Renzhi; Wu, Jinghua; Sun, Pengzhan; Liu, Xiaohe; Zhou, Kechao; Sasaki, Takayoshi

    2016-05-21

    Ni(2+)Mn(3+) layered double hydroxide (LDH) nanoplatelets have been hydrothermally synthesized in a homogeneous precipitation of mixed Ni(2+)/Mn(2+) salts at a molar ratio of 2 : 1 via the hydrolysis of hexamethylenetetramine (HMT) and in situ oxidation with H2O2. After anion-exchange, NiMn LDH was exfoliated into unilamellar nanosheets. Subsequent flocculation of NiMn LDH nanosheets with (reduced) graphene oxide (GO/rGO) into superlattice composites was achieved and further tested as electrocatalysts for oxygen evolution reaction (OER). The face-to-face heteroassembly of NiMn LDH nanosheets with conductive rGO at an alternating sequence resulted in a small overpotential of 0.26 V and a Tafel slope of 46 mV per decade, which is much superior to as-exfoliated nanosheets. The analyses of electrochemical activity surface area (ECSA) and impedance spectra clearly indicated that the superlattice structure was ideal in facilitating the migration/transfer of the charge and reactants, revealing the electrochemical energetics and mechanism behind the synergistic effect arising from molecular hybridization. The proof of concept toward total water splitting using the newly developed hybrid electrocatalyst was demonstrated by an electrolysis cell powered by a single AA battery. PMID:27142232

  19. Preparation of polymer/LDH nanocomposite by UV-initiated photopolymerization of acrylate through photoinitiator-modified LDH precursor

    SciTech Connect

    Hu, Lihua; Yuan, Yan; Shi, Wenfang

    2011-02-15

    Graphical abstract: This is the HR-TEM micrograph of UV cured nanocomposite at 5 wt% LDH-2959 loading for a-5 sample. The dark lines are the intersections of LDH platelets. It can be seen that samples a-5 dispersed in the polymer matrix and lost the ordered stacking-structure and show the completely exfoliation after UV curing. This can be explained by the fact that the sample a-5 only containing LDH-2959 exhibited a relative lower photopolymerization rate, which was propitious to further expand the LDH intergallery to form the exfoliated structure. Research highlights: {yields} The UV cured polymer/LDH nanocomposites were prepared through the photopolymerization initiated by the photoinitiator-modified LDH precursor, LDH-2959. {yields} The exfoliated UV cured nanocomposites were achieved in the presence of LDH-2959 only. However, the UV cured nanocomposites prepared using both LDH-2959 and Irgacure 2959 showed the intercalated structure. {yields} Compared with the pure polymer, the exfoliated polymer/LDH nanocomposite showed remarkable enhanced thermal stability and mechanical properties because of their well dispersion in the polymer matrix. -- Abstract: The exfoliated polymer/layered double hydroxide (LDH) nanocomposite by UV-initiated photopolymerization of acrylate systems through an Irgacure 2959-modified LDH precursor (LDH-2959) as a photoinitiator complex was prepared. The LDH-2959 was obtained by the esterification of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) with thioglycolic acid, following by the addition reaction with 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), finally intercalation into the sodium dodecyl sulfate-modified LDH. For comparison, the intercalated polymer/LDH nanocomposite was obtained with additive Irgacure 2959 addition. From the X-ray diffraction (XRD) measurements and HR-TEM observations, the LDH lost the ordered stacking-structure and well dispersed in the polymer matrix at 5 wt% LDH-2959 loading

  20. Synthesis and properties of mecoprop-intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Ahmed Khan, Modabber; Choi, Choong-Lyeal; Lee, Dong-Hoon; Park, Man; Lim, Bu-Kug; Lee, Jong-Yoon; Choi, Jyung

    2007-08-01

    This study carried out to elucidate the synthesis of MCPP LDH hybrid, release pattern of MCPP from MCPP LDH hybrid and their properties. MCPP LDH hybrid was synthesized from MCPP and Mg Al complex. Release pattern of MCPP from MCPP LDH hybrid was slower in distilled water and soil solution but it was slower in distilled water than soil solution. MCPP LDH hybrid has shown more stable condition than CO32- form of LDH in thermal and acidic condition. Therefore, MCPP LDH hybrid would lead as functional and benign pesticide to minimize the harmful effects on soil environment by bulk herbicides.

  1. Formation of layered single- and double-metal hydroxide precipitates at the mineral/water interface: A multiple-scattering XAFS analysis

    SciTech Connect

    Scheinost, A.C.; Sparks, D.L.

    2000-03-15

    Spectroscopic and microscopic studies have shown that Ni and Co sorption by clay minerals may proceed via formation of surface precipitates. Several studies employing X-ray absorption fine structure (XAFS) spectroscopy suggested the formation of turbostratic, a-type metal hydroxides, of layered double hydroxides (LDH) with Al-for-metal substitution, and of 1:1 or 2:1 phyllosilicates. Distinction of these phases is difficult because they have low crystallinity and/or a small mass compared to the sorbents, and because they have similar metal-metal distances in their hydroxide layers/sheets. Distinction of these phases is crucial, however, because they have substantially differing solubilities. In this paper the authors show that an XAFS beat pattern at about 8 {angstrom} {sup {minus}1} can be used as a fingerprint to unequivocally distinguish LDH from the {alpha}-type hydroxides and phyllosilicates. Full multiple-scattering simulations and experimental spectra of model compounds indicate that the beat pattern is due to focused multiple scattering at Me/Al ratios between 1 and 4(Me = Ni,Co). By applying the fingerprint method to new and to already published XAFS data on Ni and Co surface precipitates, the authors found that LDH preferentially forms in the presence of the Al-containing sorbents pyrophyllite, illite, kaolinite, gibbsite, and alumina above pH 7.0. However, {alpha}-type metal hydroxides form in the presence of the Al-free sorbents talc, silica, and rutile, and in the presence of the Al-containing clay minerals montmorillonite and vermiculite. The authors believe, that the high permanent charge of these latter minerals prevents or retards the release of Al. When Al is available, the formation of LDH seems to be thermodynamically and/or kinetically favored over the formation of {alpha}-type hydroxides.

  2. Formation of Layered Single- and Double-Metal Hydroxide Precipitates at the Mineral/Water Interface: A Multiple-Scattering XAFS Analysis.

    PubMed

    Scheinost; Sparks

    2000-03-15

    Spectroscopic and microscopic studies have shown that Ni and Co sorption by clay minerals may proceed via formation of surface precipitates. Several studies employing X-ray absorption fine structure (XAFS) spectroscopy suggested the formation of turbostratic, alpha-type metal hydroxides, of layered double hydroxides (LDH) with Al-for-metal substitution, and of 1:1 or 2:1 phyllosilicates. Distinction of these phases is difficult because they have low crystallinity and/or a small mass compared to the sorbents, and because they have similar metal-metal distances in their hydroxide layers/sheets. Distinction of these phases is crucial, however, because they have substantially differing solubilities. In this paper we show that an XAFS beat pattern at about 8 Å(-1) can be used as a fingerprint to unequivocally distinguish LDH from the alpha-type hydroxides and phyllosilicates. Full multiple-scattering simulations and experimental spectra of model compounds indicate that the beat pattern is due to focused multiple scattering at Me/Al ratios between 1 and 4 (Me=Ni, Co). By applying the fingerprint method to new and to already published XAFS data on Ni and Co surface precipitates, we found that LDH preferentially forms in the presence of the Al-containing sorbents pyrophyllite, illite, kaolinite, gibbsite, and alumina above pH 7.0. However, alpha-type metal hydroxides form in the presence of the Al-free sorbents talc, silica, and rutile, and in the presence of the Al-containing clay minerals montmorillonite and vermiculite. We believe that the high permanent charge of these latter minerals prevents or retards the release of Al. When Al is available, the formation of LDH seems to be thermodynamically and/or kinetically favored over the formation of alpha-type hydroxides. Copyright 2000 Academic Press. PMID:10700399

  3. Ion specific effects on the stability of layered double hydroxide colloids.

    PubMed

    Pavlovic, Marko; Huber, Robin; Adok-Sipiczki, Monika; Nardin, Corinne; Szilagyi, Istvan

    2016-05-01

    Positively charged layered double hydroxide particles composed of Mg(2+) and Al(3+) layer-forming cations and NO3(-) charge compensating anions (MgAl-NO3-LDH) were synthesized and the colloidal stability of their aqueous suspensions was investigated in the presence of inorganic anions of different charges. The formation of the layered structure was confirmed by X-ray diffraction, while the charging and aggregation properties were explored by electrophoresis and light scattering. The monovalent anions adsorb on the oppositely charged surface to a different extent according to their hydration state leading to the Cl(-) > NO3(-) > SCN(-) > HCO3(-) order in surface charge densities. The ions on the right side of the series induce the aggregation of MgAl-NO3-LDH particles at lower concentrations, whereas in the presence of the left ones, the suspensions are stable even at higher salt levels. The adsorption of multivalent anions gave rise to charge neutralization and charge reversal at appropriate concentrations. For some di, tri and tetravalent ions, charge reversal resulted in restabilization of the suspensions in the intermediate salt concentration regime. Stable samples were also observed at low salt levels. Particle aggregation was fast near the charge neutralization point and at high concentrations. These results, which evidence the colloidal stability of MgAl-NO3-LDH in the presence of various anions, are of prime fundamental interest. These are also critical for applications to develop stable suspensions of primary particles for water purification processes, with the aim of the removal of similar anions by ion exchange. PMID:26997621

  4. Use of layered double hydroxides and their derivatives as adsorbents for inorganic and organic pollutants

    NASA Astrophysics Data System (ADS)

    You, Youwen

    Contamination of surface and groundwaters by hazardous inorganic and organic pollutants has become an increasing threat to the safety of drinking waters. Cleanup of contaminated surface and groundwaters has, therefore, become a major focus of environmental research. Primary objectives of this dissertation study were to examine the adsorption properties of layered double hydroxides (LDHs) and their derivatives for inorganic and organic contaminants and to identify potential technologies that utilize LDHs and their derivatives for environment remediation. Studies examined the adsorption characteristics of anionic selenium, arsenic and dicamba (3,6 dichloro-2-methoxy benzoic acid) on original LDHs and calcined-LDHs. Adsorption of selenium and arsenic on LDHs was a function of pH. Competing anions in solution strongly affected adsorption of all three contaminants, with divalent anions decreasing adsorption more intensely than monovalent anions. Adsorbed selenium, arsenic and dicamba could be released from LDHs in anion solutions. Adsorption isotherms for selenium and arsenic retention could be fitted to a simple Langmuir equation. Calcination processes significantly increased adsorption capacities of LDHs. Because of adsorption-desorpion characteristics, LDHs could be recycled. X-ray diffraction patterns revealed an increase of d-spacing coupling with adsorption of contaminants, verifying the intercalation of contaminants into layer structure of LDHs. Long chain anionic surfactants intercalated into LDHs modified their surface properties, resulting in organo-LDHs with hydrophobic surface properties. Various organo-LDHs were developed by incorporating different surfactants into LDHs via different synthesis methods. Surfactant intercalation properties were examined and the geometrical arrangements of the intercalated surfactants were characterized. Results revealed that surfactant molecules could adopt various configurations within the LDH interlayer space. Intercalation

  5. Comparative X-ray diffraction and infrared spectroscopy study of Zn-Al layered double hydroxides: Vanadate vs nitrate

    NASA Astrophysics Data System (ADS)

    Salak, Andrei N.; Tedim, João; Kuznetsova, Alena I.; Ribeiro, José L.; Vieira, Luís G.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2012-03-01

    Zn-Al layered double hydroxides (LDH) are promising as nanocontainers of corrosion inhibitors in self-healing corrosion protection coatings. Zn(2)Al-vanadate (Zn/Al = 2:1) is prepared by anion exchange from the parent composition Zn(2)Al-nitrate at pH ˜ 8. Crystal structure and vibrational spectra of both LDHs have been studied in comparison. Their interlayer distances are rather larger than those corresponding to the most compact arrangement of the intercalated anions. Nevertheless, no sign of a turbostratic disorder has been detected in these LDH. Based on the analysis of the spectroscopic data in combination with the XRD results, it has been shown that vanadate anion, which substitutes nitrate at the anion exchange, is pyrovanadate, VO74-. The observed disorder in the hydroxide layers in Zn(2)Al-V2O7 is likely to result from strong interactions between V5+ and Zn2+/Al3. Although Zn(2)Al-NO3 is less disordered than Zn(2)Al-V2O7, it exhibits no long-range order in arrangement of cations in the hydroxide layers.

  6. Photocatalytic property and structural stability of CuAl-based layered double hydroxides

    SciTech Connect

    Lv, Ming; Liu, Haiqiang

    2015-07-15

    Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV–Vis diffuse reflectance spectrum (UV–vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO{sub 2} reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M{sup 2+} on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials. - Graphical abstract: The host–guest calculation models and XRD patterns of CuMAl-LDHs: CuMgAl-LDHs (a), CuZnAl-LDHs (b) and CuNiAl-LDHs (c). - Highlights: • Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) has been synthesized. • CuMgNi shows narrower band gap and more excellent textural properties than other LDHs. • The band gap: CuMgAl

  7. Layered double hydroxide supported gold nanoclusters by glutathione-capped Au nanoclusters precursor method for highly efficient aerobic oxidation of alcohols

    NASA Astrophysics Data System (ADS)

    Li, Lun; Dou, Liguang; Zhang, Hui

    2014-03-01

    M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h-1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity

  8. Preparation of 5-benzotriazolyl-4-hydroxy-3- sec-butylbenzenesulfonate anion-intercalated layered double hydroxide and its photostabilizing effect on polypropylene

    NASA Astrophysics Data System (ADS)

    Li, Dianqing; Tuo, Zhenjun; Evans, David G.; Duan, Xue

    2006-10-01

    An organic UV absorber has been intercalated into a layered double hydroxide (LDH) host by ion-exchange method using ZnAl-NO 3-LDH as a precursor with an aqueous solution of the sodium salt of 5-benzotriazolyl-4-hydroxy-3- sec-butylbenzenesulfonic acid (BZO). After intercalation of the UV absorber, the interlayer distance in the LDHs increases from 0.89 to 2.32 nm. Infrared spectra and thermogravimetry and differential thermal analysis (TG-DTA) curves reveal the presence of a complex system of supramolecular host-guest interactions. The thermostability of BZO is markedly enhanced by intercalation in the LDH host. ZnAl-BZO-LDHs/polypropylene composite materials exhibit excellent UV photostability.

  9. Bioinorganic magnetic core-shell nanocomposites carrying antiarthritic agents: intercalation of ibuprofen and glucuronic acid into Mg-Al-layered double hydroxides supported on magnesium ferrite.

    PubMed

    Ay, Ahmet Nedim; Zümreoglu-Karan, Birgül; Temel, Abidin; Rives, Vicente

    2009-09-21

    This paper describes the synthesis and characterization of a composite constituted by an antiarthritic agent (AA) intercalated into a layered double hydroxide (LDH) supported on magnesium ferrite. Core-shell nanocomposites were prepared by depositing Mg-Al-NO(3)-LDH on a MgFe(2)O(4) core prepared by calcination of a nonstoichiometric Mg-Fe-CO(3)-LDH. Intercalation of ibuprofen and glucuronate anions was performed by ion-exchange with nitrate ions. The structural characteristics of the obtained products were investigated by powder X-ray diffraction, element chemical analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Morphologies of the nanocomposite particles were examined by scanning electron microscopy and transmission electron microscopy. The products were shown to intercalate substantial amounts of AA with enhanced thermal stabilities. Room-temperature magnetic measurements by vibrating sample magnetometry revealed that the products show soft ferromagnetic properties suitable for potential utilization in magnetic arthritis therapy. PMID:19691269

  10. One-step hydrothermal crystallization of a layered double hydroxide/alumina bilayer film on aluminum and its corrosion resistance properties.

    PubMed

    Guo, Xiaoxiao; Xu, Sailong; Zhao, Lili; Lu, Wei; Zhang, Fazhi; Evans, David G; Duan, Xue

    2009-09-01

    A zinc-aluminum layered double hydroxide (ZnAl-LDH)/alumina bilayer film has been fabricated on an aluminum substrate by a one-step hydrothermal crystallization method. The LDH film was uniform and compact. XRD patterns and SEM images showed that the LDH film was highly oriented with the c-axis of the crystallites parallel to the substrate surface. The alumina layer existing between the LDH film and the substrate was formed prior to the LDH during the crystallization process. Polarization measurements showed that the bilayer film exhibited a low corrosion current density value of 10(-8) A/cm(2), which means that the LDH/alumina bilayer film can effectively protect aluminum from corrosion. Electrochemical impedance spectroscopy (EIS) showed that the impedance of the bilayer was 16 MOmega, meaning that the film served as a passive layer with a high charge transfer resistance. The adhesion between the film and the substrate was very strong which enhances its potential for practical application. PMID:19441823

  11. Structural Characterisation of Complex Layered Double Hydroxides and TGA-GC-MS Study on Thermal Response and Carbonate Contamination in Nitrate- and Organic-Exchanged Hydrotalcites.

    PubMed

    Conterosito, Eleonora; Palin, Luca; Antonioli, Diego; Viterbo, Davide; Mugnaioli, Enrico; Kolb, Ute; Perioli, Luana; Milanesio, Marco; Gianotti, Valentina

    2015-10-12

    Layered double hydroxides (LDHs) are versatile materials used for intercalating bioactive molecules in the fields of pharmaceuticals, nutraceuticals and cosmetics, with the purpose of protecting them from degradation, enhancing their water solubility to increase bioavailability and improving their pharmacokinetic properties and formulation stability. Moreover, LDHs are used in various technological applications to improve stability and processability. The crystal chemistry of hydrotalcite-like compounds was investigated by X-ray powder diffraction (XRPD), automated electron diffraction tomography (ADT) and thermogravimetric analysis (TGA)-GC-MS to shed light on the mechanisms involved in ion exchange and absorption of contaminants, mainly carbonate anions. For the first time, ADT allowed a structural model of LDH_NO3 to be obtained from experiment, shedding light on the conformation of nitrate inside LDH and on the loss of crystallinity due to the layer morphology. The ADT analysis of a hybrid LDH sample (LDH_EUS) clearly revealed an increase in defectivity in this material. XRPD demonstrated that the presence of carbonate can influence the intercalation of organic molecules into LDH, since CO3 -contaminated samples tend to adopt d spacings that are approximate multiples of the d spacing of LDH_CO3 . TGA-GC-MS allowed intercalated and surface- adsorbed organic molecules to be distinguished and quantified, the presence and amount of carbonate to be confirmed, especially at low concentrations (<2 wt %), and the different types and strengths of adsorption to be classified with respect to the temperature of elimination. PMID:26269963

  12. Porous Hybrid Network of Graphene and Metal Oxide Nanosheets as Useful Matrix for Improving the Electrode Performance of Layered Double Hydroxides.

    PubMed

    Gu, Tae-Ha; Gunjakar, Jayavant L; Kim, In Young; Patil, Sharad B; Lee, Jang Mee; Jin, Xiaoyan; Lee, Nam-Suk; Hwang, Seong-Ju

    2015-08-26

    Mesoporous hybrid network of reduced graphene oxide (rG-O) and layered MnO(2) nanosheets could act as an efficient immobilization matrix for improving the electrochemical activity of layered double hydroxide (LDH). The control of MnO(2) /rG-O ratio is crucial in optimizing the porous structure and electrical conductivity of the resulting hybrid structure. The immobilization of Co-Al-LDH on hybrid MnO(2) /rG-O network is more effective in enhancing its electrode activity compared with that of on pure rG-O network. The Co-Al-LDH-rG-O-MnO(2) nanohybrid deliveres a greater specific capacitance than does MnO(2) -free Co-Al-LDH-rG-O nanohybrid. The beneficial effect of MnO(2) incorporation on the electrode performance of nanohybrid is more prominent for higher current density and faster scan rate, underscoring the significant enhancement of the electron transport of Co-Al-LDH-rG-O. This is supported by electrochemical impedance spectroscopy. The present study clearly demonstrates the usefulness of the porously assembled hybrid network of graphene and metal oxide nanosheets as an effective platform for exploring efficient LDH-based functional materials. PMID:25930158

  13. Efficient removal of heavy metal ions from aqueous systems with the assembly of anisotropic layered double hydroxide nanocrystals@carbon nanosphere.

    PubMed

    Gong, Jingming; Liu, Ting; Wang, Xiaoqing; Hu, Xianluo; Zhang, Lizhi

    2011-07-15

    We report on the efficient removal of heavy metal ions from simulated wastewater with a nanostructured assembly. The nanoassembly was obtained via direct assembling the performed anisotropic layered double hydroxide nanocrystals (LDH-NCs) onto the surface of carbon nanospheres (labeled as LDH-NCs@CNs). It was found that the maximum adsorption capacity of the nanoassembly toward Cu(2+) was ∼ 19.93 mg g(-1) when the initial Cu(2+) concentration was 10.0 mg L(-1), displaying a high efficiency for the removal of heavy metal ions. The Freundlich adsorption isotherm was applicable to describe the removal processes. Kinetics of the Cu(2+) removal was found to follow pseudo-second-order rate equation. Furthermore, the as-prepared building unit of the assembly, including LDH-NCs, CNs, and the assembly, as well as Cu(2+)-adsorbed assembly, were carefully examined by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), nitrogen sorption measurements, and X-ray photoelectron spectroscopy (XPS). Based on the characterization results, a possible mechanism of Cu(2+) removal with the assembly of LDH-NCs@CNs was proposed. Comparison experiments show that the adsorption capacity of the resulting LDH-NCs@CNs assembly was much higher than its any building unit alone (CNs or LDH-NCs), exhibiting the deliberation of the assembly on water decontamination. This work provides a very efficient, fast and convenient approach for exploring promising nanoassembly materials for water treatment. PMID:21692502

  14. Synthesis and characterization of layered double hydroxides (LDHs) with intercalated chromate ions

    SciTech Connect

    Prasanna, Srinivasa V.; Kamath, P. Vishnu . E-mail: vishnukamath8@hotmail.com; Shivakumara, C.

    2007-06-05

    Chromate intercalated layered double hydroxides (LDHs) having the formula M{sup II} {sub 6}M'{sup III} {sub 2}(OH){sub 16}CrO{sub 4}.4H{sub 2}O (M{sup II} = Ca, Mg, Co, Ni, Zn with M'{sup III} = Al and M{sup II} = Mg, Co, Ni with M'{sup III} = Fe) have been prepared by coprecipitation. The products obtained are replete with stacking disorders. DIFFaX simulations show that the stacking disorders are of three kinds: (i) turbostratic disorder of an originally single layered hexagonal (1H) crystal (ii) random intergrowth of polytypes with hexagonal (2H) and rhombohedral (3R) symmetries and (iii) translation of randomly chosen layers by (2/3, 1/3, z) and (1/3, 2/3, z) leading to stacking faults having a local structure of rhombohedral symmetry. IR spectra show that the CrO{sub 4} {sup 2-} ion is incorporated either in the T {sub d} or in the C {sub 3v} symmetry. The interlayer spacing in the latter case is 7.3 A characteristic of a single atom thick interlayer showing that the CrO{sub 4} {sup 2-} ion is grafted to the metal hydroxide slab. On thermal treatment, the CrO{sub 4} {sup 2-} ion transforms into Cr(III) and is incorporated into the spinel oxide or phase separates as Cr{sub 2}O{sub 3}. In the LDH of Mg with Al, Cr(III) remains in the MgO lattice as a defect and promotes the reconstruction of the LDH on soaking in water. In different LDHs, 18-50% of the CrO{sub 4} {sup 2-} ion is replaceable with carbonate anions showing only partial mineralization of the water-soluble chromate. The extent of replaceable chromates depends upon the solubility of the corresponding LDH, which in turn is determined by the solubility of the MCrO{sub 4}. These studies have profound implications for the possible use of LDHs for chromate amelioration in green chemistry.

  15. Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state {sup 1}H and {sup 71}Ga NMR spectroscopy

    SciTech Connect

    Petersen, Line Boisen; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro

    2014-11-15

    Ordering of gallium(III) in a series of magnesium gallium (MgGa) layered double hydroxides (LDHs), [Mg{sub 1−x}Ga{sub x}(OH){sub 2}(NO{sub 3}){sub x}·yH{sub 2}O] was investigated using solid-state {sup 1}H and {sup 71}Ga NMR spectroscopy as well as powder X-ray diffraction. Three different proton environments from Mg{sub 3}-OH, Mg{sub 2}Ga-OH and intergallery water molecules were assigned and quantified using ({sup 1}H,{sup 71}Ga) HETCOR and {sup 1}H MAS NMR. A single {sup 71}Ga site originating from the unique Ga site in the MgGa LDH's was observed in {sup 71}Ga MAS and 3QMAS NMR spectra. Both {sup 1}H MAS NMR spectra recorded at 21.1 T (900 MHz) and elemental analysis show that the synthesized MgGa LDH's had a lower Mg:Ga ratio than that of the starting reactant solution. The origin of this is the formation of soluble [Ga(OH){sub 4}]{sup −} complexes formed during synthesis, and not due to formation of insoluble gallium (oxy)hydroxides. No sign of Ga-O-Ga connectivities or defects were detected for the MgGa LDH's. - Graphical abstract: Two types of hydroxides groups are observed in magnesium gallium layered double hydroxides revealing an ordering of Ga in the cation layer. - Highlights: • Ga is ordered in our magnesium gallium layered double hydroxides. • Ga depletion due to formation of soluble Ga complexes during synthesis. • No sign of Ga rich regions in magnesium gallium LDHs. • Solid state {sup 1}H and {sup 71}Ga give detailed insight into the structure.

  16. New treatment method for boron in aqueous solutions using Mg-Al layered double hydroxide: Kinetics and equilibrium studies.

    PubMed

    Kameda, Tomohito; Oba, Jumpei; Yoshioka, Toshiaki

    2015-08-15

    Mg-Al layered double hydroxides (LDHs) intercalated with NO3(-) (NO3 · Mg - Al LDHs) and with Cl(-) (Cl · Mg - Al LDHs) were found to take up boron from aqueous solutions. Boron was removed by anion exchange of B(OH)4(-) in solution with NO3(-) and Cl(-) intercalated in the interlayer of the LDH. Using three times the stoichiometric quantity of NO3 · Mg-Al LDH, the residual concentration of B decreased from 100 to 1.9 mg L(-1) in 120 min. Using five times the stoichiometric quantity of Cl · Mg - Al LDH, the residual concentration of B decreased from 100 to 5.6 mg L(-1) in 120 min. It must be emphasized that, in both cases, the residual concentration of B was less than the effluent standards in Japan (10 mg L(-1)). The rate-determining step of B removal by the NO3 · Mg - Al and Cl · Mg - Al LDHs was found to be chemical adsorption involving anion exchange of B(OH)4(-) with intercalated NO3(-) and Cl(-). The removal of B was well described by a pseudo second-order kinetic equation. The adsorption of B by NO3 · Mg - Al LDH and Cl · Mg - Al LDH followed a Langmuir-type adsorption. The values of the maximum adsorption and the equilibrium adsorption constant were 3.6 mmol g(-1) and 1.7, respectively, for NO3 · Mg - Al LDH, and 3.8 mmol g(-1) and 0.7, respectively, for Cl · Mg-Al LDH. The B(OH)4(-) in B(OH)4 · Mg - Al LDH produced by removal of B was found to undergo anion exchange with NO3(-) and Cl(-) in solution. The NO3 · Mg - Al and Cl · Mg - Al LDHs obtained after this regeneration treatment were able to remove B from aqueous solutions, indicating the possibility of recycling NO3 · Mg - Al and Cl · Mg - Al LDHs for B removal. PMID:25827268

  17. Highly Enhanced Photoelectrochemical Water Oxidation Efficiency Based on Triadic Quantum Dot/Layered Double Hydroxide/BiVO4 Photoanodes.

    PubMed

    Tang, Yanqun; Wang, Ruirui; Yang, Ye; Yan, Dongpeng; Xiang, Xu

    2016-08-01

    The water oxidation half-reaction is considered to be a bottleneck for achieving highly efficient solar-driven water splitting due to its multiproton-coupled four-electron process and sluggish kinetics. Herein, a triadic photoanode consisting of dual-sized CdTe quantum dots (QDs), Co-based layered double hydroxide (LDH) nanosheets, and BiVO4 particles, that is, QD@LDH@BiVO4, was designed. Two sets of consecutive Type-II band alignments were constructed to improve photogenerated electron-hole separation in the triadic structure. The efficient charge separation resulted in a 2-fold enhancement of the photocurrent of the QD@LDH@BiVO4 photoanode. A significantly enhanced oxidation efficiency reaching above 90% in the low bias region (i.e., E < 0.8 V vs RHE) could be critical in determining the overall performance of a complete photoelectrochemical cell. The faradaic efficiency for water oxidation was almost 90%. The conduction band energy of QDs is ∼1.0 V more negative than that of LDH, favorable for the electron injection to LDH and enabling a more efficient hole separation. The enhanced photon-to-current conversion efficiency and improved water oxidation efficiency of the triadic structure may result from the non-negligible contribution of hot electrons or holes generated in QDs. Such a band-matching and multidimensional triadic architecture could be a promising strategy for achieving high-efficiency photoanodes by sufficiently utilizing and maximizing the functionalities of QDs. PMID:27419597

  18. In-syringe extraction using dissolvable layered double hydroxide-polymer sponges templated from hierarchically porous coordination polymers.

    PubMed

    Ghani, Milad; Frizzarin, Rejane M; Maya, Fernando; Cerdà, Víctor

    2016-07-01

    Herein we report the use of cobalt porous coordination polymers (PCP) as intermediates to prepare advanced extraction media based on layered double hydroxides (LDH) supported on melamine polymer foam. The obtained dissolvable Ni-Co LDH composite sponges can be molded and used as sorbent for the in-syringe solid-phase extraction (SPE) of phenolic acids from fruit juices. The proposed sorbent is obtained due to the surfactant-assisted self-assembly of Co(II)/imidazolate PCPs on commercially available melamine foam, followed by the in situ conversion of the PCP into the final dissolvable LDH coating. Advantageous features for SPE are obtained by using PCPs with hierarchical porosity (HPCPs). The LDH-sponge prepared using intermediate HPCPs (HLDH-sponge) is placed in the headspace of a glass syringe, enabling flow-through extraction followed by analyte elution by the dissolution of the LDH coating in acidic conditions. Three phenolic acids (gallic acid, p-hydroxybenzoic acid and caffeic acid) were extracted and quantified using high performance liquid chromatography. Using a 5mL sample volume, the obtained detection limits were 0.15-0.35μgL(-1). The proposed method for the preparation of HLDH-sponges showed a good reproducibility as observed from the intra- and inter-day RSD's, which were <10% for all analytes. The batch-to-batch reproducibility for three different batches of HLDH-sponges was 10.6-11.2%. Enrichment factors of 15-21 were obtained. The HLDH-sponges were applied satisfactorily to the determination of phenolic acids in natural and commercial fruit juices, obtaining relative recoveries among 89.7-95.3%. PMID:27247213

  19. Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Caporale, A. G.; Pigna, M.; Dynes, J. J.; Cozzolino, V.; Zhu, J.; Violante, A.

    2012-04-01

    In recent decades, a class of anionic clays known as layered double hydroxides (LDHs) has attracted substantial attention due to the potential use in many applications, such as photochemistry, electrochemistry, polymerization, magnetization and biomedical science. There has also been considerable interest in using LDHs as adsorbents to remove environmental contaminants due to their large surface area, high anion exchange capacity and good thermal stability. We studied the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides (easily reproducible at low-cost) as affected by pH and varying concentrations of inorganic (nitrate, nitrite, phosphate, selenite and sulphate) and organic (oxalate and tartrate) ligands, ii) the effect of residence time on the arsenate desorption by these ligands, and iii) the kinetics of arsenate desorption by phosphate. The Fe-Mg-LDH sorbed nearly twice the amount of arsenate compared to the Al-Mg-LDH, due, in part, to its greater surface area and lower degree of crystallinity. Moreover, the Fe-Mg-LDH sorbed more arsenate than phosphate, in contrast to the Al-Mg-LDH, which adsorbed more phosphate than arsenate, probably because of the greater affinity of arsenate than phosphate for Fe sites and, vice versa, the greater affinity of phosphate than arsenate for Al sites. Arsenate sorption onto samples decreased by increasing pH, due, maybe, to the high affinity of hydroxyl ions for LDHs and/or to the value of zero point charge of two sorbents. The rate of decline in the amount of arsenate sorbed was, however, relatively constant, decreasing the fastest for the Fe-Mg-LDH compared to the Al-Mg-LDH. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrate < nitrite < sulphate < selenite < tartrate < oxalate << phosphate on Al-Mg-LDH and nitrate < sulphate ≈ nitrite < tartrate < oxalate < selenite << phosphate on Fe-Mg-LDH. The inhibition of arsenate sorption increased by increasing the initial

  20. Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions.

    PubMed

    Jia, Yueqing; Fang, Yanjun; Zhang, Yingkui; Miras, Haralampos N; Song, Yu-Fei

    2015-10-12

    The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12 O40 ](3-) (PW12 ) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73 Al0.22 (OH)2 [PW12 O40 ]0.04 ⋅0.98 H2 O (Mg3 Al-PW12 ) has been successfully obtained by applying a spontaneous flocculation method. The Mg3 Al-PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3 Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3 Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2 -Z' type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2-propanol :Vwater =2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3 Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3 Al-PW12 -catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction. PMID:26337902

  1. Evolution of biogenic amine concentrations in foods through their induced chemiluminescence inactivation of layered double hydroxide nanosheet colloids.

    PubMed

    Wang, Zhihua; Liu, Fang; Lu, Chao

    2014-10-15

    Turn-on/off fluorescence and visual sensors through hydrogen bonding recognition have been clearly established in the literature. There is apparently no good reason to disregard hydrogen bonding-induced inactivation of chemiluminescence (CL). In this work, serving as novel CL catalyst and CL resonance energy transfer acceptor (CRET), layered double hydroxide (LDH) nanosheet colloids can induce a significant increase in the CL intensity of bis(2,4,6-trichlorophenyl) oxalate (TCPO)-H2O2 system. On the other hand, biogenic amines can selectively inhibit the CL intensity of the LDH nanosheet-TCPO-H2O2 system as a result of inactivation of photoluminescence LDH nanosheets through the displacement of O-H ⋯ O bonding by O-H ⋯ N bonding. In addition, histamine is used as a common indicator of food spoilage, and it is found that the CL intensity is linear with histamine concentration in the range of 0.1-100 µM, and the detection limit for histamine (S/N=3) is 3.2 nM. The proposed method has been successfully applied to trace histamine evolution of spoiled fish and pork meat samples, displaying a time-dependent increase in the biogenic amines levels in such samples. PMID:24813913

  2. How the method of synthesis governs the local and global structure of zinc aluminum layered double hydroxides

    SciTech Connect

    Pushparaj, Suraj Shiv Charan; Forano, Claude; Prevot, Vanessa; Lipton, Andrew S.; Rees, Gregory; Hanna, John V.; Nielsen, Ulla Gro

    2015-11-10

    A series of zinc aluminum layered double hydroxides (ZnAl LDHs), [Zn1-xAlx (OH)2Ax,nH2O with A = NO3-, Cl- or CO3] were prepared by the urea and co-precipitation synthesis methods, which allowed for a detailed investigation on how synthesis parameters such as pH, metal ion concentration and post synthesis treatment influence the local and global structure of the LDH product. Information about sample composition, purity, defects and other structural aspects of the LDH products were obtained from powder X-ray diffraction, transmission electron microscopy, micro-Raman, and elemental analysis, as well as solid state 1H, 27Al and 67Zn NMR spectroscopy. Our results show that the urea method results in LDHs, which on the global scale are highly crystalline LDHs, whereas solid state NMR shows the different local environments indicating local disorder most likely linked to the presence of Al-rich phases. However, these Alrich phases are not detected by global range techniques, as they either defects within the LDH particles or separate phase(s) associated with LDHs. In contrast, samples prepared by coprecipitation especially synthesized under careful pH control and subsequently hydrothermal treated have high local order and good crystallinity (particle size). Our results show that both molecular level and macroscopic techniques are needed to assess the composition of LDHs, as the conventional PXRD and TEM analysis of LDHs failed to identify the many structural defects and/or amorphous phases.

  3. Biodiesel synthesis using calcined layered double hydroxide catalysts

    SciTech Connect

    Schumaker, J. Link; Crofcheck, Czarena; TAckett, S. Adam; Santillan-Jimenez, Eduardo; Morgan, Tonya; Ji, Yaying; Crocker, Mark; Toops, Todd J

    2008-01-01

    The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sites active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.

  4. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    SciTech Connect

    Benito, P.; Labajos, F.M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-15

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), {sup 27}Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al{sup 3+} and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M{sup 2+}/M{sup 3+} ratio and consequent modification of the cell parameters. - Graphical Abstract: The influence of the nature of the interlayer anion during the ageing process of carboxylate-intercalated (TA and ox) hydrotalcite-like compounds (HTlcs) is studied. Well crystallized for TA-containing compounds were obtained. However, the non-desired side-reaction of ox with the aluminum of the layers is enhanced by the microwaves and a partial destruction of the structure takes place.

  5. Development of an Immunosensor Based on Layered Double Hydroxides for MMR Cancer Biomarker Detection.

    PubMed

    Hammami, M; Soussou, A; Idoudi, F; Cohen-Bouhacina, T; Bouhaouala-Zahar, B; Baccar, Z M

    2015-10-01

    As a potential biomarker for the investigation of cancer inflammatory profiles, macrophage mannose receptor (MMR, CD206) is herein selected to develop an immunosensor based on layered double hydroxide (LDH). Like an endocyte C-type lectin receptor, MMR plays an important role in immune homeostasis by scavenging unwanted mannose glycoproteins. It attracts a progressive attention thanks to its particularly high expression within the tumor microenvironment. There is a great of interest to develop an immunosensor based on an antibody specific to MMR for detection of stroma versus tumor cells. In this work, we studied the feasibility of high sensitive MMR cancer Screen Printed Electrode (SPE) immunosensor. Working electrode of commercialized SPE was modified by immobilization of specific antibody (anti-MMR) into thin layer of LDH nanomaterials. Structural, morphological, and surface properties of LDHs were studied by X-Ray diffraction, atomic force microscopy and Infrared spectroscopy in ATR. Cyclic Voltammetry technique was used to study interaction between the human recombinant MMR protein (rHu-MMR, NSO derived) and an immobilized antibody into developed immunosensor. High specific response of -11.72 μA/ng.mL(-1) (with a correlation coefficient of R(2)=0.994 ) were obtained in linear range of 0.05 ng/mL to 10.0 ng/mL of specific recombinant antigen. The limit of detection (LOD) was less than 15.0 pg/mL. From these attractive results, the feasibility of an electrochemical immunosensor for cancer was proved. Additional experiments to study stability and reproducibility the immunosensor should be completed in perspective to use these anti-MMR based immunosensors for sensing human MMR in patient biopsies and sera. PMID:26316191

  6. Removal of boron from oilfield wastewater via adsorption with synthetic layered double hydroxides.

    PubMed

    Delazare, Thais; Ferreira, Letícia P; Ribeiro, Nielson F P; Souza, Mariana M V M; Campos, Juacyara C; Yokoyama, Lídia

    2014-01-01

    Hydrotalcite is a layered double hydroxide (LDH) consisting of brucite-like sheets of metal ions (Mg-Al). In this work, hydrotalcites were synthesized, and boron removal from oilfield wastewater was evaluated. LDHs were synthesized using the co-precipitation method. The calcined products (CLDHs) were obtained by heating at 500°C and characterized using X-ray diffraction, X-ray fluorescence, thermogravimetric analysis and the specific surface area (BET). The affinity of LDHs for borate ions was evaluated for calcined and uncalcined LDHs as a function of contact time, initial pH of the oilfield wastewater (pH ∼ 9) and the LDH surface area. The tests were conducted at room temperature (approximately 25ºC). The results indicated that 10 min were needed to reach a state of equilibrium during boron removal for calcined LDHs due to the high surface area (202.3 m(2) g(-1)) regardless of the initial pH of the oilfield wastewater, which resulted from the high buffering capacity of the LDHs. The adsorption capacity increased as the adsorbents levels increased for the range studied. After treatment of the oilfield wastewater containing 30 mg L(-1) of boron with Mg-Al-CO3-LDHs, the final concentration of boron was within the discharge limit set by current Brazilian environmental legislation, which is 5 mg L(-1). Pseudo-first-order and pseudo-second-order kinetic models were tested, and the latter was found to fit the experimental data better. Isotherms for boron adsorption by CLDHs were well described using the Langmuir and Freundlich equations. PMID:24766593

  7. Delaminated Layered Double Hydroxide Nanosheets as an Efficient Vector for DNA Delivery.

    PubMed

    Wang, Junya; Bao, Wenlong; Umar, Ahmad; Wang, Qiang; O'Hare, Dermot; Wan, Yinglang

    2016-05-01

    The performance of delaminated Mg-Al-lactate and Mg-Al-acetate layered double hydroxides (LDHs) nanosheets (Mg-Al-lactate-NS, Mg-Al-acetate-NS) as efficient vectors for DNA adsorption and delivery to 293T cells was investigated. Mg-Al-lactate and Mg-Al-acetate LDHs were delaminated into single layers in water and were characterized using XRD, SEM, TEM, and Zeta potential measurements. The salmon sperm DNA adsorption capacity of Mg-Al-lactate-NS and Mg-Al-acetate-NS were evaluated by varying the adsorbent dosage and contacting time, which suggested that Mg-Al-lactate-NS had much higher adsorption capacity (649.6 μg mg-1) than that of Mg-Al-acetate-NS (340.0 μg mg(-1)). XRD analysis indicated that after DNA adsorption the Mg-Al-lactate-NS-DNA bio-inorganic nanohybrid still stayed in an exfoliated form. Due to the difficulty in separating the Mg-Al-lactate-NS-DNA from solution, electrophoresis analysis was also applied to detect the free DNA in solution after adsorption. Cytotoxicity studies using 293T cells verified that Mg-Al-lactate-NS was less toxic than Mg-Al-acetate-NS as a smaller dose of this LDH was needed to deliver the same amount of salmon DNA to 293T cells. Cellular uptake and confocal imaging studies demonstrated that Mg-Al-lactate-NS was successful in transfection of ssDNA-FITC into 293T cells. However, the FITC-coupled single strand DNA was failed to be internalized into these cells. The excellent DNA adsorption and delivery capacities indicate that delaminated Mg-Al-lactate LDHs nanosheets are a better DNA vector than bulk phase LDH. PMID:27305815

  8. Synthesis, structure refinement and chromate sorption characteristics of an Al-rich bayerite-based layered double hydroxide

    SciTech Connect

    Britto, Sylvia Kamath, P. Vishnu

    2014-07-01

    “Imbibition” of Zn{sup 2+} ions into the cation vacancies of bayerite–Al(OH){sub 3} and NO{sub 3}{sup −} ions into the interlayer gallery yields an Al-rich layered double hydroxide with Al/Zn ratio ∼3. NO{sub 3}{sup −} ions are intercalated with their molecular planes inclined at an angle to the plane of the metal hydroxide slab and bonded to it by hydrogen bonds. Rietveld refinement of the structure shows that the monoclinic symmetry of the precursor bayerite is preserved in the product, showing that the imbibition is topochemical in nature. The nitrate ion is labile and is quantitatively replaced by CrO{sub 4}{sup 2−} ions from solution. The uptake of CrO{sub 4}{sup 2−} ions follows a Langmuir adsorption isotherm, thus showing that the hydroxide is a candidate material for green chemistry applications for the removal of CrO{sub 4}{sup 2−} ions from waste water. Rietveld refinement of the structure of the hydroxide after CrO{sub 4}{sup 2−} inclusion reveals that the CrO{sub 4}{sup 2−} ion is intercalated with one of its 2-fold axes parallel to the b-crystallographic axis of the crystal, also the principal 2 axis of the monoclinic cell. - Graphical abstract: The structure of the [Zn–Al4-nitrate] LDH viewed along the a-axis. - Highlights: • Synthesis of Al-rich layered double hydroxide with Al/Zn ratio ∼3. • Rietveld refinement indicates that the imbibition of Zn into Al(OH){sub 3} is topochemical in nature. • The uptake of CrO{sub 4}{sup 2−} ions follows a Langmuir adsorption isotherm.

  9. Electrochemical immunosensor with NiAl-layered double hydroxide/graphene nanocomposites and hollow gold nanospheres double-assisted signal amplification.

    PubMed

    Qiao, Lu; Guo, Yemin; Sun, Xia; Jiao, Yancui; Wang, Xiangyou

    2015-08-01

    A sensitive electrochemical immunosensor based on NiAl-layered double hydroxide/graphene nanocomposites (NiAl-LDH/G) and hollow gold nanospheres (HGNs) was proposed for chlorpyrifos detection. The NiAl-LDH/G was prepared using a conventional coprecipitation process and reduction of the supporting graphene oxide. Subsequently, the nanocomposites were dispersed with chitosan (CS). The NiAl-LDH/G possessed good electrochemical behavior and high binding affinity to the electrode. The high surface areas of HGNs and the vast aminos and hydroxyls of CS provided a platform for the covalently crosslinking of antibody. Under optimal conditions, the immunosensor exhibited a wide linear range from 5 to 150 μg/mL and from 150 to 2 μg/mL, with a detection limit of 0.052 ng/mL. The detection results showed good agreement with standard gas chromatography method. The constructed immunosensor exhibited good reproducibility, high specificity, acceptable stability and regeneration performance, which provided a new promising tool for chlorpyrifos detection in real samples. PMID:25801002

  10. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

    PubMed Central

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-01-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as −0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at −0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under −0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

  11. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst.

    PubMed

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-01-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as -0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at -0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under -0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

  12. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

    NASA Astrophysics Data System (ADS)

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-08-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as ‑0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at ‑0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under ‑0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination.

  13. Self-assembly preparation of SiO2@Ni-Al layered double hydroxide composites and their enhanced electrorheological characteristics

    PubMed Central

    Ji, Xuqiang; Zhang, Wenling; Shan, Lei; Tian, Yu; Liu, Jingquan

    2015-01-01

    The core-shell structured SiO2@Ni-Al layered double hydroxide (LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological (ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the samples was characterized by X-ray diffraction (XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy (XPS), Energy dispersive analysis of X-ray (EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances (yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field. PMID:26670467

  14. Ethanol Sensor of CdO/Al2O3/CeO2 Obtained from Ce-DOPED Layered Double Hydroxides with High Response and Selectivity

    NASA Astrophysics Data System (ADS)

    Xu, Dongmei; Guan, Meiyu; Xu, Qinghong; Guo, Ying; Wang, Yao

    2013-06-01

    In this paper, Ce-doped CdAl layered double hydroxide (LDH) was first synthesized and the derivative CdO/Al2O3/CeO2 composite oxide was prepared by calcining Ce-doped CdAl LDH. The structure, morphology and chemical state of the Ce doped CdAl LDH and CdO/Al2O3/CeO2 were also investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), solid state nuclear magnetic resonance (SSNMR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of CdO/Al2O3/CeO2 to ethanol were further studied and compared with CdO/Al2O3 prepared from CdAl LDH, CeO2 powder as well as the calcined Ce salt. It turns out that CdO/Al2O3/CeO2 sensor shows best performance in ethanol response. Besides, CdO/Al2O3/CeO2 possesses short response/recovery time (12/72 s) as well as remarkable selectivity in ethanol sensing, which means composite oxides prepared from LDH are very promising in gas sensing application.

  15. Self-assembly preparation of SiO2@Ni-Al layered double hydroxide composites and their enhanced electrorheological characteristics

    NASA Astrophysics Data System (ADS)

    Ji, Xuqiang; Zhang, Wenling; Shan, Lei; Tian, Yu; Liu, Jingquan

    2015-12-01

    The core-shell structured SiO2@Ni-Al layered double hydroxide (LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological (ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the samples was characterized by X-ray diffraction (XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy (XPS), Energy dispersive analysis of X-ray (EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances (yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field.

  16. Incorporation of transition metals into Mg Al layered double hydroxides: Coprecipitation of cations vs. their pre-complexation with an anionic chelator

    NASA Astrophysics Data System (ADS)

    Tsyganok, Andrey; Sayari, Abdelhamid

    2006-06-01

    A comparative study on two different methods for preparing Mg-Al layered double hydroxides (LDH) containing various divalent transition metals M ( M=Co, Ni, Cu) has been carried out. The first (conventional) method involved coprecipitation of divalent metals M(II) with Mg(II) and Al(III) cations using carbonate under basic conditions. The second approach was based on the ability of transition metals to form stable anionic chelates with edta 4- (edta 4-=ethylenediaminetetraacetate) that were synthesized and further introduced into LDH by coprecipitation with Mg and Al. The synthesized LDHs were characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF) methods, thermogravimetry with mass-selective detection of decomposition products (TG-MSD), Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The results obtained were discussed in terms of efficiency of transition metal incorporation into the LDH structure, thermal stability of materials and the ability of metal chelates to intercalate the interlayer space of Mg-Al LDH. Vibrational spectroscopy studies confirmed that the integrity of the metal chelates was preserved upon incorporation into the LDH.

  17. Self-assembly preparation of SiO2@Ni-Al layered double hydroxide composites and their enhanced electrorheological characteristics.

    PubMed

    Ji, Xuqiang; Zhang, Wenling; Shan, Lei; Tian, Yu; Liu, Jingquan

    2015-01-01

    The core-shell structured SiO2@Ni-Al layered double hydroxide (LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological (ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the samples was characterized by X-ray diffraction (XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy (XPS), Energy dispersive analysis of X-ray (EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances (yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field. PMID:26670467

  18. Development of efficient electrocatalysts via molecular hybridization of NiMn layered double hydroxide nanosheets and graphene

    NASA Astrophysics Data System (ADS)

    Ma, Wei; Ma, Renzhi; Wu, Jinghua; Sun, Pengzhan; Liu, Xiaohe; Zhou, Kechao; Sasaki, Takayoshi

    2016-05-01

    Ni2+Mn3+ layered double hydroxide (LDH) nanoplatelets have been hydrothermally synthesized in a homogeneous precipitation of mixed Ni2+/Mn2+ salts at a molar ratio of 2 : 1 via the hydrolysis of hexamethylenetetramine (HMT) and in situ oxidation with H2O2. After anion-exchange, NiMn LDH was exfoliated into unilamellar nanosheets. Subsequent flocculation of NiMn LDH nanosheets with (reduced) graphene oxide (GO/rGO) into superlattice composites was achieved and further tested as electrocatalysts for oxygen evolution reaction (OER). The face-to-face heteroassembly of NiMn LDH nanosheets with conductive rGO at an alternating sequence resulted in a small overpotential of 0.26 V and a Tafel slope of 46 mV per decade, which is much superior to as-exfoliated nanosheets. The analyses of electrochemical activity surface area (ECSA) and impedance spectra clearly indicated that the superlattice structure was ideal in facilitating the migration/transfer of the charge and reactants, revealing the electrochemical energetics and mechanism behind the synergistic effect arising from molecular hybridization. The proof of concept toward total water splitting using the newly developed hybrid electrocatalyst was demonstrated by an electrolysis cell powered by a single AA battery.Ni2+Mn3+ layered double hydroxide (LDH) nanoplatelets have been hydrothermally synthesized in a homogeneous precipitation of mixed Ni2+/Mn2+ salts at a molar ratio of 2 : 1 via the hydrolysis of hexamethylenetetramine (HMT) and in situ oxidation with H2O2. After anion-exchange, NiMn LDH was exfoliated into unilamellar nanosheets. Subsequent flocculation of NiMn LDH nanosheets with (reduced) graphene oxide (GO/rGO) into superlattice composites was achieved and further tested as electrocatalysts for oxygen evolution reaction (OER). The face-to-face heteroassembly of NiMn LDH nanosheets with conductive rGO at an alternating sequence resulted in a small overpotential of 0.26 V and a Tafel slope of 46 mV per decade

  19. Organo-layered double hydroxides composite thin films deposited by laser techniques

    NASA Astrophysics Data System (ADS)

    Birjega, R.; Vlad, A.; Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M.; Zavoianu, R.; Raditoiu, V.; Corobea, M. C.

    2016-06-01

    We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn2+/Al3+ ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

  20. Synthesis of protocatechuic acid-zinc/aluminium-layered double hydroxide nanocomposite as an anticancer nanodelivery system

    NASA Astrophysics Data System (ADS)

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Gani, Shafinaz Abd; Fakurazi, Sharida; Zainal, Zulkarnain

    2015-01-01

    Protocatechuic acid, an active anticancer agent, has been intercalated into Zn/Al-layered double hydroxide at Zn/Al=2) using two different preparation methods, co-precipitation and ion-exchange, which are labelled as PZAE and PZAC, respectively. The release of protocatechuate from the nanocomposites occurred in a controlled manner and was fitted satisfactorily to pseudo-second order kinetics. The basal spacing of the resulting nanocomposites PZAE and PZAC was 10.2 and 11.0 Å, respectively, indicating successful intercalation of protocatechuate anions into the interlayer galleries of Zn/Al-NO3-LDH in a monolayer arrangement with angles of 24 and 33° from the z-axis in PZAE and PZAC, respectively. The formation of nanocomposites was further confirmed by a Fourier transform infrared study. Thermogravimetric and differential thermogravimetric analyses indicated that the thermal stability of the intercalated protocatechuic acid was significantly enhanced compared to its free protocatechuic acid, and the drug content in the nanocomposites was estimated to be approximately 32.6% in PZAE and 29.2% in PZAC. Both PZAE and PZAC nanocomposites inhibit the growth of human cervical, liver and colorectal cancer cell lines and exhibit no toxic effects towards normal fibroblast 3T3 cell after 72 h of treatment.

  1. Mg-Al layered double hydroxides (LDHs) and their derived mixed oxides grown by laser techniques

    NASA Astrophysics Data System (ADS)

    Matei, A.; Birjega, R.; Nedelcea, A.; Vlad, A.; Colceag, D.; Ionita, M. D.; Luculescu, C.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2011-04-01

    Layered double hydroxides (LDHs) have been widely studied due to their applications as multifunctional materials, catalysts, host materials, anionic exchangers, adsorbents for environmental contaminants and for the immobilization of biological materials. As thin films, LDHs are good candidates for novel applications as sensors, corrosion resistant coatings or components in electro optical devices. For these applications, lamellar orientation-controlled film has to be fabricated. In this work, the successful deposition of LDH and their derived mixed oxides thin films by laser techniques is reported. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were the methods used for thin films deposition. The ability of Mg-Al LDHs as a carrier for metallic particles (Ag) has been considered. Frozen targets containing 10% powder in water were used for MAPLE, while for PLD the targets consisted in dry-pressed pellets. The structure and the surface morphology of the deposited films were examined by X-ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy and Secondary Ion Mass Spectrometry.

  2. Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface.

    PubMed

    Wang, Siming; Li, Zenghe; Lu, Chao

    2015-11-15

    Polyethyleneimine (PEI) is a positively charged polymer with hydrogen-bonding sites and hydrophobic chains. Therefore, it has been clearly established as an efficient adsorbent by means of these native properties in the literatures. However, there is apparently no good reason to disregard the use of PEI as a desired desorbent. Herein, using methyl orange as a model anionic dye, we investigated the desorption performances of PEI toward anionic dyes adsorbed on the surface of CO3-layered double hydroxides (LDHs) in a wide range of pH values. The experiment results showed that the positively charged PEI had very strong desorption capacity for anionic dyes at low pH values (<9.5) through electrostatic attraction between PEI and methyl orange because of the high degree of protonation of PEI. At high pH values (>9.5), PEI existed as neutral molecule, it could desorb methyl orange via hydrogen bonding between the amino groups of it and sulfonate group of methyl orange; simultaneously, the anion-exchange process occurred between abundant hydroxyl anions and anionic methyl orange. The adsorption capacity of the used LDH adsorbent was about 80% after five cycles of adsorption-desorption-regeneration, which was much higher than that conducted by 0.1M NaOH solution. These findings suggested that PEI could be regarded as a promising desorbent for enriching anionic dyes in wastewater and regenerating LDHs through surface adsorption-desorption cycles. PMID:26255712

  3. Synthesis and Characterization of Layered Double Hydroxides and Their Potential as Nonviral Gene Delivery Vehicles

    PubMed Central

    Balcomb, Blake; Singh, Moganavelli; Singh, Sooboo

    2015-01-01

    Layered double hydroxides (LDHs) exhibit characteristic anion-exchange chemistry making them ideal carriers of negatively charged molecules like deoxyribonucleic acid (DNA). In this study, hydrotalcite (Mg−Al) and hydrotalcite-like compounds (Mg−Fe, Zn−Al, and Zn−Fe), also known as LDHs, were evaluated for their potential application as a carrier of DNA. LDHs were prepared by coprecipitation at low supersaturation and characterized by Powder X-ray diffraction (XRD), infrared (IR), Raman, and inductively coupled plasma—optical emission spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD patterns showed strong and sharp diffraction peaks for the (003) and (006) planes indicating well-ordered crystalline materials. TEM images yielded irregular circular to hexagonal-shaped particles of 50–250 nm in size. Varying degrees of DNA binding was observed for all the compounds, and nuclease digestion studies revealed that the LDHs afford some degree of protection to the bound DNA. Minimal toxicity was observed in human embryonic kidney (HEK293), cervical cancer (HeLa) and hepatocellular carcinoma (HepG2) cell lines with most showing a cell viability in excess of 80 %. All LDH complexes promoted significant levels of luciferase gene expression, with the DNA:Mg−Al LDHs proving to be the most efficient in all cell lines. PMID:25969811

  4. Influence of emulsification process on the properties of Pickering emulsions stabilized by layered double hydroxide particles.

    PubMed

    Zhang, Nana; Zhang, Li; Sun, Dejun

    2015-04-28

    This paper reports the influence of emulsification process on the packing of layered double hydroxide (LDH) particles at the aqueous/oil phase interface and the properties of the resulting Pickering emulsions. Emulsions prepared by ultrasonication display superior long-term stability and gel-like characteristics at the dispersed phase volume fraction well below the random close packing limit, whereas emulsions with same compositions prepared by vortex mixing show some extent of sedimentation and liquid-like behaviors. Rheological measurements demonstrate that the zero-shear elastic modulus and yield stress of gel-like emulsions exhibit power-law dependences on particle concentration and independence on aqueous/oil phase ratio. The microstructural origin of this behavior is investigated by optical microscopy, revealing the droplets become strongly adhesive and a heterogeneous percolating network is formed among neighboring droplets. Fluorescent confocal microscopy measurements further confirm that the droplet adhesion is due to particle layers bridging opposite interfaces. In contrast, homogeneous, isolated, and densely packed droplets are present in emulsions prepared by vortex mixing, which results in these systems being dominantly viscous like the suspending fluid. This study shows that the emulsification process can be used as a trigger to modify long-term stability and rheology of solid-stabilized multiphase mixtures, which greatly expands their potential technological applications. PMID:25853297

  5. Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

    2016-01-01

    A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

  6. The structure and stability of CaFe layered double hydroxides with various Ca:Fe ratios studied by Mössbauer spectroscopy, X-ray diffractometry and microscopic analysis

    NASA Astrophysics Data System (ADS)

    Sipiczki, M.; Kuzmann, E.; Homonnay, Z.; Megyeri, J.; Pálinkó, I.; Sipos, P.

    2013-07-01

    The effects of the Ca(II)/Fe(III) ratios on the structure and Fe microenvironments have been studied in layered double hydroxides comprising of Ca(II) and Fe(III) (CaFe-LDH) prepared by the co-precipitation method. The Ca(II)/Fe(III) ratios were varied systematically from 2 to 6 and for characterisation 57Fe Mössbauer spectroscopy, powder X-ray diffractometry and scanning electron microscopy were applied. XRD patterns of the samples at all Ca(II)/Fe(III) ratios exhibited reflections corresponding to CaFe-LDH and 57Fe Mössbauer measurements revealed that Fe(III) was in a high-spin, somewhat disordered octahedral environment. Above the Ca(II)/Fe(III) ratio of 2 the reflections of Ca(OH)2 also appeared. This phase was found to stabilise the LDH phase, while the phase-pure LDH decomposed on ageing.

  7. Synthesis and Characterization of Chitosan-Coated Near-Infrared (NIR) Layered Double Hydroxide-Indocyanine Green Nanocomposites for Potential Applications in Photodynamic Therapy

    PubMed Central

    Wei, Pei-Ru; Kuthati, Yaswanth; Kankala, Ranjith Kumar; Lee, Chia-Hung

    2015-01-01

    We designed a study for photodynamic therapy (PDT) using chitosan coated Mg–Al layered double hydroxide (LDH) nanoparticles as the delivery system. A Food and Drug Administration (FDA) approved near-infrared (NIR) fluorescent dye, indocyanine green (ICG) with photoactive properties was intercalated into amine modified LDH interlayers by ion-exchange. The efficient positively charged polymer (chitosan (CS)) coating was achieved by the cross linkage using surface amine groups modified on the LDH nanoparticle surface with glutaraldehyde as a spacer. The unique hybridization of organic-inorganic nanocomposites rendered more effective and successful photodynamic therapy due to the photosensitizer stabilization in the interlayer of LDH, which prevents the leaching and metabolization of the photosensitizer in the physiological conditions. The results indicated that the polymer coating and the number of polymer coats have a significant impact on the photo-toxicity of the nano-composites. The double layer chitosan coated LDH–NH2–ICG nanoparticles exhibited enhanced photo therapeutic effect compared with uncoated LDH–NH2–ICG and single layer chitosan-coated LDH–NH2–ICG due to the enhanced protection to photosensitizers against photo and thermal degradations. This new class of organic-inorganic hybrid nanocomposites can potentially serve as a platform for future non-invasive cancer diagnosis and therapy. PMID:26340627

  8. Intercalation of papain enzyme into hydrotalcite type layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Zou, N.; Plank, J.

    2012-09-01

    Intercalation of proteolytic enzyme papain into hydrotalcite type LDH structure was achieved by controlled co-precipitation at pH=9.0 in the presence of papain. Characterization of the MgAl-papain-LDH phase was carried out using X-ray powder diffraction (XRD), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). According to XRD, papain was successfully intercalated. The d-value for the basal spacing of MgAl-papain-LDH was found at ˜5.3 nm. Consequently, original papain (hydrodynamic diameter ˜7.2 nm) attains a compressed conformation during intercalation.Formation of MgAl-papain-LDH was confirmed by elemental analysis and transmission electron microscopy (TEM). Under SEM, MgAl-papain-LDH phases appear as nanothin platelets which are intergrown to flower-like aggregates. Steric size and activity of the enzyme was retained after deintercalation from MgAl-LDH framework, as was evidenced by light scattering and UV/vis measurements. Thus, papain is not denatured during intercalation, and LDH is a suitable host structure which can provide a time-controlled release of the biomolecule.

  9. Hierarchical Co-based Porous Layered Double Hydroxide Arrays Derived via Alkali Etching for High-performance Supercapacitors

    PubMed Central

    Abushrenta, Nasser; Wu, Xiaochao; Wang, Junnan; Liu, Junfeng; Sun, Xiaoming

    2015-01-01

    Hierarchical nanoarchitecture and porous structure can both provide advantages for improving the electrochemical performance in energy storage electrodes. Here we report a novel strategy to synthesize new electrode materials, hierarchical Co-based porous layered double hydroxide (PLDH) arrays derived via alkali etching from Co(OH)2@CoAl LDH nanoarrays. This structure not only has the benefits of hierarchical nanoarrays including short ion diffusion path and good charge transport, but also possesses a large contact surface area owing to its porous structure which lead to a high specific capacitance (23.75 F cm−2 or 1734 F g−1 at 5 mA cm−2) and excellent cycling performance (over 85% after 5000 cycles). The enhanced electrode material is a promising candidate for supercapacitors in future application. PMID:26278334

  10. Cu-Ce-O mixed oxides from Ce-containing layered double hydroxide precursors: Controllable preparation and catalytic performance

    NASA Astrophysics Data System (ADS)

    Chang, Zheng; Zhao, Na; Liu, Junfeng; Li, Feng; Evans, David G.; Duan, Xue; Forano, Claude; de Roy, Marie

    2011-12-01

    Cu/Zn/Al layered double hydroxide (LDH) precursors have been synthesized using an anion exchange method with anionic Ce complexes containing the dipicolinate (pyridine-2,6-dicarboxylate) ligand. Cu-Ce-O mixed oxides were obtained by calcination of the Ce-containing LDHs. The materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry-differential thermal analysis, elemental analysis, and low temperature N 2 adsorption/desorption measurements. The results reveal that the inclusion of Ce has a significant effect on the specific surface area, pore structure, and chemical state of Cu in the resulting Cu-Ce-O mixed metal oxides. The resulting changes in composition and structure, particularly the interactions between Cu and Ce centers, significantly enhance the activity of the Ce-containing materials as catalysts for the oxidation of phenol by hydrogen peroxide.

  11. Ultrasonically-enhanced mechanochemical synthesis of CaAl-layered double hydroxides intercalated by a variety of inorganic anions.

    PubMed

    Szabados, Márton; Mészáros, Rebeka; Erdei, Szabolcs; Kónya, Zoltán; Kukovecz, Ákos; Sipos, Pál; Pálinkó, István

    2016-07-01

    CaAl-layered double hydroxides (CaAl-LDHs) were synthesised with various interlayer anions (CO3(2-), F(-), Cl(-), Br(-) and I(-)) by mechanochemical pre-treatment followed by ultrasonic irradiation in aqueous media. The parameters of the syntheses (duration of pre-milling and sonication, quality of the aqueous media, temperature) were altered in order to optimise the procedure and to understand the formation of LDH and other secondary products. The products were characterised by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The optimisation resulted in close-to-phase-pure CaAl-LDHs, not only with carbonate and chloride interlayer anions, but the hard-to-intercalate bromide and iodide as well. PMID:26964966

  12. Hierarchical Co-based Porous Layered Double Hydroxide Arrays Derived via Alkali Etching for High-performance Supercapacitors

    NASA Astrophysics Data System (ADS)

    Abushrenta, Nasser; Wu, Xiaochao; Wang, Junnan; Liu, Junfeng; Sun, Xiaoming

    2015-08-01

    Hierarchical nanoarchitecture and porous structure can both provide advantages for improving the electrochemical performance in energy storage electrodes. Here we report a novel strategy to synthesize new electrode materials, hierarchical Co-based porous layered double hydroxide (PLDH) arrays derived via alkali etching from Co(OH)2@CoAl LDH nanoarrays. This structure not only has the benefits of hierarchical nanoarrays including short ion diffusion path and good charge transport, but also possesses a large contact surface area owing to its porous structure which lead to a high specific capacitance (23.75 F cm-2 or 1734 F g-1 at 5 mA cm-2) and excellent cycling performance (over 85% after 5000 cycles). The enhanced electrode material is a promising candidate for supercapacitors in future application.

  13. Surfactant-modified flowerlike layered double hydroxide-coated magnetic nanoparticles for preconcentration of phthalate esters from environmental water samples.

    PubMed

    Zhao, Xiaoli; Liu, Shuangliu; Wang, Peifang; Tang, Zhi; Niu, Hongyun; Cai, Yaqi; Wu, Fengchang; Wang, Hao; Meng, Wei; Giesy, John P

    2015-10-01

    A novel type of layered, flowerlike magnetic double hydroxide (MLDH) nanoparticles modified by surfactants has been successfully synthesized and was applied as an effective sorbent for pre-concentration of several phthalate ester pollutants (PAEs) from water prior to quantification. The MLDH was obtained via a simple ultrasound-assisted method by using silica coated Fe3O4 as the core and anisotropic Mg-Al layered double hydroxide (Mg-Al LDH) nanocrystals as the shell to which analytes were absorbed. Orientation and dimensionality hierarchical structure as well as the large expandable interlayer free space and positive charge of the Mg-Al LDH shell make it easier to form anionic surfactant micelles on its surface via self-assembly. Due to its high adsorption area, compared with non-mesoporous nano solid-phase extraction agents, mesoporous channel shell and reduction diffusion path, MLDH exhibited high extraction efficiency of organic target residues. Under optimized conditions, with a total of 30mg of adsorbant added to from samples containing 400mL water from the environment recoveries of DPP, DBP, DCP and DOP were consistent with ranges of 69-101%, 79-101%, 86-102% and 63-100%, respectively. Standard deviations of recoveries ranged from 1 to 7%, respectively and the method was sensitive with limits of detection of 12.3, 18.7, 36.5 and 15.6ngL(-1). To the best of our knowledge, this is the first report of use of surfactant-modified MLDH nanoparticles and its application as adsorbent to pre-concentration of PAEs from environmental water samples prior to instrumental analyses. PMID:26342875

  14. Closing the Phosphorus Loop by Recovering Phosphorus From Waste Streams With Layered Double Hydroxide Nanocomposites and Converting the Product into an Efficient Fertilizer

    NASA Astrophysics Data System (ADS)

    Yan, H.; Shih, K.

    2015-12-01

    Phosphorus (P) recovery has been frequently discussed in recent decades due to the uncertain availability and uneven distribution of global phosphate rock reserves. Sorption technology is increasingly considered as a reliable, efficient and environmentally friendly P removal method from aqueous solution. In this study, a series of Mg-Al-based layered double hydroxide nanocomposites and their corresponding calcined products were fabricated and applied as phosphate adsorbents. The prepared samples were with average size at ~50 nm and self-assembled into larger particles in irregular shapes. The results of batch adsorption experiments demonstrated that calcination significantly enhanced the adsorption ability of LDHs for phosphorus, and the maximum adsorption capacity of calcined Mg-Al-LDH was as high as 100.7 mg-P/g. Furthermore, incorporation of Zr4+ and La3+ into LDH materials increases the sorption selectivity as well as sorption amount of phosphorus in LDHs, which was confirmed by experiments operated in synthetic human urine. For the first time ammonia (NH4OH) and potassium hydroxide (KOH) solutions were employed to desorb the P-loaded LDH. Identification of solids derived from two eluting solutions showed that struvite (MgNH4PO4•6H2O, MAP) was precipitated in ammonia solution while most phosphate was desorbed into liquid phase in KOH system without crystallization of potassium struvite (MgKPO4•6H2O) due to its higher solubility. Quantitative X-ray diffraction technique was used to determine struvite contents in obtained solids and the results revealed that ~ 30% of adsorbed P was transferred into struvite form in the sample extracted by 0.5M NH4OH. Leaching tests suggested that the phosphorus releasing kinetics of ammonia treated LDH was comparable to that of pure struvite product, indicating that postsorption Mg-Al-LDH desorbed with ammonia could serve as a slow-releasing fertilizer in agriculture (see Figure 1).

  15. Cu-Ce-O mixed oxides from Ce-containing layered double hydroxide precursors: Controllable preparation and catalytic performance

    SciTech Connect

    Chang Zheng; Zhao Na; Liu Junfeng; Li Feng; Evans, David G.; Duan Xue; Forano, Claude; Roy, Marie de

    2011-12-15

    Cu/Zn/Al layered double hydroxide (LDH) precursors have been synthesized using an anion exchange method with anionic Ce complexes containing the dipicolinate (pyridine-2,6-dicarboxylate) ligand. Cu-Ce-O mixed oxides were obtained by calcination of the Ce-containing LDHs. The materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry-differential thermal analysis, elemental analysis, and low temperature N{sub 2} adsorption/desorption measurements. The results reveal that the inclusion of Ce has a significant effect on the specific surface area, pore structure, and chemical state of Cu in the resulting Cu-Ce-O mixed metal oxides. The resulting changes in composition and structure, particularly the interactions between Cu and Ce centers, significantly enhance the activity of the Ce-containing materials as catalysts for the oxidation of phenol by hydrogen peroxide. - Graphical Abstract: Cu-Ce-O mixed oxides calcined from [Ce(dipic){sub 3}]{sup 3-}- intercalated Cu/Zn/Al layered double hydroxides were synthesized and displayed good catalytic performances in phenol oxidation due to the Cu-Ce interactions. Highlights: Black-Right-Pointing-Pointer [Ce(dipic){sub 3}]{sup 3-}-intercalated Cu/Zn/Al layered double hydroxides were synthesized. Black-Right-Pointing-Pointer Cu-Ce-O mixed oxides derivated from the LDHs were characterized as catalysts. Black-Right-Pointing-Pointer Presence of Ce influenced physicochemical property and catalytic performance. Black-Right-Pointing-Pointer Cu-Ce interaction was largely responsible for enhanced catalytic ability.

  16. Reversible hydration and aqueous exfoliation of the acetate-intercalated layered double hydroxide of Ni and Al: Observation of an ordered interstratified phase

    NASA Astrophysics Data System (ADS)

    Manohara, G. V.; Vishnu Kamath, P.; Milius, Wolfgang

    2012-12-01

    Acetate-intercalated layered double hydroxides (LDHs) of Ni and Al undergo reversible hydration in the solid state in response to the ambient humidity. The LDH with a high layer charge (0.33/formula unit) undergoes facile hydration in a single step, whereas the LDH with a lower layer charge (0.24/formula unit) exhibits an ordered interstratified intermediate, comprising the hydrated and dehydrated layers stacked alternatively. This phase, also known as the staged S-2 phase, coexists with the end members suggesting the existence of a solution-type equilibrium between the S-2 phase and the end members of the hydration cycle. These LDHs also undergo facile aqueous exfoliation into 2-5 nm-thick tactoids with a radial dimension of 0.2-0.5 μm.

  17. Synthesis, characterization, and immune efficacy of layered double hydroxide@SiO2 nanoparticles with shell-core structure as a delivery carrier for Newcastle disease virus DNA vaccine

    PubMed Central

    Zhao, Kai; Rong, Guangyu; Guo, Chen; Luo, Xiaomei; Kang, Hong; Sun, Yanwei; Dai, Chunxiao; Wang, Xiaohua; Wang, Xin; Jin, Zheng; Cui, Shangjin; Sun, Qingshen

    2015-01-01

    Layered double hydroxide (LDH)@SiO2 nanoparticles were developed as a delivery carrier for the plasmid DNA expressing the Newcastle disease virus F gene. The LDH was hydrotalcite-like materials. The plasmid DNA encapsulated in the LDH@SiO2 nanoparticles (pFDNA-LDH@SiO2-NPs) was prepared by the coprecipitation method, and the properties of pFDNA-LDH@SiO2-NPs were characterized by transmission electron microscopy, zeta potential analyzer, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The results demonstrated that the pFDNA-LDH@SiO2-NPs had a regular morphology and high stability with a mean diameter of 371.93 nm, loading capacity of 39.66%±0.45%, and a zeta potential of +31.63 mV. A release assay in vitro showed that up to 91.36% of the total plasmid DNA could be sustainably released from the pFDNA-LDH@SiO2-NPs within 288 hours. The LDH@SiO2 nanoparticles had very low toxicity. Additionally, their high transfection efficiency in vitro was detected by fluorescent microscopy. Intranasal immunization of specific pathogen-free chickens with pFDNA-LDH@SiO2-NPs induced stronger cellular, humoral, and mucosal immune responses and achieved a greater sustained release effect than intramuscular naked plasmid DNA, and the protective efficacy after challenge with the strain F48E9 with highly virulent (mean death time of chicken embryos ≤60 hours, intracerebral pathogenicity index in 1 -day-old chickens >1.6) was 100%. Based on the results, LDH@SiO2 nanoparticles can be used as a delivery carrier for mucosal immunity of Newcastle disease DNA vaccine, and have great application potential in the future. PMID:25926734

  18. Synthesis, characterization, and immune efficacy of layered double hydroxide@SiO2 nanoparticles with shell-core structure as a delivery carrier for Newcastle disease virus DNA vaccine.

    PubMed

    Zhao, Kai; Rong, Guangyu; Guo, Chen; Luo, Xiaomei; Kang, Hong; Sun, Yanwei; Dai, Chunxiao; Wang, Xiaohua; Wang, Xin; Jin, Zheng; Cui, Shangjin; Sun, Qingshen

    2015-01-01

    Layered double hydroxide (LDH)@SiO2 nanoparticles were developed as a delivery carrier for the plasmid DNA expressing the Newcastle disease virus F gene. The LDH was hydrotalcite-like materials. The plasmid DNA encapsulated in the LDH@SiO2 nanoparticles (pFDNA-LDH@SiO2-NPs) was prepared by the coprecipitation method, and the properties of pFDNA-LDH@SiO2-NPs were characterized by transmission electron microscopy, zeta potential analyzer, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The results demonstrated that the pFDNA-LDH@SiO2-NPs had a regular morphology and high stability with a mean diameter of 371.93 nm, loading capacity of 39.66%±0.45%, and a zeta potential of +31.63 mV. A release assay in vitro showed that up to 91.36% of the total plasmid DNA could be sustainably released from the pFDNA-LDH@SiO2-NPs within 288 hours. The LDH@SiO2 nanoparticles had very low toxicity. Additionally, their high transfection efficiency in vitro was detected by fluorescent microscopy. Intranasal immunization of specific pathogen-free chickens with pFDNA-LDH@SiO2-NPs induced stronger cellular, humoral, and mucosal immune responses and achieved a greater sustained release effect than intramuscular naked plasmid DNA, and the protective efficacy after challenge with the strain F48E9 with highly virulent (mean death time of chicken embryos ≤60 hours, intracerebral pathogenicity index in 1 -day-old chickens >1.6) was 100%. Based on the results, LDH@SiO2 nanoparticles can be used as a delivery carrier for mucosal immunity of Newcastle disease DNA vaccine, and have great application potential in the future. PMID:25926734

  19. 8-Hydroxypyrene-1,3,6-trisulphonate and octanesulphonate co-assembled layered double hydroxide and its controllable solid-state luminescence by hydrothermal synthesis

    SciTech Connect

    Dang Sile; Yan Dongpeng; Lu Jun

    2012-01-15

    8-Hydroxy-pyrene-1,3,6-trisulphonate (HPTS) and octanesulphonate (OS) have been co-intercalated into the ZnAl layered double hydroxide (LDH) host by a hydrothermal co-precipitation method, with samples denoted as HPTS (x%)-OS/Zn{sub 2}Al-LDH (x stands for the molar percentage content of HPTS with respect to total amount of HPTS and OS). The structure and chemical compositions of the as-prepared compounds were characterized by X-ray diffraction (XRD) and elemental analysis. The steady-state and time-decay fluorescent studies show that HPTS (2%)-OS/Zn{sub 2}Al-LDH has the optimal luminous emission and the longest fluorescent lifetime. Moreover, these samples exhibit controllable dual fluorescence between the blue and green regions upon changing the interlayer HPTS content, external pH values, and host-guest interaction, illustrating that these organic-inorganic samples have potential application in the field of tunable solid luminescent materials. - Graphical Abstract: 8-Hydroxy-pyrene-1,3,6-trisulphonate and octanesulfonate co-intercalated ZnAl layered double hydroxide can exhibit tunable solid-state blue and green fluorescence by treating the sample at acid and neutral media under hydrothermal condition. Highlights: Black-Right-Pointing-Pointer 8-hydroxy-pyrene-1,3,6-trisulphonate (HPTS) was intercalated into ZnAl LDHs. Black-Right-Pointing-Pointer They show the controllable dual fluorescence response to the HPTS content and pH values. Black-Right-Pointing-Pointer Fluorescence of the HPTS/LDH film was insensitive to the quencher (Cu{sup 2+}) concentration.

  20. Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc iron layered double hydroxides by one-step coprecipitation route

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Wen, Xing; Wang, Yingxia

    2007-05-01

    Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Mössbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO 42--containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO 42--containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn 0.435·Fe II0.094·Fe III0.470·(OH) 2]·(SO 42-) 0.235·1.0H 2O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO 42--containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS.

  1. Magnetic nanomaterial derived from graphene oxide/layered double hydroxide hybrid for efficient removal of methyl orange from aqueous solution.

    PubMed

    Yang, Zhe; Ji, Shanshan; Gao, Wei; Zhang, Chao; Ren, Lulu; Tjiu, Weng Weei; Zhang, Zheng; Pan, Jisheng; Liu, Tianxi

    2013-10-15

    Magnetic hybrid nanomaterials composed of reduced graphene oxide, zero-valent nickel, and NiAl-mixed metal oxides (rGO/Ni/MMO) have been synthesized by calcining graphene oxide (GO)/layered double hydroxide (LDH) hybrid in nitrogen atmosphere. Structural characterizations demonstrate that with the presence of GO substrate, NiAl-LDHs can be reduced into zero-valent Ni and NiAl-MMOs during calcination. Transmission electron microscopy (TEM) is used to investigate the morphology of the as-prepared hybrid nanomaterials, demonstrating that the introduction of GO substrate prevents the aggregation of LDHs. Magnetism characterization proves the ferromagnetic property of rGO/Ni/MMO hybrid. This magnetic hybrid nanomaterial exhibits excellent adsorption ability toward methyl orange (MO) in aqueous solutions. The kinetics of the adsorption process and the adsorption isotherm are investigated. The MO removal process is found to obey the Redlich-Peterson isotherm model, and its kinetics follows pseudo-second-order rate equation. In addition, the magnetic hybrid also exhibits good recycle ability for MO removal. This novel magnetic hybrid nanomaterial derived from GO/LDH hybrid demonstrates great potential in the applications of water treatment. PMID:23928490

  2. High performance NiFe layered double hydroxide for methyl orange dye and Cr(VI) adsorption.

    PubMed

    Lu, Yi; Jiang, Bin; Fang, Liang; Ling, Faling; Gao, Jiemei; Wu, Fang; Zhang, Xihua

    2016-06-01

    The NiFe layered double hydroxides (LDHs) with different mole ratio of Ni/Fe (4:1, 3:1, 7:3 and 1:1) were prepared by a simple coprecipitation method. The adsorption performance were evaluated by the removal of methyl orange (MO) dye and hexavalent chromium(VI) heavy metal ion. It is found that Ni4Fe1-LDH can remove more than 92% of MO in 10 min at the 10 mg/L MO initial concentration, and 97% of Cr(VI) in 1 h at 4 mg/L Cr2O7(2-) initial concentration. The saturated adsorption capacity of Ni4Fe1-LDH is found to be as large as 205.76 mg/g for MO and 26.78 mg/g for Cr(VI). The adsorption behavior of this new adsorbent is fitted well with Langmuir isotherm and the pseudo-second-order kinetic model, indicative of a monolayer and chemical adsorption that synergistically originates from exchangeable anions mechanism and layer charge density. Due to the excellent removal capacity of MO and Cr(VI), the NiFe-LDHs could be a promising adsorbent for wastewater treatment. PMID:26999751

  3. Phase behavior of aqueous suspensions of Mg(2)Al layered double hydroxide: the competition among nematic ordering, sedimentation, and gelation.

    PubMed

    Zhang, Jie; Luan, Lingyu; Zhu, Wenxia; Liu, Shangying; Sun, Dejun

    2007-05-01

    Birefringence observations and rheological measurements were used to monitor the phase behavior of Mg/Al (the molar ratio of Mg(2+) to Al(3+) being 2:1) layered double hydroxide (LDH) suspensions. The suspensions of concentration lower than 16% (w/w) appear isotropic (I) between crossed polarizers. In contrast, the suspensions of concentration between 16% and 30% (w/w) showed an isotropic (I)-nematic (N) biphasic coexistence. Detailed observations led us to divide the suspensions in the gap into three groups according to their behaviors: the suspensions with concentration between 16% and 25% (w/w) experienced an I-N phase transition and particle sedimentation simultaneously, while the suspensions of 25% to 27% (w/w) showed I-N transition after particle sedimentation, and in the suspension of 30% (w/w), a critical sol-gel transition appeared with an I-N transition. Above 33% (w/w), the gel network hindered a complete I-N separation in the suspensions. Upon raising the NaCl concentration, the liquid crystalline phase transition and the sol-gel transition shifted to higher particle concentrations. The facts demonstrate that the phase behavior of aqueous LDH suspensions is controlled by the competition among liquid crystal phase transition, sedimentation, and gelation. PMID:17439162

  4. Supported catalysts based on layered double hydroxides for catalytic oxidation and hydrogenation: general functionality and promising application prospects.

    PubMed

    Feng, Junting; He, Yufei; Liu, Yanan; Du, Yiyun; Li, Dianqing

    2015-08-01

    Oxidation and hydrogenation catalysis plays a crucial role in the current chemical industry for the production of key chemicals and intermediates. Because of their easy separation and recyclability, supported catalysts are widely used in these two processes. Layered double hydroxides (LDHs) with the advantages of unique structure, composition diversity, high stability, ease of preparation and low cost have shown great potential in the design and synthesis of novel supported catalysts. This review summarizes the recent progress in supported catalysts by using LDHs as supports/precursors for catalytic oxidation and hydrogenation. Particularly, partial hydrogenation of acetylene, hydrogenation of dimethyl terephthalate, methanation, epoxidation of olefins, elimination of NOx and SOx emissions, and selective oxidation of biomass have been chosen as representative reactions in the petrochemical, fine chemicals, environmental protection and clean energy fields to highlight the potential application and the general functionality of LDH-based catalysts in catalytic oxidation and hydrogenation. Finally, we concisely discuss some of the scientific challenges and opportunities of supported catalysts based on LDH materials. PMID:25962432

  5. Luminescent ultrathin film of anionic styrylbiphenyl derivative-layered double hydroxide and its reversible sensing for heavy metal ions.

    PubMed

    Yan, Dongpeng; Lu, Jun; Wei, Min; Li, Shuangde; Evans, David G; Duan, Xue

    2012-06-28

    Ordered ultrathin films (UTFs) with blue luminescence based on a styrylbiphenyl derivative (BTBS) and Mg-Al-layered double hydroxide (LDH) nanosheets have been constructed employing the layer-by-layer assembly technique. UV-visible absorption and fluorescence spectroscopy showed a stepwise and regular growth of the films upon increasing the number of deposition cycles. XRD, AFM and SEM indicated that the films possess a periodic layered structure with a period of ca. 1.5 nm, and uniform surface morphology. The film thickness can be precisely controlled in the range ca. 15-53 nm. The BTBS-LDH UTFs exhibit improved UV-light resistance capability compared with the pristine BTBS and show well-defined polarized photoemission, with anisotropy of ca. 0.24. The UTFs show a fast, selective and reversible luminescent response to aqueous solutions containing different heavy metal ions, with the most significant luminescent quenching occurring for the Hg(2+) solution, shedding light on the fact that these films can serve as a new type of selective solid luminescent metal-ion sensor. PMID:22491140

  6. Preparation of an anionic azo pigment-pillared layered double hydroxide and the thermo- and photostability of the resulting intercalated material

    NASA Astrophysics Data System (ADS)

    Guo, Shengchang; Li, Dianqing; Zhang, Weifeng; Pu, Min; Evans, David G.; Duan, Xue

    2004-12-01

    A large anionic pigment has been intercalated into a layered double hydroxide (LDH) host by ion-exchange of an Mg/Al LDH-nitrate precursor with a solution of C.I. Pigment Red 48:2 (the calcium salt of 4-((5-chloro-4-methyl-2-sulfophenyl)azo)-3-hydroxy-2-naphthalene-carboxylic acid), in ethane-1,2-diol. After intercalation of the pigment, the interlayer distance in the LDH increases from 0.86 to 1.72 nm. Infrared spectra and TG-DTA curves reveal the presence of a complex system of supramolecular host-guest interactions. The UV-visible diffuse reflectance spectra of C.I. Pigment Red 48:2 show marked changes after heating at 200 °C and above, whereas there are no significant changes in the spectra of the intercalated pigment after heating at temperatures up to 300 °C, showing that the thermostability is markedly enhanced by intercalation in the LDH host. The pigment-intercalated LDHs exhibits much higher photostability to UV light than the pristine pigment, in the case of both the pure solids and their composites with polypropylene, as shown by measurement of CIE 1976 L*a*b* color difference ( ΔE) values.

  7. Selective extraction by dissolvable (nitriloacetic acid-nickel)-layered double hydroxide coupled with reaction with potassium thiocyanate for sensitive detection of iron(III).

    PubMed

    Tang, Sheng; Chang, Yuepeng; Shen, Wei; Lee, Hian Kee

    2016-07-01

    A highly selective method has been proposed for the determination of iron cation (Fe(3+)). (Nitriloacetic acid-nickel)-layered double hydroxide ((NTA-Ni)-LDH) was successfully synthesized and used as dissolvable sorbent in dispersive solid-phase extraction to pre-concentrate and separate Fe(3+) from aqueous phase. Since Fe(3+) has a larger formation constant with NTA compared to Ni(2+), subsequently ion exchange occurred when (NTA-Ni)-LDH was added to the sample solution. The resultant (NTA-Fe)-LDH sol was isolated and transferred in an acidic medium containing potassium thiocyanate (KSCN). Since (NTA-Fe)-LDH could be dissolved in acidic conditions, Fe(3+)was released and reacted with SCN(-) to form an Fe-SCN complex. The resulting product was measured by ultraviolet-visible spectrometry for quantitative detection of Fe(3+). Extraction factors, including sample pH, reaction pH, extraction temperature, extraction time, reaction time and concentration of KSCN were optimized. This method achieved a low limit of detection of 15.2nM and a good linear range from 0.05 to 50μM (r(2)=0.9937). A nearly 18-fold enhancement of signal intensity was achieved after selective extraction. The optimized conditions were validated by applying the method to determine Fe(3+) in seawater samples. PMID:27154694

  8. Formation of Zn-rich phyllosilicate, Zn-layered double hydroxide and hydrozincite in contaminated calcareous soils

    SciTech Connect

    Jacquat, Olivier; Voegelin, Andreas; Villard, Andre; Marcus, Matthew A.; Kretzschmar, Ruben

    2007-10-15

    Recent studies demonstrated that Zn-phyllosilicate- and Zn-layered double hydroxide-type (Zn-LDH) precipitates may form in contaminated soils. However, the influence of soil properties and Zn content on the quantity and type of precipitate forming has not been studied in detail so far. In this work, we determined the speciation of Zn in six carbonate-rich surface soils (pH 6.2 to 7.5) contaminated by aqueous Zn in the runoff from galvanized power line towers (1322 to 30090 mg/kg Zn). Based on 12 bulk and 23 microfocused extended X-ray absorption fine structure (EXAFS) spectra, the number, type and proportion of Zn species were derived using principal component analysis, target testing, and linear combination fitting. Nearly pure Zn-rich phyllosilicate and Zn-LDH were identified at different locations within a single soil horizon, suggesting that the local availabilities of Al and Si controlled the type of precipitate forming. Hydrozincite was identified on the surfaces of limestone particles that were not in direct contact with the soil clay matrix. With increasing Zn loading of the soils, the percentage of precipitated Zn increased from {approx}20% to {approx}80%, while the precipitate type shifted from Zn-phyllosilicate and/or Zn-LDH at the lowest studied soil Zn contents over predominantly Zn-LDH at intermediate loadings to hydrozincite in extremely contaminated soils. These trends were in agreement with the solubility of Zn in equilibrium with these phases. Sequential extractions showed that large fractions of soil Zn ({approx}30% to {approx}80%) as well as of synthetic Zn-kerolite, Zn-LDH, and hydrozincite spiked into uncontaminated soil were readily extracted by 1 M NH{sub 4}NO{sub 3} followed by 1 M NH{sub 4}-acetate at pH 6.0. Even though the formation of Zn precipitates allows for the retention of Zn in excess to the adsorption capacity of calcareous soils, the long-term immobilization potential of these precipitates is limited.

  9. Formation of Zn-rich Phyllosilicate, Zn-Layered Double Hydroxide and Hydrozincite in Contaminated Calcareous Soils

    SciTech Connect

    Jacquat, O.; Voegelin, A; Villard, A; Marcus, M; Kretaschmar, R

    2008-01-01

    Recent studies demonstrated that Zn-phyllosilicate- and Zn-layered double hydroxide-type (Zn-LDH) precipitates may form in contaminated soils. However, the influence of soil properties and Zn content on the quantity and type of precipitate forming has not been studied in detail so far. In this work, we determined the speciation of Zn in six carbonate-rich surface soils (pH 6.2-7.5) contaminated by aqueous Zn in the runoff from galvanized power line towers (1322-30,090 mg/kg Zn). Based on 12 bulk and 23 micro-focused extended X-ray absorption fine structure (EXAFS) spectra, the number, type and proportion of Zn species were derived using principal component analysis, target testing, and linear combination fitting. Nearly pure Zn-rich phyllosilicate and Zn-LDH were identified at different locations within a single soil horizon, suggesting that the local availabilities of Al and Si controlled the type of precipitate forming. Hydrozincite was identified on the surfaces of limestone particles that were not in direct contact with the soil clay matrix. With increasing Zn loading of the soils, the percentage of precipitated Zn increased from {approx}20% to {approx}80%, while the precipitate type shifted from Zn-phyllosilicate and/or Zn-LDH at the lowest studied soil Zn contents over predominantly Zn-LDH at intermediate loadings to hydrozincite in extremely contaminated soils. These trends were in agreement with the solubility of Zn in equilibrium with these phases. Sequential extractions showed that large fractions of soil Zn ({approx}30-80%) as well as of synthetic Zn-kerolite, Zn-LDH, and hydrozincite spiked into uncontaminated soil were readily extracted by 1 M NH4NO3 followed by 1 M NH4-acetate at pH 6.0. Even though the formation of Zn-precipitates allows for the retention of Zn in excess to the adsorption capacity of calcareous soils, the long-term immobilization potential of these precipitates is limited.

  10. Structure of oxides prepared by decomposition of layered double Mg–Al and Ni–Al hydroxides

    SciTech Connect

    Cherepanova, Svetlana V.; Leont’eva, Natalya N.; Arbuzov, Aleksey B.; Drozdov, Vladimir A.; Belskaya, Olga B.; Antonicheva, Nina V.

    2015-05-15

    Abstracts: Thermal decomposition of Mg–Al and Ni–Al layered double hydroxides LDH at temperatures lower than 800 °C leads to the formation of oxides with different structures. Mg–Al oxide has a very defective structure and consists of octahedral layers as in periclase MgO and mixed octahedral–tetrahedral layers as in spinel MgAl{sub 2}O{sub 4}. Mixed Ni–Al oxide has a sandwich-like structure, consisting of a core with Al-doped NiO-like structure and some surface layers with spinel NiAl{sub 2}O{sub 4} structure epitaxial connected with the core. Suggested models were verified by simulation of X-ray diffraction patterns using DIFFaX code, as well as HRTEM, IR-, UV-spectroscopies, and XPS. - Graphical abstract: In the Mg–Al layered double hydroxide Al{sup 3+} ions migrate into interlayers during decomposition. The Mg–Al oxide represents sequence of octahedral and octahedral–tetrahedral spinel layers with vacancies. The Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers as a result of migration of Al{sup 3+} ions on the surface. The models explain the presence and absence of “memory effect” for the Mg–Al and Ni–Al oxides, respectively. - Highlights: • We study products of Mg(Ni)–Al LDH decomposition by calcination at 500(400)–800 °C. • In Mg–Al/Ni–Al LDH Al ions migrate into interlayers/on the surface during decomposition. • Mg–Al oxide represents sequence of periclase- and spinel-like layers with vacancies. • Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers. • The models explain the presence/absence of “memory effect” for Mg–Al/Ni–Al oxides.

  11. Efficient defluoridation of water using reusable nanocrystalline layered double hydroxides impregnated polystyrene anion exchanger.

    PubMed

    Cai, Jianguo; Zhang, Yanyang; Pan, Bingcai; Zhang, Weiming; Lv, Lu; Zhang, Quanxing

    2016-10-01

    Water decontamination from fluoride is still a challenging task of global concern. Recently, Al-based layered double hydroxides (LDHs) have been extensively studied for specific fluoride adsorption from water. Unfortunately, they cannot be readily applied in scaled-up application due to their ultrafine particles as well as the regeneration issues caused by their poor stability at alkaline pHs. Here, we developed a novel (LDH)-based hybrid adsorbent, i.e., LALDH-201, by impregnating nanocrystalline Li/Al LDHs (LADLH) inside a commercial polystyrene anion exchanger D201. TEM image and XRD spectra of the resultant nanocomposite confirmed that the LDHs particles were nanosized inside the pores of D201 of highly crystalline nature and well-ordered layer structure. After impregnation, the chemical and mechanical stability of LALDH were significantly improved against pH variation, facilitating its application at a wide pH range (3.5-12). Fluoride adsorption onto LALDH-201 was compared to D201 and activated alumina, evidencing the preferable removal fluoride of LALDH-201. Fluoride adsorption onto LALDH-201 followed pseudo-second-order model, with the maximum capacity (62.5 mg/g from the Sips model) much higher than the other two adsorbents. Fixed-bed adsorption run indicated the qualified treatable volume of the fluoride contaminated groundwater (4.1 mg/L initially) with LALDH-201 was about 11 times as much as with the anion exchanger D201 when the breakthrough point was set as 1.5 mg/L. The capacity of LALDH-201 could be effectively refreshed for continuous column operation without observable loss by using the mixed solution of 0.01 M NaOH + 1 M NaCl. The above results suggested that the hybrid adsorbent LALDH-201 is very promising for water defluoridation in scaled-up application. PMID:27337346

  12. Synthesis of protocatechuic acid–zinc/aluminium–layered double hydroxide nanocomposite as an anticancer nanodelivery system

    SciTech Connect

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Gani, Shafinaz Abd; Fakurazi, Sharida; Zainal, Zulkarnain

    2015-01-15

    Protocatechuic acid, an active anticancer agent, has been intercalated into Zn/Al–layered double hydroxide at Zn/Al=2) using two different preparation methods, co-precipitation and ion-exchange, which are labelled as PZAE and PZAC, respectively. The release of protocatechuate from the nanocomposites occurred in a controlled manner and was fitted satisfactorily to pseudo-second order kinetics. The basal spacing of the resulting nanocomposites PZAE and PZAC was 10.2 and 11.0 Å, respectively, indicating successful intercalation of protocatechuate anions into the interlayer galleries of Zn/Al–NO{sub 3}–LDH in a monolayer arrangement with angles of 24 and 33° from the z-axis in PZAE and PZAC, respectively. The formation of nanocomposites was further confirmed by a Fourier transform infrared study. Thermogravimetric and differential thermogravimetric analyses indicated that the thermal stability of the intercalated protocatechuic acid was significantly enhanced compared to its free protocatechuic acid, and the drug content in the nanocomposites was estimated to be approximately 32.6% in PZAE and 29.2% in PZAC. Both PZAE and PZAC nanocomposites inhibit the growth of human cervical, liver and colorectal cancer cell lines and exhibit no toxic effects towards normal fibroblast 3T3 cell after 72 h of treatment. - Graphical abstract: Protocatechuate anions were arranged in monolayer mode with the angle of 24° for PZAE and 33° for PZAC from Z axis to maximize interaction between carboxylate groups and brucite-like layers. - Highlights: • Two methods gave nanocomposites with slightly different physico-chemical properties. • PZAE and PZAC have the potential to be used as a controlled release formulation. • The thermal stability of PA is markedly enhanced upon the intercalation process. • Higher cancer cell growth inhibition for PZAE and PZAC nanocomposites than for PA.

  13. Layered double hydroxide catalyst for the conversion of crude vegetable oils to a sustainable biofuel

    NASA Astrophysics Data System (ADS)

    Mollaeian, Keyvan

    Over the last two decades, the U.S. has developed the production of biodiesel, a mixture of fatty acid methyl esters, using chiefly vegetable oils as feedstocks. However, there is much concern about the availability of high-quality vegetable oils for longterm biodiesel production. Problems have also risen due to the production of glycerol, an unwanted byproduct, as well as the need for process wash water. Therefore, this study was initiated to produce not only fatty acid methyl esters (FAMEs) but also fatty acid glycerol carbonates (FAGCs) by replacing methanol with dimethyl carbonate (DMC). The process would have no unnecessary byproducts and would be a simplified process compared to traditional biodiesel. In addition, this altering of the methylating agent could convert triglycerides, free fatty acids, and phospholipids to a sustainable biofuel. In this project, Mg-Al Layered Double Hydroxide (LDH) was optimized by calcination in different temperature varied from 250°C to 450°C. The gallery between layers was increased by intercalating sodium dodecylsulfate (SDS). During catalyst preparation, the pH was controlled ~10. In our experiment, triazabicyclodecene (TBD) was attached with trimethoxysilane (3GPS) as a coupling agent, and N-cetyl-N,N,N-trimethylammonium bromide (CTAB) was added to remove SDS from the catalyst. The catalyst was characterized by XRD, FTIR, and Raman spectroscopy. The effect of the heterogeneous catalyst on the conversion of canola oil, corn oil, and free fatty acids was investigated. To analyze the conversion of lipid oils to biofuel an in situ Raman spectroscopic method was developed. Catalyst synthesis methods and a proposed mechanism for converting triglycerides and free fatty acids to biofuel will be presented.

  14. Nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets with a 3D nanonetwork structure as supercapacitive materials

    SciTech Connect

    Yan, Tao; Li, Ruiyi; Li, Zaijun

    2014-03-01

    Graphical abstract: The microwave heating reflux approach was developed for the fabrication of nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets, in which ammonia and ethanol were used as the precipitator and medium for the synthesis. The obtained composite shows a 3D flowerclusters morphology with nanonetwork structure and largely enhanced supercapacitive performance. - Highlights: • The paper reported the microwave synthesis of nickel–cobalt layered double hydroxide/graphene composite. • The novel synthesis method is rapid, green, efficient and can be well used to the mass production. • The as-synthesized composite offers a 3D flowerclusters morphology with nanonetwork structure. • The composite offers excellent supercapacitive performance. • This study provides a promising route to design and synthesis of advanced graphene-based materials with the superiorities of time-saving and cost-effective characteristics. - Abstract: The study reported a novel microwave heating reflux method for the fabrication of nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets (GS/NiCo-LDH). Ammonia and ethanol were employed as precipitant and reaction medium for the synthesis, respectively. The resulting GS/NiCo-LDH offers a 3D flowerclusters morphology with nanonetwork structure. Due to the greatly enhanced rate of electron transfer and mass transport, the GS/NiCo-LDH electrode exhibits excellent supercapacitive performances. The maximum specific capacitance was found to be 1980.7 F g{sup −1} at the current density of 1 A g{sup −1}. The specific capacitance can remain 1274.7 F g{sup −1} at the current density of 15 A g{sup −1} and it has an increase of about 2.9% after 1500 cycles. Moreover, the study also provides a promising approach for the design and synthesis of metallic double hydroxides/graphene hybrid materials with time-saving and cost-effective characteristics, which can be

  15. Layered double hydroxide formation in Bayer liquor and its promotional effect on oxalate precipitation

    SciTech Connect

    Perrotta, A.J.; Williams, F.

    1996-10-01

    Enhancing the precipitation of sodium oxalate from Bayer process liquor to improve the quality of alumina product remains an important objective for Bayer refining. The formation of layered double hydroxides by the reaction of alkaline earth oxides, such as lime and magnesia, with Bayer liquor gives a crystal structure which is capable of intercalating anions, both inorganic and organic, within its structure. Both lime and magnesia, with long contact times in Bayer liquor, show layered double hydroxide formation. This layered double hydroxide formation is accompanied with a decrease in the sodium oxalate content in the liquor from about 3 g/L to below 1 g/L. Short contact times lead to a destabilization of the liquor which facilitates sodium oxalate precipitation. Additional work on magnesium hydroxide shows, in comparison to lime and magnesia, much less layered double hydroxide formation with equivalent residence time in the liquor. Destabilization of the liquor also occurs, giving enhanced oxalate precipitation with less alumina being consumed in agreement with lower layered double hydroxide formation. Thermal regeneration of these structures, followed by in-situ recrystallization in Bayer liquor, also gives enhanced oxalate precipitation, suggesting that there is an opportunity for a regenerable oxalate reduction system. The implementation of these experiments and other related technology into the plant has resulted in the Purox Process for enhancing the precipitation of sodium oxalate from Bayer liquor.

  16. Synthesis of Li-Al layered double hydroxide intercalated with amino tris(methylene phosphonic acid) and kinetic and equilibrium studies of the uptake of Nd3+ and Sr2+ ions

    NASA Astrophysics Data System (ADS)

    Kameda, Tomohito; Shinmyou, Tetsu; Yoshioka, Toshiaki

    2016-03-01

    A Li-Al layered double hydroxide intercalated with amino tris(methylene phosphonic acid) (AMP·Li-Al LDH) was synthesized by the drop-wise addition of an Al-containing solution to a Li-AMP solution at a constant pH of 8.0. The AMP·Li-Al LDH was found to take up Nd3+ and Sr2+ ions from aqueous solutions; this phenomenon was attributable to the metal-chelating functionality of the AMP ions in the interlayers of the AMP·Li-Al LDH. Further, the AMP·Li-Al LDH was found to take up Nd3+ ions preferentially than Sr2+ ions. This was attributable to the stability of the Nd-AMP complex being higher than that of the Sr-AMP complex. The mass-transfer-controlled shrinking-core model could describe the uptake behavior better than the surface-reaction-control model. The AMP ions in the AMP·Li-Al LDH interlayers rapidly formed chelate complexes with the Nd3+ or Sr2+ ions. As a result, the transfer of Nd3+ and Sr2+ ions through the product layer was the rate-limiting step. Furthermore, this reaction could be explained by a Langmuir-type adsorption mechanism, indicating that it involved chemical adsorption; this was consistent with the formation of chelate complexes between Nd3+ and Sr2+ ions and the AMP ions in the interlayers of the AMP·Li-Al LDH.

  17. Enhanced Removal of Arsenic and Antimony in the Mining Site by Calcined γ-Fe2O3/Layered Double Hydroxide Nanocomposite

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Ho; Choi, Heechul; Kim, Kyoung-Woong

    2016-04-01

    Arsenic (As) and Antimony (Sb) have been recognized as harmful contaminants in aquatic environment due to its high toxicity and carcinogenicity. Especially, the contamination of arsenic in the mining areas is considered as a serious emerging environmental issue in Korea. Due to the hazardous effect of arsenic, the United States Environmental Protection Agency (US EPA) regulated maximum contamination level of arsenic to 10 μg/L in drinking water. The harmful effect on human health by excessive intake of antimony was also reported by previous studies, and severe contamination level (100 - 7,000 μg/L) of antimony reported in surface and groundwater of abandoned mining area in China and Slovakia. Therefore, US EPA regulated maximum contaminants level of antimony in drinking water to 6 μg/L. In order to remove anionic contaminants in drinking water, various type of nanomaterials have been developed. Layered double hydroxide (LDH) is the artificial anionic clay that is based on the layered structure of positively charged brucite-like layers with interlayers of anions. The LDH is one of the promising nanomaterials for the removal of anionic contaminants because it has high selectivity for arsenic, phosphate, chromium and antimony. However, the biggest problem of LDH for wastewater treatment is that the particles cannot be easily separated after the removal of contaminants. In this study, magnetic nanoparticles (γ-Fe2O3) supported LDH nanocomposite (γ-Fe2O3/LDH) was investigated to enhance magnetic particle recovery and removal efficiency for arsenic and antimony. The calcined γ-Fe2O3/LDH nanocomposites synthesized by co-precipitation method, and the crystallographic properties of maghemite (γ-Fe2O3) and layered structure of LDH were confirmed by X-ray diffraction. The nano-sized γ-Fe2O3 (30 to 50 nm) was stably attached on the surface of LDH (100 to 150 nm) and O1s spectrum by X-ray photoelectron spectroscopy (XPS) explained that there are both physical and

  18. Real-time tracking of hydrogen peroxide secreted by live cells using MnO2 nanoparticles intercalated layered doubled hydroxide nanohybrids.

    PubMed

    Asif, Muhammad; Aziz, Ayesha; Dao, Anh Quang; Hakeem, Abdul; Wang, Haitao; Dong, Shuang; Zhang, Guoan; Xiao, Fei; Liu, Hongfang

    2015-10-22

    We report a facile and green method for the fabrication of new type of electrocatalysts based on MnO2 nanoparticles incorporated on MgAl LDH P-type semiconductive channel and explore its practical applications as high-performance electrode materials for electrochemical biosensor. A series of MgAl layered doubled hydroxide (LDH) nanohybrids with fixed Mg/Al (M(2+)/M(3+) atomic ratio of 3) and varied amount of MnCl2.4H2O are fabricated by a facile co-precipitation method. This approach demonstrates the combination of distinct properties including excellent intercalation features of LDH for entrapping nanoparticles and high loading of MnO2 nanoparticles in the host layers of LDH. Among all samples, Mn5-MgAl with 0.04% loaded manganese has a good crystalline morphology. A well-dispersed MnO2 nanoparticles encapsulated into the host matrix of hydrotalcite exhibit enhanced electrocatalytic activity towards the reduction of H2O2 as well as excellent stability, selectivity and reproducibility due to synergistic effect of good catalytic ability of MnO2 and conductive MgAl LDH. Glass carbon electrode (GCE) modified with Mn5-MgAl possesses a wide linear range of 0.05-78 mM, lowest detection limit 5 μM (S/N = 3) and detection sensitivity of 0.9352 μAmM(-1). This outstanding performance enables it to be used for real-time tracking of H2O2 secreted by live HeLa cells. This work may provide new insight in clinical diagnosis, on-site environmental analysis and point of care testing devices. PMID:26526908

  19. Investigation of the electrochemical and photoelectrochemical properties of Ni-Al LDH photocatalysts.

    PubMed

    Iguchi, Shoji; Kikkawa, Soichi; Teramura, Kentaro; Hosokawa, Saburo; Tanaka, Tsunehiro

    2016-05-18

    Layered double hydroxide (LDH) photocatalysts, including Ni-Al LDH, are active for the photocatalytic conversion of CO2 in water under UV light irradiation. In this study, we found that a series of LDHs exhibited anodic photocurrent which is a characteristic feature corresponding to n-type materials. Also, we estimated the potentials of photogenerated electrons and holes for LDHs, which are responsible for the photocatalytic reactions, using electrochemical techniques. The flat band potential of the Ni-Al LDH photocatalyst was estimated to be -0.40 V vs. NHE (pH = 0), indicating that the potential of the photogenerated electron is sufficient to reduce CO2 to CO. Moreover, we revealed that the flat band potentials of M(2+)-M(3+) LDH are clearly influenced by the type of trivalent metal (M(3+)) components. PMID:27145887

  20. Layer-by-layer assembled multilayer films of exfoliated layered double hydroxide and carboxymethyl-β-cyclodextrin for selective capacitive sensing of acephatemet.

    PubMed

    Gong, Jingming; Han, Xinmei; Zhu, Xiaolei; Guan, Zhangqiong

    2014-11-15

    Novel organic-inorganic hybrid ultrathin films were fabricated by alternate assembly of cationic exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets and carboxymethyl-β-cyclodextrin (CMCD) as a polyanion onto a glassy carbon electrode (GCE) via a layer-by-layer (LBL) approach. The multilayer films were then characterized by means of X-ray powder diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). These films were found to possess a long range stacking order in the normal direction of the substrate with a continuous and uniform morphology. Its electrochemical performance was systematically investigated. Our results demonstrate that such a newly designed (LDH/CMCD)n multilayer film, combining the individual properties of CMCD (a high supramolecule recognition and enrichment capability) together with LDH nanosheets (a rigid inorganic matrix), can be applied to a sensitive, simple, and label-free capacitive detection of acephatemet (AM). Molecular docking calculations further disclose that the selective sensing behavior toward AM may be attributed to the specific binding ability of CMCD to AM. Under the optimized conditions, the capacitive change of AM was proportional to its concentration ranging from 0.001 to 0.10 μg mL(-1) and 0.1 to 0.8 μg mL(-1) with a detection limit 0.6 ng mL(-1) (S/N=3). Toward the goal for practical applications, this simple probe was further evaluated by monitoring AM in real samples. PMID:24912039

  1. Rich surface Co(iii) ions-enhanced Co nanocatalyst benzene/toluene oxidation performance derived from Co(II)Co(III) layered double hydroxide.

    PubMed

    Mo, Shengpeng; Li, Shuangde; Li, Jiaqi; Deng, Yuzhou; Peng, Shengpan; Chen, Jiayuan; Chen, Yunfa

    2016-08-25

    A hierarchical CoCo layered double hydroxide (LDH) nanostructure was constructed through a facile topochemical transformation route under a dynamic oxygen atmosphere. Self-assembled coral-like CoAl LDH nanostructures via the homogeneous precipitation method were also inspected under different ammonia-releasing reagents and solvents. Benzene and toluene were chosen as probe molecules to evaluate their catalytic performance over the metal oxide CoCoO and CoAlO calcined from their corresponding LDH precursors. Nanocatalyst of trivalent Co ions replaced Al(3+) ions in the bruited-like layer had a higher catalytic activity (T99(benzene) = 210 °C and T99(toluene) = 220 °C at a space velocity = 60 000 mL g(-1) h(-1)). Raman spectroscopy, XPS and H2-TPR demonstrated the existence of abundant high valence Co ions that serve as active sites. TPD verified the types of active oxygen species and surface acid properties. It was concluded that the high valence Co ions induced excellent low-temperature reducibility. Surface Lewis acid sites and the surface Oads/Olatt molar ratio (0.61) played relevant roles in determining its catalytic oxidation performance. Our design in this work provides a promising approach for the development of nanocatalysts with exposed desirable defects. PMID:27531821

  2. Reversible hydration and aqueous exfoliation of the acetate-intercalated layered double hydroxide of Ni and Al: Observation of an ordered interstratified phase

    SciTech Connect

    Manohara, G.V.; Vishnu Kamath, P.; Milius, Wolfgang

    2012-12-15

    Acetate-intercalated layered double hydroxides (LDHs) of Ni and Al undergo reversible hydration in the solid state in response to the ambient humidity. The LDH with a high layer charge (0.33/formula unit) undergoes facile hydration in a single step, whereas the LDH with a lower layer charge (0.24/formula unit) exhibits an ordered interstratified intermediate, comprising the hydrated and dehydrated layers stacked alternatively. This phase, also known as the staged S-2 phase, coexists with the end members suggesting the existence of a solution-type equilibrium between the S-2 phase and the end members of the hydration cycle. These LDHs also undergo facile aqueous exfoliation into 2-5 nm-thick tactoids with a radial dimension of 0.2-0.5 {mu}m. - Graphical abstract: Schematic of the hydrated, dehydrated and interstratified phases observed during the hydration-dehydration of Ni/Al-CH{sub 3}COO LDH. Highlights: Black-Right-Pointing-Pointer Ni/Al-acetate LDHs were synthesized by HPFS method by hydrolysis of acetamide. Black-Right-Pointing-Pointer Intercalated acetate ion shows reversible hydration with variation in humidity. Black-Right-Pointing-Pointer An ordered interstratified phase was observed during hydration/dehydration cycle. Black-Right-Pointing-Pointer A solution type equilibrium is observed between hydration-dehydration phases. Black-Right-Pointing-Pointer These LDHs undergo facile aqueous exfoliation.

  3. Gold Nanoclusters@Ru(bpy)₃²⁺-Layered Double Hydroxide Ultrathin Film as a Cathodic Electrochemiluminescence Resonance Energy Transfer Probe.

    PubMed

    Yu, Yingchang; Lu, Chao; Zhang, Meining

    2015-08-01

    Herein, it is the first report that a cathodic electrochemiluminescence (ECL) resonance energy transfer (ERET) system is fabricated by layer-by-layer (LBL) electrostatic assembly of CoAl layered double hydroxide (LDH) nanosheets with a mixture of blue BSA-gold nanoclusters (AuNCs) and Ru(bpy)3(2+) (denoted as AuNCs@Ru) on an Au electrode. The possible ECL mechanism indicates that the appearance of CoAl-LDH nanosheets generates a long-range stacking order of the AuNCs@Ru on an Au electrode, facilitating the occurrence of the ERET between BSA-AuNC donors and Ru(bpy)3(2+) acceptors on the as-prepared AuNCs@Ru-LDH ultrathin films (UTFs). Furthermore, it is observed that the cathodic ECL intensity can be quenched efficiently in the presence of 6-mercaptopurine (6-MP) in a linear range of 2.5-100 nM with a detection limit of 1.0 nM. On the basis of these interesting phenomena, a facile cathodic ECL sensor has successfully distinguished 6-MP from other thiol-containing compounds (e.g., cysteine and glutathione) in human serum and urine samples. The proposed sensing scheme opens a way for employing the layered UTFs as a platform for the cathodic ECL of Ru(bpy)3(2+). PMID:26159772

  4. Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Fan, Ke; Chen, Hong; Ji, Yongfei; Huang, Hui; Claesson, Per Martin; Daniel, Quentin; Philippe, Bertrand; Rensmo, Håkan; Li, Fusheng; Luo, Yi; Sun, Licheng

    2016-06-01

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm-2 (57 mA cm-2 after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.

  5. Nickel–vanadium monolayer double hydroxide for efficient electrochemical water oxidation

    PubMed Central

    Fan, Ke; Chen, Hong; Ji, Yongfei; Huang, Hui; Claesson, Per Martin; Daniel, Quentin; Philippe, Bertrand; Rensmo, Håkan; Li, Fusheng; Luo, Yi; Sun, Licheng

    2016-01-01

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel–vanadium-layered double hydroxide that shows a current density of 27 mA cm−2 (57 mA cm−2 after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel–iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel–vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting. PMID:27306541

  6. Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation.

    PubMed

    Fan, Ke; Chen, Hong; Ji, Yongfei; Huang, Hui; Claesson, Per Martin; Daniel, Quentin; Philippe, Bertrand; Rensmo, Håkan; Li, Fusheng; Luo, Yi; Sun, Licheng

    2016-01-01

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm(-2) (57 mA cm(-2) after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting. PMID:27306541

  7. Highly Stable and Sensitive Paper-Based Bending Sensor Using Silver Nanowires/Layered Double Hydroxides Hybrids.

    PubMed

    Wei, Yong; Chen, Shilong; Li, Fucheng; Lin, Yong; Zhang, Ying; Liu, Lan

    2015-07-01

    Highly sensitive flexible piezoresistive materials using silver nanowires (AgNWs) composites have been widely researched due to their excellent electrical, optical, and mechanical properties. Intrinsically, AgNWs tend to aggregate in polymer matrix because of the intense depletion-induced interactions, which seriously influence the percolation threshold of the composites. In this study, we report a highly stable and sensitive paper-based bending sensor using the AgNWs and layered double hydroxides (LDHs) to construct a hybrid conductive network in waterborne polyurethane that is easy to destruct and reconstruct under bending deformation. The nonconductive 2D LDH nanosheets are embedded into AgNWs network and assist dispersion of AgNWs, which depends on the hydrogen bonding between the two nanostructures. The percolation threshold of the composites decreases from 10.8 vol % (55 wt %) to 3.1 vol % (23.8 wt %), and the composites reaches a very low resistivity (10(-4) Ω·cm) with a small amount of AgNWs (8.3 vol %) due to the dispersion improvement of AgNWs with the effect of LDH nanosheets. The as-prepared conductive composites with low percolation threshold can be manufactured on paper via various methods such as rollerball pen writing, inkjet printing, or screen printing. The bending sensor prepared by manufacturing the composites on paper shows low-cost, excellent conductivity, flexibility (>3000 bending cycles), sensitivity (0.16 rad(-1)), fast response (120 ms) and relaxation time (105 ms), and nontoxicity. Therefore, a simple but efficient wearable sensor is developed to monitor the human motions (such as fingers and elbow joints movements) and presents good repeatability, stability, and responsiveness, making the bending sensor possibly able to meet the needs in numerous applications for robotic systems. PMID:26083146

  8. Aluminum doped nickel oxide thin film with improved electrochromic performance from layered double hydroxides precursor in situ pyrolytic route

    NASA Astrophysics Data System (ADS)

    Shi, Jingjing; Lai, Lincong; Zhang, Ping; Li, Hailong; Qin, Yumei; Gao, Yuanchunxue; Luo, Lei; Lu, Jun

    2016-09-01

    Electrochromic materials with unique performance arouse great interest on account of potential application values in smart window, low-power display, automobile anti-glare rearview mirror, and e-papers. In this paper, high-performing Al-doped NiO porous electrochromic film grown on ITO substrate has been prepared via a layered double hydroxides(LDHs) precursor in situ pyrolytic route. The Al3+ ions distributed homogenously within the NiO matrix can significantly influence the crystallinity of Ni-Al LDH and NiO:Al3+ films. The electrochromic performance of the films were evaluated by means of UV-vis absorption spectroscopy, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry(CA) measurements. In addition, the ratio of Ni3+/Ni2+ also varies with Al content which can lead to different electrochemical performances. Among the as-prepared films, NiO film prepared from Ni-Al (19:1) LDH show the best electrochromic performance with a high transparency of 96%, large optical modulation range (58.4%), fast switching speed (bleaching/coloration times are 1.8/4.2 s, respectively) and excellent durability (30% decrease after 2000 cycles). The improved performance was owed to the synergy of large NiO film specific surface area and porous morphology, as well as Al doping stifled the formation of Ni3+ making bleached state more pure. This LDHs precursor pyrolytic method is simple, low-cost and environmental benign and is feasible for the preparation of NiO:Al and other Al-doped oxide thin film.

  9. Thermal evolution of the Cl(-)-LiAl(2) layered double hydroxide: a multinuclear MAS NMR and XRD perspective.

    PubMed

    Hou, X; Kirkpatrick, R J

    2001-12-01

    Layered double hydroxides (LDHs) with a cation composition of LiAl(2) have a wide range of potential applications as catalysts, catalyst supports, and precursors for refractory oxide materials, including several industrially important lithium aluminate phases. The understanding of the calcination behavior of this group of LDH phases is essential to advancing these applications, and the research described here focuses on the thermal decomposition and structural evolution of LiAl(2)(OH)(6)Cl.nH(2)O in the temperature range of 20-1100 degrees C. (27)Al, (35)Cl, and (6,7)Li magic angle spinning nuclear magnetic resonance spectroscopy, powder X-ray diffraction, thermal analysis (including thermogravimetric and differential scanning calorimetry), and compositional analysis provide a highly consistent picture of the thermally induced phase formation and transformations of this LDH. The loss of the surface and interlayer water can begin as low as room temperature, depending on the relative humidity. Beginning at about 300 degrees C, the simultaneous volatilization of H(2)O and HCl and the exsolution of crystalline LiCl result in the formation of amorphous Li-Al-O-OH. By at least 500 degrees C, volumes with the structures of alpha-LiAlO(2) and LiAl(5)O(8) appear, and these phases become progressively more ordered with increasing temperature. LiCl begins to volatilize by 850 degrees C and is present only in trace amounts above ca. 1000 degrees C. alpha-LiAlO(2) converts to gamma-LiAlO(2) between 970 and 1100 degrees C. Because of the delithiation due to LiCl volatilization, the final products are dominated by LiAl(5)O(8), in contrast to the calcination products of previously studied LiAl(2) LDHs which are dominated by LiAlO(2). PMID:11720493

  10. Synthesis of Zn–Fe layered double hydroxides via an oxidation process and structural analysis of products

    SciTech Connect

    Morimoto, Kazuya; Tamura, Kenji; Anraku, Sohtaro; Sato, Tsutomu; Suzuki, Masaya; Yamada, Hirohisa

    2015-08-15

    The synthesis of Zn–Fe(III) layered double hydroxides was attempted, employing different pathways using either Fe(II) or Fe(III) species together with Zn as the initial reagents. The product derived from the synthesis employing Fe(II) was found to transition to a Zn–Fe(III) layered double hydroxides phase following oxidation process. In contrast, the product obtained with Fe(III) did not contain a layered double hydroxides phase, but rather consisted of simonkolleite and hydrous ferric oxide. It was determined that the valency of the Fe reagent used in the initial synthesis affected the generation of the layered double hydroxides phase. Fe(II) species have ionic radii and electronegativities similar to those of Zn, and therefore are more likely to form trioctahedral hydroxide layers with Zn species. - Graphical abstract: The synthesis of Zn–Fe(III) layered double hydroxides was attempted, employing different pathways using either Fe(II) or Fe(III) species together with Zn as the initial reagents. - Highlights: • Iron valency affected the generation of Zn–Fe layered double hydroxides. • Zn–Fe layered double hydroxides were successfully synthesized using Fe(II). • Fe(II) species were likely to form trioctahedral hydroxide layers with Zn species.

  11. Oxidative stress by layered double hydroxide nanoparticles via an SFK-JNK and p38-NF-κB signaling pathway mediates induction of interleukin-6 and interleukin-8 in human lung epithelial cells

    PubMed Central

    Choi, Soo-Jin; Paek, Hee-Jeong; Yu, Jin

    2015-01-01

    Anionic nanoclays are layered double hydroxide nanoparticles (LDH-NPs) that have been shown to exhibit toxicity by inducing reactive oxidative species and a proinflammatory mediator in human lung epithelial A549 cells. However, the molecular mechanism responsible for this LDH-NP-induced toxicity and the relationship between oxidative stress and inflammatory events remains unclear. In this study, we focused on intracellular signaling pathways and transcription factors induced in response to oxidative stress caused by exposure to LDH-NPs in A549 cells. Mitogen-activated protein kinase (MAPK) cascades, such as extracellular signal-regulated kinase, c-Jun-N-terminal kinase (JNK), and p38, were investigated as potential signaling mechanisms responsible for regulation of oxidative stress and cytokine release. Src family kinases (SFKs), which are known to mediate activation of MAPK, together with redox-sensitive transcription factors, including nuclear factor kappa B and nuclear factor-erythroid 2-related factor-2, were also investigated as downstream events of MAPK signaling. The results obtained suggest that LDH-NP exposure causes oxidative stress, leading to expression of antioxidant enzymes, such as catalase, glucose reductase, superoxide dismutase, and heme oxygenase-1, via a SFK-JNK and p38-nuclear factor kappa B signaling pathway. Further, activation of this signaling was also found to regulate release of inflammatory cytokines, including interleukin-6 and interleukin-8, demonstrating the inflammatory potential of LDH-NP. PMID:25995631

  12. The Effect of Aging Time on the Properties of Mg-Al-CO3 Layered Double Hydroxides and Its Application as a Catalyst Support for TiO2.

    PubMed

    Guo, Yang; Cui, Xianlu; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

    2016-06-01

    By using chloride salts as the raw materials, Mg-Al-CO3 layered double hydroxides (Mg-Al-CO3 LDHs) with Mg/Al molar ratio 2:1 were prepared via a coprecipitation method. The effect of the aging time on the crystallinity, particle size, chemical composition, morphology, specific surface area, and pore size distribution of Mg-Al-CO3 LDHs were studied in details. The effect of aging time during LDHs preparation process on adsorption capacity of LDHs and their calcined products (mixed metal oxide, MMO) were investigated by removing the pollutant acid red 1 (AR1) from aqueous solution. The results showed that LDHs prepared at 90 degrees C for 4 h (LDH-4) had a higher specific area of 103.7 m2/g and LDHs prepared at 90 degrees C for 8 h (LDH-8) exhibited well-formed hexagonal crystals with a relative smooth surface. The LDH-4 and its calcined product are more effective in removing AR1 than LDH-8, which is related to the differences in their specific surface area. Meanwhile, anatase TiO2-coated MMO with MMO/TiO2 mass ratios at 1:1 and.2:1 were prepared via a chemical precipitation route in the presence of LDH, the composites showed an efficiently photocatalytic activity in the removal of AR1. PMID:27427611

  13. Effect of hydrothermal treatment on properties of Ni-Al layered double hydroxides and related mixed oxides

    SciTech Connect

    Kovanda, Frantisek Rojka, Tomas; Bezdicka, Petr; Jiratova, Kveta; Obalova, Lucie; Pacultova, Katerina; Bastl, Zdenek; Grygar, Tomas

    2009-01-15

    The Ni-Al layered double hydroxides (LDHs) with Ni/Al molar ratio of 2, 3, and 4 were prepared by coprecipitation and treated under hydrothermal conditions at 180 deg. C for times up to 20 h. Thermal decomposition of the prepared samples was studied using thermal analysis and high-temperature X-ray diffraction. Hydrothermal treatment increased significantly the crystallite size of coprecipitated samples. The characteristic LDH diffraction lines disappeared completely at ca. 350 deg. C and a gradual crystallization of NiO-like mixed oxide was observed at higher temperatures. Hydrothermal treatment improved thermal stability of the Ni2Al and Ni3Al LDHs but only a slight effect of hydrothermal treatment was observed with the Ni4Al sample. The Rietveld refinement of powder XRD patterns of calcination products obtained at 450 deg. C showed a formation of Al-containing NiO-like oxide and a presence of a considerable amount of Al-rich amorphous component. Hydrothermal aging of the LDHs resulted in decreasing content of the amorphous component and enhanced substitution of Al cations into NiO-like structure. The hydrothermally treated samples also exhibited a worse reducibility of Ni{sup 2+} components. The NiAl{sub 2}O{sub 4} spinel and NiO still containing a marked part of Al in the cationic sublattice were detected in the samples calcined at 900 deg. C. The Ni2Al LDHs hydrothermally treated for various times and related mixed oxides obtained at 450 deg. C showed an increase in pore size with increasing time of hydrothermal aging. The hydrothermal treatment of LDH precursor considerably improved the catalytic activity of Ni2Al mixed oxides in N{sub 2}O decomposition, which can be explained by suppressing internal diffusion effect in catalysts grains. - Graphical Abstract: Hydrothermal treatment of Ni-Al LDH precursors influenced the porous structure of related mixed oxides and considerably improved their catalytic activity in N{sub 2}O decomposition; the higher catalytic

  14. CO₂ sorbents with scaffold-like Ca-Al layered double hydroxides as precursors for CO₂ capture at high temperatures.

    PubMed

    Chang, Po-Hsueh; Lee, Tai-Jung; Chang, Yen-Po; Chen, San-Yuan

    2013-06-01

    A highly stable high-temperature CO₂ sorbent consisting of scaffold-like Ca-rich oxides (Ca-Al-O) with rapid absorption kinetics and a high capacity is described. The Ca-rich oxides were prepared by annealing Ca-Al-NO₃ layered double hydroxide (LDH) precursors through a sol-gel process with Al(O(i)P)₃ and Ca(NO₃)₂ with Ca(2+)/Al(3+) ratios of 1:1, 2:1, 4:1, and 7:1. XRD indicated that only LDH powders were formed for Ca(2+)/Al(3+) ratios of 2:1. However, both LDH and Ca(OH)₂ phases were produced at higher ratios. Both TEM and SEM observations indicated that the Ca-Al-NO₃ LDHs displayed a scaffold-like porous structure morphology rather than platelet-like particles. Upon annealing at 600 °C, a highly stable porous network structure of the CaO-based Ca-Al-O mixed oxide (CAMO), composed of CaO and Ca₁₂Al₁₄O₃₃, was still present. The CAMO exhibited high specific surface areas (up to 191 m(2)g(-1)) and a pore size distribution of 3-6 nm, which allowed rapid diffusion of CO₂ into the interior of the material, inducing fast carbonation/calcination and enhancing the sintering-resistant nature over multiple carbonation/calcination cycles for CO₂ absorption at 700 °C. Thermogravimetric analysis results indicated that a CO₂ capture capacity of approximately 49 wt% could be obtained with rapid absorption from the porous 7:1 CAMO sorbents by carbonation at 700 °C for 5 min. Also, 94-98% of the initial CO₂ capture capability was retained after 50 cycles of multiple carbonation/calcination tests. Therefore, the CAMO framework is a good isolator for preventing the aggregation of CaO particles, and it is suitable for long-term cyclic operation in high-temperature environments. PMID:23650194

  15. Selective oxidation catalysts obtained by immobilization of iron(III) porphyrins on thiosalicylic acid-modified Mg-Al layered double hydroxides.

    PubMed

    de Freitas Castro, Kelly Aparecida Dias; Wypych, Fernando; Antonangelo, Ariana; Mantovani, Karen Mary; Bail, Alesandro; Ucoski, Geani Maria; Ciuffi, Kátia Jorge; Cintra, Thais Elita; Nakagaki, Shirley

    2016-09-15

    Nitrate-intercalated Mg-Al layered double hydroxides (LDHs) were synthesized and exfoliated in formamide. Reaction of the single layer suspension with thiosalicylic acid under different conditions afforded two types of solids: LDHA1, in which the outer surface was modified with the anion thiosalicylate, and LDHA2, which contained the anion thiosalicylate intercalated between the LDH layers. LDHA1 and LDHA2 were used as supports to immobilize neutral (FeP1 and FeP2) and anionic (FeP3) iron(III) porphyrins. For comparison purposes, the iron(III) porphyrins (FePs) were also immobilized on LDH intercalated with nitrate anions obtained by the co-precipitation method. Chemical modification of LDH facilitated immobilization of the FePs through interaction of the functionalizing groups in LDH with the peripheral substituents on the porphyrin ring. The resulting FePx-LDHAy solids were characterized by X-ray diffraction (powder) and UV-Vis and EPR spectroscopies and were investigated as catalysts in the oxidation of cyclooctene and cyclohexane. The immobilized neutral FePs and their homogeneous counterparts gave similar product yields in the oxidation of cyclooctene, suggesting that immobilization of the FePs on the thiosalicylate-modified LDHs only supported the catalyst species without interfering in the catalytic outcome. On the other hand, in the oxidation of cyclohexane, the thiosalicylate anions on the outer surface of LDHA1 or intercalated between the LDHA2 layers influenced the catalytic activity of FePx-LDHAy, leading to different efficiency and selectivity results. FeP1-LDHA2 performed the best (29.6% alcohol yield) due to changes in the polarity of the surface of the support and the presence of FeP1. Interestingly, FeP1 also performed better in solution as compared to the other FePs. Finally, it was possible to recycle FeP1-LDHA2 at least three times. PMID:27322950

  16. A comparative study of supercapacitive performances of nickel cobalt layered double hydroxides coated on ZnO nanostructured arrays on textile fibre as electrodes for wearable energy storage devices

    NASA Astrophysics Data System (ADS)

    Trang, Nguyen Thi Hong; Ngoc, Huynh Van; Lingappan, Niranjanmurthi; Kang, Dae Joon

    2014-01-01

    We demonstrated an efficient method for the fabrication of novel, flexible electrodes based on ZnO nanoflakes and nickel-cobalt layered double hydroxides (denoted as ZnONF/NiCoLDH) as a core-shell nanostructure on textile substrates for wearable energy storage devices. NiCoLDH coated ZnO nanowire (denoted as ZnONW/NiCoLDH) flexible electrodes are also prepared for comparison. As an electrode for supercapacitors, ZnONF/NiCoLDH exhibits a high specific capacitance of 1624 F g-1, which is nearly 1.6 times greater than ZnONW/NiCoLDH counterparts. It also shows a maximum energy density of 48.32 W h kg-1 at a power density of 27.53 kW kg-1, and an excellent cycling stability with capacitance retention of 94% and a Coulombic efficiency of 93% over 2000 cycles. We believe that the superior performance of the ZnONF/NiCoLDH hybrids is due primarily to the large surface area of the nanoflake structure and the open spaces between nanoflakes, both of which provide a large space for the deposition of NiCoLDH, resulting in reduced internal resistance and improved capacitance performance. Our results are significant for the development of electrode materials for high-performance wearable energy storage devices.We demonstrated an efficient method for the fabrication of novel, flexible electrodes based on ZnO nanoflakes and nickel-cobalt layered double hydroxides (denoted as ZnONF/NiCoLDH) as a core-shell nanostructure on textile substrates for wearable energy storage devices. NiCoLDH coated ZnO nanowire (denoted as ZnONW/NiCoLDH) flexible electrodes are also prepared for comparison. As an electrode for supercapacitors, ZnONF/NiCoLDH exhibits a high specific capacitance of 1624 F g-1, which is nearly 1.6 times greater than ZnONW/NiCoLDH counterparts. It also shows a maximum energy density of 48.32 W h kg-1 at a power density of 27.53 kW kg-1, and an excellent cycling stability with capacitance retention of 94% and a Coulombic efficiency of 93% over 2000 cycles. We believe that the

  17. Synthesis of [Zn-Al-CO 3] layered double hydroxides by a coprecipitation method under steady-state conditions

    NASA Astrophysics Data System (ADS)

    Chang, Z.; Evans, D. G.; Duan, X.; Vial, C.; Ghanbaja, J.; Prevot, V.; de Roy, M.; Forano, C.

    2005-09-01

    A continuous co-precipitation method under steady-state conditions has been investigated for the preparation of nanometer-size layered double hydroxide (LDH) particles using Zn 2Al(OH) 6(CO 3) 0.5·2H 2O as a prototype. The objective was to shorten the preparation time by working without an aging step, using a short and controlled residence time in order to maintain a constant supersaturation level in the reactor and constant particle properties in the exit stream over time. The effects of varying the operating conditions on the structural and textural properties of the LDHs have been studied, including total cation concentration, solvent, residence time, pH and intercalation anion. The products have been characterized using ICP, XRD, FTIR, BET, SEM and TEM. The LDHs prepared by the continuous coprecipitation method have a poorer crystallinity and lower crystallite sizes than those synthesized by the conventional batch method. The results have shown that increasing either cation concentration or the fraction of monoethylene glycol (MEG) in MEG/H 2O mixtures up to 80% (v/v) affect salt solubility and supersaturation, which gives rise to smaller crystallites, larger surface areas and more amorphous compounds. This increase is however limited by the precipitation of zinc and aluminum hydroxides occurring around a total cation concentration of 3.0×10 -1 M in pure water and 3.0×10 -2 M in H 2O/EtOH mixtures. Crystallite size increases with residence time, suggesting a precipitation process controlled by growth. Finally, the continuous coprecipitation method under steady-state conditions has been shown to be a promising alternative to the traditional coprecipitation technique in either pure water or mixed H 2O/MEG solvents.

  18. Structure Analysis and Fluorescence of Mg-Al-Tb Ternary Layered Double Hydroxides and Their Calcined Products

    NASA Astrophysics Data System (ADS)

    Chen, Junfei; Lei, Zhigao; Wang, Anqi; Liu, Jie; Wu, Xiuling; Chang, Tianci; Zhang, Yang; Li, Muqing

    2015-02-01

    Layered double hydroxides (LDHs) doped with Tb3+ ions in the brucite-like layers were prepared successfully by the co-precipitation method. The structure and fluorescence properties of Mg-Al-Tb ternary LDHs and their products calcined at different temperatures were studied for the first time. X-ray diffraction patterns indicated that as-synthesized LDH samples maintained a hexagonal crystal structure, and Tb(OH)3 was detected as Tb3+ dopant content increasing to 5 at.%. In the fluorescent spectra, the green emission intensity arising from 5D4 → 7F5 transition became stronger with the increasing ratio of Tb3+ dopant. When the annealing temperature rose above 500°C, the layer structure collapsed and phases of MgO and MgAl2O4 formed. Meanwhile, compared with MgAlTb-LDHs, the Tb-doped calcined LDHs (CLDHs) showed stronger luminescent intensity of 5D4 → 7F5 transition. These results revealed that the calcined Mg-Al-Tb ternary LDHs may become a series of novel materials with potential applications in fluorescent devices.

  19. Acid and redox properties of mixed oxides prepared by calcination of chromate-containing layered double hydroxides

    SciTech Connect

    Arco, M. del; Carriazo, D.; Martin, C.; Perez-Grueso, A.M.; Rives, V. . E-mail: vrives@usal.es

    2005-11-15

    Layered double hydroxides (LDHs) with Mg and Al in the layers and carbonate, nitrate or chloride in the interlayer, or with Zn and Al in the layers and chloride in the interlayer, have been prepared by coprecipitation, and have been used as precursors to prepare chromate-containing LDHs. All these systems, as well as those obtained upon their calcination up to 800 deg. C, have been characterised by powder X-ray diffraction, FT-IR and vis-UV spectroscopies, temperature-programmed reduction (TPR), nitrogen adsorption at -196 deg. C for surface texture and porosity assessment, and FT-IR monitoring of pyridine adsorption for surface acidity determination. The results obtained show that the crystallinity of the chromate-containing LDH depends on the precursor used. The layered structure of the Mg, Al systems is stabilised up to 400 deg. C upon incorporation of chromate; however, the Zn,Al-chromate samples collapse between 200 and 300 deg. C, with simultaneous formation of ZnO. Calcination of the samples above 400 deg. C gives rise to a reduction of Cr(VI) to Cr(III), as concluded from vis-UV spectroscopic studies. The TPR profiles show that chromate in ZnAl hydrotalcite is more easily reduced than that incorporated in the magnesium ones. Moderately strong surface Lewis acid sites exist in all samples calcined below 500 deg. C.

  20. A combined FTIR and infrared emission spectroscopy investigation of layered double hydroxide as an effective electron donor.

    PubMed

    Zhang, Jia; Wei, Feng; Liang, Ying; Zhou, Jizhi; Xi, Yunfei; Qian, Guangren; Frost, Ray

    2016-02-01

    A novel method has been presented to characterize electron transfer in layered double hydroxides (LDHs) utilizing an investigation combing FTIR and infrared emission spectroscopy. At room temperature, electron could transfer to interlayer Fe(3+) through monodentate ligand cyanide, and resulted in a reduction of 40% Fe(3+) to Fe(2+). When the environmental temperature increased from 25 to 300°C, reduction of Fe(3+) and Ni(2+) increased to 94% and 42%. Furthermore, electron also transferred to interlayer cation through multidentate ligand EDTA. As a result, LDHs has been proven to be an effective electron donor, and FTIR was a feasible tool in characterizing this property by monitoring the valence state of cations. It was also concluded that octahedral units with OH(-) groups in LDH layer functioned as electron donor centers. Driving force for electron transfer is attributed to the charge density difference between cation layer and probe anion. These results could help to explain the mechanism of various applications of LDHs in catalysis and photocatalysis. PMID:26490800

  1. A combined FTIR and infrared emission spectroscopy investigation of layered double hydroxide as an effective electron donor

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Wei, Feng; Liang, Ying; Zhou, Jizhi; Xi, Yunfei; Qian, Guangren; Frost, Ray

    2016-02-01

    A novel method has been presented to characterize electron transfer in layered double hydroxides (LDHs) utilizing an investigation combing FTIR and infrared emission spectroscopy. At room temperature, electron could transfer to interlayer Fe3 + through monodentate ligand cyanide, and resulted in a reduction of 40% Fe3 + to Fe2 +. When the environmental temperature increased from 25 to 300 °C, reduction of Fe3 + and Ni2 + increased to 94% and 42%. Furthermore, electron also transferred to interlayer cation through multidentate ligand EDTA. As a result, LDHs has been proven to be an effective electron donor, and FTIR was a feasible tool in characterizing this property by monitoring the valence state of cations. It was also concluded that octahedral units with OH- groups in LDH layer functioned as electron donor centers. Driving force for electron transfer is attributed to the charge density difference between cation layer and probe anion. These results could help to explain the mechanism of various applications of LDHs in catalysis and photocatalysis.

  2. Interstratified nanohybrid assembled by alternating cationic layered double hydroxide nanosheets and anionic layered titanate nanosheets with superior photocatalytic activity.

    PubMed

    Lin, Bizhou; Sun, Ping; Zhou, Yi; Jiang, Shaofeng; Gao, Bifen; Chen, Yilin

    2014-09-15

    Oppositely charged 2D inorganic nanosheets of ZnAl-layered double hydroxide and layered titanate were successfully assembled into an interstratified nanohybrid through simply mixing the corresponding nanosheet suspensions. Powder X-ray diffraction and high-resolution transmission electron microscope clearly revealed that the component nanosheets in the as-obtained nanohybrid ZnAl-Ti3O7 retain the 2D sheet skeletons of the pristine materials and that the two kinds of nanosheets are well arranged in a layer-by-layer alternating fashion with a basal spacing of about 1.3 nm, coincident with the thickness summation of the two component nanosheets. The effective interfacial heterojunction between them and the high specific surface area resulted in that the nanohybrid exhibits a superior photocatalytic activity in the degradation of methylene blue with a reaction constant k of 2.81 × 10(-2)min(-1), which is about 9 and 4 times higher than its precursors H2Ti3O7 and ZnAl-LDH, respectively. Based on UV-vis, XPS and photoelectrochemical measurements, a proposed photoexcitation model was provided to understand its photocatalytic behavior. PMID:25151238

  3. Intercalation and controlled release of pharmaceutically active compounds from a layered double hydroxide.

    PubMed

    Khan, A I; Lei, L; Norquist, A J; O'Hare, D

    2001-11-21

    A series of pharmaceutically active compounds including diclofenac, gemfibrozil, ibuprofen, naproxen, 2-propylpentanoic acid, 4-biphenylacetic acid and tolfenamic acid can be reversibly intercalated into a layered double hydroxide, initial studies suggest that these materials may have application as the basis of a novel tuneable drug delivery system. PMID:12240066

  4. Zn-Al layered double hydroxide prepared at different molar ratios: Preparation, characterization, optical and dielectric properties

    SciTech Connect

    Ahmed, Abdullah Ahmed Ali; Talib, Zainal Abidin; Zobir bin Hussein, Mohd; Zakaria, Azmi

    2012-07-15

    The co-precipitation method was used to prepare Zn-Al-NO{sub 3}-LDH at different Zn{sup 2+}/Al{sup 3+} molar ratios (2, 3, 4, 5 and 6) and pH value of 7.5. The structure, textural, composition and morphological properties were investigated using powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) and scanning electron microscope (SEM), respectively. The crystallinity of LDH samples were found to improve as molar ratio decreased which is attributed to the distortion of the hydroxide layers networks of the LDH crystal by the larger difference in ionic radii of Zn{sup 2+} and Al{sup 3+}. The optical band gap energy of LDH samples were evaluated using absorbance data from UV-Vis-NIR Diffuse reflectance spectroscopy. Band gaps were affected by the variation of the Zn{sup 2+}/Al{sup 3+} molar ratio is due to the formation of the low crystalline phases (ZnO and ZnAl{sub 2}O{sub 4}). The water molecules and anionic NO{sub 3}{sup -} in the LDH interlayer were responsible for the generation of the dielectric response. This response can be described by an anomalous low frequency dispersion using the second type of Universal Power Law. The dominance of ZnO dipoles and charge carriers (NO{sub 3}{sup -} ions) in the dielectric relaxation increases with the increasing molar ratio. - Graphical abstract: (a) Schematic diagram of Zn-Al- NO{sub 3}-LDH shows the LDH structure, (b) Kubelka-Munk transformed reflectance spectra and c. The dielectric constant versus frequency of Zn-Al- NO{sub 3}-LDH samples. Highlights: Black-Right-Pointing-Pointer Zn-Al-NO{sub 3}-LDH was prepared at different Zn{sup 2+}/Al{sup 3+} molar ratios (2, 3, 4, 5 and 6). Black-Right-Pointing-Pointer The crystallinity of LDH phase decreased with increase of Zn{sup 2+}/Al{sup 3+} molar ratio. Black-Right-Pointing-Pointer The optical band gaps of LDH samples have been measured. Black-Right-Pointing-Pointer Dielectric response of LDH can be described by anomalous low

  5. Highly Selective and Efficient Removal of Heavy Metals by Layered Double Hydroxide Intercalated with the MoS4(2-) Ion.

    PubMed

    Ma, Lijiao; Wang, Qing; Islam, Saiful M; Liu, Yingchun; Ma, Shulan; Kanatzidis, Mercouri G

    2016-03-01

    The MoS4(2-) ion was intercalated into magnesium-aluminum layered double hydroxide (MgAl-NO3-LDH) to produce a single phase material of Mg0.66Al0.34(OH)2(MoS4)0.17·nH2O (MgAl-MoS4-LDH), which demonstrates highly selective binding and extremely efficient removal of heavy metal ions such as Cu(2+), Pb(2+), Ag(+), and Hg(2+). The MoS4-LDH displays a selectivity order of Co(2+), Ni(2+), Zn(2+) < Cd(2+) ≪ Pb(2+) < Cu(2+) < Hg(2+) < Ag(+) for the metal ions. The enormous capacities for Hg(2+) (∼500 mg/g) and Ag(+) (450 mg/g) and very high distribution coefficients (Kd) of ∼10(7) mL/g place the MoS4-LDH at the top of materials known for such removal. Sorption isotherm for Ag(+) agrees with the Langmuir model suggesting a monolayer adsorption. It can rapidly lower the concentrations of Cu(2+), Pb(2+), Hg(2+), and Ag(+) from ppm levels to trace levels of ≤1 ppb. For the highly toxic Hg(2+) (at ∼30 ppm concentration), the adsorption is exceptionally rapid and highly selective, showing a 97.3% removal within 5 min, 99.7% removal within 30 min, and ∼100% removal within 1 h. The sorption kinetics for Cu(2+), Ag(+), Pb(2+), and Hg(2+) follows a pseudo-second-order model suggesting a chemisorption with the adsorption mechanism via M-S bonding. X-ray diffraction patterns of the samples after adsorption demonstrate the coordination and intercalation structures depending on the metal ions and their concentration. After the capture of heavy metals, the crystallites of the MoS4-LDH material retain the original hexagonal prismatic shape and are stable at pH ≈ 2-10. The MoS4-LDH material is thus promising for the remediation of heavy metal polluted water. PMID:26829617

  6. Synthesis and characterisation of a new stable organo-mineral hybrid nanomaterial: 4-Chlorobenzenesulfonate in the zinc-aluminium layered double hydroxide

    SciTech Connect

    Lakraimi, Mohamed; Legrouri, Ahmed . E-mail: legrouri@aui.ma; Barroug, Allal; De Roy, Andre; Besse, Jean Pierre

    2006-09-14

    4-Chlorobenzenesulfonate (4-CBS) was intercalated between layers of Zn-Al layered double hydroxides (LDHs). Two methods of incorporation were applied: (1) direct synthesis by coprecipitation of metal nitrates and sodium 4-CBS and (2) ion exchange of the LDH nitrate with the organic ion. The solids were characterized by X-ray diffraction and infrared spectroscopy. The direct method, effected at different pH values, led to a hybrid material with good degree of intercalation. In order to optimise the exchange conditions, particular attention was given to the effect of solution pH, 4-CBS/NO{sub 3} ratio and exchange temperature. The total exchange was successful and a new stable hybrid nanostructured material was obtained at pH 8 and with a 4-CBS concentration of 0.0028 M. This solid was further characterised by chemical and thermal analyses.

  7. Transesterification of edible, non-edible and used cooking oils for biodiesel production using calcined layered double hydroxides as reusable base catalysts.

    PubMed

    Sankaranarayanan, Sivashunmugam; Antonyraj, Churchil A; Kannan, S

    2012-04-01

    Fatty acid methyl esters (FAME) were produced from edible, non-edible and used cooking oils with different fatty acid contents by transesterification with methanol using calcined layered double hydroxides (LDHs) as solid base catalysts. Among the catalysts, calcined CaAl2-LDH (hydrocalumite) showed the highest activity with >90% yield of FAME using low methanol:oil molar ratio (<6:1) at 65 °C in 5 h. The activity of the catalyst was attributed to its high basicity as supported by Hammett studies and CO(2)-TPD measurements. The catalyst was successfully reused in up to four cycles. Some of the properties such as density, viscosity, neutralization number and glycerol content of the obtained biodiesel matched well with the standard DIN values. It is concluded that a scalable heterogeneously catalyzed process for production of biodiesel in high yields from a wide variety of triglyceride oils including used oils is possible using optimized conditions. PMID:22305480

  8. Direct coating for layered double hydroxide/4,4'-diaminostilbene-2,2'-disulfonic acid nanocomposite with silica by seeded polymerization technique

    NASA Astrophysics Data System (ADS)

    El-Toni, Ahmed Mohamed; Yin, Shu; Sato, Tsugio

    2004-09-01

    Organic ultraviolet (UV) ray absorbents have been used as sunscreen materials, but may pose a safety problem when used at high concentration. In order to prevent direct contact of organic UV rays absorbent by the human skin, an organic UV absorbent such as 4,4'-diaminostilbene-2,2'-disulfonic acid (DASDSA) was intercalated into Zn 2Al-layered double hydroxide (Zn 2Al-LDHs) by coprecipiation reaction. The problem of deintercalation of organic molecules from LDHs by the anion exchange reaction with carbonate ion could be greatly depressed by forming a protection film of silica on the surface. Zn 2Al-LDH/DASDSA was directly coated with silica by means of a polymerization technique based on the Stöber method. The deintercalation behavior as well as UV-shielding properties were investigated for coated particles.

  9. One-pot synthesis of NiFe layered double hydroxide/reduced graphene oxide composite as an efficient electrocatalyst for electrochemical and photoelectrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Youn, Duck Hyun; Park, Yoon Bin; Kim, Jae Young; Magesh, Ganesan; Jang, Youn Jeong; Lee, Jae Sung

    2015-10-01

    As an efficient non-precious metal catalyst for oxygen evolution reaction (OER) in electrochemical and photoelectrochemical water splitting, NiFe layered double hydroxide (LDH)/reduced graphene oxide (NiFe/RGO) composite is synthesized by a simple solvothermal method in one-pot. NiFe LDHs are uniformly deposited on RGO layers of high electrical conductivity and large surface area. In electrochemical water splitting, NiFe/RGO shows superior OER performance compared to bare NiFe and reference IrO2 with a lower benchmark η10 value (required overpotential to drive 10 mA cm-2) of 0.245 V. Furthermore, NiFe/RGO substantially increases the performance of a hematite photoanode in photoelectrochemical water oxidation, demonstrating its potential as an OER co-catalyst for photoelectrodes.

  10. Thermal decomposition and reconstruction of CaFe-layered double hydroxide studied by X-ray diffractometry and 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Bugris, Valéria; Ádok-Sipiczki, Mónika; Anitics, Tamás; Kuzmann, Ernő; Homonnay, Zoltán; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

    2015-06-01

    In spite of numerous investigations on the various processes of the thermal decomposition and rehydration of layered double hydroxides (LDHs) by a variety sophisticated experimental means, many details are still unexplored and some contradictions are still unresolved. In this work, our efforts were focussed on clarifying the composition, structure and properties of thermally decomposed metaphases originating from CaFe-LDH, heat treated in the 373-973 K temperature range. The structure reconstruction ability of mixed metal oxide phases obtained after heat treatments was also investigated, mainly concentrating on the changes in the microenvironment of Fe(III), in the presence of controlled amount of water vapour (i.e., at different relative humidities). All samples were characterised by X-ray diffractometry, and the iron-containing phases were studied by 57Fe Mössbauer spectroscopy.

  11. A facile synthesis of strong near infrared fluorescent layered double hydroxide nanovehicles with an anticancer drug for tumor optical imaging and therapy

    NASA Astrophysics Data System (ADS)

    Chen, Chunping; Yee, Lee Kim; Gong, Hua; Zhang, Yong; Xu, Rong

    2013-05-01

    In this work, a new multifunctional nanovehicle for tumor optical imaging and therapy was developed using Y2O3:Er3+,Yb3+ nanoparticles as near infrared fluorescent nanophosphors, and MgAl-layered double hydroxide (LDH) nanosheets as anticancer drug nanovehicles. Monodispersed Y2O3:Er3+,Yb3+ nanophosphors were readily synthesized by the urea assisted homogenous precipitation method. Hierarchically structured LDH nanosheets intercalated with an anticancer drug, fluorouracil (5FU), were deposited on the surface of Y2O3:Er3+,Yb3+@SiO2 by a simple precipitation method followed by hydrothermal treatment. The resultant Y2O3:Er3+,Yb3+@SiO2@LDH-5FU nanovehicles exhibit strong red upconversion fluorescence under the excitation of a 980 nm laser, which allows tracking of the nanovehicles after localization in cancer cells. A better anticancer efficiency was obtained over the nanovehicles than the free drug which can be attributed to their positively charged surfaces for favorable interaction with the negatively charged cell membranes. The multifunctional nanovehicles designed in this work are expected to be promising material candidates for simultaneous tumor optical imaging and therapy.In this work, a new multifunctional nanovehicle for tumor optical imaging and therapy was developed using Y2O3:Er3+,Yb3+ nanoparticles as near infrared fluorescent nanophosphors, and MgAl-layered double hydroxide (LDH) nanosheets as anticancer drug nanovehicles. Monodispersed Y2O3:Er3+,Yb3+ nanophosphors were readily synthesized by the urea assisted homogenous precipitation method. Hierarchically structured LDH nanosheets intercalated with an anticancer drug, fluorouracil (5FU), were deposited on the surface of Y2O3:Er3+,Yb3+@SiO2 by a simple precipitation method followed by hydrothermal treatment. The resultant Y2O3:Er3+,Yb3+@SiO2@LDH-5FU nanovehicles exhibit strong red upconversion fluorescence under the excitation of a 980 nm laser, which allows tracking of the nanovehicles after

  12. Concomitant Intercalation and Decomplexation of Ferrocene Sulfonates in Layered Double Hydroxides

    NASA Astrophysics Data System (ADS)

    Morlat-Thérias, Sandrine; Mousty, Christine; Palvadeau, Pierre; Molinié, Philippe; Léone, Philippe; Rouxel, Jean; Taviot-Guého, Christine; Ennaqui, Abderrahman; de Roy, André; Besse, Jean Pierre

    1999-04-01

    In the [Zn-Cr-Cl] lamellar double hydroxide corresponding to the chemical formula [Zn2+2Cr3+(OH-)6] [Cl-, 2H2O], chlorine anions can be easily exchanged by various moieties. For example, it is possible to replace Cl-ions with ferrocene mono- and disulfonate salts in the interlamellar space. In a second step, these organic molecules can be removed by carbonate ions. XPS, EXAFS, Mössbauer spectroscopy, and magnetic measurements show that during this last exchange ferrocene sulfonates are de-complexed, liberating Fe3+ions which then would be introduced into the hydroxide layers. The main consequence is a modification of magnetic properties.

  13. Synthesis of Zn-Fe layered double hydroxides via an oxidation process and structural analysis of products

    NASA Astrophysics Data System (ADS)

    Morimoto, Kazuya; Tamura, Kenji; Anraku, Sohtaro; Sato, Tsutomu; Suzuki, Masaya; Yamada, Hirohisa

    2015-08-01

    The synthesis of Zn-Fe(III) layered double hydroxides was attempted, employing different pathways using either Fe(II) or Fe(III) species together with Zn as the initial reagents. The product derived from the synthesis employing Fe(II) was found to transition to a Zn-Fe(III) layered double hydroxides phase following oxidation process. In contrast, the product obtained with Fe(III) did not contain a layered double hydroxides phase, but rather consisted of simonkolleite and hydrous ferric oxide. It was determined that the valency of the Fe reagent used in the initial synthesis affected the generation of the layered double hydroxides phase. Fe(II) species have ionic radii and electronegativities similar to those of Zn, and therefore are more likely to form trioctahedral hydroxide layers with Zn species.

  14. Nickel-Aluminum Layered Double Hydroxide Coating on the Surface of Conductive Substrates by Liquid Phase Deposition.

    PubMed

    Maki, Hideshi; Takigawa, Masashi; Mizuhata, Minoru

    2015-08-12

    The direct synthesis of the adhered Ni-Al LDH thin film onto the surface of electrically conductive substrates by the liquid phase deposition (LPD) reaction is carried out for the development of the positive electrode. The complexation and solution equilibria of the dissolved species in the LPD reaction have been clarified by a theoretical approach, and the LPD reaction conditions for the Ni-Al LDH depositions are shown to be optimized by controlling the fluoride ion concentration and the pH of the LPD reaction solutions. The yields of metal oxides and hydroxides by the LPD method are very sensitive to the supersaturation state of the hydroxide in the reaction solution. The surfaces of conductive substrates are completely covered by the minute mesh-like Ni-Al LDH thin film; furthermore, there is no gap between the surfaces of conductive substrates and the deposited Ni-Al LDH thin film. The active material layer thickness was able to be controlled within the range from 100 nm to 1 μm by the LPD reaction time. The high-crystallinity and the arbitrary-thickness thin films on the conductive substrate surface will be beneficial for the interface control of charge transfer reaction fields and the internal resistance reduction of various secondary batteries. PMID:26189509

  15. Intercalation studies of zinc hydroxide chloride: Ammonia and amino acids

    SciTech Connect

    Arizaga, Gregorio Guadalupe Carbajal

    2012-01-15

    Zinc hydroxide chloride (ZHC) is a layered hydroxide salt with formula Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}2H{sub 2}O. It was tested as intercalation matrix for the first time and results were compared with intercalation products of the well-known zinc hydroxide nitrate and a Zn/Al layered double hydroxide. Ammonia was intercalated into ZHC, while no significant intercalation occurred in ZHN. Aspartic acid intercalation was only achieved by co-precipitation at pH=10 with ZHC and pH=8 with zinc hydroxide nitrate. Higher pH resistance in ZHC favored total deprotonation of both carboxylic groups of the Asp molecule. ZHC conferred more thermal protection against Asp combustion presenting exothermic peaks even at 452 Degree-Sign C while the exothermic event in ZHN was 366 Degree-Sign C and in the LDH at 276 Degree-Sign C. - Graphical abstract: The zinc hydroxide chloride (ZHC) with formula Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}2H{sub 2}O was tested as intercalation matrix. In comparison with the well-known zinc hydroxide nitrate (ZHN) and layered double hydroxides (LDH), ZHC was the best matrix for thermal protection of Asp combustion, presenting exothermic peaks even at 452 Degree-Sign C, while the highest exothermic event in ZHN was at 366 Degree-Sign C, and in the LDH it was at 276 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Zinc hydroxide chloride (ZHC) was tested as intercalation matrix for the first time. Black-Right-Pointing-Pointer ZHC has higher chemical and thermal stability than zinc hydroxide nitrate and LDH. Black-Right-Pointing-Pointer NH{sub 3} molecules can be intercalated into ZHC. Black-Right-Pointing-Pointer The amino group of amino acids limits the intercalation by ion-exchange.

  16. Degradability Enhancement of Poly(Lactic Acid) by Stearate-Zn3Al LDH Nanolayers

    PubMed Central

    Eili, Mahboobeh; Shameli, Kamyar; Ibrahim, Nor Azowa; Yunus, Wan Md Zin Wan

    2012-01-01

    Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn3Al LDH. A solution casting method was used to prepare PLA/stearate-Zn3Al LDH nanocomposites. The anionic clay Zn3Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn3Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn3Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn3Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn3Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn3Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA. PMID:22942682

  17. Structural characterization and thermal properties of polyamide 6.6/Mg, Al/adipate-LDH nanocomposites obtained by solid state polymerization

    SciTech Connect

    Herrero, M.; Benito, P.; Labajos, F.M.; Rives, V.; Zhu, Y.D.; Allen, G.C.; Adams, J.M.

    2010-07-15

    A new nanocomposite was obtained by dispersing an adipate-modified layered double hydroxide (Ad-LDH) with adipic acid and hexamethylene diamine. These samples were polymerized in the solid phase under a nitrogen flow for 200 min at 190 {sup o}C. The structural and compositional details of the nanocomposite were determined by powder X-ray diffraction (PXRD), fourier transform infrared (FTIR) spectroscopy, focused ion beam (FIB), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The PXRD patterns and FIB images show a partially intercalated and partially exfoliated dispersion of layered crystalline materials in the polyamide 6.6 matrix. The best dispersion level is achieved in polyamide 6.6/LDH nanocomposites with low LDH loading. Some residual tactoids and particle agglomerates are also evident at high concentration. The best thermal stability of the nanocomposites is shown by the sample with 0.1% LDH content, for which it is higher than that of pure polyamide. - Graphical abstract: A new nanocomposite was obtained by compounding an adipate-modified layered double hydroxides (LDH) with adipic acid and hexamethylene diamine. These samples were polymerized in the solid phase under a nitrogen flow for 200 min at 190 {sup o}C. The nanodispersion of LDH in polyamide 6.6 may be qualitatively estimated from the analysis and PXRD patterns and FIB images. The decomposition temperature in the nanocomposite with 0.1 % LDH increases significantly compared to that for pristine PA6.6. .

  18. CO2 capture at low temperatures (30-80 °C) and in the presence of water vapor over a thermally activated Mg-Al layered double hydroxide.

    PubMed

    Torres-Rodríguez, Daniela A; Lima, Enrique; Valente, Jaime S; Pfeiffer, Heriberto

    2011-11-10

    The carbonation process of a calcined Mg-Al layered double hydroxide (LDH) was systematically analyzed at low temperatures, varying the relative humidity. Qualitative and quantitative experiments were performed. In a first set of experiments, the relative humidity was varied while maintaining a constant temperature. Characterization of the rehydrated products by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and solid-state NMR revealed that the samples did not recover the LDH structure; instead hydrated MgCO(3) was produced. The results were compared with similar experiments performed on magnesium oxide for comparison purposes. Then, in the second set of experiments, a kinetic analysis was performed. The results showed that the highest CO(2) capture was obtained at 50 °C and 70% of relative humidity, with a CO(2) absorption capacity of 2.13 mmol/g. PMID:21936518

  19. Preparation and properties of UV-cured acrylated silane intercalated polymer/LDH nanocomposite

    SciTech Connect

    Yuan, Yan; Shi, Wenfang

    2011-01-15

    A novel UV-cured polymer/layered double hydroxide (LDH) nanocomposite was prepared by modifying the LDH with sodium dodecyl sulfate (SDS) and [3-(methyl-acroloxy)propyl]trimethoxysilane (KH570) followed by UV irradiation after blended into a acrylate system. From the XRD analyses, the SDS-modified LDH-DS presented the basal spacing of 2.67 nm, whereas the further KH570-intercalated LDH-KH showed a slight decrease to 2.41 nm. After UV irradiated the exfoliated microstructure was formed, and observed by TEM and HR-TEM, showing the fine dispersion and random orientation of LDH in the polymer matrix. The storage modulus and glass transition temperature of the nanocomposite containing 5% LDH-KH increased to 47.5 MPa and 67.8 {sup o}C, respectively, from 39.7 MPa and 66 {sup o}C of the pure polymer from DMTA measurements. The tensile strength and Persoz hardness were enhanced to 10.6 MPa and 111 s, respectively, from 7.7 MPa and 85 s of the pure polymer.

  20. Ethylene Glycol Intercalated Cobalt/Nickel Layered Double Hydroxide Nanosheet Assemblies with Ultrahigh Specific Capacitance: Structural Design and Green Synthesis for Advanced Electrochemical Storage.

    PubMed

    Wang, Changhui; Zhang, Xiong; Xu, Zhongtang; Sun, Xianzhong; Ma, Yanwei

    2015-09-01

    Because of the rapid depletion of fossil fuels and severe environmental pollution, more advanced energy-storage systems need to possess dramatically improved performance and be produced on a large scale with high efficiency while maintaining low-enough costs to ensure the higher and wider requirements. A facile, energy-saving process was successfully adopted for the synthesis of ethylene glycol intercalated cobalt/nickel layered double hydroxide (EG-Co/Ni LDH) nanosheet assembly variants with higher interlayer distance and tunable transitional-metal composition. At an optimized starting Co/Ni ratio of 1, the nanosheet assemblies display a three-dimensional, spongelike network, affording a high specific surface area with advantageous mesopore structure in 2-5 nm containing large numbers of about 1.2 nm micropores for promoting electrochemical reaction. An unprecedented electrochemical performance was achieved, with a specific capacitance of 4160 F g(-1) at a discharge current density of 1 A g(-1) and of 1313 F g(-1) even at 50 A g(-1), as well as excellent cycling ability. The design and optimization of EG-Co/Ni LDH nanosheets in compositions, structures, and performances, in conjunction with the easy and relatively "green" synthetic process, will play a pivotal role in meeting the needs of large-scale manufacture and widespread application for advanced electrochemical storage. PMID:26258432

  1. Insight of an easy topochemical oxidative reaction in obtaining high performance electrochemical capacitor based on CoIICoIII monometallic cobalt Layered Double Hydroxide

    NASA Astrophysics Data System (ADS)

    Vialat, Pierre; Rabu, Pierre; Mousty, Christine; Leroux, Fabrice

    2015-10-01

    A series of monometallic Layered Double Hydroxides (LDH) using electroactive cation, i.e. divalent or trivalent cobalt, was prepared by Topochemical Oxidation Reaction (TOR) under O2 atmosphere at 40 °C from pristine β-Co(OH)2 platelets. The oxidation state of the ill-defined layered materials was evaluated by coupling thermal measurements and chemical titration (iodometry). Their characterization by ancillary techniques was completed by the study of their magnetic behavior. The obtained magnetic moments suggest the presence of structural local deformation around the CoII ions, unhomogeneous charge distribution yielding to clustering effects cannot be discarded. Their pseudo-faradic properties as supercapacitor in KOH solution was thoroughly investigated by using Cyclic Voltammetry (CV), Galvanostatic Cycling with Potential Limitation (GCPL) and Electrochemical Impedance Spectroscopy (EIS) techniques. As a function of the oxygen treatment, the relative amount of CoII/CoIII was found to range into 5.3 and 13.3, which is unusually high when compared to classical LDH charge distribution. Pseudocapacitance as high as 1540 F g-1 was obtained underlining a high percentage of CoII, ≈40%, involved in electrochemical process. This high percentage is tentatively explained by an extended outer-active electrochemical surface which demonstrates that TOR is a quick and easy process to get a high pseudocapacitive performance.

  2. Adsorption of charged protein residues on an inorganic nanosheet: Computer simulation of LDH interaction with ion channel

    NASA Astrophysics Data System (ADS)

    Tsukanov, Alexey A.; Psakhie, Sergey G.

    2016-08-01

    Quasi-two-dimensional and hybrid nanomaterials based on layered double hydroxides (LDH), cationic clays, layered oxyhydroxides and hydroxides of metals possess large specific surface area and strong electrostatic properties with permanent or pH-dependent electric charge. Such nanomaterials may impact cellular electrostatics, changing the ion balance, pH and membrane potential. Selective ion adsorption/exchange may alter the transmembrane electrochemical gradient, disrupting potential-dependent cellular processes. Cellular proteins as a rule have charged residues which can be effectively adsorbed on the surface of layered hydroxide based nanomaterials. The aim of this study is to attempt to shed some light on the possibility and mechanisms of protein "adhesion" an LDH nanosheet and to propose a new direction in anticancer medicine, based on physical impact and strong electrostatics. An unbiased molecular dynamics simulation was performed and the combined process free energy estimation (COPFEE) approach was used.

  3. Magnetic, luminescent Eu-doped Mg-Al layered double hydroxide and its intercalation for ibuprofen.

    PubMed

    Wang, Jun; Zhou, Jideng; Li, Zhanshuang; Song, Yanchao; Liu, Qi; Jiang, Zhaohua; Zhang, Milin

    2010-12-27

    A magnetic, luminescent Eu-doped Mg-Al layered double hydroxide with ibuprofen (IBU) intercalated in the gallery has been successfully prepared by a simple coprecipitation method. The physicochemical properties of the samples were well characterized by powder XRD, TEM, FTIR, TGA, inductively coupled plasma MS (ICP-MS), vibrating sample magnetometry (VSM), and fluorospectrophotometry. The results revealed that Fe(3)O(4) nanoparticles are coated on the surface of layered double hydroxides and the obtained (Mg(2)Al(0.95)Eu(0.05))(Fe)-(IBU) sample exhibits both superparamagnetic and luminescent properties, with a saturation magnetization value of 1.86 emu  g(-1) and a strong emission band at 610 nm, respectively. Additionally, it was found that the ibuprofen loading amount is about 31 % (w/w), and the intercalated ibuprofen possesses sustained release behavior when the magnetic, luminescent composite is immersed in simulated body fluid (SBF). PMID:21038324

  4. Thermodynamic equilibrium analyses of the uptake of aromatic compounds from an aqueous solution by magnesium-aluminum (Mg-Al) layered double hydroxide intercalated with 1-naphthol-3,8-disulfonate

    NASA Astrophysics Data System (ADS)

    Kameda, Tomohito; Uchiyama, Tomomi; Yoshioka, Toshiaki

    2013-06-01

    Magnesium-aluminum layered double hydroxide (Mg-Al LDH) intercalated with 1-naphthol-3,8-disulfonate (1-N-3,8-DS2-) was prepared by coprecipitation. Thermodynamically, the prepared Mg-Al LDH showed greater preferential uptake of 1,3-dinitrobenzene (DNB) than of 1,2-dimethoxybenzene (DMB). This preferential uptake of aromatic compounds, which is adequately expressed by the Dubinin-Radushkevich adsorption isotherm, was attributed to the π-π stacking interactions between the benzene ring of the aromatic compounds and the naphthalene core of 1-N-3,8-DS2- intercalated in the interlayer spaces of Mg-Al LDH. Negative values of ΔG for DNB and DMB indicate that the adsorption process is spontaneous at all temperatures. The value of ΔS for DNB was much lower than that for DMB. This implies that DNB was far more strongly adsorbed to 1-N-3,8-DS2- than was DMB, resulting in a lower degree of freedom for and higher uptake of DNB than those in the case DMB. The absolute values of |ΔH| for DNB and DMB were less than 20 kJ mol-1, indicating that the uptake of DNB or DMB by 1-N-3,8-DS·Mg-Al LDH can be considered a physical adsorption process caused by π-π stacking interactions.

  5. Biomass-Derived Nitrogen-Doped Carbon Nanofiber Network: A Facile Template for Decoration of Ultrathin Nickel-Cobalt Layered Double Hydroxide Nanosheets as High-Performance Asymmetric Supercapacitor Electrode.

    PubMed

    Lai, Feili; Miao, Yue-E; Zuo, Lizeng; Lu, Hengyi; Huang, Yunpeng; Liu, Tianxi

    2016-06-01

    The development of biomass-based energy storage devices is an emerging trend to reduce the ever-increasing consumption of non-renewable resources. Here, nitrogen-doped carbonized bacterial cellulose (CBC-N) nanofibers are obtained by one-step carbonization of polyaniline coated bacterial cellulose (BC) nanofibers, which not only display excellent capacitive performance as the supercapacitor electrode, but also act as 3D bio-template for further deposition of ultrathin nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets. The as-obtained CBC-N@LDH composite electrodes exhibit significantly enhanced specific capacitance (1949.5 F g(-1) at a discharge current density of 1 A g(-1) , based on active materials), high capacitance retention of 54.7% even at a high discharge current density of 10 A g(-1) and excellent cycling stability of 74.4% retention after 5000 cycles. Furthermore, asymmetric supercapacitors (ASCs) are constructed using CBC-N@LDH composites as positive electrode materials and CBC-N nanofibers as negative electrode materials. By virtue of the intrinsic pseudocapacitive characteristics of CBC-N@LDH composites and 3D nitrogen-doped carbon nanofiber networks, the developed ASC exhibits high energy density of 36.3 Wh kg(-1) at the power density of 800.2 W kg(-1) . Therefore, this work presents a novel protocol for the large-scale production of biomass-derived high-performance electrode materials in practical supercapacitor applications. PMID:27135301

  6. Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective.

    PubMed

    Abellán, Gonzalo; Martí-Gastaldo, Carlos; Ribera, Antonio; Coronado, Eugenio

    2015-06-16

    Design of functional hybrids lies at the very core of synthetic chemistry as it has enabled the development of an unlimited number of solids displaying unprecedented or even improved properties built upon the association at the molecular level of quite disparate components by chemical design. Multifunctional hybrids are a particularly appealing case among hybrid organic/inorganic materials. Here, chemical knowledge is used to deploy molecular components bearing different functionalities within a single solid so that these properties can coexist or event interact leading to unprecedented phenomena. From a molecular perspective, this can be done either by controlled assembly of organic/inorganic molecular tectons into an extended architecture of hybrid nature or by intercalation of organic moieties within the empty channels or interlamellar space offered by inorganic solids with three-dimensional (MOFs, zeolites, and mesoporous hosts) or layered structures (phosphates, silicates, metal dichalcogenides, or anionic clays). This Account specifically illustrates the use of layered double hydroxides (LDHs) in the preparation of magnetic hybrids, in line with the development of soft inorganic chemistry processes (also called "Chimie Douce"), which has significantly contributed to boost the preparation hybrid materials based on solid-state hosts and subsequent development of applications. Several features sustain the importance of LDHs in this context. Their magnetism can be manipulated at a molecular level by adequate choice of constituting metals and interlayer separation for tuning the nature and extent of magnetic interactions across and between planes. They display unparalleled versatility in accommodating a broad range of anionic species in their interlamellar space that encompasses not only simple anions but chemical systems of increasing dimensionality and functionalities. Their swelling characteristics allow for their exfoliation in organic solvents with high

  7. Thermodynamical and structural insights of orange II adsorption by Mg{sub R}AlNO{sub 3} layered double hydroxides

    SciTech Connect

    Mustapha Bouhent, Mohamed; Derriche, Zoubir; Denoyel, Renaud; Prevot, Vanessa; Forano, Claude

    2011-05-15

    [Mg{sub 1-x} Al{sub x}(OH){sub 2}][(NO{sub 3}){sub x}, nH{sub 2}O] Layered Double Hydroxide (LDH) sorbents with variable Mg/Al molar (R=(1-x)/x) ratios were investigated for adsorption of azo dye, orange II (OII) at various pH and temperature conditions. Mg{sub 2}AlNO{sub 3} displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg{sub 2}AlNO{sub 3} at 40 {sup o}C. Adsorption isotherms have been fitted using the Langmuir model and free energy of adsorption ({Delta}G{sup o}), enthalpy ({Delta}H{sup o}) and entropy ({Delta}S{sup o}) were calculated. The experimental values for {Delta}G{sup o} in temperature range between 10 and 40 {sup o}C were found to be negative indicating that a spontaneous process occurred. Positive calculated enthalpy values, characteristic of an endothermic process were found. Characterization of solids (PXRD, FTIR, UV-vis, TGA/DTA, adsorption isotherm BET analysis, SEM and Zetametry) before and after adsorption showed that adsorption proceeds in two steps. First, adsorption occurs at the LDH surface, followed by intercalation via anion exchange. -- Graphical Abstract: Structural and thermodynamical insight of adsorption/Intercalation of OII in Mg{sub R}Al LDH Display Omitted Highlights: {yields} The nitrate containing hydrotalcite-like compounds (Mg{sub R}AlNO{sub 3} LDH) were prepared by the coprecipitation method. {yields} Adsorption of anionic orange dye(OII) is studied on LDHs at different temperatures. {yields} The adsorption process is well described by the Langmuir isotherm model. {yields} Mg{sub 2}AlNO{sub 3} displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg{sub 2}AlNO{sub 3} at 40 {sup o}C. {yields} Adsorption process does not occur on the surface of the LDH only but an intercalation process is also occurring concomitantly according to the thermodynamical values.

  8. Preparation and controlled-release studies of a protocatechuic acid-magnesium/aluminum-layered double hydroxide nanocomposite

    PubMed Central

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Hussein-Al-Ali, Samer Hasan; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2013-01-01

    In the study reported here, magnesium/aluminum (Mg/Al)-layered double hydroxide (LDH) was intercalated with an anticancer drug, protocatechuic acid, using ion-exchange and direct coprecipitation methods, with the resultant products labeled according to the method used to produce them: “PANE” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the ion-exchange method) and “PAND” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the direct method), respectively. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirmed the intercalation of protocatechuic acid into the inter-galleries of Mg/Al-LDH. The protocatechuic acid between the interlayers of PANE and PAND was found to be a monolayer, with an angle from the z-axis of 8° for PANE and 15° for PAND. Thermogravimetric and differential thermogravimetric analysis results revealed that the thermal stability of protocatechuic acid was markedly enhanced upon intercalation. The loading of protocatechuic acid in PANE and PAND was estimated to be about 24.5% and 27.5% (w/w), respectively. The in vitro release study of protocatechuic acid from PANE and PAND in phosphate-buffered saline at pH 7.4, 5.3, and 4.8 revealed that the nanocomposites had a sustained release property. After 72 hours incubation of PANE and PAND with MCF-7 human breast cancer and HeLa human cervical cancer cell lines, it was found that the nanocomposites had suppressed the growth of these cancer cells, with a half maximal inhibitory concentration of 35.6 μg/mL for PANE and 36.0 μg/mL for PAND for MCF-7 cells, and 19.8 μg/mL for PANE and 30.3 μg/mL for PAND for HeLa cells. No half maximal inhibitory concentration for either nanocomposite was found for 3T3 cells. PMID:23737666

  9. Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc-iron layered double hydroxides by one-step coprecipitation route

    SciTech Connect

    Zhang Hui Wen Xing; Wang Yingxia

    2007-05-15

    Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Moessbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO{sub 4} {sup 2-}-containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO{sub 4} {sup 2-}-containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn{sub 0.435}.Fe{sup II} {sub 0.094}.Fe{sup III} {sub 0.470}.(OH){sub 2}].(SO{sub 4} {sup 2-}){sub 0.235}.1.0H{sub 2}O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO{sub 4} {sup 2-}-containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS. - Graphical abstract: For Zn{sup 2+}-Fe{sup 2+}-Fe{sup 3+} GR2(SO{sub 4} {sup 2-}), according to the derived chemical formula, Fe{sup 3+} was arranged at 1a (0, 0, 0) position, while all Zn{sup 2+} were in 2d position with the occupancy 0.645, and the left part of 2d positions were taken by Fe{sup 2+}/Fe{sup 3+}.

  10. Synthesis, characterization, and efficacy of antituberculosis isoniazid zinc aluminum-layered double hydroxide based nanocomposites

    PubMed Central

    Saifullah, Bullo; El Zowalaty, Mohamed Ezzat; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin Mahler; Hussein, Mohd Zobir

    2016-01-01

    The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly. PMID:27486322

  11. Synthesis, characterization, and efficacy of antituberculosis isoniazid zinc aluminum-layered double hydroxide based nanocomposites.

    PubMed

    Saifullah, Bullo; El Zowalaty, Mohamed Ezzat; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin Mahler; Hussein, Mohd Zobir

    2016-01-01

    The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly. PMID:27486322

  12. Ni/Ti layered double hydroxide: synthesis, characterization and application as a photocatalyst for visible light degradation of aqueous methylene blue.

    PubMed

    Roy Chowdhury, Priyadarshi; Bhattacharyya, Krishna G

    2015-04-21

    Visible light responsive 2 : 1 Ni/Ti layered double hydroxide (LDH) was synthesized by a single step hydrothermal route using commercially available Ni(NO3)2·6H2O, TiCl4 and urea. The material exhibited significant absorption in the visible range with a very narrow band gap (2.68 eV). This could be attributed to structural defects as confirmed by diffuse reflectance spectroscopy (DRS), photoluminescence (PL), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. FT-IR, TGA, DTA, DSC, HR-TEM and SEM-EDX measurements yielded information about structural aspects, thermal stability and surface morphology. Surface and pore characteristics of the material were obtained from the BET isotherm for N2 adsorption at 77 K. Zeta potential measurements were used to characterize the electrical properties of the surface while XPS revealed changes in surface states and oxygen deficiencies. The material was found to be an excellent photocatalyst for the degradation of aqueous methylene blue in visible light. The photocatalytic properties of the material were explained on the basis of the narrow band gap, the high surface area and the presence of surface defects. The photocatalytic activity improved in alkaline media [pH 11.0, catalyst load 15 mg in 200 ml dye solution, dye concentration 1 × 10(-6) M (= 0.3198 mg L(-1))] due to the electrostatic attractions between the dye cations and the negative charges on the Ni/Ti LDH surface. The catalytic activity was found to be higher than the common commercial catalysts like ZnO, ZnS, NiO, TiO2 and Degussa P25. The catalytic activity was retained even after five methylene blue degradation cycles, demonstrating that the LDH could be an important addition to the field of wastewater treatment. PMID:25763803

  13. Controlling the fluorescence behavior of 1-pyrenesulfonate by cointercalation with a surfactant in a layered double hydroxide.

    PubMed

    Costa, Ana L; Gomes, Ana C; Pillinger, Martyn; Gonçalves, Isabel S; Seixas de Melo, J Sérgio

    2015-04-28

    Zn-Al layered double hydroxides (LDHs) containing solely 1-pyrenesulfonate (PS) or 1-heptanesulfonate (HS) anions, or a mixture of the two with HS/PS molar ratios ranging between ca. 7.5 and 82, were prepared by the direct synthesis method and characterized by powder X-ray diffraction, thermal and elemental analyses, scanning electron microscopy, and FT-IR, FT-Raman, and (13)C{(1)H} CP MAS NMR spectroscopies. Well-ordered intercalates were obtained with basal spacings of 18.8 Å for the LDH intercalated by PS and 19.2-19.4 Å for the other materials containing HS. The photophysics of the solids, as well as the PS probe dissolved in water and common organic solvents (aiming to compare the behavior of the "isolated" molecule with that in the solid), were investigated by steady-state and time-resolved fluorescence techniques. The fluorescence spectra of the solid samples display two bands with maxima at 376 and 495 nm. Depending on the HS/PS ratios, the band intensity ratio (obtained at 375 and 520 nm) changes, reflecting different contributions from monomer and dimer species. The decays collected at 375 nm are biexponentials with a major component (∼97% of the total fluorescence) of 105 ns for the highest HS/PS ratio, which further loses importance with an increase in the PS content. When the decays are collected at 480 and 520 nm, the fits are triexponentials with a major component varying from 108 to 124 ns, attributed to an excimer. Steady-state and time-resolved measurements with PS in solution (ethanol, methanol, DMF, DMSO, and water) were also measured, and a comparison of the vibronic I1/I3 ratio and lifetimes in water (65 ns) with those in the LDHs indicates that the PS probe in the cointercalated LDHs is surrounded by the HS surfactant. PMID:25848919

  14. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

    SciTech Connect

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2014-09-15

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro. - Highlights: • We intercalated chlorogenic into Zn/Al-layered double hydroxide by ion-exchange and coprecipitation methods. • The two methods gave nanocomposites

  15. The investigation of Ni-Al and Co-Al based layered double hydroxides and their derived mixed oxides thin films deposited by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Birjega, R.; Matei, A.; Filipescu, M.; Stokker-Cheregi, F.; Luculescu, C.; Colceag, D.; Zavoianu, R.; Pavel, O. D.; Dinescu, M.

    2013-08-01

    Layered Double Hydroxides (LDHs) are host-guest materials consisting of positively charged metal/hydroxides sheets with intercalated anions and water molecules. LDHs can be described by the generic formula [[ṡmHO and their structure is formed by layers containing divalent cations (M2+: Mg, Zn, Ni, Co,…) and trivalent cations (M3+: Al, Ga, Cr,…) with an octahedral coordination. LDH films with well-oriented structure and controlled thickness are needed for numerous applications like sensors, protective coatings, catalysts, components for optoelectronics etc. In this work, we report on the deposition of Ni-Al and Co-Al based LDHs and their derived mixed oxides by pulsed laser deposition as a new approach to fabricate oriented LDHs or highly dispersed metallic mixed oxides. The influence of the laser characteristics, such as wavelength and fluence, on the films properties was studied. The films investigation techniques were X-Ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy combined with energy dispersive X-ray analysis, and Secondary Ions Mass Spectrometry.

  16. A molecular dynamic study of layered hydroxide induced depletion of mobile anions within the extracellular medium

    NASA Astrophysics Data System (ADS)

    Tsukanov, Alexey A.; Psakhie, Sergey G.

    2015-10-01

    The strong surface electric charge density of clay mineral host nanolayers enables their use as host-guest nanohybrids in many different areas of application. In particular, layered double hydroxides (LDH) of metals have found applications in medicine. Drug-LDH or gene-LDH nanohybrids are used for targeted delivery of biomedical agents to diseased cells or cancer cells. Fragments of the LDH host nanolayers may remain both within the cell and in the extracellular medium after drug delivery. How these charged nanosheets affect the cell electrostatics is still poorly understood. In the present paper, the idealized case of a single pure Mg2/Al-LDH nanolayer interacting with the extracellular anion environment was investigated to estimate the order of magnitude of a possible shift of the cell membrane equilibrium potential. An approximate dependence of the change in the chloride equilibrium membrane potential on the concentration of pure Mg2/Al-LDH nanosheets was determined.

  17. Preparation, characterization and antimicrobial applications of Zn-Fe LDH against MRSA.

    PubMed

    Moaty, S A Abdel; Farghali, A A; Khaled, Rehab

    2016-11-01

    Facile and simple processes to get Zn-Fe layered double hydroxide (LDH) with nitrate as the interlayer anion are reported. The method of co-precipitation produced high crystallinity LDH that is marked by XRD, SEM, TEM and FT-IR. Results showed that 99.8% of Cd(+2) removals were at pH11 and 4h. To get the adsorption isotherms, the concentration of metal ions extending from 6 to 18mg/L was utilized. Results supported the Langmuir adsorption model. In contrary, the adsorption process followed the pseudo-second-order reaction kinetics. Interestingly, the prepared LDH shows durable antimicrobial activities against Gram-negative (Proteous vulgaris, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pyogenes and MRSA) and fungi (Candida albicans, Aspergillus fumigatus, Geotricumcandidum, and Trichophyton mentagrophytes). The minimum inhibitory concentration (MIC) of Zn-Fe LDH varied from 0.49 to 15.60μg/mL according to the types of microorganisms. The prepared LDH achieved 90% at pH8.50 which is the pH of wastewater and at the same time exhibited durable antimicrobial activities against MRSA, Gram-negative, Gram-positive and fungi. Results have significant implications in the field of bioremediation of water with little cost, simple operation, high productivity and easiness of the equipment. PMID:27524011

  18. Efficient delivery of anticancer drug MTX through MTX-LDH nanohybrid system

    NASA Astrophysics Data System (ADS)

    Oh, Jae-Min; Park, Man; Kim, Sang-Tae; Jung, Jin-Young; Kang, Yong-Gu; Choy, Jin-Ho

    2006-05-01

    We have been successful to intercalate anticancer drug, methotrexate (MTX), into layered double hydroxides (LDHs), Mg2Al(OH)6(NO3)·0.1H2O, through conventional co-precipitation method. Layered double hydroxides (LDHs) are endowed with great potential for delivery vector, since their cationic layers lead to safe reservation of biofunctional molecules such as drug molecules or genes. And their ion exchangeability and solubility in acidic media (pH<4) give rise to the controlled release of drug molecules. Moreover, it has been partly confirmed that LDH itself is non-toxic and facilitate the cellular permeation. To check the toxicity of LDHs, the osteosarcoma cell culture lines (Saos-2 and MG-63) and the normal one (human fibroblast) were used for in vitro test. The anticancer efficacy of MTX intercalated LDHs (MTX-LDH nanohybrids) was also estimated in vitro by the bioassay such as MTT and BrdU (5-bromo-2-deoxyuridine) with the bone cancer cell culture lines (Saos-2 and MG-63). According to the toxicity test results, LDHs do not harm to both the normal and cancer cells upto the concentration of 500 ug/mL. The anticancer efficacy test for the MTX-LDH nanohybrids turn out to be much more effective in cell suppression compared to the MTX itself. According to the cell-line tests, the MTX-LDH shows same drug efficacy to the MTX itself in spite of the low concentration by ˜5000 times. Such a high cancer suppression effect of MTX-LDH hybrid is surely due to the excellent delivery efficiency of inorganic delivery vector, LDHs.

  19. Preparation of Tween 80-Zn/Al-Levodopa-Layered Double Hydroxides Nanocomposite for Drug Delivery System

    PubMed Central

    Kura, Aminu Umar; Hussein-Al-Ali, Samer Hasan; Hussein, Mohd Zobir; Fakurazi, Sharida

    2014-01-01

    We incorporated anti-Parkinsonian drug, levodopa (dopa), in Zn/Al-LDH by coprecipitation method to form dopa-LDH nanocomposite. Further coating of Tween-80 on the external surfaces of dopa-LDH nanocomposite was achieved through the oxygen of C=O group of Tween-80 with the layer of dopa-LDH nanocomposite. The final product is called Tween-dopa-LDH nanocomposite. The X-ray diffraction indicates that the Tween-dopa-LDH nanocomposite was formed by aggregation structure. From the TGA data, the Tween-80 loading on the surface of LDH and dopa-LDH was 8.6 and 7.4%, respectively. The effect of coating process on the dopa release from Tween-dopa-LDH nanocomposite was also studied. The release from Tween-dopa-LDH nanocomposite shows slower release compared to the release of the drug from dopa-LDH nanocomposite as done previously in our study, presumably due to the retarding shielding effect. The cell viability study using PC12 showed improved viability with Tween-80 coating on dopa-LDH nanocomposite as studied by mitochondrial dehydrogenase activity (MTT assay). PMID:24782658

  20. New layered double hydroxides by prepared by the intercalation of gibbsite

    SciTech Connect

    Rees, Jennifer R.; Burden, Chloe S.; Fogg, Andrew M.

    2015-04-15

    New layered double hydroxides (LDHs) with the composition [MAl{sub 4}(OH){sub 12}]Cl{sub 2}·1.5H{sub 2}O (M=Co, Ni) have been prepared by reacting gibbsite, γ-Al(OH){sub 3}, with the appropriate chloride salt in a synthesis in which the water of crystallization is the only solvent present and fully characterized. These LDHs have been shown to undergo facile anion exchange reactions with both organic and inorganic anions at room temperature making them comparable to other LDHs in this respect. Reactions under the same conditions with CuCl{sub 2}·2H{sub 2}O and ZnCl{sub 2} failed to form the desired LDHs but those with nitrate salts did lead to the formation of the previously reported [MAl{sub 4}(OH){sub 12}](NO{sub 3}){sub 2}·1.5H{sub 2}O (M=Co, Ni) compounds. - Graphical abstract: New layered double hydroxides (LDHs) with the composition [MAl{sub 4}(OH){sub 12}]Cl{sub 2}·1.5H{sub 2}O (M=Co, Ni) have been prepared by reacting gibbsite, γ-Al(OH){sub 3}, with the appropriate chloride salt in a synthesis in which no additional solvent is used and fully characterized. These LDHs have been shown to undergo facile anion exchange reactions with both organic and inorganic anions at room temperature. - Highlights: • Synthesis of new layered double hydroxides, [MAl{sub 4}(OH){sub 12}]Cl{sub 2}·1.5H{sub 2}O (M=Co, Ni). • Demonstration of the anion exchange capacity with both organic and inorganic anions. • Demonstration of the generality of the synthesis for LDHs.

  1. Anion exchange in Zn-Al layered double hydroxides: In situ X-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Salak, Andrei N.; Tedim, João; Kuznetsova, Alena I.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2010-07-01

    Anion exchange capacity is a key factor for the application of Zn-Al layered double hydroxides (LDHs) as nano-containers in active corrosion protection. In this work, the nitrate-pyrovanadate anion exchange/re-exchange processes in these LDHs were investigated in situ. We demonstrate that the exchange reactions lead to a decrease of the average crystallite size of LDHs as a result of mechanical fragmentation of the crystallites rather than dissolution/recrystallization. The fragmentation occurs due to fast anion exchange in the initial stage, and can be controlled by changing the ratio of the available substituent anions to the replacement anions and application of a mechanical activation.

  2. Removal of borate by coprecipitation with Mg/Al layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Kurashina, Masashi; Inoue, Tatsuki; Tajima, Chihiro; Kanezaki, Eiji

    2015-03-01

    Borate has been used for various industrial products and excessive dose of boron is harmful to humans. We investigated the removal of borate by direct coprecipitation with Mg/Al layered double hydroxide. In this study, the maximum removal of boron was 90% when Mg 30 mmol and Al 15 mmol at pH = 10 were used for 498 mg/l as B. The boron adsorption isotherms could be fitted to Langmuir model. The calculated constant Ws, saturation limit of boron adsorption, is 25 ± 2 mg/g and it is larger than that of ion exchange reaction (Ws = 15±1 mg/g).

  3. Mössbauer and XRD study of intercalated CaFe-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Sipiczki, Mónika; Kuzmann, Ernő; Pálinkó, István; Homonnay, Zoltán; Sipos, Pál; Kukovecz, Ákos; Kónya, Zoltán

    2014-04-01

    N-containing fully saturated (L-prolinate) or aromatic (indole-2-carboxylate) heterocyclic anions were immobilised in CaFe-layered double hydroxide with the dehydration-rehydration method from aqueous ethanol or acetone. The structure of the resulting organic-inorganic hybrids was characterised mainly with powder X-ray diffraction and 57Fe Mössbauer spectroscopy, and as supplementary analysis scanning electron microscopy, energy dispersive X-ray spectroscopy with elemental mapping and molecular modelling were also applied. It was found that the solvent mixture used for the synthesis caused enormous difference in the interlayer spacings of the obtained inorganic-organic hybrids.

  4. Double layer hydroxide minerals as host structures for bioorganic molecules. [Abstract only

    NASA Technical Reports Server (NTRS)

    Lee, Ton; Arrhenius, Meichia L.; Hui, Stella S.-Y.; Ring, Ken M.; Gedulin, Benjamin I.; Orgel, Leslie E.; Arrhenius, Gustaf

    1994-01-01

    A central problem in molecular evolution concerns the selective concentration from dilute, multicomponent solution of source molecules into a reactive environment, where formation of larger molecular assemblages can take place. Minerals consisting of positively charged, separable metal hydroxide sheets have proven capable of these functions. This common structural type is represented by minerals such as pyroaurite (Mg-Fe(3+) hydroxide), hydrotalcite (Mg-Al), green rust Fe(2+)-Fe(3+) and others. Effective interlayer sorption is demonstrated for orthophosphate and condensed phosphates, anionic alkyl compounds, polypeptides, nucleic acids, cyanide complexes and glycolaldehyde phosphate, the latter shown to readily oligomerize to form and selectively retain racemic hexose -2, 4, 6-phosphates, preferentially of altrose (Pitsch, et al, 1993). The selective aldomerization and retention effects correlate with the charge distribution in the host mineral structure and the stereochemistry of the substrate molecules. Interaction between nucleic acid bases, and between the cyanide groups of glycolaldehyde phosphate nitrile at the low water activity in the mineral interlayer is indicated by doubling of the monomeric separation of the hydroxide mineral sheets.

  5. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

    NASA Astrophysics Data System (ADS)

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2014-09-01

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro.

  6. The intercalation of bicyclic and tricyclic carboxylates into layered double hydroxides

    SciTech Connect

    Khan, Aamir I.; Williams, Gareth R.; Hu, Gang; Rees, Nicholas H.; O'Hare, Dermot

    2010-12-15

    Twenty-four nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised for the first time. Eight carboxylates were successfully intercalated into [LiAl{sub 2}(OH){sub 6}]Cl.yH{sub 2}O, [Ca{sub 2}Al(OH){sub 6}]NO{sub 3}.yH{sub 2}O, and [Mg{sub 2}Al(OH){sub 6}]NO{sub 3}.yH{sub 2}O, and the products fully characterised. Guest species incorporated include 1-adamantane carboxylate (1-AC) and 5-norbornene-2-endo-3-exo-dicarboxylate. In some cases, carbonate anions were co-intercalated with the organic guest, and in others poorly crystalline aluminium hydroxides formed as by-products. Sharper resonances were observed in the {sup 13}C solid-state NMR spectra of the 1-AC intercalates than in the spectrum of pure 1-AC, suggesting increased order in the arrangement of the cyclic cages in the intercalates. Where possible, time-resolved in situ X-ray diffraction was employed to study the nanoscopic steps involved in the intercalation reactions. These investigations showed that the reactions are one-step processes, proceeding directly to the fully exchanged intercalate with no intermediate phases. The intercalation processes were found to be nucleation controlled. -- Graphical abstract: Twenty-four novel nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised and fully characterised. In situ X-ray diffraction was used to study reaction mechanisms and kinetics. Display Omitted

  7. Adsorption of Cd(II) by Mg-Al-CO3- and magnetic Fe3O4/Mg-Al-CO3-layered double hydroxides: Kinetic, isothermal, thermodynamic and mechanistic studies.

    PubMed

    Shan, Ran-ran; Yan, Liang-guo; Yang, Kun; Hao, Yuan-feng; Du, Bin

    2015-12-15

    Understanding the adsorption mechanisms of metal cations on the surfaces of solids is important for determining the fate of these metals in water and wastewater treatment. The adsorption kinetic, isothermal, thermodynamic and mechanistic properties of cadmium (Cd(II)) in an aqueous solution containing Mg-Al-CO3- and magnetic Fe3O4/Mg-Al-CO3-layered double hydroxide (LDH) were studied. The results demonstrated that the adsorption kinetic and isotherm data followed the pseudo-second-order model and the Langmuir equation, respectively. The adsorption process of Cd(II) was feasible, spontaneous and endothermic in nature. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to explain the adsorption mechanisms. The characteristic XRD peaks and FTIR bands of CdCO3 emerged in the LDH spectra after Cd(II) adsorption, which indicated that the adsorption of Cd(II) by LDHs occurred mainly via CdCO3 precipitation, surface adsorption and surface complexation. Furthermore, the magnetic Fe3O4/Mg-Al-CO3-LDH can be quickly and easily separated using a magnet before and after the adsorption process. PMID:26073520

  8. Shape and size control of nano dispersed Mg/Al layered double hydroxide.

    PubMed

    Panda, H S; Srivastava, R; Bahadur, D

    2008-08-01

    Controlling the shape and size of the layered inorganic-organic hybrid particles is a challenge with conventional methods of synthesis. The co-precipitation method has been modified to synthesize Mg/Al Layered double hydroxide by controlling the particle growth using ultrasonic wave at the time of nucleation. In this project, magnesium and aluminum ions were considered as model systems with carbonate anion as intercalating agent. The resulting particles are compared with those of LDHs produced by conventional co-precipitation method at constant pH. Powder X-ray diffraction confirmed formation of the layered double hydroxide phases having crystallite size 19-20 nm in both 'a' and 'c' crystallographic directions. Transmission electron microscope and dynamic light scattering revealed nano disperse hexagonal platelets with narrow size distribution and average size was around 48 nm. The modified method reduces the particle size, increases the surface charge, narrows down the size distribution and also reduces the aspect ratio of the particles. Therefore, it is suggested that low amplitude ultrasonic wave prevents the aggregation of the nuclei, thus restricting the particle growth and results in uniform size particles. PMID:19049206

  9. Nickel-aluminum layered double hydroxides prepared via inverse micelles formation

    SciTech Connect

    Perez-Bernal, Maria E.; Ruano-Casero, Ricardo J.; Benito, Fatima; Rives, Vicente

    2009-06-15

    Nickel-aluminum layered double hydroxides have been prepared by conventional coprecipitation and by coprecipitation in the presence of a surfactant. The solids have been characterised by several physicochemical techniques. Calcination leads to formation of homogeneously dispersed mixed oxides, which have been characterised as well. The colour properties (lightness and chromaticity coordinates) of both series of solids (layered precursors and calcined ones) have been measured. It has been found that both the preparation method and the calcination treatment have an important effect on the luminosity (whiteness/darkness) of the solids, although the effect on the precise chromaticity coordinates (green/red and blue/yellow) is less marked. - Graphical abstract: Nickel-aluminum layered double hydroxides have been prepared by conventional coprecipitation and by coprecipitation in the presence of a surfactant. It has been found that both the preparation method and the calcination treatment have an important effect on the luminosity (whiteness/darkness) of the solids, although the effect on the precise chromaticity coordinates (green/red and blue/yellow) is less marked.

  10. Speciation of As(III)/As(V) in water samples by a magnetic solid phase extraction based on Fe₃O₄/Mg-Al layered double hydroxide nano-hybrid followed by chemiluminescence detection.

    PubMed

    Abdolmohammad-Zadeh, Hossein; Talleb, Zeynab

    2014-10-01

    A novel magnetic solid phase extraction method was developed for the speciation of As(III)/As(V) in aqueous solutions utilizing Fe3O4-doped Mg-Al layered double hydroxide (LDH) as a nano-sorbent. The method is based on the separation and pre-concentration of As(V) by Fe3O4/Mg-Al LDH nano-hybrid prior to determination by a chemiluminescence (CL) technique. The CL route involves the oxidation of luminol by vanadomolybdoarsenate heteropoly acid in a basic media. Since the existing cations cannot be adsorbed by positively charged layers of the LDH and other potentially interferent anions had no considerable effect on the CL reaction, it provides a very selective and sensitive determination approach for As(V). The determination of total arsenic and hence indirectly As(III) involve the pre-oxidation of As(III) to As(V) by a mixture of hydrogen peroxide and potassium hydroxide. Several factors affecting the extraction and determination of the analyte were investigated and optimized. Under optimum conditions, the calibration graph was linear in the range of 5.0-5000 ng L(-1). The limit of detection and enrichment factor was 2.0 ng L(-1) and 80, respectively. The method was validated by the analysis of a standard reference material (NIST SRM 1643e), and successfully applied to the speciation of arsenic in several water samples with recoveries in the range of 93.3-106.7% for the spiked samples. PMID:25059142

  11. Intercalation of sulfonated melamine formaldehyde polycondensates into a hydrocalumite LDH structure

    NASA Astrophysics Data System (ADS)

    von Hoessle, F.; Plank, J.; Leroux, F.

    2015-05-01

    A series of sulfonated melamine formaldehyde (SMF) polycondensates possessing different anionic charge amounts and molecular weights was synthesized and incorporated into a hydrocalumite type layered double hydroxide structure using the rehydration method. For this purpose, tricalcium aluminate was dispersed in water and hydrated in the presence of these polymers. Defined inorganic-organic hybrid materials were obtained as reaction products. All SMF polymers tested intercalated readily into the hydrocalumite structure, independent of their different molecular weights (chain lengths) and anionic charge amounts. X-ray diffraction revealed typical patterns for weakly ordered, highly polymer loaded LDH materials which was confirmed via elemental analysis and thermogravimetry. IR spectroscopy suggests that the SMF polymers are interleaved between the [Ca2Al(OH)6]+ main sheets via electrostatic interaction, and that no chemical bond between the host matrix and the guest anion is formed. The SMF polymers well ensconced within the LDH structure exhibit significantly slower thermal degradation.

  12. The intercalation of bicyclic and tricyclic carboxylates into layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Khan, Aamir I.; Williams, Gareth R.; Hu, Gang; Rees, Nicholas H.; O'Hare, Dermot

    2010-12-01

    Twenty-four nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised for the first time. Eight carboxylates were successfully intercalated into [LiAl 2(OH) 6]Cl· yH 2O, [Ca 2Al(OH) 6]NO 3· yH 2O, and [Mg 2Al(OH) 6]NO 3· yH 2O, and the products fully characterised. Guest species incorporated include 1-adamantane carboxylate (1- AC) and 5-norbornene-2- endo-3- exo-dicarboxylate. In some cases, carbonate anions were co-intercalated with the organic guest, and in others poorly crystalline aluminium hydroxides formed as by-products. Sharper resonances were observed in the 13C solid-state NMR spectra of the 1- AC intercalates than in the spectrum of pure 1- AC, suggesting increased order in the arrangement of the cyclic cages in the intercalates. Where possible, time-resolved in situ X-ray diffraction was employed to study the nanoscopic steps involved in the intercalation reactions. These investigations showed that the reactions are one-step processes, proceeding directly to the fully exchanged intercalate with no intermediate phases. The intercalation processes were found to be nucleation controlled.

  13. Double-blind clinical, endoscopic and histological comparison of hydrotalcite/dimethicone suspension and magnesium hydroxide/aluminum hydroxide suspension in the treatment of symptomatic gastritis.

    PubMed

    Cobden, I; McMahon, M J; Dixon, M F; Axon, A T

    1981-01-01

    A double-blind, randomized trial was undertaken to compare the clinical, endoscopic and histological response to 6-weeks' treatment with hydrotalcite/dimethicone suspension or magnesium hydroxide/aluminum hydroxide suspension in 36 patients with symptomatic gastritis. Significantly more patients (P less than 0.05) showed symptomatic improvement in the antacid-treated group than in the hydrotalcite/dimethicone-treated group and more had a reduction in histological inflammatory scores (P less than 0.01), although there was little correlation between histology and symptoms. There was no evidence from this study that the bile acid binding and anti-foaming properties of hydrotalcite/dimethicone suspension were of any benefit in the treatment of patients with symptomatic gastritis. PMID:7267678

  14. Intercalation studies of zinc hydroxide chloride: Ammonia and amino acids

    NASA Astrophysics Data System (ADS)

    Arízaga, Gregorio Guadalupe Carbajal

    2012-01-01

    Zinc hydroxide chloride (ZHC) is a layered hydroxide salt with formula Zn5(OH)8Cl2·2H2O. It was tested as intercalation matrix for the first time and results were compared with intercalation products of the well-known zinc hydroxide nitrate and a Zn/Al layered double hydroxide. Ammonia was intercalated into ZHC, while no significant intercalation occurred in ZHN. Aspartic acid intercalation was only achieved by co-precipitation at pH=10 with ZHC and pH=8 with zinc hydroxide nitrate. Higher pH resistance in ZHC favored total deprotonation of both carboxylic groups of the Asp molecule. ZHC conferred more thermal protection against Asp combustion presenting exothermic peaks even at 452 °C while the exothermic event in ZHN was 366 °C and in the LDH at 276 °C.

  15. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study.

    PubMed

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells. PMID:26354264

  16. Stabilization of Co{sup 2+} in layered double hydroxides (LDHs) by microwave-assisted ageing

    SciTech Connect

    Herrero, M.; Benito, P.; Labajos, F.M.; Rives, V.

    2007-03-15

    Co-containing layered double hydroxides at different pH have been prepared, and aged following different routes. The solids prepared have been characterized by element chemical analysis, powder X-ray diffraction, thermogravimetric and differential thermal analyses (both in nitrogen and in oxygen), FT-IR and Vis-UV spectroscopies, temperature-programmed reduction and surface area assessment by nitrogen adsorption at -196 deg. C. The best conditions found to preserve the cobalt species in the divalent oxidation state are preparing the samples at controlled pH, and then submit them to ageing under microwave irradiation. - Graphical abstract: The use of microwave-hydrothermal treatment, controlling both temperature and ageing time, permits to synthesize well-crystallized nanomaterials with controlled surface properties. An enhancement in the crystallinity degree and an increase in the particle size are observed when the irradiation time is prolonged.

  17. Electrochemical study of ferrocenemethanol-modified layered double hydroxides composite matrix: application to glucose amperometric biosensor.

    PubMed

    Shan, Dan; Yao, Wenjuan; Xue, Huaiguo

    2007-10-31

    A novel amperometric glucose sensor based on co-immobilization of ferrocenemethanol (MeOHFc) and glucose oxidase (GOD) in the layered double hydroxides (LDHs) was described. MeOHFc immobilized in LDHs played effectively the role of an electron shuttle and allowed the detection of glucose at 0.25 V (versus SCE), with dramatically reduced interference from easily oxidizable constituents. The sensor (LDHs/MeOHFc/GOD) exhibited a relatively fast response (response time was about 5s), low detection limit (3 microM), and high sensitivity (ca. 60 mA M(-1)cm(-2)) with a linear range of 6.7 x 10(-6) to 3.86 x 10(-4)M of glucose. Apparent Michaelis-Menten constant was calculated to be 2.25 mM. PMID:17720475

  18. New layered double hydroxides by prepared by the intercalation of gibbsite

    NASA Astrophysics Data System (ADS)

    Rees, Jennifer R.; Burden, Chloe S.; Fogg, Andrew M.

    2015-04-01

    New layered double hydroxides (LDHs) with the composition [MAl4(OH)12]Cl2·1.5H2O (M=Co, Ni) have been prepared by reacting gibbsite, γ-Al(OH)3, with the appropriate chloride salt in a synthesis in which the water of crystallization is the only solvent present and fully characterized. These LDHs have been shown to undergo facile anion exchange reactions with both organic and inorganic anions at room temperature making them comparable to other LDHs in this respect. Reactions under the same conditions with CuCl2·2H2O and ZnCl2 failed to form the desired LDHs but those with nitrate salts did lead to the formation of the previously reported [MAl4(OH)12](NO3)2·1.5H2O (M=Co, Ni) compounds.

  19. Enhanced photocatalytic activity of TiO2-impregnated with MgZnAl mixed oxides obtained from layered double hydroxides for phenol degradation

    NASA Astrophysics Data System (ADS)

    de Almeida, Marciano Fabiano; Bellato, Carlos Roberto; Mounteer, Ann Honor; Ferreira, Sukarno Olavo; Milagres, Jaderson Lopes; Miranda, Liany Divina Lima

    2015-12-01

    A series of TiO2/MgZnAl photocatalysts were successfully synthesized from ternary (Mg, Zn and Al) layered double hydroxides impregnated with TiO2 nanoparticles by the co-precipitation method at variable pH with different Zn2+/Mg2+ molar ratios. The composite photocatalysts were calcined at 500 °C resulting in the incorporation of oxide zinc, in the calcined MgZnAl LDH structure. Synergistic effect between ZnO and TiO2 lead to significant enhancement of TiO2/MgZnAl photocatalytic activity. Composite photocatalysts were characterized by ICP-MS, N2 adsorption-desorption, XRD, SEM, EDS, IR and UV-vis DRS. Phenol in aqueous solution (50 mg/L) was used as a model compound for evaluation of UV-vis (filter cut-off for λ > 300 nm) photocatalytic activity. The most efficient photocatalyst composite was obtained at a 5% Zn2+/Mg2+ molar ratio, in the catalyst identified as TiO2/MgZnAl-5. This composite catalyst had high photocatalytic activity, completely destroying phenol and removing 80% of total organic carbon in solution after 360 min. The TiO2/MgZnAl-5 catalyst remained relatively stable, presenting a 15% decrease in phenol degradation efficiency after five consecutive photocatalytic cycles.

  20. Selective Tumor Cell Inhibition Effect of Ni-Ti Layered Double Hydroxides Thin Films Driven by the Reversed pH Gradients of Tumor Cells.

    PubMed

    Wang, Donghui; Ge, Naijian; Li, Jinhua; Qiao, Yuqin; Zhu, Hongqin; Liu, Xuanyong

    2015-04-22

    Nitinol is widely fabricated as stents for the palliation treatment of many kinds of cancers. It is of great importance to develop nitinol stents with selective tumor cell inhibition effects. In this work, a series of pH sensitive films composed of Ni(OH)2 and Ni-Ti layered double hydroxide (Ni-Ti LDH) with different Ni/Ti ratios were prepared on the surface of nitinol via hydrothermal treatment. The films with specific Ni/Ti ratios would release a large amount of nickel ions under acidic environments but were relatively stable in neutral or weak alkaline medium. Cell viability tests showed that the films can effectively inhibit the growth of cancer cells but have little adverse effects to normal cells. Besides, extraordinarily high intracellular nickel content and reactive oxygen species (ROS) level were found in cancer cells, indicating the death of cancer cells may be induced by the excessive intake of nickel ions. Such selective cancer cell inhibition effect of the films is supposed to relate with the reversed pH gradients of tumor cells. PMID:25825800

  1. Treatment of waste H₂SO₄ with Mg-Al oxide obtained by calcination of NO₃⁻-intercalated Mg-Al layered double hydroxide: Kinetics and equilibrium.

    PubMed

    Kameda, Tomohito; Fubasami, Yuki; Yoshioka, Toshiaki

    2012-01-01

    Mg-Al oxide obtained by calcination of NO(3)(-)-intercalated Mg-Al layered double hydroxide (NO(3)•Mg-Al LDH) was used to treat H(2)SO(4), acting as both a neutralizer of the acid and a fixative for SO(4)(2-). The fraction of SO(4)(2-) removed increased with time and with increasing Mg-Al oxide quantity and temperature. The rate of SO(4)(2-) removal followed first-order kinetics with apparent rate constants of 2.0 × 10(-3), 4.4 × 10(-3), and 5.3 × 10(-2) min(-1) at 10, 30, and 60°C, respectively. The apparent activation energy was 52.1 kJ mol(-1), confirming that the SO(4)(2-) removal by Mg-Al oxide proceeded under chemical reaction control. Furthermore, the adsorption isotherm of SO(4)(2-) by Mg-Al oxide obeyed the Langmuir equation. The maximum adsorption amount was 2.0 mmol g(-1), or 4.0 meq g(-1), indicating that Mg-Al oxide has a large capacity for uptake of SO(4)(2-) from H(2)SO(4). PMID:22416865

  2. Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging.

    PubMed

    Sommella, Alessia; Caporale, Antonio G; Denecke, Melissa A; Mangold, Stefan; Pigna, Massimo; Santoro, Anna; Terzano, Roberto; Violante, Antonio

    2015-12-30

    Arsenic (As) co-precipitation is one of the major processes controlling As solubility in soils and waters. When As is co-precipitated with Al and Mg, the possible formation of layered double hydroxides (LDHs) and other nanocomposites can stabilize As in their structures thus making this toxic element less available. We investigated the nature and reactivity of Mg-Al-arsenate [As(V)] co-precipitated LDHs formed in solution affected by As concentration, pH, and aging. At the beginning of the co-precipitation process, poorly crystalline LDH and non-crystalline Al(Mg)-oxides form. Prolonged aging of the samples promotes crystallization of LDHs, evidenced by an increase in As K XANES intensities and XRD peak intensities. During aging Al- and/or Mg-oxides are likely transformed by dissolution/re-precipitation processes into more crystalline but still defective LDHs. Surface area, chemical composition, reactivity of the precipitates, and anion exchange properties of As(V) in the co-precipitates are influenced by pH, aging, and As concentration. This study demonstrates that (i) As(V) retards or inhibits the formation and transformation of LDHs and (ii) more As(V) is removed from solution if co-precipitated with Mg and Al than by sorption onto well crystallized LDHs. PMID:26241870

  3. Controlled synthesis and investigation of the mechanism of formation of hollow hemispherical protrusions on laurate anion-intercalated Zn/Al layered double hydroxide hybrid films.

    PubMed

    Yue, Caili; Chen, Hongyun; Xu, Sailong; Zhang, Fazhi

    2012-11-01

    Films of laurate (La) anion-intercalated zinc-aluminum layered double hydroxides (ZnAl-La-LDHs) with hollow hemispherical protrusions on the surface of the hybrid film have been conveniently prepared by an ion-exchange reaction of a nitrate-containing LDH film previously grown in situ on a porous anodic alumina/aluminum (PAO/Al) substrate. No template is required to form the hemispherical protrusions, thus avoiding a complicated template removal process. The dimensions, morphology, and resistance to bursting of the hollow hemispherical protrusions can be easily tuned by varying the experimental conditions such as sodium laurate concentration, reaction time, and reaction temperature. The evolution of the hollow protrusions was investigated by scanning electron microscopy (SEM), and a "bubble template-reconfiguration assembly" mechanism, in which air bubbles on the film surface act as a template, has been proposed to explain their formation. When the ion-exchange reaction was carried out on a film that had been treated by ultrasound to eliminate surface air bubbles, no hemispherical protrusions were formed, which is consistent with the proposed mechanism. PMID:22840873

  4. Effect of intercalated aromatic sulfonates on uptake of aromatic compounds from aqueous solutions by modified Mg-Al layered double hydroxide

    SciTech Connect

    Kameda, Tomohito; Yamazaki, Takashi; Yoshioka, Toshiaki

    2010-06-15

    In this study, we utilized Mg-Al layered double hydroxide (Mg-Al LDH) modified by intercalation with three aromatic sulfonates-2,7-naphthalene disulfonate (2,7-NDS{sup 2-}), benzenesulfonate (BS{sup -}), and benzenedisulfonate (BDS{sup 2-})-for the uptake of two aromatics-1,3-dinitrobenzene (DNB) and anisole (AS)-from aqueous solution and determined the effect of the aromatic sulfonates on the uptake of these aromatics. We found that the electron-rich aromatic ring of the intercalated aromatic sulfonates such as 2,7-NDS{sup 2-} undergoes strong {pi}-{pi} stacking interactions with the electron-poorer benzene ring of DNB in aqueous solution, and these interactions result in a higher uptake of DNB by the modified Mg-Al LDHs. In contrast, the electron-poor aromatic ring of the aromatic sulfonates such as BDS{sup 2-} undergoes weak {pi}-{pi} stacking interactions with the electron-poorer benzene ring of DNB, and these interactions result in a lower uptake of DNB by the modified Mg-Al LDHs.

  5. Radiation induced topotactic [2 + 2] dimerisation of acrylate derivatives among the layers of a CaFe layered double hydroxide followed by IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Srankó, D. F.; Canton, S.; Enghdahl, A.; Muráth, Sz.; Kukovecz, Á.; Kónya, Z.; Sipiczki, M.; Sipos, P.; Pálinkó, I.

    2013-07-01

    Various acrylates [E-phenylpropenoate, E-3(4‧-nitrophenyl)propenoate, E-3(2‧,5‧-difluorphenyl)propenoate, E-3(2‧-thienyl)propenoate, E-3(4‧-imidazolyl)propenoate or E-2,3-dimethylpropenoate] were successfully intercalated into Ca(II)Fe(III) layered double hydroxide (CaFe-LDH) verified by a range of instrumental methods. The possible arrangements for the organic anions were suggested on the basis of basal spacing data, layer thickness and the dimensions of the quantum chemically optimised structures of the acrylate ions. Using the acrylate-CaFe-LDHs as reactant-filled nanoreactors, photoinitiated topotactic [2 + 2] cyclisation reactions followed by IR spectroscopy could be performed with many representatives [E-phenylpropenoate-, E-3(4‧-nitrophenyl)propenoate-, E-3(2‧,5‧-difluorphenyl)propenoate- or E-3(2‧-thienyl)propenoate-CaFe-LDHs] resulting in cyclobutane derivatives within the layers of the host material indicating that there were domains where the intercalated anions were in close proximity to each other and in proper arrangement for the reaction to occur.

  6. Intercalation of Layered Silicates, Layered Double Hydroxides, and Lead Iodide: Synthesis, Characterization and Properties.

    NASA Astrophysics Data System (ADS)

    Mehrotra, Vivek

    Layered silicates, layered double hydroxides, and lead iodide are lamellar solids that can incorporate guest species into the galleries between their layers. Various intercalated forms of these layered materials have been synthesized and their properties studied. The dielectric behavior of pristine fluorohectorite, a typical layered silicate, and Zn-Al layered double hydroxide is explained by considering the structural ordering and mobility of the intercalated water molecules, as well as models invoking fractal time processes and fractal structure. Intercalative polymerization of aniline and pyrrole into fluorohectorite leads to a multilayered structure consisting of single polymer chains alternately stacked with the 9.6 A thick silicate layers. The polymer chains are confined to the quasi two-dimensional interlayer space between the rigid host layers. The hybrid films exhibit highly anisotropic properties. The optical, electrical and mechanical behavior is discussed in terms of the molecular confinement of the polymer chains. Ethylenediamine functionalized C _{60} clusters have also been intercalated into fluorohectorite via an ion-exchange procedure. Intercalation results in an improved thermal stability of the functionalized C_{60} clusters. Rutherford backscattering spectrometry has been used to elucidate the mechanism of intercalative ion exchange of silver in muscovite mica, a layered silicate with a layer charge density of 2e per unit cell. It is proposed that ion-exchange progresses by intercalating successive galleries through the edges of the mica layers. Guest-host interactions have been studied in the system aniline-PbI_2. The optical and structural effects of aniline intercalation in lead iodide thin films is discussed. Intercalation leads to a large shift in the optical band gap of PbI_2. The observed change in band gap is not only due to the increased separation between the PbI_2 layers but also because of an electrostatic interaction between the

  7. A novel platform designed by Au core/inorganic shell structure conjugated onto MTX/LDH for chemo-photothermal therapy.

    PubMed

    Tian, De-Ying; Wang, Wei-Yuan; Li, Shu-Ping; Li, Xiao-Dong; Sha, Zhao-Lin

    2016-05-30

    A novel platform making up of methotrexate intercalated layered double hydroxide (MTX/LDH) hybrid doped with gold nanoparticles (NPs) may have great potential both in chemo-photothermal therapy and the simultaneous drug delivery. In this paper, a promising platform of Au@PDDA-MTX/LDH was developed for anti-tumor drug delivery and synergistic therapy. Firstly, Au NPs were coated using Layer-by-Layer (LbL) technology by alternate deposition of poly (diallyldimethylammonium chloride) (PDDA) and MTX molecules, and then the resulting core-shell structures (named as Au@PDDA-MTX) were directly conjugated onto the surface of MTX/LDH hybrid by electrostatic attraction to afford Au@PDDA-MTX/LDH NPs. Here MTX was used as both the agent for surface modification and the anti-tumor drug for chemotherapy. The platform of Au@PDDA-MTX/LDH NPs not only had a high drug-loading capacity, but also showed excellent colloidal stability and interesting pH-responsive release profile. In vitro drug release studies demonstrated that MTX released from Au@PDDA-MTX/LDH was relatively slow under normal physiological pH, but it was enhanced significantly at a weak acidic pH value. Furthermore, the combined treatment of cancer cells by using Au@PDDA-MTX/LDH for synergistic hyperthermia ablation and chemotherapy was demonstrated to exhibit higher therapeutic efficacy than either single treatment alone, underscoring the great potential of the platform for cancer therapy. PMID:26997424

  8. Structural characterization and thermal and chemical stability of bioactive molecule-hydrotalcite (LDH) nanocomposites.

    PubMed

    Conterosito, Eleonora; Croce, Gianluca; Palin, Luca; Pagano, Cinzia; Perioli, Luana; Viterbo, Davide; Boccaleri, Enrico; Paul, Geo; Milanesio, Marco

    2013-08-28

    Layered double hydroxides (LDH) are versatile materials used for intercalating bioactive molecules, both in pharmaceutical and cosmetic fields, with the purpose of protecting them from degradation, enhancing their water solubility to increase bioavailability, and/or obtaining modified release properties. The properties of the intercalation compounds of Mg/Al_LDH and Zn/Al_LDH with different drugs and sunscreens, namely diclofenac, ketoprofen, gliclazide, retinoic acid, furosemide, para-aminobenzoic acid and 2-phenylbenzimidazolsulfonic (Eusolex) acid, have been studied by crystallographic, spectroscopic and thermogravimetric techniques and by solid state NMR, to shed light on their structure, their molecular interactions and their stability from the thermal and chemical viewpoint. The structural features were described with particular attention to the interaction between the organic and inorganic components and to the stability of the intercalation products. For the first time two synchrotron radiation powder diffraction patterns of organic-containing LDH were solved and refined by Rietveld methods to obtain an experimental crystal structure. PMID:23873340

  9. Photochemistry in constrained spaces: Zeolites and layered double metal hydroxides. Progress report, September 15, 1993--September 15, 1994

    SciTech Connect

    Dutta, P.K.

    1995-02-01

    The authors have continued their research in the area of assembly and reactivity of photochemical systems in zeolites and double layered metal hydroxides. Over the last year, the authors have focused on two issues, increasing the photochemical efficiency of charge separation in a triad system and the chemistry of Ru(bpy){sup 3+}{sub 3} in zeolites.

  10. Combined chemotherapy and photodynamic therapy using a nanohybrid based on layered double hydroxides to conquer cisplatin resistance.

    PubMed

    Wang, Zhigang; Ma, Rong; Yan, Li; Chen, Xianfeng; Zhu, Guangyu

    2015-07-25

    A nanohybrid is assembled by ratiometrically co-loading Pt(IV) prodrugs and photosensitizers into layered double hydroxide nanoparticles. The nanohybrid shows synergistic cell-killing effects and is significantly active against the proliferation of cisplatin-resistant human cancer cells with nanomolar IC50 values. Profound mechanistic investigations confirm its action mode of combined chemo- and photodynamic therapy. PMID:26096645

  11. Synthesis of Zn/Co/Fe-layered double hydroxide nanowires with controllable morphology in a water-in-oil microemulsion

    SciTech Connect

    Wu Hongyu; Jiao Qingze; Zhao Yun; Huang Silu; Li Xuefei; Liu Hongbo; Zhou Mingji

    2010-02-15

    The Zn/Co/Fe-layered double hydroxide nanowires were synthesized via a reverse microemulsion method by using cetyltrimethyl ammonium bromide (CTAB) /n-hexane/n-hexanol/water as Soft-Template. ZnSO{sub 4}, CoSO{sub 4}, Fe{sub 2}(SO{sub 4}){sub 3} and urea were used as raw materials. The influence of reaction temperature, time, urea concentration and Cn (molar ratio of cetyltrimethyl ammonium bromide to water) on the structure and morphology of Zn/Co/Fe-layered double hydroxides was investigated. The samples were characterized using Transmission Electron Microscopy (TEM), Inductively Coupled Plasma (ICP), X-ray Diffraction (XRD) and Infrared Absorption Spectrum (IR). The results indicate that higher temperature is beneficial to the formation of layered double hydroxides, but particles apart from nanowires could be produced if temperature is up to 120 deg. C. By varying the temperature, reaction time, urea concentration and Cn, we got the optimum conditions of synthesizing uniform Zn/Co/Fe-layered double hydroxide nanowires: 100 deg. C, more than 12 h, Cn: 30-33, urea concentration: 0.3 M.

  12. Fe(CN){sub 6}{sup 3-}/Fe(CN){sub 6}{sup 4-} redox in the interlayer determined by the charge density of Zn{sub n}Cr-layered double hydroxides

    SciTech Connect

    Zhang, Jia; Xu, Yunfeng; Liu, Jiangyong; Zhou, Jizhi; Xu, Zhi Ping; Qian, Guangren

    2013-02-15

    Redox of Fe(CN){sub 6}{sup 3-} and Fe(CN){sub 6}{sup 4-} in the ZnCr layered double hydroxide interlayer has been investigated. The conversion from Fe(CN){sub 6}{sup 3-} to Fe(CN){sub 6}{sup 4-} or from Fe(CN){sub 6}{sup 4-} to Fe(CN){sub 6}{sup 3-} in the ZnCr-LDH interlayer has been confirmed, depending on the Zn:Cr molar ratio. Both Fe(CN){sub 6}{sup 3-} and Fe(CN){sub 6}{sup 4-} are observed in all samples no matter whether the initial anion is Fe(CN){sub 6}{sup 3-} or Fe(CN){sub 6}{sup 4-} before precipitation. Deconvolution of the FTIR band around 2100 cm{sup -1} reveals that the relative amount of Fe(CN){sub 6}{sup 4-} and Fe(CN){sub 6}{sup 3-} in the LDH interlayer is considerably dependent on the Zn:Cr molar ratio. In brief, Fe(CN){sub 6}{sup 4-} is preferred at the ratio of 2:1 while there is more Fe(CN){sub 6}{sup 3-} in the ratio of 4:1. Therefore, it is our hypothesis that the charge density of the hydroxide layer is a key factor that directs the redox of Fe(CN){sub 6}{sup 3-}/Fe(CN){sub 6}{sup 4-}. The possible redox processes have also been proposed. - Graphical abstract: Redox reactions of Fe(CN){sub 6}{sup 3-} and Fe(CN){sub 6}{sup 4-} take place in the ZnCr layered double hydroxide (LDH) interlayer, which are reflected by Fe(CN){sub 6}{sup 3-}/Fe(CN){sub 6}{sup 4-} FTIR area ratio. Highlights: Black-Right-Pointing-Pointer An interlayer redox phenomena was observed in Fe(CN){sub 6}{sup 3/4-} intercalated ZnCr-LDHs. Black-Right-Pointing-Pointer The ratio of interlayer redox was examined by FTIR fitting analysis. Black-Right-Pointing-Pointer The tendency of redox was influenced by Zn:Cr molar ratio. Black-Right-Pointing-Pointer The mechanism relies on the charge density of metal hydroxyl layer.

  13. Intercalation of amino acids and oligopeptides into Zn Al layered double hydroxide by coprecipitation reaction

    NASA Astrophysics Data System (ADS)

    Aisawa, Sumio; Sasaki, Shuji; Takahashi, Satoshi; Hirahara, Hidetoshi; Nakayama, Hirokazu; Narita, Eiichi

    2006-05-01

    The coprecipitation of amino acids and oligopeptides with the Zn Al LDH was investigated using phenylalanine (Phe), phenylalanyl-phenylalanine (Phe-Phe), glycyl-phenylalanine (Gly Phe), glycine (Gly), glycyl-glycine (Gly Gly), glycyl-glycyl-glycine (Gly Gly Gly) and N-(N-γ-glutamyl-cysteinyl)-glycine (GSH) as guest species. The coprecipitation behavior of amino acids and oligopeptides was found to be influenced by the solution pH and the kind of their side chain groups, and reached the maximum at pH 8 or 9. The basal spacing, d003, of the Phe, Phe-Phe and GSH/LDH was 1.81, 2.41 and 1.64 nm, supporting that guests were arranged vertical to the LDH basal layer. Acceding to the basal spacing of the Gly, Gly Gly and Gly Gly Gly/LDH (d003=0.84 0.88 nm), these guests were oriented horizontal to the LDH basal layer with the co-intercalated NO3-. Moreover, the amount of Phe-Phe, Gly Gly and Gly Gly Gly intercalated was almost the same as that of Phe and Gly despite increasing the number peptide bond and the molecular size. GSH was intercalated into the LDH interlayer space as GSH oxidized form with bridged LDH layers by their carboxylate groups.

  14. Friction behavior of Mg-Al-CO3 layered double hydroxide prepared by magnesite

    NASA Astrophysics Data System (ADS)

    Wang, Xiaobo; Bai, Zhimin; Zhao, Dong; Zhao, Fuyan

    2013-07-01

    In this paper, Mg-Al-CO3 LDH was prepared by magnesite under chemical precipitation and hydrothermal methods. In order to improve the dispersion of LDH in base oil, the as-prepared sample was modified with sodium laurate. The obtained material (GMAC-LDH) was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry and thermo gravimetric analyzer (DSC-TGA) and scanning electron microscope (SEM). The results show that the modified LDH has platelet morphology with a near hexagon shape. In addition, the tribological properties of GMAC-LDH were evaluated by four-ball friction tester and gear tester. As a lubricant, GMAC-LDH possesses an excellent property on reducing friction and wear of friction pair. The results of friction tests indicated that the friction coefficient, diameter of wear scar and power consumption of the oil with GMAC-LDH was reduced by 11.0%, 8.5% and 2.1% as compared with that of base oil.

  15. DOUBLE SHELL TANK (DST) HYDROXIDE DEPLETION MODEL FOR CARBON DIOXIDE ABSORPTION

    SciTech Connect

    OGDEN DM; KIRCH NW

    2007-10-31

    This document generates a supernatant hydroxide ion depletion model based on mechanistic principles. The carbon dioxide absorption mechanistic model is developed in this report. The report also benchmarks the model against historical tank supernatant hydroxide data and vapor space carbon dioxide data. A comparison of the newly generated mechanistic model with previously applied empirical hydroxide depletion equations is also performed.

  16. Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: an experimental and mechanistic modeling study.

    PubMed

    Regelink, Inge C; Temminghoff, Erwin J M

    2011-03-01

    Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At pH ≥ 7.2 both adsorption and Ni-Al LDH precipitation occurred. In batch experiments with the sandy soil up to 70% of oxalate-extractable Al was taken up in LDH formation during 56 days. In a long term column experiment 99% of influent Ni was retained at pH 7.5 due to Ni adsorption (≈ 34%) and Ni-Al LDH precipitation (≈ 66%) based on mechanistic reactive transport modeling. The subsequent leaching at pH 6.5 could be largely attributed to desorption. Our results show that even in sandy aquifers with relatively low Al content, Ni-Al LDH precipitation is a promising mechanism to immobilize Ni. PMID:21186070

  17. Computational NMR, IR/RAMAN calculations in sodium pravastatin: Investigation of the Self-Assembled Nanostructure of Pravastatin-LDH (Layered Double Hydroxides) Systems

    NASA Astrophysics Data System (ADS)

    Petersen, Philippe; Cunha, Vanessa; Gonçalves, Marcos; Petrilli, Helena; Constantino, Vera

    2013-03-01

    Response of neutral water clusters (H2O)n, n = 9 through 20; to external electrostatic fields (0 to 1V/Å), is studied for the lowest-energy conformers within in the energy band ~2 kcal/mol, for each ``n,'' employing the versatile B3LYP hybrid prescription of density functional theory in conjunction with the polarized basis 6-311++G(2d, 2p). Increase in the field elongates and weakens hydrogen-bond networks; ``opening up'' three-dimensional cluster morphologies to complex net-like structures culminating into their disintegration at specific threshold values. All conformations are stable: they manifest as local minima on their potential energy surfaces. Field-induced structural transitions are invariably accompanied by an abrupt increase in the electric dipole moment, which is marked at breakdown, where the highest-occupied and lowest-unoccupied molecular orbital energy gap diminishes to zero. Remarkably, as a consequence of their zero or very small electric dipole moments, certain conformers endowed with molecular symmetry exceptionally exhibit a peculiar behavior: they either remain completely robust to increase in the field, or break up into smaller, identical, robust building units with tetramer, pentamer and hexamer ring- or cubic-geometries. BCUD Research Grant from University of Pune is gratefully acknowledged.

  18. Heterogeneous photocatalytic degradation of pesticides using decatungstate intercalated macroporous layered double hydroxides.

    PubMed

    Da Silva, Eliana S; Prevot, Vanessa; Forano, Claude; Wong-Wah-Chung, Pascal; Burrows, Hugh D; Sarakha, Mohamed

    2014-10-01

    Decatungstate W10O32(4-) was efficiently intercalated between the layers of three-dimensionally ordered macroporous Mg2Al-layered double hydroxide. The structural and textural properties of as-prepared intercalated compound were characterized using different solid-state characterization techniques such as X-ray powder diffraction, FTIR and Raman spectroscopies and electronic microscopy. The photocatalytic properties of immobilized W10O32 (4-) within Mg2Al structure were investigated using 2-(1-naphthyl) acetamide (NAD) as a model of pesticide. The influence of different parameters such as amount of catalyst, pH and oxygen concentration were investigated. An optimal NAD degradation was obtained for a photocatalyst concentration of 60 mg l(-1). Under our experimental conditions, this heterogeneous photocatalyst induces photodegradation of 60 % of NAD after 17 h of irradiation at 365 nm and at pH 6.6. Interestingly, pesticide photodegradation leads to the mineralization of substrates to H2O and CO2 and the photocatalyst can be recycled and reused without any loss of activity over four cycles. PMID:24838128

  19. Chromium and yttrium-doped magnesium aluminum oxides prepared from layered double hydroxides

    NASA Astrophysics Data System (ADS)

    García-García, J. M.; Pérez-Bernal, M. E.; Ruano-Casero, R. J.; Rives, V.

    2007-12-01

    Layered double hydroxides with the hydrotalcite-like structures, containing Mg 2+ and Al 3+, doped with Cr 3+ and Y 3+, have been prepared by precipitation at constant pH. The weight percentages of Cr 3+ and Y 3+ were 1, 2, or 3%, and 0.5 or 1%, respectively. Single phases were obtained in all cases, whose crystallinity decreased as the content in Cr and Y was increased. The solids have been characterised by element chemical analysis, powder X-ray diffraction, thermal analyses (differential, thermogravimetric and programmed reduction), FT-IR and UV-vis spectroscopies; the specific surface areas have been determined from nitrogen adsorption isotherms at -196 °C. Upon calcination at 1200 °C for 5 h in air all solids display a mixed structure (spinel and rock salt for MgO); these solids have also been characterised by these techniques and their chromatic coordinates (CIE - L∗a∗b∗) have been determined. Their pink colour makes these solids suitable for being used as ceramic pigments.

  20. Methotrexate intercalated layered double hydroxides with different particle sizes: structural study and controlled release properties.

    PubMed

    Zhang, Xiao-Qing; Zeng, Mei-Gui; Li, Shu-Ping; Li, Xiao-Dong

    2014-05-01

    To study the influence of particle size on release properties, drug efficacy and other properties, a series of methotrexate intercalated layered double hydroxides (MTX/LDHs) nanohybrids with different particle sizes were synthesized through traditional coprecipitation method, by using the mixture of water and polyethylene glycol (volume ratio is 3:1) as solvent. The relationship between particle size and hydrothermal treatment conditions (i.e., time and temperature) had been systematically investigated, and the results indicate that the particle size can be precisely controlled between 70 and 300 nm. Elemental C/H/N and inductive coupled plasma (ICP) analysis indicated that different hydrothermal treatment almost has no effect on compositions of the nanohybrids. X-ray diffraction (XRD) patterns and fourier transform infrared spectroscopy (FTIR) investigations manifested the successful intercalation of MTX anions. MTX/LDHs particles exhibited hexagonal platelet morphology with round corner, due to the adsorption of MTX anions on positively charged LDHs surface. In addition, the crystallinity of MTX/LDHs increased with the particle diameters and the thermal stability of MTX anions was enhanced by holding together with LDHs layers. The in vitro release showed that bigger particles have much longer release duration, and the bioassay tests indicated that bigger particles are more efficient in the suppression of the tumor cells. PMID:24632036

  1. Adsorption properties of Mg-Al layered double hydroxides thin films grown by laser based techniques

    NASA Astrophysics Data System (ADS)

    Matei, A.; Birjega, R.; Vlad, A.; Filipescu, M.; Nedelcea, A.; Luculescu, C.; Zavoianu, R.; Pavel, O. D.; Dinescu, M.

    2012-09-01

    Powdered layered double hydroxides (LDHs) have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic and/or organic molecules. Assembling nano-sized LDHs onto flat solid substrates forming thin films is an expanding area of research due to the prospects of novel applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. Continuous and adherent thin films were grown by laser techniques (pulsed laser deposition - PLD and matrix assisted pulsed laser evaporation - MAPLE) starting from targets of Mg-Al LDHs. The capacity of the grown thin films to retain a metal (Ni) from contaminated water has been also explored. The thin films were immersed in an Ni(NO3)2 aqueous solutions with Ni concentrations of 10-3% (w/w) (1 g/L) and 10-4% (w/w) (0.1 g/L), respectively. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) were the techniques used to characterize the prepared materials.

  2. Ephemeral Fe(II)/Fe(III) layered double hydroxides in hydromorphic soils: A review

    NASA Astrophysics Data System (ADS)

    Vodyanitskii, Yu. N.; Shoba, S. A.

    2015-03-01

    Ephemeral green rust is formed seasonally in some hydromorphic soils. It consists of Fe(II)/Fe(III) layered double hydroxides with different types of interlayer anions and different oxidation degrees of iron ( x). In synthetized stoichiometric green rust, x = 0.25-0.33; in soil fougerite, it may reach 0.50-0.66. The mineral stability is provided by the partial substitution of Mg2+ for Fe2+. The ephemeral properties of the green rust are manifested in the high sensitivity to the varying redox regime in hydromorphic soils. Green rust disappears during oxidation stages, which complicates its diagnostics in soils. For green rust formation, excessively moist mineral soil needs organic matter as a source of energy for the vital activity of iron-reducing bacteria. In a gleyed Cambisol France, where fougerite is formed in the winter, the index of hydrogen partial pressure rH2 is 7.0-8.2, which corresponds to highly reducing conditions; upon the development of oxidation, fougerite is transformed into lepidocrocite. In the mineral siderite horizon of peatbogs in Belarus, where green rust is formed in the summer, rH2 is 11-14, which corresponds to the lower boundary of reducing conditions ( rH2 = 10-18); magnetite is formed in these soils in the winter season upon dehydration of the soil mass.

  3. Structure, molecular simulation, and release of aspirin from intercalated Zn-Al-layered double hydroxides.

    PubMed

    Meng, Zilin; Li, Xiaowei; Lv, Fengzhu; Zhang, Qian; Chu, Paul K; Zhang, Yihe

    2015-11-01

    Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn-Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4(-) and H2PO4(-) can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets. PMID:26263219

  4. Anion-intercalated layered double hydroxides modified test strips for detection of heavy metal ions.

    PubMed

    Wang, Nan; Sun, Jianchao; Fan, Hai; Ai, Shiyun

    2016-02-01

    In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)6(4-) or S(2-) anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10(-6) mol L(-1). Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields. PMID:26653453

  5. Concentration of simple aldehydes by sulfite-containing double-layer hydroxide minerals: implications for biopoesis

    NASA Technical Reports Server (NTRS)

    Pitsch, S.; Krishnamurthy, R.; Arrhenius, G.; Bada, J. L. (Principal Investigator)

    2000-01-01

    Environmental conditions play an important role in conceptual studies of prebiotically relevant chemical reactions that could have led to functional biomolecules. The necessary source compounds are likely to have been present in dilute solution, raising the question of how to achieve selective concentration and to reach activation. With the assumption of an initial 'RNA World', the questions of production, concentration, and interaction of aldehydes and aldehyde phosphates, potential precursors of sugar phosphates, come into the foreground. As a possible concentration process for simple, uncharged aldehydes, we investigated their adduct formation with sulfite ion bound in the interlayer of positively charged expanding-sheet-structure double-layer hydroxide minerals. Minerals of this type, initially with chloride as interlayer counter anion, have previously been shown to induce concentration and subsequent aldolization of aldehyde phosphates to form tetrose, pentose, and hexose phosphates. The reversible uptake of the simple aldehydes formaldehyde, glycolaldehyde, and glyceraldehyde by adduct formation with the immobilized sulfite ions is characterized by equilibrium constants of K=1.5, 9, and 11, respectively. This translates into an observable uptake at concentrations exceeding 50 mM.

  6. Deconstruction of Lignin Model Compounds and Biomass-Derived Lignin using Layered Double Hydroxide Catalysts

    SciTech Connect

    Chmely, S. C.; McKinney, K. A.; Lawrence, K. R.; Sturgeon, M.; Katahira, R.; Beckham, G. T.

    2013-01-01

    Lignin is an underutilized value stream in current biomass conversion technologies because there exist no economic and technically feasible routes for lignin depolymerization and upgrading. Base-catalyzed deconstruction (BCD) has been applied for lignin depolymerization (e.g., the Kraft process) in the pulp and paper industry for more than a century using aqueous-phase media. However, these efforts require treatment to neutralize the resulting streams, which adds significantly to the cost of lignin deconstruction. To circumvent the need for downstream treatment, here we report recent advances in the synthesis of layered double hydroxide and metal oxide catalysts to be applied to the BCD of lignin. These catalysts may prove more cost-effective than liquid-phase, non-recyclable base, and their use obviates downstream processing steps such as neutralization. Synthetic procedures for various transition-metal containing catalysts, detailed kinetics measurements using lignin model compounds, and results of the application of these catalysts to biomass-derived lignin will be presented.

  7. Examination of fatty acid exchanged layered double hydroxides as supports for photochemical assemblies

    SciTech Connect

    Robins, D.S.; Dutta, P.K.

    1996-01-24

    The incorporation of titanium oxide into the interlayers of a myristic acid exchanged lithium aluminum layered double hydroxide was done by partitioning of titanium butoxide into the interlayer, followed by hydrolysis under ambient conditions. Upon excitation with near-ultraviolet radiation in the presence of viologens and thiocyanate ion, viologen radical is formed. Cationic viologen radicals were held onto the solid surface, indicating that the titanium oxide is negatively charged. [Tetrakis(4-carboxyphenyl)-porphyrinato]zinc(II)(ZnTPPC) was ion exchanged into the interlayers. Electronic spectral changes upon incorporation suggest that the ZnTPPC is in the monomeric form. In the presence of ethylenediamine tetraacetic acid (EDTA) as a sacrificial electron donor, the interlayer ZnTPPC was capable of reducing viologen molecules in solution upon visible radiation. Yields of viologen radical were higher for neutral viologens than cationic viologens, presumably due to the restricted access of cations into the interlayer space. The sensitization of the titanium oxide by ZnTPPC was also possible, resulting in viologen radicals upon visible light excitation. The anionic nature of the titanium oxide was exploited to confirm that sensitization was indeed taking place. 27 refs., 12 figs., 2 tabs.

  8. Leaching of iodide (I(-)) and iodate (IO3(-)) anions from synthetic layered double hydroxide materials.

    PubMed

    Theiss, Frederick L; Ayoko, Godwin A; Frost, Ray L

    2016-09-15

    Several studies have previously demonstrated that layered double hydroxides (LDHs) show considerable potential for the adsorption of radioiodine from aqueous solution; however, few studies have demonstrated that these materials are able to store radioactive (131)I for an acceptable period. The leaching of iodide (I(-)) and iodate (IO3(-)) form Mg/Al LDHs has been carried out. Contact time appeared to be a more significant variable for the leaching of iodate (IO3(-)) compared to that of iodide (I(-)). Experimental results are fitted to the pseudo second order model, suggesting that diffusion is likely to be the rate-limiting step. The presence of carbonate in the leaching solution appeared to significantly increase the leaching of iodide (I(-)) as did the presence of chloride to a lesser extent. The maximum amount of iodate (IO3(-)) leached using ultrapure water as the leaching solution was 21% of the iodate (IO3(-)) originally present. The corresponding result for iodide (I(-)) was even lower at 3%. PMID:27309951

  9. Mesoporous mixed metal oxides derived from P123-templated Mg-Al layered double hydroxides

    SciTech Connect

    Wang Jun; Zhou Jideng; Li Zhanshuang; He Yang; Lin Shuangshuang; Liu Qi; Zhang Milin; Jiang Zhaohua

    2010-11-15

    We report the preparation of mesoporous mixed metal oxides (MMOs) through a soft template method. Different amounts of P123 were used as structure directing agent to synthesize P123-templated Mg-Al layered double hydroxides (LDHs). After calcination of as-synthesized LDHs at 500 {sup o}C, the ordered mesopores were obtained by removal of P123. The mesoporous Mg-Al MMOs fabricated by using 2 wt% P123 exhibited a high specific surface area of 108.1 m{sup 2}/g, and wide distribution of pore size (2-18 nm). An investigation of the 'memory effect' of the mesoporous MMOs revealed that they were successfully reconstructed to ibuprofen intercalated LDHs having different gallery heights, which indicated different intercalation capacities. Due to their mesoporosity these unique MMOs have particular potential as drug or catalyst carriers. - Graphical abstract: Ordered mesoporous Mg-Al MMOs can be obtained through the calcination of P123-templated Mg-Al-CO{sub 3} LDHs. The pore diameter is 2.2 nm. At the presence of ibuprofen, the Mg-Al MMOs can recover to Mg-Al-IBU LDHs, based on its 'remember effect'. Display Omitted

  10. Incorporation of rare-earth ions in Mg-Al layered double hydroxides: intercalation with an [Eu(EDTA)] - chelate

    NASA Astrophysics Data System (ADS)

    Li, Cang; Wang, Ge; Evans, David G.; Duan, Xue

    2004-12-01

    Reaction of an aqueous slurry of an Mg 2Al-NO 3 layered double hydroxide with a four-fold excess of Na[Eu(EDTA)] gives a material which analyses for Mg 0.68Al 0.32(OH) 2[Eu(EDTA)] 0.10(CO 3) 0.11·0.66H 2O. The interlayer spacing of the material is 13.8 Å, corresponding to a gallery height of 9.0 Å, which accords with the maximal dimensions (9-10 Å) of the anion in metal-EDTA complex salts as determined by single crystal X-ray diffraction. Geometrical considerations show that the charge density on the layered double hydroxide layers is too high to be balanced by intercalation of [Eu(EDTA)] - alone, necessitating the co-intercalation of carbonate ions which have a much higher charge density.

  11. Control of crystallite and particle size in the synthesis of layered double hydroxides: Macromolecular insights and a complementary modeling tool.

    PubMed

    Galvão, Tiago L P; Neves, Cristina S; Caetano, Ana P F; Maia, Frederico; Mata, Diogo; Malheiro, Eliana; Ferreira, Maria J; Bastos, Alexandre C; Salak, Andrei N; Gomes, José R B; Tedim, João; Ferreira, Mário G S

    2016-04-15

    Zinc-aluminum layered double hydroxides with nitrate intercalated (Zn(n)Al-NO3, n=Zn/Al) is an intermediate material for the intercalation of different functional molecules used in a wide range of industrial applications. The synthesis of Zn(2)Al-NO3 was investigated considering the time and temperature of hydrothermal treatment. By examining the crystallite size in two different directions, hydrodynamic particle size, morphology, crystal structure and chemical species in solution, it was possible to understand the crystallization and dissolution processes involved in the mechanisms of crystallite and particle growth. In addition, hydrogeochemical modeling rendered insights on the speciation of different metal cations in solution. Therefore, this tool can be a promising solution to model and optimize the synthesis of layered double hydroxide-based materials for industrial applications. PMID:26828278

  12. Ultrathin nanoflakes of cobalt-manganese layered double hydroxide with high reversibility for asymmetric supercapacitor

    NASA Astrophysics Data System (ADS)

    Jagadale, Ajay D.; Guan, Guoqing; Li, Xiumin; Du, Xiao; Ma, Xuli; Hao, Xiaogang; Abudula, Abuliti

    2016-02-01

    CoMn LDH electrode is successfully prepared via facile and cost-effective electrodeposition method. The effect of Co2+/Mn2+ molar ratio on supercapacitive performance is systematically investigated. It is found that the presence of Mn(OH)6 unit in CoMn LDH offers an excellent reversibility as well as highly electrochemical activity for supercapacitor application. The CoMn LDH film with a Co2+/Mn2+ molar ratio of 9:1 loaded on Ni foam electrode exhibits the maximum specific capacitance of 1062.6 F/g at the current density of 0.7 A/g with an excellent cyclic stability of 96.3% over 5000 CD cycles. It indicates that CoMn LDH nanoflakes loaded on Ni foam can minimize the lattice mismatch which leads to an excellent cyclic stability. The asymmetric supercapacitor assembled with CoMn LDH/Ni foam and AC electrodes shows an excellent cyclic life of 84.2% and an energy density of 4.4 Wh/kg with a power density of 2500 W/kg.

  13. Study of bi-enzyme immobilization onto layered double hydroxides nanomaterials for histamine biosensor application.

    PubMed

    Baccar, Z M; Hidouri, S; Errachid, A; Sanchez, O Ruiz

    2011-10-01

    In this work, we present the development of a hybrid biomembrane based on the immobilization of diamine oxidase (DAO) into LDH thin films for histamine detection. The LDHs preselected as host matrixes are: hydrotalcites (Mg2Al(CO3)0.5(OH)6), lowaite (Mg4Fe(OH)10Cl) and hydrocalumite (Ca2Al(OH)6Cl). The immobilized probes were characterized by atomic force microscopy (AFM) and attenuated total reflection infrared spectroscopy (IR-ATR mode). The analysis of these results shows that the immobilization of DAO occurs with all type of selected LDH and is stable after a 7 day-immersion in phosphate buffer solution. The LDH incorporating magnesium or calcium divalent cations present high-quality surface topology for DAO immobilization and the ability to keep the enzyme in a well conformation for biogenic amines catabolism and histamine detection. PMID:22400262

  14. Enhanced photocatalytic activity of Ce-doped Zn-Al multi-metal oxide composites derived from layered double hydroxide precursors.

    PubMed

    Zhu, Jianyao; Zhu, Zhiliang; Zhang, Hua; Lu, Hongtao; Qiu, Yanling; Zhu, Linyan; Küppers, Stephan

    2016-11-01

    In this work, a series of novel Zn-Al-Ce multi-metal oxide (Zn-Al-Ce-MMO) photocatalysts with different Ce doping contents were prepared by calcination of Ce-doped Zn-Al layered double hydroxide (Zn-Al-Ce-LDH) precursors at various temperatures in air atmosphere. The synthesized Zn-Al-Ce-MMO materials were characterized by XRD, FTIR, TGA, BET, SEM, TEM, XPS and UV-vis DRS. The photocatalytic activities of the Zn-Al-Ce-MMO materials were evaluated by the photodegradation of rhodamine B (RhB) dye and paracetamol in aqueous solution under simulated solar light irradiation. The result of photodegradation of RhB showed that the Zn-Al-Ce-MMO samples exhibit much higher photocatalytic activity than that of Zn-Al-MMO, and the optimal Ce doping content is 5% of mole ratio (nCe/n(Zn+Al+Ce)). The enhanced photocatalytic activity of the Zn-Al-Ce-MMO was mainly attributed to the increasing in the separation efficiency of electrons and holes. The effect of calcination temperature was also studied. The photocatalytic activity of Zn-Al-Ce-MMO increased with increasing calcination temperature up to 750°C, which can be ascribed to the formation of well-crystallized metal oxides during calcination. Under experimental conditions, 97.8% degradation efficiency of RhB and 98.9% degradation efficiency of paracetamol were achieved after 240min. Active species trapping and EPR experiments suggested that hole (h(+)), superoxide radical (O2(-)) and hydroxyl radical (OH) played important roles during the RhB photocatalytic process. Moreover, the results indicated that the synthesized Zn-Al-Ce-MMO materials had good stability and reusability. PMID:27474815

  15. Influence of reduction temperature on composition, particle size, and magnetic properties of CoFe alloy nanomaterials derived from layered double hydroxide precursors.

    PubMed

    Yang, Shuangxia; Wang, Lianying; Yue, Shuang; Lu, Yanluo; He, Jing; Zhao, Dongye

    2014-06-14

    Individual CoFe alloy nanoparticles and CoFe-MgO nanocomposites were prepared through thermal reduction of single-source layered double hydroxide (LDH) precursors at various temperatures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analyses to investigate the influence of reduction temperature on the composition, particle size and size distribution, as well as the magnetic properties of the resulting materials. XRD and SEM results show that the as-prepared CoFe alloy nanoparticles and CoFe-MgO nanocomposites display high crystallinity and high purity. The average particle size of individual CoFe nanoparticles increases with the increase of reduction temperature. In the presence of the MgO matrix, uniform CoFe alloy nanoparticles with a narrow diameter distribution (8-11 nm) were obtained. Magnetic measurements indicate that the saturation magnetization strength (Ms) of the resulting materials increases with reduction temperature. The individual CoFe alloy nanoparticles exhibit excellent soft magnetic behavior with an extremely high Ms value (213 emu g(-1) at 800 °C), comparable to that of bulk CoFe alloy (230 emu g(-1)). For CoFe-MgO nanocomposites, small Ms values were obtained due to the small CoFe alloy particle size and low percentage of magnetic component. However, the coercivities are greatly enhanced (663 Oe at 450 °C) for the composites, implying their potential applications in data storage and other magnetic devices. PMID:24695765

  16. Layered Double Hydroxides: Proposal of a One-Layer Cation-Ordered Structure Model of Monoclinic Symmetry.

    PubMed

    Jayanthi, K; Nagendran, Supreeth; Kamath, P Vishnu

    2015-09-01

    Layered double hydroxides are obtained by partial isomorphous substitution of divalent metal ions by trivalent metal ions in the structure of mineral brucite, Mg(OH)2. The widely reported three-layer polytype of rhombohedral symmetry, designated as polytype 3R1, is actually a one-layer polytype of monoclinic symmetry (space group C2/m, a = 5.401 Å, b = 9.355 Å, c = 11.02 Å, β = 98.89°). This structure has a cation-ordered metal hydroxide layer defined by a supercell a = √3 × a0; b = 3 × a0 (a0 = cell parameter of the cation-disordered rhombohedral cell). Successive layers are translated by (1/3, 0, 1) relative to one another. When successive metal hydroxide layers are translated by (2/3, 0, 1) relative to one another, the resultant crystal, also of monoclinic symmetry, generates a powder pattern corresponding to the polytype hitherto designated as 3R2. This structure model not only removes all the anomalies intrinsic to the widely accepted cation-disordered structure but also abides by Pauling's rule that forbids trivalent cations from occupying neighboring sites and suggests that it is unnecessary to invoke rhombohedral symmetry when the metal hydroxide layer is cation ordered. These results have profound implications for the correct description of polytypism in this family of layered compounds. PMID:26267263

  17. Synthesis, structure refinement and chromate sorption characteristics of an Al-rich bayerite-based layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Britto, Sylvia; Kamath, P. Vishnu

    2014-07-01

    “Imbibition” of Zn2+ ions into the cation vacancies of bayerite-Al(OH)3 and NO3- ions into the interlayer gallery yields an Al-rich layered double hydroxide with Al/Zn ratio ~3. NO3- ions are intercalated with their molecular planes inclined at an angle to the plane of the metal hydroxide slab and bonded to it by hydrogen bonds. Rietveld refinement of the structure shows that the monoclinic symmetry of the precursor bayerite is preserved in the product, showing that the imbibition is topochemical in nature. The nitrate ion is labile and is quantitatively replaced by CrO42- ions from solution. The uptake of CrO42- ions follows a Langmuir adsorption isotherm, thus showing that the hydroxide is a candidate material for green chemistry applications for the removal of CrO42- ions from waste water. Rietveld refinement of the structure of the hydroxide after CrO42- inclusion reveals that the CrO42- ion is intercalated with one of its 2-fold axes parallel to the b-crystallographic axis of the crystal, also the principal 2 axis of the monoclinic cell.

  18. Arsenate removal by layered double hydroxides embedded into spherical polymer beads: Batch and column studies.

    PubMed

    Nhat Ha, Ho Nguyen; Kim Phuong, Nguyen Thi; Boi An, Tran; Mai Tho, Nguyen Thi; Ngoc Thang, Tran; Quang Minh, Bui; Van Du, Cao

    2016-01-01

    In this study, the performance of poly(layered double hydroxides) [poly(LDHs)] beads as an adsorbent for arsenate removal from aqueous solution was investigated. The poly(LDHs) beads were prepared by immobilizing LDHs into spherical alginate/polyvinyl alcohol (PVA)-glutaraldehyde beads (spherical polymer beads). Batch adsorption studies were conducted to assess the effect of contact time, solution pH, initial arsenate concentrations and co-existing anions on arsenate removal performance. The potential reuse of these poly(LDHs) beads was also investigated. Approximately 79.1 to 91.2% of arsenic was removed from an arsenate solution (50 mg As L(-1)) by poly(LDHs). The adsorption data were well described by the pseudo-second-order kinetics model and the Langmuir isotherm model, and the adsorption capacities of these poly(LDHs) beads at pH 8 were from 1.64 to 1.73 mg As g(-1), as calculated from the Langmuir adsorption isotherm. The adsorption ability of the poly(LDHs) beads decreased by approximately 5-6% after 5 adsorption-desorption cycles. Phosphates markedly decreased arsenate removal. The effect of co-existing anions on the adsorption capacity declined in the following order: HPO4 (2-) > HCO3 (-) > SO4 (2-) > Cl(-). A fixed-bed column study was conducted with real-life arsenic-containing water. The breakthrough time was found to be from 7 to 10 h. Under optimized conditions, the poly(LDHs) removed more than 82% of total arsenic. The results obtained in this study will be useful for further extending the adsorbents to the field scale or for designing pilot plants in future studies. From the viewpoint of environmental friendliness, the poly(LDHs) beads are a potential cost-effective adsorbent for arsenate removal in water treatment. PMID:26818806

  19. Glyphosate and glufosinate detection at electrogenerated NiAl-LDH thin films.

    PubMed

    Khenifi, Aicha; Derriche, Zoubir; Forano, Claude; Prevot, Vanessa; Mousty, Christine; Scavetta, Erika; Ballarin, Barbara; Guadagnini, Lorella; Tonelli, Domenica

    2009-11-10

    An amperometric sensor based on Ni(1-x)Al(x)(OH)(2)NO(3x).nH(2)O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Glyp and Gluf is possible at the Ni(3+) centres of the structure. The electrochemical responses of the NiAl-LDH modified electrode were obtained by cyclic voltammetry and chronoamperometry at 0.49V/SCE as a function of herbicide concentration in 0.1M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9mM with a detection limit of 1muM and sensitivity 287mA/Mcm(2). The sensitivity found for Gluf was lower (178mA/Mcm(2)). PMID:19854339

  20. Molecular modeling of the structure and dynamics of the interlayer species of ZnAlCl layered double hydroxide.

    PubMed

    Pisson, J; Morel, J P; Morel-Desrosiers, N; Taviot-Guého, C; Malfreyt, P

    2008-07-01

    Molecular dynamics simulations of the ZnAl layered double hydroxide containing interlayer chloride anions have been performed in the NpT and Np(zz)T statistical ensembles for metal Zn/Al ratios of 2 and 3. We have monitored the interlayer spacing as a function of the number of intercalated water molecules for each statistical ensemble. We have studied how these profiles are affected by the method of calculation of the charges of the hydroxide layer atoms. Diffusion coefficients of the interlayer water molecules have been calculated for different Zn/Al ratios. The calculation of the chemical potential of the interlayer water molecules has been carried out for three amounts of interlayer water molecules. The calculation showed a qualitative agreement with the bulk water chemical potential within a range of interlayer water molecule contents. PMID:18543873

  1. ANTS-anchored Zn-Al-CO3-LDH particles as fluorescent probe for sensing of folic acid

    NASA Astrophysics Data System (ADS)

    Liu, Pengfei; Liu, Dan; Liu, Yanhuan; Li, Lei

    2016-09-01

    A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO3-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn2+ ions of Zn-Al-CO3-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO3-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO3-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO3 groups in ANTS-anchored on the surface of Zn-Al-CO3-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO3-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution.

  2. Electrochemiluminescence detection of reduced and oxidized glutathione ratio by quantum dot-layered double hydroxide film.

    PubMed

    Yu, Yingchang; Shi, Jingjing; Zhao, Xiaocen; Yuan, Zhiqin; Lu, Chao; Lu, Jun

    2016-05-23

    The ratio of reduced and oxidized glutathione (GSH/GSSG ratio) is a greater first indication of disease risk than the total concentration of GSH. However, the interferences from thiolated biomolecules, especially cysteine (Cys), make the accurate detection of GSH/GSSG ratio a technical problem. In this work, we successfully used a mixture of quantum dots (QDs) and ZnAl-LDH nanosheets to fabricate a high electrochemiluminescence resonance energy transfer (ERET) efficiency sensor for GSH from the disturbances of amino acids, especially Cys and GSSG. The mechanisms of high ERET efficiency and selectivity were well investigated with spectroscopy analysis and theoretical calculation. The results showed that the interaction force between ZnAl-LDH nanosheets and molecules proved a long-range-ordered space and selective transmission for molecules. On the basis of these interesting phenomena, we successfully measured the GSH/GSSG ratio in whole blood and serum samples. PMID:27109740

  3. Analysis of ldh genes in Lactobacillus casei BL23: role on lactic acid production.

    PubMed

    Rico, Juan; Yebra, María Jesús; Pérez-Martínez, Gaspar; Deutscher, Josef; Monedero, Vicente

    2008-06-01

    Lactobacillus casei is a lactic acid bacterium that produces L-lactate as the main product of sugar fermentation via L-lactate dehydrogenase (Ldh1) activity. In addition, small amounts of the D-lactate isomer are produced by the activity of a D-hydroxycaproate dehydrogenase (HicD). Ldh1 is the main L-lactate producing enzyme, but mutation of its gene does not eliminate L-lactate synthesis. A survey of the L. casei BL23 draft genome sequence revealed the presence of three additional genes encoding Ldh paralogs. In order to study the contribution of these genes to the global lactate production in this organism, individual, as well as double mutants (ldh1 ldh2, ldh1 ldh3, ldh1 ldh4 and ldh1 hicD) were constructed and lactic acid production was assessed in culture supernatants. ldh2, ldh3 and ldh4 genes play a minor role in lactate production, as their single mutation or a mutation in combination with an ldh1 deletion had a low impact on L-lactate synthesis. A Deltaldh1 mutant displayed an increased production of D-lactate, which was probably synthesized via the activity of HicD, as it was abolished in a Deltaldh1 hicD double mutant. Contrarily to HicD, no Ldh1, Ldh2, Ldh3 or Ldh4 activities could be detected by zymogram assays. In addition, these assays revealed the presence of extra bands exhibiting D-/L-lactate dehydrogenase activity, which could not be attributed to any of the described genes. These results suggest that L. casei BL23 possesses a complex enzymatic system able to reduce pyruvic to lactic acid. PMID:18231816

  4. In situ growth of ZIF-8 nanocrystals on layered double hydroxide nanosheets for enhanced CO2 capture.

    PubMed

    Liu, Peng-Fei; Tao, Kai; Li, Guo-Chang; Wu, Meng-Ke; Zhu, Shuai-Ru; Yi, Fei-Yan; Zhao, Wen-Na; Han, Lei

    2016-08-01

    A hexagonal nanosheet LDH@ZIF-8 composite was fabricated by in situ growth of ZIF-8 on Zn-Al LDH without adding any zinc precursor, and exhibited a CO2 adsorption capacity of 1.0 mmol g(-1) at room temperature and 1 bar, which was significantly higher than that of pure Zn-Al LDH or ZIF-8, indicating a synergy between ZIF-8 and Zn-Al LDH. PMID:27356046

  5. Factors Affecting MoO4(2-) Inhibitor Release from Zn2Al Based Layered Double Hydroxide and Their Implication in Protecting Hot Dip Galvanized Steel by Means of Organic Coatings.

    PubMed

    Shkirskiy, V; Keil, P; Hintze-Bruening, H; Leroux, F; Vialat, P; Lefèvre, G; Ogle, K; Volovitch, P

    2015-11-18

    Zn2Al/-layered double hydroxide (LDH) with intercalated MoO4(2-) was investigated as a potential source of soluble molybdate inhibitor in anticorrosion coatings for hot dip galvanized steel (HDG). The effect of solution pH, soluble chlorides, and carbonates on the release kinetics of the interleaved MoO4(2-) ions from the LDH powder immersed in solutions containing different anions was studied by X-ray diffraction, in situ attenuated total reflectance infrared (ATR-IR) spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The effect of the solution composition on the total release and the release kinetics was demonstrated. Less than 30% of the total amount of the intercalated MoO4(2-) was released after 24 h of the immersion in neutral 0.005-0.5 M NaCl and 0.1 M NaNO3 solutions whereas the complete release of MoO4(2-) was observed after 1 h in 0.1 M NaHCO3 or Na2SO4 and in alkaline solutions. The in situ ATR-IR experiments and quantification of the released soluble species by ICP-AES demonstrated the release by an anion exchange in neutral solutions and by the dissolution of Zn2Al/-LDH in alkaline solutions. The anion exchange kinetics with monovalent anions was described by the reaction order n = 0.35 ± 0.05 suggesting the diffusion control; for divalent anions, n = 0.70 ± 0.06 suggested the control by a surface reaction. Dissolution of Zn from coated HDG with and without Zn2Al/-MoO4(2-) fillers, leaching of MoO4(2-) from the coating, and the electrochemical impedance spectroscopy response of the coated systems were measured during the immersion in 0.5 M NaCl solutions with and without 0.1 M NaHCO3. Without carbonates, the release of soluble MoO4(2-) was delayed for 24 h with no inhibiting effect whereas with 0.1 M NaHCO3 the immediate release was accompanied by the immediate and strong inhibiting effect on Zn dissolution. The concept of controlling the inhibition performance of LDH hybrid coatings by means of the environment

  6. Structural features of intercalated CaFe-layered double hydroxides studied by X-ray diffractometry, infrared spectroscopy and computations

    NASA Astrophysics Data System (ADS)

    Ferencz, Zs.; Ádok-Sipiczki, M.; Hannus, I.; Sipos, P.; Pálinkó, I.

    2015-06-01

    The intercalation of various N-containing carboxylic acid anions into CaFe-layered double hydroxides was performed by the dehydration-rehydration method. Particular attention was paid to the effect of solvent mixture used during preparation. It was found that various solvent mixtures resulted in different interlayer distances and, thus, different arrangements of the anions between the layers. The dimensions of the intercalated anions and detailed analysis of the infrared spectra gave clues for the reasonable prediction of the spatial arrangements of the anions in the interlamellar space.

  7. Synthesis of a novel green fluorescent material Ca3Al2O6:Tb3+ based on a layered double hydroxide precursor

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Jiang, Kangle; Hao, Yongjing; Chang, Tao; Yin, Yaobing

    2015-08-01

    A novel green light emitting material, Ca3Al2O6:Tb3+ was synthesized by calcination of a terbium doped Ca/Al layered double hydroxide precursor at 1350°C. The precursor was prepared by coprecipitation from metal nitrates with sodium hydroxide. The material shows characteristic green emission at 543 nm when excited with 266 nm UV source. The photoluminescence intensity reaches its maximum at Tb3+ concentration of 0.5 mol %.

  8. Successful transfer of plasmid DNA into in vitro cells transfected with an inorganic plasmid-Mg/Al-LDH nanobiocomposite material as a vector for gene expression

    NASA Astrophysics Data System (ADS)

    Jaffri Masarudin, Mas; Yusoff, Khatijah; Rahim, Raha Abdul; Zobir Hussein, Mohd

    2009-01-01

    The delivery of a full plasmid, encoding the green fluorescent protein gene into African monkey kidney (Vero3) cells, was successfully achieved using nanobiocomposites based on layered double hydroxides. This demonstrated the potential of using the system as an alternative DNA delivery vector. Intercalation of the circular plasmid DNA, pEGFP-N2, into Mg/Al-NO3- layered double hydroxides (LDH) was accomplished through anion exchange routes to form the nanobiocomposite material. The host was previously synthesized at the Mg2+ to Al3+ molar ratio Ri = 2 and subsequently intercalated with plasmid DNA. Size expansion of the interlamellae host from 8.8 Å in LDH to 42 Å was observed in the resulting nanobiocomposite, indicating stable hybridization of the plasmid DNA. The powder x-ray diffraction (PXRD) results, supplemented with Fourier-transform infrared (FTIR) spectroscopy, compositional and electrophoresis studies confirmed the encapsulation episode of the biomaterial. In order to elucidate the use of this resulting nanobiocomposite as a delivery vector, an MTT assay was performed to determine any cytotoxic effects of the host towards cells. The intercalated pEGFP-N2 anion was later successfully recovered through acidification with HNO3 after treatment with DNA-degrading enzymes, thus also showing the ability of the LDH host to protect the intercalated biomaterial from degradation. Cell transfection studies on Vero3 cells were then performed, where cells transfected with the nanobiocomposite exhibited fluorescence as early as 12 h post-treatment compared to naked delivery of the plasmid itself.

  9. Photocatalytic O{sub 2} evolution from water over Zn–Cr layered double hydroxides intercalated with inorganic anions

    SciTech Connect

    Hirata, Naoya; Tadanaga, Kiyoharu; Tatsumisago, Masahiro

    2015-02-15

    Graphical abstract: The photocatalytic activity of Zn–Cr LDHs intercalated with various inorganic anions was studied by O{sub 2} evolution from aqueous solution of AgNO{sub 3} as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. The interlayer anions affected the photocatalytic activity of the LDHs. - Highlights: • Zn–Cr layered double hydroxides intercalated with inorganic anions were synthesized. • Photocatalytic activity of the LDHs was studied by O{sub 2} evolution. • All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. • The interlayer anions affected the photocatalytic activity of the LDHs. - Abstract: Zn–Cr layered double hydroxides (LDHs) intercalated with inorganic anions (CO{sub 3}{sup 2−}, Cl{sup −}, SO{sub 4}{sup 2−} and NO{sub 3}{sup −}) were synthesized by the co-precipitation method and the anion exchange process. The photocatalytic activity of the LDHs was studied by O{sub 2} evolution from aqueous solution of AgNO{sub 3} as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. Besides, the interlayer anions affected the photocatalytic activity of the LDHs. After irradiation, Ag particles were formed on the LDHs by accepting the electrons generated during the photocatalytic reaction.

  10. Water decontamination via the removal of Pb (II) using a new generation of highly energetic surface nano-material: Co(+2)Mo(+6) LDH.

    PubMed

    Mostafa, Mohsen S; Bakr, Al-Sayed A; El Naggar, Ahmed M A; Sultan, El-Sayed A

    2016-01-01

    CoMo(CO3(2-)) layered double hydroxide of a highly energetic surface, as a new LDH consisting of divalent and hexavalent cations (M(+2)/M(+6)-LDH), was prepared by a homogeneous co-precipitation method. The structure and morphology of the prepared material was confirmed by several analytical techniques namely; X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), Fourier transform infra-red (FT-IR) spectroscopy, differential scanning calorimetry and thermal gravimetric analysis (DSC-TGA), N2 adsorption-desorption isotherm and scanning electron microscope (SEM). The highly energetic surface of the prepared LDH was demonstrated via the X-ray photoelectron spectroscopy (XPS). The surface energy is due to the formation of +4 surface charges in the brucite layer between Co(+2) and Mo(+6). The prepared LDH was applied as a novel adsorbent for the removal of Pb (II) from its aqueous solution at different experimental conditions of time, temperature and initial Pb (II) concentrations. The change of the Pb (II) concentrations; due to adsorption, was monitored by atomic absorption spectrophotometer (AAS). The maximum uptake of Pb (II) by the Co Mo LDH was (73.4 mg/g) at 298 K. The Pb (II) adsorption was found to follow Langmuir isotherm and pseudo second order model. The adsorption process was spontaneous and endothermic. The interference of other cations on the removal of the Pb (II) was studied. Na(+) and K(+) were found to increase the adsorption capacity of the Co Mo LDH toward Pb (II) while it was slightly decreased by the presence of Mn(+2) and Cu(+2). The synthesized LDH showed a great degree of recoverability (7 times) while completely conserving its parental morphology and adsorption capacity. The mechanism of the lead ions removal had exhibited more reliability through a surface adsorption by the coordination between the Mo(+6) of the brucite layers and the oxygen atoms of the nitrates counter ions. PMID:26402785

  11. Efficient Fluorinating Agent through Topochemical Fluorination of Co-Fe Layered Double Hydroxides

    SciTech Connect

    Louvain, Nicolas; Peyroux, Jérémy; Dubois, Marc; Simond, Wikenson; Leroux, Fabrice

    2014-02-13

    Mixed-metal inorganic fluoride, Co0.60Fe0.40F3, solid solutions are obtained through topochemical reactions of Co2FeCl(OH)6·2H2O LDH with molecular fluorine, F2, at temperatures as low as 100 °C. This solid solution possesses interesting F-releasing ability, and its efficiency as a solid-state fluorinating agent is demonstrated on a commercial polyethylene film. 19F solid state NMR and contact angle measurements underline the efficient fluorination of this polymer.

  12. A facile approach for synthesizing Fe-based layered double hydroxides with high purity and its exfoliation.

    PubMed

    Wang, Yinling; Li, Fajun; Dong, Shengye; Liu, Xiaowang; Li, Maoguo

    2016-04-01

    Transition metal (e.g., Fe, Co, Ni)-based layered double hydroxides (LDHs) and their exfoliated nanosheets have great potential applications due to their redox and magnetic properties. Here we report a facile approach for the preparation of Co-Fe LDHs with good crystallinity and high purity. The proposed approach includes two steps: (1) The mixed divalent metal (e.g., Co(2+), Fe(2+)) hydroxides were first synthesized using a homogeneous precipitation without piping N2 into the system; hexamethylenetetramine (HMT) was the hydrolysis agent providing OH(-), and hydroxylamine hydrochloride (HAH) was used as both a reducing and a complexing reagent. (2) Then the as-prepared hydroxides were slowly oxidated by air and simultaneously intercalated by CO3(2-) to form CO3-intercalated LDHs. The Co-Fe LDHs were roundly characterized by XRD, SEM, EDX and FT-IR. The effect of HAH on the morphology and structure of the Co-Fe LDHs was also studied. The magnetism of Co-Fe LDHs at room temperature was investigated and the results showed that the LDHs displayed a low saturation magnetization value of 6.3emug(-1), suggesting that the purity of the products was very high. In addition, the intercalated CO3(2-) in the Co-Fe LDHs could be successfully exchanged with other anions such as Cl(-) and ClO4(-). Furthermore, the exchanged-LDHs could be exfoliated in formamide. This work establishes a new method for the synthesis of Fe-based LDHs with good crystallinity and high purity under mild conditions, and can accelerate the development of applications using these layered materials. PMID:26773611

  13. Antibiofilm efficacy of photoactivated curcumin, triple and double antibiotic paste, 2% chlorhexidine and calcium hydroxide against Enterococcus fecalis in vitro

    PubMed Central

    Devaraj, Sharmila; Jagannathan, Nithya; Neelakantan, Prasanna

    2016-01-01

    Root canal disinfection is one of the most important factors governing success of root canal treatment, especially when regenerative strategies are used. This study evaluated the efficacy of 5 intracanal medicaments against mature biofilms of Enterococcus fecalis in vitro: Light activated curcumin, triple antibiotic paste (TAP), double antibiotic paste (DAP), chlorhexidine, calcium hydroxide. Untreated teeth with biofilms served as controls. Confocal microscopy was used to analyse the biofilm mass and percentage of live/dead bacteria within the root canal as well as dentinal tubules. Dentinal shavings obtained from the root canal walls (at 200 and 400 microns depth) were used to quantify the colony forming units/mL. The results showed that light activated curcumin and triple antibiotic paste brought about complete disruption of the biofilm structure (P < 0.05) while chlorhexidine and calcium hydroxide were not significantly different from the control (P > 0.05). Light activated curcumin brought about the highest percentage of dead cells at both depths, but this was not significantly different from triple antibiotic paste (P > 0.05). Curcumin, TAP and DAP brought about a significant reduction of CFU/mL at both depths compared to the control and other groups (P < 0.05). Light activated curcumin brought about a 7 log reduction of bacteria at both depths. PMID:27097667

  14. Antibiofilm efficacy of photoactivated curcumin, triple and double antibiotic paste, 2% chlorhexidine and calcium hydroxide against Enterococcus fecalis in vitro.

    PubMed

    Devaraj, Sharmila; Jagannathan, Nithya; Neelakantan, Prasanna

    2016-01-01

    Root canal disinfection is one of the most important factors governing success of root canal treatment, especially when regenerative strategies are used. This study evaluated the efficacy of 5 intracanal medicaments against mature biofilms of Enterococcus fecalis in vitro: Light activated curcumin, triple antibiotic paste (TAP), double antibiotic paste (DAP), chlorhexidine, calcium hydroxide. Untreated teeth with biofilms served as controls. Confocal microscopy was used to analyse the biofilm mass and percentage of live/dead bacteria within the root canal as well as dentinal tubules. Dentinal shavings obtained from the root canal walls (at 200 and 400 microns depth) were used to quantify the colony forming units/mL. The results showed that light activated curcumin and triple antibiotic paste brought about complete disruption of the biofilm structure (P < 0.05) while chlorhexidine and calcium hydroxide were not significantly different from the control (P > 0.05). Light activated curcumin brought about the highest percentage of dead cells at both depths, but this was not significantly different from triple antibiotic paste (P > 0.05). Curcumin, TAP and DAP brought about a significant reduction of CFU/mL at both depths compared to the control and other groups (P < 0.05). Light activated curcumin brought about a 7 log reduction of bacteria at both depths. PMID:27097667

  15. Synthesis and characterization of a mixture of CoFe2O4 and MgFe2O4 from layered double hydroxides: Band gap energy and magnetic responses

    NASA Astrophysics Data System (ADS)

    Agú, Ulises A.; Oliva, Marcos I.; Marchetti, Sergio G.; Heredia, Angélica C.; Casuscelli, Sandra G.; Crivello, Mónica E.

    2014-11-01

    A mixture of nanocrystals of cobalt ferrite and magnesium ferrite was obtained from Layered Double Hydroxides (LDH) through a co-precitation method with a theoretical molar ratio M2+:Fe3+=3:1, where M2+represents Mg2+ and/or Co2+. The molar ratios between Co2+:Fe3+ were 0.0 (0Co), 0.2 (5Co), and 0.4 (10Co). In order to assess the effect on the properties of the LDH and their oxides, the molar percentages were 0, 5 and 10%. Two different synthesis methods were evaluated; (i) ageing at room temperature (rt), and (ii) hydrothermal ageing at 200 °C in autoclave (ht), both methods needed 15 h of ageing. Then, these LDH were calcined in air atmosphere at 550 °C for 10 h. The calcined materials were characterized by X-ray diffraction (XRD), thermogravymetric analysis (TGA), temperature-programmed reduction (TPR), infrared spectroscopy with Fourier transform (FTIR), Diffuse Reflectance UV-visible spectroscopy (UV-vis-DRS), Mössbauer spectroscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES). The magnetic response was analyzed using a vibrating sample magnetometer (VSM). The band gap energy of the iron oxides was determined through the UV-vis-DRS analysis. Through these studies it was possible to identify the presence of a mixture of cobalt ferrite and magnesium ferrite. Samples did not show hematite and cobalt oxides, but the presence of MgO in the periclase phase was determined. This magnesium oxide promoted a good dispersion of the ferrites. Moreover, when a single ferrite phase of Co or Mg was formed, a diminution of the crystal size with consequent enlarged values of band gap energy was observed. Thus, materials synthesized by room temperature ageing promoted the superparamagnetic behaviour of samples, attributed to the content of the cobalt ferrite structure in nanocrystals. In regard to the estimated band gap energy, all samples exhibited low levels. These results indicate that these solids would be suitable for photocatalysts use in all

  16. Insights into the behaviour of biomolecules on the early Earth: The concentration of aspartate by layered double hydroxide minerals

    NASA Astrophysics Data System (ADS)

    Grégoire, Brian; Erastova, Valentina; Geatches, Dawn L.; Clark, Stewart J.; Greenwell, H. Christopher; Fraser, Donald G.

    2016-03-01

    The role of mineral surfaces in concentrating and facilitating the polymerisation of simple protobiomolecules during the Hadean and Archean has been the subject of much research in order to constrain the conditions that may have led to the origin of life on early Earth. Here we examine the adsorption of the amino acid aspartate on layered double hydroxide minerals, and use a combined computer simulation - experimental spectroscopy approach to gain insight into the resulting structures of the host-aspartate material. We show that the uptake of aspartate occurs in alkaline solution by anion exchange of the dianion form of aspartate, rather than by surface adsorption. Anion exchange only occurs at values of pH where a significant population of aspartate has the amino group deprotonated, and is then highly efficient up to the mineral anion exchange capacity.

  17. Self-assembled 3D flower-like Ni2+-Fe3+ layered double hydroxides and their calcined products.

    PubMed

    Xiao, Ting; Tang, Yiwen; Jia, Zhiyong; Li, Dawei; Hu, Xiaoyan; Li, Bihui; Luo, Lijuan

    2009-11-25

    This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs). Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degrees C in nitrogen gas, porous NiO/NiFe2O4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe2O4 nanosheets. PMID:19858561

  18. Insitu grown superhydrophobic Zn-Al layered double hydroxides films on magnesium alloy to improve corrosion properties

    NASA Astrophysics Data System (ADS)

    Zhou, Meng; Pang, Xiaolu; Wei, Liang; Gao, Kewei

    2015-05-01

    A hierarchical superhydrophobic zinc-aluminum layered double hydroxides (Zn-Al LDHs) film has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method following chemical modification. The characteristics of the films were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectroscopy (EDS). XRD patterns and SEM images showed that the micro/nanoscale hierarchical LDHs film surfaces composed of ZnO nanorods and Zn-Al LDHs nanowalls structures. The static contact angle (CA) for the prepared surfaces was observed at around 165.6°. The corrosion resistance of the superhydrophobic films was estimated by electrochemical impedance spectroscopy (EIS) and potentiondynamic polarization measurement. EIS and polarization measurements revealed that the superhydrophobic Zn-Al LDHs coated magnesium alloy had better corrosion resistance in neutral 3.5 wt.% NaCl solution.

  19. Development of a biocompatible nanodelivery system for tuberculosis drugs based on isoniazid-Mg/Al layered double hydroxide

    PubMed Central

    Saifullah, Bullo; Arulselvan, Palanisamy; El Zowalaty, Mohamed Ezzat; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin M; Hussein, Mohd Zobir

    2014-01-01

    The primary challenge in finding a treatment for tuberculosis (TB) is patient non-compliance to treatment due to long treatment duration, high dosing frequency, and adverse effects of anti-TB drugs. This study reports on the development of a nanodelivery system that intercalates the anti-TB drug isoniazid into Mg/Al layered double hydroxides (LDHs). Isoniazid was found to be released in a sustained manner from the novel nanodelivery system in humans in simulated phosphate buffer solutions at pH 4.8 and pH 7.4. The nanodelivery formulation was highly biocompatible compared to free isoniazid against human normal lung and 3T3 mouse fibroblast cells. The formulation was active against Mycobacterium tuberculosis and gram-positive bacteria and gram-negative bacteria. Thus results show significant promise for the further study of these nanocomposites for the treatment of TB. PMID:25336952

  20. Preparation of Mg-Al layered double hydroxides intercalated with 1,3,6-naphthalenetrisulfonate and 3-amino-2,7-naphthalenedisulfonate and assessment of their selective uptake of aromatic compounds from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Kameda, Tomohito; Yamazaki, Takashi; Yoshioka, Toshiaki

    2010-05-01

    Mg-Al layered double hydroxides (Mg-Al LDHs) intercalated with 1,3,6-naphthalenetrisulfonate (NTS 3-) and 3-amino-2,7-naphthalenedisulfonate (ANDS 2-) ions were prepared by coprecipitation and were characterized by X-ray diffraction and chemical analyses. Based on X-ray diffraction patterns, the naphthalene rings of NTS 3- and ANDS 2- were most likely oriented parallel to the brucite-like host layers of the Mg-Al LDH, midway between layers. The prepared Mg-Al LDHs were able to selectively take up aromatics from aqueous solutions, and the order of percentage uptake was as follows: 1,3-dinitrobenzene > nitrobenzene > benzaldehyde > N,N-dimethylaniline > anisole > 1,2-dimethoxybenzene. The differences in the extent of π-π stacking interactions occurring between the benzene rings of the aromatics and the naphthalene ring of the intercalated NTS 3- and ANDS 2- probably resulted in these differences among the absorbed quantities of the various aromatics.

  1. Pectins filled with LDH-antimicrobial molecules: preparation, characterization and physical properties.

    PubMed

    Gorrasi, Giuliana; Bugatti, Valeria; Vittoria, Vittoria

    2012-06-01

    Nanohybrids of layered double hydroxide (LDH) with intercalated active molecules: benzoate, 2,4-dichlorobenzoate, para-hydroxybenzoate and ortho-hydroxybenzoate, were incorporated into pectins from apples through high energy ball milling in the presence of water. Cast films were obtained and analysed. X-ray diffraction analysis showed a complete destructuration of all nanohybrids in the pectin matrix. Thermogravimetric analysis showed a better thermal resistance of pectin in the presence of fillers, especially para-hydroxybenzoate and ortho-hydroxybenzoate. Mechanical properties showed an improvement of elastic modulus in particular for LDH-para-hydroxybenzoate nanohybrid, due probably to a better interaction between pectin matrix and nanohybrid layers. Barrier properties (sorption and diffusion) to water vapour showed improvement in the dependence on the intercalated active molecule, the best improvement was achieved for composites containing para-hydroxybenzoate molecules, suggesting that the interaction between the filler phase and the polymer plays an important role in sorption and diffusion phenomena. Incorporation of these active molecules gave antimicrobial properties to the composite films giving opportunities in the field of active packaging. PMID:24750614

  2. Synergetic Effect of SLN-Curcumin and LDH-5-Fu on SMMC-7721 Liver Cancer Cell Line

    PubMed Central

    Zhu, Rongrong; Wu, Xianzheng; Xiao, Yu; Gao, Bo; Xie, Qian

    2013-01-01

    Abstract Curcumin and 5-Fluorouracil (5-Fu) have been reported to have anticancer potentials and show certain synergetic effect on some cancer cell lines. However, the poor bioavailability and rapid metabolism limited their medical application. In this study, we encapsulated curcumin with solid lipid nanoparticles (SLN), 5-Fu with Layered double hydroxides (LDHs) separately and tested its properties and anticancer potentials. SLN-curcumin and LDH-5-Fu were determined to be 100 and 60 nm by Transmission Electron Microscopy detection, and the loading efficiency were 28%±2.5% and 16.7%±1.8%, individually. Furthermore, SLN-curcumin and LDH-5-Fu showed a significantly synergetic effect on SMMC-7721 cell stronger than plain drugs together, of which the Idrug loaded nano-carriers was only 0.315. FACS analysis revealed that the combination of SLN-curcumin and LDH-5-Fu induced 80.1% apoptosis in SMMC-7721 cells, which were 1.7-folds of the sum of the two plain drug loaded carriers. The results demonstrated the significant synergetic anticancer potentials of nano-encapsulated curcumin and 5-Fu, which could be further explored for the treatment of other carcinoma. PMID:23808828

  3. Synergetic effect of SLN-curcumin and LDH-5-Fu on SMMC-7721 liver cancer cell line.

    PubMed

    Zhu, Rongrong; Wu, Xianzheng; Xiao, Yu; Gao, Bo; Xie, Qian; Liu, Hui; Wang, Shilong

    2013-10-01

    Curcumin and 5-Fluorouracil (5-Fu) have been reported to have anticancer potentials and show certain synergetic effect on some cancer cell lines. However, the poor bioavailability and rapid metabolism limited their medical application. In this study, we encapsulated curcumin with solid lipid nanoparticles (SLN), 5-Fu with Layered double hydroxides (LDHs) separately and tested its properties and anticancer potentials. SLN-curcumin and LDH-5-Fu were determined to be 100 and 60 nm by Transmission Electron Microscopy detection, and the loading efficiency were 28%±2.5% and 16.7%±1.8%, individually. Furthermore, SLN-curcumin and LDH-5-Fu showed a significantly synergetic effect on SMMC-7721 cell stronger than plain drugs together, of which the Idrug loaded nano-carriers was only 0.315. FACS analysis revealed that the combination of SLN-curcumin and LDH-5-Fu induced 80.1% apoptosis in SMMC-7721 cells, which were 1.7-folds of the sum of the two plain drug loaded carriers. The results demonstrated the significant synergetic anticancer potentials of nano-encapsulated curcumin and 5-Fu, which could be further explored for the treatment of other carcinoma. PMID:23808828

  4. Photocatalytic organic transformation by layered double hydroxides: highly efficient and selective oxidation of primary aromatic amines to their imines under ambient aerobic conditions.

    PubMed

    Yang, Xiu-Jie; Chen, Bin; Li, Xu-Bing; Zheng, Li-Qiang; Wu, Li-Zhu; Tung, Chen-Ho

    2014-06-25

    We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation. PMID:24827163

  5. Defect-Rich Ultrathin ZnAl-Layered Double Hydroxide Nanosheets for Efficient Photoreduction of CO2 to CO with Water.

    PubMed

    Zhao, Yufei; Chen, Guangbo; Bian, Tong; Zhou, Chao; Waterhouse, Geoffrey I N; Wu, Li-Zhu; Tung, Chen-Ho; Smith, Lorna J; O'Hare, Dermot; Zhang, Tierui

    2015-12-16

    Defect-rich ultrathin ZnAl-layered double hydroxide nanosheets are successfully prepared. Under UV-vis irradiation, these nanosheets are superior efficient catalysts for the photoreduction of CO2 to CO with water. The formed oxygen vacancies lead to the formation of coordinatively unsaturated Zn(+) centers within the nanosheets, responsible for the very high photocatalytic activities. PMID:26509528

  6. Impact of size, secondary structure, and counterions on the binding of small ribonucleic acids to layered double hydroxide nanoparticles.

    PubMed

    Rodriguez, Blanca V; Pescador, Jorge; Pollok, Nicole; Beall, Gary W; Maeder, Corina; Lewis, L Kevin

    2015-01-01

    Use of ribonucleic acid (RNA) interference to regulate protein expression has become an important research topic and gene therapy tool, and therefore, finding suitable vehicles for delivery of small RNAs into cells is of crucial importance. Layered double metal hydroxides such as hydrotalcite (HT) have shown great promise as nonviral vectors for transport of deoxyribose nucleic acid (DNA), proteins, and drugs into cells, but the adsorption of RNAs to these materials has been little explored. In this study, the binding of small RNAs with different lengths and levels of secondary structure to HT nanoparticles has been analyzed and compared to results obtained with small DNAs in concurrent experiments. Initial experiments established the spectrophotometric properties of HT in aqueous solutions and determined that HT particles could be readily sedimented with near 100% efficiencies. Use of RNA+HT cosedimentation experiments as well as electrophoretic mobility shift assays demonstrated strong adsorption of RNA 25mers to HT, with twofold greater binding of single-stranded RNAs relative to double-stranded molecules. Strong affinities were also observed with ssRNA and dsRNA 54mers and with more complex transfer RNA molecules. Competition binding and RNA displacement experiments indicated that RNA-HT associations were strong and were only modestly affected by the presence of high concentrations of inorganic anions. PMID:26620852

  7. Direct Synthesis of Unilamellar MgAl-LDH Nanosheets and Stacking in Aqueous Solution.

    PubMed

    Liang, Dujuan; Yue, Wenbo; Sun, Genban; Zheng, Dong; Ooi, Kenta; Yang, Xiaojing

    2015-11-17

    Two-dimensional (2D) materials, such as graphene, inorganic oxides, and hydroxides, are one of the most extensively studied classes of materials due to their unilamellar crystallites or nanosheet structures. In this study, instead of using the universal exfoliation method of the bulky crystal precursor, 2D crystals/nanosheets of MgAl-layered double hydroxides (LDHs) were synthesized in formamide. We propose that the obtained crystals are unilamellar according to the XRD, TEM, and AFM observations. The HRTEM and fast Fourier transform images confirm that the crystal structures are the same as those of the exfoliated MgAl-LDH nanosheets. The directly synthesized sheets can stack into a 3D crystal structure, which is the same as that of typical LDHs except for the disordered orientation of the a-/b- crystal axis of each sheet. This result provides not only a novel approach to the preparation of 2D crystals but also insight into the formation mechanism of LDHs. PMID:26505991

  8. Aluminum Hydroxide and Magnesium Hydroxide

    MedlinePlus

    Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They ... They combine with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription. ...

  9. Reversible intercalation of ammonia molecules into a layered double hydroxide structure without exchanging nitrate counter-ions

    SciTech Connect

    Carbajal Arizaga, Gregorio Guadalupe; Wypych, Fernando; Castillon Barraza, Felipe; Contreras Lopez, Oscar Edel

    2010-10-15

    A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 A, typical for nitrate-containing LDHs, and another phase with a basal distance of 13.9 A. Thermal treatment at 150 {sup o}C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 A. Intense N-H stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH{sub 4}(NH{sub 3}){sub n}]{sup +} species. When additional samples were precipitated with pure ammonia, the conventional LDH nitrate structure was obtained (8.9 A basal distance) at pH=7, as well as a pure crystalline phase with 13.9 A basal distance at pH=10 due to ammonia intercalation that can be removed by heating at 150 {sup o}C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions. - Graphical abstract: LDH-nitrate precipitated with ammonia expands the interlayer space if ammonia is bubbled up to pH 10. The basal distance decreased when the compound was heated at 150 {sup o}C or stirred in acetone. Nitrate ions are not exchanged.

  10. Effect of added zinc on the properties of cobalt-containing ceramic pigments prepared from layered double hydroxides

    SciTech Connect

    Perez-Bernal, M.E.; Ruano-Casero, R.J.; Rives, V.

    2009-09-15

    Layered double hydroxides (LDHs) with the hydrotalcite-type structure containing Co and Al, or Zn, Co and Al in the brucite-like layers and carbonate in the interlayer have been prepared by coprecipitation. The Zn/Co molar ratio was kept to 1 in all samples, while the divalent/trivalent molar ratio was varied from 2/1 to 1/2. The samples have been characterised by element chemical analysis, powder X-ray diffraction, differential thermal and thermogravimetric analysis, temperature-programmed reduction and FT-IR spectroscopy. A single hydrotalcite-like phase is formed for samples with molar ratio 2/1, which crystallinity decreases as the Al content is increased, developing small amounts of diaspore and dawsonite and probably an additional amorphous phase. Calcination at 1200 deg. C in air led to formation of spinels; a small amount of NaAlO{sub 2} was observed in the Al-rich samples, which was removed by washing. The nature of the spinels formed (containing Co{sup II}, Co{sup III}, Al{sup III} and Zn{sup II}) strongly depends on the cations molar ratio in the starting materials and the calcination treatment, leading to a partial oxidation of Co{sup II} species to Co{sup III} ones. Colour properties (L*a*b*) of the original and calcined solids have been measured. While the original samples show a pink colour (lighter for the series containing Zn), the calcined Co,Al samples show a dark blue colour and the Zn,Co,Al ones a green colour. Changes due to the different molar ratios within a given calcined series are less evident than between samples with the same composition in different series. These calcined materials could be usable as ceramic pigments. - Abstract: Mixed oxides from layered double hydroxides (LDHs) with the hydrotalcite-type structure containing Co and Al or Zn, Co and Al in the brucite-like layers are potential candidates for ceramic pigments with tunable colour properties. Display Omitted

  11. Chemiluminescence flow biosensor for glucose using Mg-Al carbonate layered double hydroxides as catalysts and buffer solutions.

    PubMed

    Wang, Zhihua; Liu, Fang; Lu, Chao

    2012-01-01

    In this work, serving as supports in immobilizing luminol reagent, catalysts of luminol chemiluminescence (CL), and buffer solutions for the CL reaction, Mg-Al-CO(3) layered double hydroxides (LDHs) were found to trigger luminol CL in weak acid solutions (pH 5.8). The silica sol-gel with glucose oxidase and horseradish peroxidase was immobilized in the first half of the inside surface of a clear quartz tube, and luminol-hybrid Mg-Al-CO(3) LDHs were packed in the second half. Therefore, a novel CL flow-through biosensor for glucose was constructed in weak acid solutions. The CL intensity was linear with glucose concentration in the range of 0.005-1.0mM, and the detection limit for glucose (S/N=3) was 0.1 μM. The proposed biosensor exhibited excellent stability, high reproducibility and high selectivity for the determination of glucose and has been successfully applied to determine glucose in human plasma samples with satisfactory results. The success of this work has broken the bottleneck of the pH incompatibility between luminol CL and enzyme activity. PMID:22770831

  12. Novel hollow microspheres of hierarchical zinc-aluminum layered double hydroxides and their enhanced adsorption capacity for phosphate in water.

    PubMed

    Zhou, Jiabin; Yang, Siliang; Yu, Jiaguo; Shu, Zhan

    2011-09-15

    Hollow microspheres of hierarchical Zn-Al layered double hydroxides (LDHs) were synthesized by a simple hydrothermal method using urea as precipitating agent. The morphology and microstructure of the as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), nitrogen adsorption-desorption isotherms and fourier transform infrared (FTIR) spectroscopy. It was found that the morphology of hierarchical Zn-Al LDHs can be tuned from irregular platelets to hollow microspheres by simply varying concentrations of urea. The effects of initial phosphate concentration and contact time on phosphate adsorption using various Zn-Al LDHs and their calcined products (LDOs) were investigated from batch tests. Our results indicate that the equilibrium adsorption data were best fitted by Langmuir isothermal model, with the maximum adsorption capacity of 54.1-232 mg/g; adsorption kinetics follows the pseudo-second-order kinetic equation and intra-particle diffusion model. In addition, Zn-Al LDOs are shown to be effective adsorbents for removing phosphate from aqueous solutions due to their hierarchical porous structures and high specific surface areas. PMID:21719194

  13. Removal efficiency of fluoride by novel Mg-Cr-Cl layered double hydroxide by batch process from water.

    PubMed

    Mandal, Sandip; Tripathy, Swagatika; Padhi, Tapswani; Sahu, Manoj Kumar; Patel, Raj Kishore

    2013-05-01

    The fluoride ion removal from aqueous solution using synthesized Mg-Cr-Cl layered double hydroxide has been reported. Mg-Cr-Cl was characterized by X-ray powder diffraction, Fourier-transform infrared, thermo-gravimetric analysis, differential thermal analysis, and scanning electron microscope. Adsorption experiments were carried out in batch mode as a function of adsorption dosages, contact time, pH, and initial fluoride concentration to get optimum adsorption capacity. The adsorption kinetic study showed that the adsorption process followed first order kinetics. The fluoride removal was 88.5% and 77.4% at pH 7 with an adsorbent dose of 0.6 g/100 mL solution and initial fluoride concentration of 10 mg/L and 100 mg/L, respectively. The equilibrium was established at 40 min. Adsorption experiment data were fitted well with Langmuir isotherm with R2 = 0.9924. Thermodynamic constants were also measured and concluded that the adsorption process was spontaneous and endothermic in nature. The removal percentage decreased slowly with increasing pH. This process is suitable for industrial effluents. The regeneration of the material is not possible. PMID:24218830

  14. Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides

    PubMed Central

    Wang, Lili; Li, Bin; Zhao, Xiaohong; Chen, Chunxia; Cao, Jingjing

    2012-01-01

    Background The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. Methodology/Principal Findings The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. Conclusions/Significance S-Ni0.1MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni0.1MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites. PMID:22693627

  15. Functionalization of layered double hydroxides by intumescent flame retardant: Preparation, characterization, and application in ethylene vinyl acetate copolymer

    NASA Astrophysics Data System (ADS)

    Huang, Guobo; Fei, Zhengdong; Chen, Xiaoying; Qiu, Fangli; Wang, Xu; Gao, Jianrong

    2012-10-01

    A phosphorussbnd nitrogen containing compound, N-(2-(5,5-dimethyl-1,3,2-dioxaphosphinyl-2-ylamino)-hexylacetamide-2-propyl acid (PAHPA), is synthesized and characterized. A novel flame retardant, namely layered double hydroxides (LDHs) modified with PAHPA (PAHPA-LDHs), is prepared by ion-exchange of LDHs with PAHPA. The results from Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and energy dispersive X-ray analysis with a high-angle annular dark-field scanning transmission electron microscope show that PAHPA intercalated LDHs. The X-ray diffraction and transmission electron microscopy (TEM) results show that PAHPA-LDHs achieve well dispersion in ethylene vinyl acetate copolymer (EVA) matrix and the EVA/PAHPA-LDHs nanocomposites (i.e. EVA filled with 5 wt% PAHPA-LDHs) are formed by polymer melt intercalation. Thermal stability and flammability properties are investigated by thermogravimetric analysis and cone calorimeter tests. The results show that the addition of PAHPA-LDHs improves thermal stability and reduces obviously the flammability of EVA resin. Compared with pure EVA resin, the peak heat release rate of the EVA/PAHPA-LDHs nanocomposites is reduced by about 43%. The results of scanning electron microscopy and TEM indicate that a compact and dense intumescent char is formed for the EVA/PAHPA-LDHs nanocomposites after combustion.

  16. Influence of calcination on the adsorptive removal of phosphate by Zn-Al layered double hydroxides from excess sludge liquor.

    PubMed

    Cheng, Xiang; Huang, Xinrui; Wang, Xingzu; Sun, Dezhi

    2010-05-15

    The influence of calcination of Zn-Al layered double hydroxides (LDHs) on their phosphate adsorption capacity was studied in order to improve phosphorus removal from an excess sludge liquor. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and nitrogen adsorption-desorption were employed to characterize the raw Zn-Al and the calcined products. The results reveal that the Zn-Al LDHs evolved to a phase of mixed metal oxides with the calcination temperature increasing to 300 degrees C and finally to spinel ZnAl(2)O(4) at 600 degrees C. When the Zn-Al was calcined at 300 degrees C, the interlayer carbonate ions were removed and the greatest BET surface area of 81.20 m(2)/g was achieved. The tested phosphate adsorption capacities of the raw and calcined Zn-Al were closely related to the evolution of physicochemical properties of the LDHs during the calcination. The Zn-Al-300 (Zn-Al LDHs calcined at 300 degrees C) exhibited the highest P uptake of 41.26 mg P/g in 24h. The phosphate adsorption by the raw Zn-Al and the Zn-Al-300 both follows a pseudo-second-order kinetic model; the adsorption isotherms show a good fit with a Langmuir-type equation. PMID:20060217

  17. The decomposition of the layered double hydroxides of Co and Al: Phase segregation of a new single phase spinel oxide

    NASA Astrophysics Data System (ADS)

    Babay, Salem; Bulou, Alain; Mercier, Anne Marie; Toumi, Mouhamed

    2015-04-01

    Monophasic Co-Al-CO3-like layered double hydroxides has been prepared by the coprecipitation method. It has been characterised by Rietveld refinement of the X-ray powder diffraction pattern, DTA-TGA, infrared and Raman spectroscopies. Its structure is trigonal, R 3 bar m with cell parameters a = 0.3061(4) nm and c = 2.252 (3) nm. The decomposition of this hydrotalcite-like structure on heating up to 800 °C yields to a single phase spinel oxide. Besides, infrared and Raman spectroscopies showed the presence of spinel-like domains. The results of Rietveld refinement have revealed that this compound has the Fd 3 bar m space group (a = 0.8088(4) nm), with crystallographic formula [CoII0.75Al0.25]8a[CoII0.252CoIII0.77Al0.98]16dO4, which is of the general formula Co1.77Al1.23O4. This structure is also validated by the charge distribution (CD) analysis.

  18. Adsorption and photodegradation kinetics of herbicide 2,4,5-trichlorophenoxyacetic acid with MgFeTi layered double hydroxides.

    PubMed

    Nguyen, Thi Kim Phuong; Beak, Min-wook; Huy, Bui The; Lee, Yong-Ill

    2016-03-01

    The calcined layered double hydroxides (cLDHs) Ti-doped and undoped MgFe for this study were prepared by co-precipitation method followed by calcination at 500 °C. The as-prepared samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) and UV-Vis diffuse reflectance spectrum (DRS) techniques and tested for adsorption and photodegradation (including photocatalytic and photo-Fenton-like) of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous solutions under visible light irradiation. In the range of studied operating conditions, the as-prepared samples exhibited excellent photo-Fenton-like activity, leading to more than 80-95% degradation of 2,4,5-T at initial concentration of 100 mg L(-1) with 4 g calcined LDHs per liter, was accomplished in 360 min, while 2,4,5-T half-life time was as short as 99-182 min. The kinetics of adsorption and photodegradation of 2,4,5-T were also discussed. These results offered a green, low cost and high efficiency photocatalyst for environmental remediation. PMID:26706931

  19. Synthesis of higher alcohols over highly dispersed Cu-Fe based catalysts derived from layered double hydroxides.

    PubMed

    Han, Xinyou; Fang, Kegong; Zhou, Juan; Zhao, Lu; Sun, Yuhan

    2016-05-15

    Highly dispersed Cu-Fe based catalysts with Fe/Cu molar ratios ranging from 0.2 to 1 were prepared via thermal decomposition of layered double hydroxides (LDHs) precursors and tested for higher alcohol synthesis (HAS) via CO hydrogenation. The catalysts were characterized using different techniques such as XRD, TEM, XPS, and H2-TPR. It was demonstrated that the Cu and Fe ions were highly dispersed in the brucite-like layers of the LDHs. With increased Fe/Cu atomic ratio, the tetrahedrally coordinated Cu ion content, Cu reduction temperatures, and the spacing of layers initially increase until the Fe/Cu ratio reaches 0.5 and then decrease. In addition to the catalytic evaluation for CO hydrogenation and catalyst characterization, the relationships between the physical-chemical properties of the catalysts and their catalytic performances were also investigated. It was also found that the alcohols/hydrocarbons ratios correlate linearly with the tetrahedrally coordinated Cu ion content. Moreover, higher reduction temperatures of Cu species as well as larger spacing between the layers in the catalyst are favorable for the synthesis of alcohols. The incorporation of a suitable amount of Fe is beneficial for the production of higher alcohols, with the best catalytic performance (alcohol selectivity of 20.77% and C2+ alcohol selectivity of 48.06%) obtained from a Fe/Cu atomic ratio of 0.5. PMID:26943001

  20. An Inexpensive Co-Intercalated Layered Double Hydroxide Composite with Electron Donor-Acceptor Character for Photoelectrochemical Water Splitting

    NASA Astrophysics Data System (ADS)

    Zheng, Shufang; Lu, Jun; Yan, Dongpeng; Qin, Yumei; Li, Hailong; Evans, David G.; Duan, Xue

    2015-07-01

    In this paper, the inexpensive 4,4-diaminostilbene-2,2-disulfonate (DAS) and 4,4-dinitro-stilbene-2,2- disulfonate (DNS) anions with arbitrary molar ratios were successfully co-intercalated into Zn2Al-layered double hydroxides (LDHs). The DAS(50%)-DNS/LDHs composite exhibited the broad UV-visible light absorption and fluorescence quenching, which was a direct indication of photo-induced electron transfer (PET) process between the intercalated DAS (donor) and DNS (acceptor) anions. This was confirmed by the matched HOMO/LUMO energy levels alignment of the intercalated DAS and DNS anions, which was also compatible for water splitting. The DAS(50%)-DNS/LDHs composite was fabricated as the photoanode and Pt as the cathode. Under the UV-visible light illumination, the enhanced photo-generated current (4.67 mA/cm2 at 0.8 V vs. SCE) was generated in the external circuit, and the photoelectrochemical water split was realized. Furthermore, this photoelectrochemical water splitting performance had excellent crystalline, electrochemical and optical stability. Therefore, this novel inorganic/organic hybrid photoanode exhibited potential application prospect in photoelectrochemical water splitting.

  1. An Inexpensive Co-Intercalated Layered Double Hydroxide Composite with Electron Donor-Acceptor Character for Photoelectrochemical Water Splitting

    PubMed Central

    Zheng, Shufang; Lu, Jun; Yan, Dongpeng; Qin, Yumei; Li, Hailong; Evans, David G.; Duan, Xue

    2015-01-01

    In this paper, the inexpensive 4,4-diaminostilbene-2,2-disulfonate (DAS) and 4,4-dinitro-stilbene-2,2- disulfonate (DNS) anions with arbitrary molar ratios were successfully co-intercalated into Zn2Al-layered double hydroxides (LDHs). The DAS(50%)-DNS/LDHs composite exhibited the broad UV-visible light absorption and fluorescence quenching, which was a direct indication of photo-induced electron transfer (PET) process between the intercalated DAS (donor) and DNS (acceptor) anions. This was confirmed by the matched HOMO/LUMO energy levels alignment of the intercalated DAS and DNS anions, which was also compatible for water splitting. The DAS(50%)-DNS/LDHs composite was fabricated as the photoanode and Pt as the cathode. Under the UV-visible light illumination, the enhanced photo-generated current (4.67 mA/cm2 at 0.8 V vs. SCE) was generated in the external circuit, and the photoelectrochemical water split was realized. Furthermore, this photoelectrochemical water splitting performance had excellent crystalline, electrochemical and optical stability. Therefore, this novel inorganic/organic hybrid photoanode exhibited potential application prospect in photoelectrochemical water splitting. PMID:26174201

  2. Enhanced removal performance by the core-shell zeolites/MgFe-layered double hydroxides (LDHs) for municipal wastewater treatment.

    PubMed

    Guo, Lu; Zhang, Xiangling; Chen, Qiaozhen; Ruan, Congying; Leng, Yujie

    2016-04-01

    The application of powdered layer double hydroxides (LDHs) in constructed rapid infiltration system (CRIS) appears to be an appreciable problem still unsolved due to the small particle size and the low density. Therefore, the core-shell zeolites/MgFe-LDHs composites were prepared via using co-precipitation method in present study. To investigate the practical applicability, a detailed organics, ammonia, and total phosphorus removal study were carried out in columns to treat the municipal wastewater. The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) results confirmed the successful synthesis of core-shell zeolites/MgFe-LDHs through coating on the surface of zeolites. Accordingly, the zeolites/MgFe-LDHs largely reduced the COD by 81.14 %, NH4 (+)-N by 81.50%, and TP by 83.29%. Phosphate adsorption study revealed that the equilibrium adsorption data were better fitted by Langmuir isothermal model, with the maximum adsorption capacity of 79.3651 mg/kg for zeolites/MgFe-LDHs and 38.4615 mg/kg for the natural zeolites. In addition, economic analysis indicated that the reagent cost of synthesis of zeolites/MgFe-LDHs was economical. Herein, the zeolites/MgFe-LDHs solved the natural zeolites problem for poor P removal and the application of powdered LDHs in the solid/liquid separation process, suggesting that it was applicable as potential substrates for the removal of organics, ammonia, and total phosphorus in CRIS. PMID:26662562

  3. Tribological performance of Mg/Al/Ce layered double hydroxides nanoparticles and intercalated products as lubricant additives

    NASA Astrophysics Data System (ADS)

    Li, Shuo; Qin, Haojing; Zuo, Ranfang; Bai, Zhimin

    2015-10-01

    Mg/Al/Ce ternary layered double hydroxides (LDHs) were synthesized via coprecipitation and intercalated by succinic acid and lauric acid through ion exchange method respectively. The LDHs products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR). Tribological properties of LDHs as lubricant additives were evaluated by four-ball friction and air compressor test. The results indicated that Mg/Al/Ce LDHs were prepared successfully with Ce/Al molar ratio of 0.05 and crystallization temperature of 140 °C. The interlayer spacing of LDHs precursor was expanded by succinic acid and lauric acid to 8.838 and 17.519 Å respectively. All the three LDHs products can reduce friction and wear of engine lubricating oil in the tests. LDHs intercalated with lauric acid showed best tribological performance among them which was attributed to sliding each other between laminates, good dispersibility in oil medium and a protective tribofilm formed on the worn surface.

  4. Enhancing phosphate adsorption by Mg/Al layered double hydroxide functionalized biochar with different Mg/Al ratios.

    PubMed

    Li, Ronghua; Wang, Jim J; Zhou, Baoyue; Awasthi, Mukesh Kumar; Ali, Amjad; Zhang, Zengqiang; Gaston, Lewis A; Lahori, Altaf Hussain; Mahar, Amanullah

    2016-07-15

    Mg/Al ratio plays a significant role for anion adsorption by Mg/Al-layered double hydroxides (Mg/Al-LDHs) modified biochar. In this study, Mg/Al-LDHs biochar with different Mg/Al ratios (2, 3, 4) were prepared by co-precipitation for phosphate removal from aqueous solution. Factors on phosphate adsorption including Mg/Al ratio, pH, and the presence of other inorganic anions were investigated through batch experiments. Increasing Mg/Al ratio in the Mg/Al-LDHs biochar composites generally enhanced phosphate adsorption with Langmuir adsorption maximum calculated at 81.83mg phosphorous (P) per gram of 4:1Mg/Al-LDHs biochar at pH3.0. The adsorption process was best described by the pseudo-second-order kinetic model. Solution pH had greater effects on the phosphate adsorption by Mg/Al LDHs biochar composites with lower Mg/Al ratios. The presence of other inorganic anions decreased the phosphate adsorption efficiency in the order of F(-) > SO4(2-) > NO2(-) >Cl(-). Phosphate adsorption mechanism involves ion exchange, electrostatic attraction and surface inner-sphere complex formation. Overall, Mg/Al-LDHs biochar composites offer a potential alternative of carbon-based adsorbent for phosphate removal from aqueous solution. PMID:27058131

  5. The decomposition of the layered double hydroxides of Co and Al: phase segregation of a new single phase spinel oxide.

    PubMed

    Babay, Salem; Bulou, Alain; Mercier, Anne Marie; Toumi, Mouhamed

    2015-04-15

    Monophasic Co-Al-CO3-like layered double hydroxides has been prepared by the coprecipitation method. It has been characterised by Rietveld refinement of the X-ray powder diffraction pattern, DTA-TGA, infrared and Raman spectroscopies. Its structure is trigonal, R3̅m with cell parameters a=0.3061(4) nm and c=2.252 (3) nm. The decomposition of this hydrotalcite-like structure on heating up to 800 °C yields to a single phase spinel oxide. Besides, infrared and Raman spectroscopies showed the presence of spinel-like domains. The results of Rietveld refinement have revealed that this compound has the Fd3̅m space group (a=0.8088(4) nm), with crystallographic formula [Co(II)0.75Al0.25](8a)[Co(II)0.252Co(III)0.77Al0.98](16d)O4, which is of the general formula Co1.77Al1.23O4. This structure is also validated by the charge distribution (CD) analysis. PMID:25659816

  6. Layered double hydroxides as carriers for quantum dots@silica nanospheres

    NASA Astrophysics Data System (ADS)

    Stoica, Georgiana; Castelló Serrano, Iván.; Palomares, Emilio

    2013-02-01

    Quantum dot-hydrotalcite layered nanoplatforms were successfully prepared following a one-pot synthesis. The process is very fast and a priori delamination of hydrotalcite is not a prerequisite for the intercalation of quantum dots. The novel materials were extensively characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, transmission electron microscopy, true color fluorescence microscopy, photoluminescence, and nitrogen adsorption. The quantum dot-hydrotalcite nanomaterials display extremely high stability in mimicking physiological media such as saline serum (pH 5.5) and PBS (pH 7.2). Yet, quantum dot release from the solid structure is noted. In order to prevent the leaking of quantum dots we have developed a novel strategy which consists on using tailor made double layered hydrotalcites as protecting shells for quantum dots embedded into silica nanospheres without changing either the materials or the optical properties.

  7. Layered double hydroxides as carriers for quantum dots@silica nanospheres

    NASA Astrophysics Data System (ADS)

    Stoica, Georgiana; Castelló Serrano, Iván; Figuerola, Albert; Ugarte, Irati; Pacios, Roberto; Palomares, Emilio

    2012-08-01

    Quantum dot-hydrotalcite layered nanoplatforms were successfully prepared following a one-pot synthesis. The process is very fast and a priori delamination of hydrotalcite is not a prerequisite for the intercalation of quantum dots. The novel materials were extensively characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, transmission electron microscopy, true color fluorescence microscopy, photoluminescence, and nitrogen adsorption. The quantum dot-hydrotalcite nanomaterials display extremely high stability in mimicking physiological media such as saline serum (pH 5.5) and PBS (pH 7.2). Yet, quantum dot release from the solid structure is noted. In order to prevent the leaking of quantum dots we have developed a novel strategy which consists of using tailor made double layered hydrotalcites as protecting shells for quantum dots embedded into silica nanospheres without changing either the materials or the optical properties.

  8. Synthesis, sustained release properties of magnetically functionalized organic-inorganic materials: Amoxicillin anions intercalated magnetic layered double hydroxides via calcined precursors at room temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Liu, Qi; Zhang, Guangchun; Li, Zhanshuang; Yang, Piaoping; Jing, Xiaoyan; Zhang, Milin; Liu, Tianfu; Jiang, Zhaohua

    2009-09-01

    Zinc-aluminum-carbonate-layered double hydroxides (ZnAl-CO 3-LDHs), loaded with magnetic substrates (Fe 3O 4), were prepared for sustained drug-targeting delivery. From the X-ray diffraction results, it was found that the magnetic substrates were successfully incorporated with LDHs and highly dispersed in the hydrotalcite structure. After intercalation with an antibiotic drug (amoxicillin) by using a calcinations-reconstruction method, the basal spacing of layered double hydroxides increased from 7.51 Å to 12.35 Å, indicating that amoxicillin was successfully intercalated into the interlay space of LDHs as a monolayer. Furthermore, in vitro drug release experiments in pH 7.4 phosphate buffer solution (PBS) showed sustained release profiles with amoxicillin as a model drug. Magnetic measurements revealed that the composite possessed paramagnetic properties at room temperature.

  9. Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

    NASA Astrophysics Data System (ADS)

    Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

    2005-08-01

    Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

  10. Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR spectroscopy

    SciTech Connect

    Petersen, Line B.; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro

    2014-11-01

    Ordering of gallium(III) in a series of magnesium gallium layered double hydroxides (LDH’s), [Mg1-xGax(OH)2(NO3)x yH2O], was determined using solid-state 1H and 71Ga NMR spectroscopy. Depletion of Ga in these LDH’s is demonstrated to be the result of soluble [Ga(OH)4]-complexes formed during synthesis.

  11. Comparative study of Mg/Al- and Zn/Al-layered double hydroxide-perindopril erbumine nanocomposites for inhibition of angiotensin-converting enzyme

    PubMed Central

    Hussein Al Ali, Samer Hasan; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

    2012-01-01

    The intercalation of a drug active, perindopril, into Mg/Al-layered double hydroxide for the formation of a new nanocomposite, PMAE, was accomplished using a simple ion exchange technique. A relatively high loading percentage of perindopril of about 36.5% (w/w) indicates that intercalation of the active took place in the Mg/Al inorganic interlayer. Intercalation was further supported by Fourier transform infrared spectroscopy, and thermal analysis shows markedly enhanced thermal stability of the active. The release of perindopril from the nanocomposite occurred in a controlled manner governed by pseudo-second order kinetics. MTT assay showed no cytotoxicity effects from either Mg/Al-layered double hydroxide or its nanocomposite, PMAE. Mg/Al-layered double hydroxide showed angiotensin-converting enzyme inhibitory activity, with 5.6% inhibition after 90 minutes of incubation. On incubation of angiotensin-converting enzyme with 0.5 μg/mL of the PMAE nanocomposite, inhibition of the enzyme increased from 56.6% to 70.6% at 30 and 90 minutes, respectively. These results are comparable with data reported in the literature for Zn/Al-perindopril. PMID:22904631

  12. Improving the low-temperature capacitance of CoNiAl three-component layered double hydroxide in a redox electrolyte

    SciTech Connect

    Su, Linghao Song, Zuwei; Lu, Lihua; Pang, Guanglong

    2013-09-01

    Graphical abstract: The specific capacitance of CoNiAl layered double hydroxide in 6 M KOH reduces sharply from room temperature to −20 °C, which is effectively enhanced by adding redox pair Fe(CN){sub 6}{sup 3−}/Fe(CN){sub 6}{sup 4−} in the electrolyte. - Highlights: • CoNiAl layered double hydroxide is synthesized by homogeneous precipitation. • The specific capacitance reduces sharply with the decrease of temperature. • At −20 °C the specific capacitance is increased by 178% in a redox electrolyte. - Abstract: CoNiAl three-component layered double hydroxide with a lamellar structure similar to hydrotalcite-like compounds is synthesized via homogeneous precipitation and the effect of temperature on its capacitive performances in 6 M KOH is investigated. Electrochemical tests show its specific capacitance reduces sharply with the decrease of temperature from 18 to −20 °C. At −20 °C an increase of specific capacitance by 178% is achieved by adding redox pair Fe(CN){sub 6}{sup 3−}/Fe(CN){sub 6}{sup 4−} as the electron shuttle in the electrolyte due to their cooperation with the electrode reaction during the charge/discharge processes.

  13. Preparation of single phase Zn2TiO4 spinel from a new ZnTi layered double hydroxide precursor.

    PubMed

    Song, Jianye; Leng, Mingzhe; Xiao, Hongdi; Zhang, Liangji; Qin, Yaowei; Hou, Wanguo; Du, Na; Liu, Jianqiang

    2014-06-01

    A single-source ZnTi-layered double hydroxide precursor was used to prepare single phase Zn2TiO4. This approach involves two steps: the calcination of a ZnTi-layered double hydroxide precursor and selective leaching zinc oxide from the resultant calcined products. The materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) thermogravimetric and differential thermal analysis (TG-DTA), transmission electron microscope (TEM), surface area measurement and UVvis diffuse reflection spectroscopy. The results indicated that a single phase Zn2TiO4 could be successfully obtained from a ZnTi-layered double hydroxide precursor at a relatively low temperature in short calcination time. The TEM and SEM show that the diameter of Zn2TiO4 particles prepared at 900 degrees C is in the range of 20-100 nm and smaller than that prepared by the solid-state method. UV-Vis diffuse reflection spectroscopy demonstrates that the material has an energy bandgap around 3.7 eV. PMID:24738443

  14. Inorganic metal hydroxide nanoparticles for targeted cellular uptake through clathrin-mediated endocytosis.

    PubMed

    Oh, Jae-Min; Choi, Soo-Jin; Lee, Go-Eun; Kim, Jung-Eun; Choy, Jin-Ho

    2009-01-01

    Layered double hydroxides (LDHs) are biocompatible materials which can be used as drug-delivery nanovehicles. In order to define the optimum size of LDH nanoparticles for efficient cellular uptake and drug-delivery pathway, we prepared different sized LDH nanoparticles with narrow size distribution by modulating the crystal growth rate, and labelled each LDH particle with a fluorophore using a silane coupling reaction. The cellular uptake rate of LDHs was found to be highly dependent on particle size (50 > 200 > or = 100 > 350 nm), whose range of 50 to 200 nm was selectively internalized into cells through clathrin-mediated endocytosis with enhanced permeability and retention. Our study clearly shows that not only the particle size plays an important role in the endocytic pathway and processing, but also the size control of LDH nanoparticles results in their targeted uptake to site-specific clathrin-mediated endocytosis. This result provides a new perspective for the design of LDH nanoparticles with maximum ability towards targeted drug delivery. PMID:18988236

  15. Fluorescence of Zn-Al-Eu ternary layered hydroxide response to phenylalanine

    NASA Astrophysics Data System (ADS)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Yang, Xiaojing

    2012-02-01

    We reported the fluorescence of a Zn-Al-Eu ternary layered double hydroxide (LDH) response to an amino acid (phenylalanine) for the first time. As shown in fluorescence, the red emissions attributed to 5D 0- 7F J transitions ( J = 1, 2, 3, 4) of Eu 3+ ions were quenched by the phenylalanine (Phe), and a strong blue emission at around 445 nm appeared. The fluorescent changes may be due to ligand-to-metal charges transfer, which was caused by the interaction between the Zn-Al-Eu LDH and Phe. This interaction was manifested by markedly different chemical shift positions of the Zn 3p 3/2, Al 2p, Eu 4d 3/2, O 1s, and C 1s peaks in the XPS spectra from those of the Zn-Al-Eu LDH and Zn-Al-Eu/Phe composite. Furthermore, the interaction between the LDH and Phe was supported by the results of X-ray diffraction (XRD) measurements, Fourier transform infrared (FT-IR) spectra, and thermogravimetric and differential thermogravimetric (TG-DTG) analysis. The fluorescence of Zn-Al-Eu LDH response to Phe may be potential application in biological techniques.

  16. Effect of silicate on the formation and stability of Ni-Al LDH at the γ-Al2O3 surface.

    PubMed

    Tan, Xiaoli; Fang, Ming; Ren, Xuemei; Mei, Huiyang; Shao, Dadong; Wang, Xiangke

    2014-11-18

    The formation of mixed metal precipitates has been identified as a significant mechanism for the immobilization and elimination of heavy metal ions. Silicate is present in natural systems ubiquitously, which may interfere with metal uptake on the mineral surface and thereby influences the solubility of the precipitate. Herein, kinetic sorption and dissolution experiments combined with extended X-ray absorption fine structure spectroscopy (EXAFS) were performed to elucidate the effect of silicate on the formation of Ni precipitates at the γ-Al2O3 surfaces. The uptake of Ni on γ-Al2O3 decreased with increasing amounts of silicate coated onto the γ-Al2O3 surface. Results of EXAFS analyses suggested the formation of Ni-Al layered double hydroxide (LDH) phases. The surface coating of silicate on γ-Al2O3 reduced Al release and finally resulted in a high Ni:Al ratio due to a lower extent of Al substitution into the precipitates. The presence of silicate prevented the growth of the precipitates and led to the formation of less stable Ni-Al LDH. The influence of silicate on the precipitate formation provided the evidence for the growth relationship between the precipitate and mineral substrate in the real environment. Increased rates of proton-promoted dissolution of Ni surface precipitates were mainly attributed to higher Ni:Al ratios in Ni-Al LDH precipitates formed in the presence of silicate. PMID:25339547

  17. Adsorption and subsequent partial photodegradation of methyl violet 2B on Cu/Al layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Guzmán-Vargas, Ariel; Lima, Enrique; Uriostegui-Ortega, Gisselle A.; Oliver-Tolentino, Miguel A.; Rodríguez, Esaú E.

    2016-02-01

    Uncalcined Cu/Al LDH was studied as adsorbent and photocatalyst in the adsorption and subsequent photodegradation of methyl violet 2B dye (MV2B). Physicochemical characterization was carried out by XRD, FTIR, UV-vis, including photoactive properties, DSC/TGA and SEM. Kinetic and thermodynamic models showed great affinity and sorption capacity, the maximum adsorption capacity was 361.0 mg g-1 obtained by Langmuir model, in addition, the results showed that the dye was adsorbed on the LDH surface. Photocatalytic activity was evaluated in the MV2B dye photodegradation process, and it was confirmed by the presence rad OH radicals monitored by EPR spin trapping technique, additionally, COD and TOC parameters were measured, 13C NMR showed differences for the adsorbed and photodegraded samples.

  18. 5-Fluorouracil intercalated iron oxide@layered double hydroxide core-shell nano-composites with isotropic and anisotropic architectures for shape-selective drug delivery applications.

    PubMed

    Tuncelli, Gülsevde; Ay, Ahmet Nedim; Zümreoglu-Karan, Birgül

    2015-10-01

    We report the synthesis, characterization and in vitro release behavior of anti-cancer drug carrying iron oxide@layered double hydroxide core-shell nanocomposites with sizes ranging from 40 to 300 nm, good drug loading capacities and soft ferromagnetic properties. HRTEM analyses verified that nearly spherical isotropic carriers were obtained by coating spherical magnetite particles while anisotropic carriers were obtained by coating spindle-shaped hematite particles. They both displayed a fluctuating in vitro release profile with a higher release percentage for the anisotropic carrier. PMID:26117790

  19. Magnesium Hydroxide

    MedlinePlus

    Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as ...

  20. Aluminum Hydroxide

    MedlinePlus

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  1. In vitro inhibition of histamine release behavior of cetirizine intercalated into Zn/Al- and Mg/Al-layered double hydroxides.

    PubMed

    Hussein-Al-Ali, Samer Hasan; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

    2012-01-01

    The intercalation of cetirizine into two types of layered double hydroxides, Zn/Al and Mg/Al, has been investigated by the ion exchange method to form CTZAN and CTMAN nanocomposites, respectively. The basal spacing of the nanocomposites were expanded to 31.9 Å for CTZAN and 31.2 Å for CTMAN, suggesting that cetirizine anion was intercalated into Layered double hydroxides (LDHs) and arranged in a tilted bilayer fashion. A Fourier transform infrared spectroscopy (FTIR) study supported the formation of both the nanocomposites, and the intercalated cetirizine is thermally more stable than its counterpart in free state. The loading of cetirizine in the nanocomposite was estimated to be about 57.2% for CTZAN and 60.7% CTMAN. The cetirizine release from the nanocomposites show sustained release manner and the release rate of cetirizine from CTZAN and CTMAN nanocomposites at pH 7.4 is remarkably lower than that at pH 4.8, presumably due to the different release mechanism. The inhibition of histamine release from RBL2H3 cells by the free cetirizine is higher than the intercalated cetirizine both in CTZAN and CTMAN nanocomposites. The viability in human Chang liver cells at 1000 μg/mL for CTZAN and CTMAN nanocomposites are 74.5 and 91.9%, respectively. PMID:22754339

  2. Dissolvable layered double hydroxide coated magnetic nanoparticles for extraction followed by high performance liquid chromatography for the determination of phenolic acids in fruit juices.

    PubMed

    Saraji, Mohammad; Ghani, Milad

    2014-10-31

    A magnesium-aluminum layered double hydroxide coated on magnetic nanoparticles was synthesized and used as a sorbent to extract some phenolic acids including p-hydroxy benzoic acid, caffeic acid, syringic acid, p-coumaric acid and ferulic acid from fruit juices. After extraction, the elution step was performed through dissolving double hydroxide layers containing the analytes by changing the solution pH. The extracted phenolic acids were separated and quantified using high performance liquid chromatography-photodiode array detection. Experimental parameters such as sorbent amount, solution pH, desorption solvent volume and extraction time were studied and optimized. The linearity range of the method was between 2 and 500μgL(-1) with the determination coefficient (r(2)) higher than 0.991. Relative standard deviations for intra- and inter-day precision for the analytes at 100μgL(-1) were in the range of 4.3-9.2% and 4.9-8.6%, respectively. Batch-to-batch reproducibility at 100μgL(-1) concentration level was in the range of 7.8-11% (n=3). The limits of detection were between 0.44 and 1.3μgL(-1). Relative recoveries higher than 81% with RSDs in the range of 4.2-9.7% were obtained in the analysis of fruit juice samples. PMID:25260344

  3. Controlled release and angiotensin-converting enzyme inhibition properties of an antihypertensive drug based on a perindopril erbumine-layered double hydroxide nanocomposite

    PubMed Central

    Al Ali, Samer Hasan Hussein; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

    2012-01-01

    Background The intercalation of perindopril erbumine into Zn/Al-NO3-layered double hydroxide resulted in the formation of a host-guest type of material. By virtue of the ion-exchange properties of layered double hydroxide, perindopril erbumine was released in a sustained manner. Therefore, this intercalated material can be used as a controlled-release formulation. Results Perindopril was intercalated into the interlayers and formed a well ordered, layered organic-inorganic nanocomposite. The basal spacing of the products was expanded to 21.7 Å and 19.9 Å by the ion-exchange and coprecipitation methods, respectively, in a bilayer and a monolayer arrangement, respectively. The release of perindopril from the nanocomposite synthesized by the coprecipitation method was slower than that of its counterpart synthesized by the ion-exchange method. The rate of release was governed by pseudo-second order kinetics. An in vitro antihypertensive assay showed that the intercalation process results in effectiveness similar to that of the antihypertensive properties of perindopril. Conclusion Intercalated perindopril showed better thermal stability than its free counterpart. The resulting material showed sustained-release properties and can therefore be used as a controlled-release formulation. PMID:22619549

  4. In Vitro Inhibition of Histamine Release Behavior of Cetirizine Intercalated into Zn/Al- and Mg/Al-Layered Double Hydroxides

    PubMed Central

    Hussein-Al-Ali, Samer Hasan; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

    2012-01-01

    The intercalation of cetirizine into two types of layered double hydroxides, Zn/Al and Mg/Al, has been investigated by the ion exchange method to form CTZAN and CTMAN nanocomposites, respectively. The basal spacing of the nanocomposites were expanded to 31.9 Å for CTZAN and 31.2 Å for CTMAN, suggesting that cetirizine anion was intercalated into Layered double hydroxides (LDHs) and arranged in a tilted bilayer fashion. A Fourier transform infrared spectroscopy (FTIR) study supported the formation of both the nanocomposites, and the intercalated cetirizine is thermally more stable than its counterpart in free state. The loading of cetirizine in the nanocomposite was estimated to be about 57.2% for CTZAN and 60.7% CTMAN. The cetirizine release from the nanocomposites show sustained release manner and the release rate of cetirizine from CTZAN and CTMAN nanocomposites at pH 7.4 is remarkably lower than that at pH 4.8, presumably due to the different release mechanism. The inhibition of histamine release from RBL2H3 cells by the free cetirizine is higher than the intercalated cetirizine both in CTZAN and CTMAN nanocomposites. The viability in human Chang liver cells at 1000 μg/mL for CTZAN and CTMAN nanocomposites are 74.5 and 91.9%, respectively. PMID:22754339

  5. Structure and luminescence behaviour of as-synthesized, calcined, and restored MgAlEu-LDH with high crystallinity.

    PubMed

    Zhao, Yushuang; Li, Ji-Guang; Fang, Fang; Chu, Nankai; Ma, Hui; Yang, Xiaojing

    2012-10-21

    Highly crystalline Eu(3+)-incorporated MgAl layered double hydroxides (LDHs) were synthesized by the homogeneous precipitation method. For the crystals as-prepared, after their calcination from 200-1000 °C, and, further, after restoration in a Na(2)CO(3) solution, the structural and luminescent changes were investigated for the first time. Eu(3+) ions with a coordination number of, probably, 8, were incorporated into the hydrotalcite layer, which led to a basal spacing (d(basal)) increase, microstrain formation, and crystalline morphology imperfections, while retaining the original lattice symmetry, R3[combining macron]m. In the deconstruction process due to calcination, the Eu(3+) ions restrained the formation of the spinel phase from the layered double oxide (LDO), but did not significantly change the memory effect, by which LDOs can convert to LDHs during the hydration process. For the reversible phase transformation between LDH and LDO, the morphology observation revealed that, in addition to the formation of pores on the surface, nano-slabs were formed, especially for the restored crystals. A layered phase with a d(basal) of 5.8 Å, due to bridging bidentate carbonates with the hydrotalcite layer, was formed in the calcination process at low temperature (300 °C) before the formation of LDO, but could not be restored to a large spacing. Typical (5)D(0) → (7)F(J) (J = 0-4) transitions of Eu(3+) at 579, 593, 615, 653, and 698 nm were observed in the photoluminescence spectra and the intensity of the dominating 615 nm band decreased with the LDH deconstruction and the formation of free water, and then increased with the formation of LDOs in the calcination process, and vice versa in the reconstruction process. The Eu(3+) ions had a probable 9- or 10-coordination mode in addition to the probable 8-coordination mode as the spinel phase appeared. PMID:22930336

  6. Synthesis of layered double hydroxides containing Mg2+, Zn2+, Ca2+ and Al3+ layer cations by co-precipitation methods-A review

    NASA Astrophysics Data System (ADS)

    Theiss, Frederick L.; Ayoko, Godwin A.; Frost, Ray L.

    2016-10-01

    Co-precipitation is a common method for the preparation of layered double hydroxides (LDHs) and related materials. This review article is aimed at providing newcomers to the field with some examples of the types of co-precipitation reactions that have been reported previously and to briefly investigate some of the properties of the products of these reactions. Due to the sheer volume of literature on the subject, the authors have had to limit this article to the synthesis of Mg/Al, Zn/Al and Ca/Al LDHs by co-precipitation and directly related methods. LDHs have been synthesised from various reagents including metal salts, oxides and hydroxides. Co-precipitation is also useful for the direct synthesis of LDHs with a wide range of interlayer anions and various bases have been successfully employed to prepare LDHs. Examples of other synthesis techniques including the urea method, hydrothermal synthesis and various mechanochemical methods that are undoubtedly related to co-precipitation have also been included in this review. The effect of post synthesis hydrothermal has also been summarised.

  7. Nanohybrids from NiCoAl-LDH coupled with carbon for pseudocapacitors: understanding the role of nano-structured carbon

    NASA Astrophysics Data System (ADS)

    Yu, Chang; Yang, Juan; Zhao, Changtai; Fan, Xiaoming; Wang, Gang; Qiu, Jieshan

    2014-02-01

    Transition metal layered double hydroxides (LDHs) are one of the great potential electrode materials for pseudocapacitors. However, the aggregation and low conductivity of these metal compounds will constrain electrolyte ion and electron transfer and further affect their electrochemical performances. The nano-structured carbon coupled with the LDH matrix can act as an active component or conducting scaffold to enhance or improve the rate capacity and cycle life. Here, various nano-structured carbon species, including zero-dimensional carbon black (CB), one-dimensional carbon nanotubes (CNTs), two-dimensional reduced graphene oxide (RGO), and CNT/RGO composites were used to couple with the NiCoAl-LDHs to construct LDH-carbon nanohybrid electrodes for pseudocapacitors, and the role of the nanostructured carbon was investigated and discussed in terms of the pore structure of nanohybrids and electrical conductivity. The results show that all of the carbons can be well incorporated into the LDH nanosheets to form homogeneous nanohybrid materials. The pore structure properties and electrical conductivity of nanohybrids have statistically significant effects on the electrochemical performances of the LDH-carbon nanohybrids. Of the electrodes adopted, the nanohybrid electrode consisting of NiCoAl-LDHs, CNTs, and RGO exhibits excellent electrochemical performance with a specific capacitance as high as 1188 F g-1 at a current density of 1 A g-1 due to the synergistic effect of NiCoAl-LDHs, RGO, and CNTs, in which the RGO nanosheets are favorable for high specific surface area while the CNT has a fast electron transport path for enhancing the electrical conductivity of nanohybrids. This will shed a new light on the effect of nano-structured carbon within the electrode matrix on the electrochemical activity and open a new way for the carbon-related electrode configuration/design for supercapacitors, and other energy storage and conversion devices.Transition metal layered

  8. Preparation of C.I. Pigment 52:1 anion-pillared layered double hydroxide and the thermo- and photostability of the resulting intercalated material

    NASA Astrophysics Data System (ADS)

    Guo, Shengchang; Evans, David G.; Li, Dianqing

    2006-05-01

    Intercalation of 2-naphthalenecarboxylic acid, 4-((4-chloro-5-methyl-2-sulfophenyl) azo)-3-hydroxy-, calcium salt (1:1) (C.I. Pigment Red 52:1, also known as New Rubine S6B) into a layered double hydroxide (LDHs) host was carried out using MgAl NO3 LDHs as a precursor in an effort to improve the thermal and photo stability of the pigment. After intercalation, the powder X-ray diffraction (XRD) pattern shows that the basal spacing of the LDHs increased from 0.86 to 1.92 nm. Infrared spectra and TG DTA curves demonstrate that there are supramolecular host guest interactions. It was found that the intercalated material is more stable than the pristine pigment at high temperatures. The pigment anion-pillared LDHs also exhibit much higher photostablity to UV-light than the pristine pigment.

  9. DNA-enhanced peroxidase-like activity of layered double hydroxide nanosheets and applications in H2O2 and glucose sensing

    NASA Astrophysics Data System (ADS)

    Chen, Lijian; Sun, Kaifang; Li, Peipei; Fan, Xianzhong; Sun, Jianchao; Ai, Shiyun

    2013-10-01

    LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA-LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA-LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl-LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields.LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA-LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA-LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl-LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03031h

  10. Facile assembly of Ni-Co hydroxide nanoflakes on carbon nanotube network with highly electrochemical capacitive performance.

    PubMed

    Chen, Hongyuan; Cai, Feng; Kang, Yiran; Zeng, Sha; Chen, Minghai; Li, Qingwen

    2014-11-26

    Herein, we demonstrate the high-density assembly of Ni-Co hydroxide nanoflakes on conductive carbon nanotube (CNT) network through a simple and rapid chemical precipitation method, presenting a low-cost and high-performance scaffold for pseudosupercapacitor. It is found that the Ni-Co layered double hydroxide (LDH) nanoflakes prefer to proliferate around large-diameter CNTs (diameter>50 nm), with conductive CNT network well-maintained. Such hierarchical nanostructures show greatly improved specific surface areas compared with bare CNT network and are freestanding without other organic binder, which can be directly employed as a binder-free compact electrode assembly. By optimizing the chemical composition of as-precipitated LDH nanoflakes, the resultant Co0.4Ni0.6(OH)2 LDH/CNT composite nanostructures exhibit the largest specific electrochemical capacitance and the best rate performance, with their capacitance up to 1843 F/g under a low current density of 0.5 A/g and maintained at 1231 F/g when the current density is increased 20 times to 10 A/g. Importantly, such hierarchical nanostructures tend to prevent the electrode from severe structural damage and capacity loss during hundreds of charge/discharge under a high rate (2 A/g), ensuring the electrode with high-energy density (51 W h/kg) at power density of 3.3 kW/kg. PMID:25314093

  11. Single-step in situ synthesis of double bond-grafted yttrium-hydroxide nanotube core-shell structures.

    PubMed

    Li, Weijia; Wang, Xun; Li, Yadong

    2004-01-21

    Novel MMA-Y(OH)(3) nanotube core-shell structures have been successfully prepared with double bonds successfully grafted on the surface through a single-step in-situ hydrothermal method. PMID:14737530

  12. Multivariate optimization of process parameters in the synthesis of calcined Ca‒Al (NO3) LDH for defluoridation using 3(3) factorial, central composite and Box-Behnken design.

    PubMed

    Ghosal, Partha S; Gupta, Ashok K; Sulaiman, Ayoob

    2016-01-01

    Response surface methodology was applied for the first time in the optimization of the preparation of layered double hydroxide (LDH) for defluoridation. The influence of three vital process parameters (viz. pH, molar ratio and calcination temperature) in the synthesis of the adsorbent 'Calcined Ca‒Al (NO3) LDH' was thoroughly examined to maximize its fluoride scavenging potential. The process parameters were optimized using the 3(3) factorial, face centered central composite and Box-Behnken designs and a comparative assessment of the methods was conducted. The maximum fluoride removal efficiency was achieved at a calcination temperature of approximately 500ºC; however, the efficiency decreased with increasing pH and molar ratio. The outcome of the comparative assessment clearly delineates the case specific nature of the models. A better predictability over the entire experimental domain was obtained with the 3(3) factorial method, whereas the Box-Behnken design was found to be the most efficient model with lesser number of experimental runs. The desirability function technique was performed for optimizing the response, wherein face centered central composite design exhibited a maximum desirability. The calcined Ca‒Al (NO3) LDH, synthesized under the optimum conditions, demonstrated the removal efficiencies of 95% and 99% for the doses of 3 g L(-1) and 5 g L(-1), respectively. PMID:26549036

  13. Synthesis and anion exchange properties of a Zn/Ni double hydroxide salt with a guarinoite structure

    NASA Astrophysics Data System (ADS)

    Delorme, F.; Seron, A.; Licheron, M.; Veron, E.; Giovannelli, F.; Beny, C.; Jean-Prost, V.; Martineau, D.

    2009-09-01

    In this study, the first route to synthesize a compound with the guarinoite structure (Zn,Co,Ni) 6(SO 4)(OH,Cl) 10·5H 2O is reported. Zn/Ni guarinoite is obtained from the reaction of NiSO 4·7H 2O with solid ZnO in aqueous solution. The resulting green Zn/Ni guarinoite ((Zn 3.52Ni 1.63)(SO 4) 1.33(OH 7.64)·4.67H 2O) was characterized by X-ray diffraction, infrared spectrometry, UV-Visible spectrometry and thermal analysis. It is shown that its structure is similar to the one described for the layered Zn sulfate hydroxide hydrate, i.e. brucite layers with {1}/{4} empty octahedra presenting tetrahedrally coordinated divalent atoms above and below the empty octahedra. Ni atoms are located in the octahedra and zinc atoms in tetrahedra and octahedra. In this structure the exchangeable anions are located at the apex of tetrahedra. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations show that the Zn/Ni guarinoite is composed of aggregates of hexagonal plates of several hundreds of nanometers. Due to its interest for industrial or environmental applications, the exchange of sulfate groups by carbonates has been investigated. Results show a limited exchange and a higher affinity of the Zn/Ni guarinoite for sulfates compared to carbonates.

  14. Aluminum Hydroxide

    MedlinePlus

    ... penicillamine (Cuprimine, Depen), prednisone (Deltasone, Orasone), products containing iron, tetracycline (Sumycin, Tetracap, and others), ticlopidine (Ticlid), and vitamins.be aware that aluminum hydroxide may interfere with other medicines, making them less effective. Take your other medications 1 ...

  15. Synthesis and characterization of the LDH hydrotalcite-pyroaurite solid-solution series

    SciTech Connect

    Rozov, K.; Berner, U.; Taviot-Gueho, C.; Leroux, F.; Renaudin, G.; Kulik, D.; Diamond, L.W.

    2010-08-15

    A layered double hydroxide (LDH) hydrotalcite-pyroaurite solid-solution series Mg{sub 3}(Al{sub x}Fe{sub 1-x})(CO{sub 3}){sub 0.5}(OH){sub 8} with 1 - x = 0.0, 0.1...1.0 was prepared by co-precipitation at 23 {+-} 2 {sup o}C and pH = 11.40 {+-} 0.03. The compositions of the solids and the reaction solutions were determined using ICP-OES (Mg, Al, Fe, and Na) and TGA techniques (CO{sub 3}{sup 2-}, OH{sup -}, and H{sub 2}O). Powder X-ray diffraction was employed for phase identification and determination of the unit cell parameters a{sub o} and c{sub o} from peak profile analysis. The parameter a{sub o} = b{sub o} was found to be a linear function of the composition. This dependency confirms Vegard's law and indicates the presence of a continuous solid-solution series in the hydrotalcite-pyroaurite system. TGA data show that the temperatures at which interlayer H{sub 2}O molecules and CO{sub 3}{sup 2-} anions are lost, and at which dehydroxylation of the layers occurs, all decrease with increasing mole fraction of iron within the hydroxide layers. Features of the Raman spectra also depend on the iron content. The absence of Raman bands for Fe-rich members (x{sub Fe} > 0.5) is attributed to possible fluorescence phenomena. Based on chemical analysis of both the solids and the reaction solutions after synthesis, preliminary Gibbs free energies of formation have been estimated. Values of {Delta}G{sup o}{sub f}(hydrotalcite) = - 3773.3 {+-} 51.4 kJ/mol and {Delta}G{sup o}{sub f}(pyroaurite) = - 3294.5 {+-} 95.8 kJ/mol were found at 296.15 K. The formal uncertainties of these formations constants are very high. Derivation of more precise values would require carefully designed solubility experiments and improved analytical techniques.

  16. NICKEL HYDROXIDES

    SciTech Connect

    MCBREEN,J.

    1997-11-01

    Nickel hydroxides have been used as the active material in the positive electrodes of several alkaline batteries for over a century. These materials continue to attract a lot of attention because of the commercial importance of nickel-cadmium and nickel-metal hydride batteries. This review gives a brief overview of the structure of nickel hydroxide battery electrodes and a more detailed review of the solid state chemistry and electrochemistry of the electrode materials. Emphasis is on work done since 1989.

  17. Effects of Varying Particle Sizes and Different Types of LDH-Modified Anthracite in Simulated Test Columns for Phosphorous Removal

    PubMed Central

    Zhang, Xiangling; Chen, Qiaozhen; Guo, Lu; Huang, Hualing; Ruan, Chongying

    2015-01-01

    A comparative study was carried out for the removal of phosphorus in simulated unplanted vertical-flow constructed wetlands with different layered double hydroxide (LDHs) coated anthracite substrates. Three particle sizes of anthracites were selected and modified separately with nine kinds of LDH coating. The simulated substrates test columns loaded with the original and modified anthracites were constructed to treat the contaminated water. For the medium and large particle size modified anthracite substrates, the purification effects of total phosphorus, total dissolved phosphorus and phosphate were improved by various degrees, and the purification effect of the medium particle size anthracite is better than that of the large size one. The medium size anthracite modified by ZnCo-LDHs had optimal performance with average removal efficiencies of total phosphorus, total dissolved phosphorus and phosphate reaching 95%, 95% and 98%, respectively. The maximum adsorption capacity on ZnCo-LDHs and ZnAl-LDHs modified medium sizes anthracites were 65.79 (mg/kg) and 48.78 (mg/kg), respectively. In comparison, the small size anthracite is not suitable for LDHs modification. PMID:26086702

  18. Spherical LDH-Ag°-montmorillonite heterocoagulated system with a pH-dependent sol-gel structure for controlled accessibility of AgNPs immobilized on the clay lamellae.

    PubMed

    Deák, Ágota; Janovák, László; Tallósy, Szabolcs Péter; Bitó, Tamás; Sebők, Dániel; Buzás, Norbert; Pálinkó, István; Dékány, Imre

    2015-02-17

    Aqueous suspensions of spherical ZnMgAl-layered double hydroxides [LDH(sph)] and antibacterial silver nanoparticles (AgNPs) deposited on the lamellae of montmorillonite were used for the synthesis of composites, which behave like coherent gels at low pH (≲4.5) and incoherent sols at higher pH (≳4.5). The composition of the composite was chosen as LDH(sph)/Ag°-montm. = 25:75 wt % in order to ensure a sol-gel transition that can also be characterized by viscometry. This pH-sensitive heterocoagulated system consisting of oppositely charged colloid particles was suitable for the release of antimicrobial AgNPs immobilized on the clay lamellae via a pH-controlled gel-sol transition. The heterocoagulation process was also characterized by surface charge titration measurements. Spherical LDH/Ag°-montmorillonite composite samples were identified by X-ray diffraction (XRD) measurements. The morphological properties of the composites were studied, and the presence of the heterocoagulated structure was confirmed by scanning electron microscopy (SEM). The nanoscale structure of the LDH(sph)-Ag°-montmorillonite composite obtained was also verified by small-angle X-ray scattering (SAXS), and the rheological characteristics were studied at various pH values. The viscosity and yield value of the composite decreased by an order of magnitude upon increasing the pH from 3.0 to 5.5. The sol-gel transition of the composite suspension was reversible in the previously mentioned pH range. PMID:25619227

  19. Efficient removal of dyes by a novel magnetic Fe3O4/ZnCr-layered double hydroxide adsorbent from heavy metal wastewater.

    PubMed

    Chen, Dan; Li, Yang; Zhang, Jia; Li, Wenhui; Zhou, Jizhi; Shao, Li; Qian, Guangren

    2012-12-01

    A novel magnetic Fe(3)O(4)/ZnCr-layered double hydroxide adsorbent was produced from electroplating wastewater and pickling waste liquor via a two-step microwave hydrothermal method. Adsorption of methyl orange (MO) from water was studied using this material. The effects of three variables have been investigated by a single-factor method. The response surface methodology (RSM) based on Box-Behnken design was successfully applied to the optimization of the preparation conditions. The maximum adsorption capacity of MO was found to be 240.16 mg/g, indicating that this material may be an effective adsorbent. It was shown that 99% of heavy metal ions (Fe(2+), Fe(3+), Cr(3+), and Zn(2+)) can be effectively removed into precipitates and released far less in the adsorption process. In addition, this material with adsorbed dye can be easily separated by a magnetic field and recycled after catalytic regeneration with advanced oxidation technology. Meanwhile, kinetic models, FTIR spectra and X-ray diffraction pattern were applied to the experimental data to examine uptake mechanism. The boundary layer and intra-particle diffusion played important roles in the adsorption mechanisms. PMID:23122732

  20. Enhancing electrochemical reaction sites in nickel-cobalt layered double hydroxides on zinc tin oxide nanowires: a hybrid material for an asymmetric supercapacitor device.

    PubMed

    Wang, Xu; Sumboja, Afriyanti; Lin, Mengfang; Yan, Jian; Lee, Pooi See

    2012-11-21

    Conducting nanowires are of particular interest in energy-related research on devices such as supercapacitors, batteries, water splitting electrodes and solar cells. Their direct electrode/current collector contact and highly conductive 1D structure enable conducting nanowires to provide ultrafast charge transportation. In this paper, we report the facile synthesis of nickel cobalt layered double hydroxides (LDHs) on conducting Zn(2)SnO(4) (ZTO) and the application of this material to a supercapacitor. This study also presents the first report of an enhancement of the active faradic reaction sites (electroactive sites) resulting from the heterostructure. This novel material demonstrates outstanding electrochemical performance with a high specific capacitance of 1805 F g(-1) at 0.5 A g(-1), and an excellent rate performance of 1275 F g(-1) can be achieved at 100 A g(-1). Furthermore, an asymmetric supercapacitor was successfully fabricated using active carbon as a negative electrode. This asymmetric device exhibits a high energy density of 23.7 W h kg(-1) at a power density of 284.2 W kg(-1). Meanwhile, a high power density of 5817.2 W kg(-1) can be achieved at an energy density of 9.7 W h kg(-1). More importantly, this device exhibits long-term cycling stability, with 92.7% capacity retention after 5000 cycles. PMID:23076678

  1. Fe(II)-Al(III) layered double hydroxides prepared by ultrasound-assisted co-precipitation method for the reduction of bromate.

    PubMed

    Zhong, Yu; Yang, Qi; Luo, Kun; Wu, Xiuqiong; Li, Xiaoming; Liu, Yang; Tang, Wangwang; Zeng, Guangming; Peng, Bo

    2013-04-15

    Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this paper, Fe(II)-Al(III) layered double hydroxides (Fe-Al LDHs) prepared by the ultrasound-assisted co-precipitation method were used for the reduction of bromate in solution. The Fe-Al LDHs particles were characterized by X-ray diffractometer, scanning electron microscopy and thermogravimetry-differential scanning calorimetry. It was found that ultrasound irradiation assistance promoted the formation of the hydrotalcite-like phase and then improved the removal efficiency of bromate. In addition, the effects of solid-to-solution ratio, contact time, initial bromate concentration, initial pH, coexisting anions on the bromate removal were investigated. The results showed the bromate with an initial concentration of 1.56 μmol/L could be completely removed from solution by Fe-Al LDHs within 120 min. When the initial bromate concentration was 7.81 μmol/L, the Fe-Al LDHs with irradiation time of 30 min exhibited the optimum removal efficiency and the bromate removal capacity (qe) was 6.80 μmol/g. In addition, the appearance of sulfate and production of bromide were observed simultaneously in this process, which suggested that ion-exchange between sulfate and bromate, and the reduction of bromate to bromide by Fe(2+) were the main mechanisms responsible for the bromate removal by Fe-Al LDHs. PMID:23474408

  2. Solvothermal synthesis of NiAl double hydroxide microspheres on a nickel foam-graphene as an electrode material for pseudo-capacitors

    SciTech Connect

    Momodu, Damilola; Bello, Abdulhakeem; Dangbegnon, Julien; Barzeger, Farshad; Taghizadeh, Fatimeh; Fabiane, Mopeli; Manyala, Ncholu; Johnson, A. T. Charlie

    2014-09-15

    In this paper, we demonstrate excellent pseudo-capacitance behavior of nickel-aluminum double hydroxide microspheres (NiAl DHM) synthesized by a facile solvothermal technique using tertbutanol as a structure-directing agent on nickel foam-graphene (NF-G) current collector as compared to use of nickel foam current collector alone. The structure and surface morphology were studied by X-ray diffraction analysis, Raman spectroscopy and scanning and transmission electron microscopies respectively. NF-G current collector was fabricated by chemical vapor deposition followed by an ex situ coating method of NiAl DHM active material which forms a composite electrode. The pseudocapacitive performance of the composite electrode was investigated by cyclic voltammetry, constant charge–discharge and electrochemical impedance spectroscopy measurements. The composite electrode with the NF-G current collector exhibits an enhanced electrochemical performance due to the presence of the conductive graphene layer on the nickel foam and gives a specific capacitance of 1252 F g{sup −1} at a current density of 1 A g{sup −1} and a capacitive retention of about 97% after 1000 charge–discharge cycles. This shows that these composites are promising electrode materials for energy storage devices.

  3. Synthesis of self-assembled layered double hydroxides/carbon composites by in situ solvothermal method and their application in capacitors

    SciTech Connect

    Wei, Jinbo; Wang, Jun; Song, Yanchao; Li, Zhanshuang; Gao, Zan; Mann, Tom; Zhang, Milin

    2012-12-15

    Nickel-aluminum layered double hydroxides/carbon (Ni-Al LDHs/C) composites have been successfully fabricated via a facile in situ water-ethanol system. LDHs nanosheets could highly disperse on the surface of colloidal carbonaceous spheres through the interfacial electrostatic force. Ni-Al LDHs/C composite electrode prepared at 50% ethanol system exhibits the highest capacitance of 1064 F g{sup -1} at a current of 2.5 A g{sup -1}, leading to a significant improvement in relation to each individual counterpart (3.5 and 463 F g{sup -1} for carbon and Ni-Al LDHs at 2.5 A g{sup -1}, respectively). And a possible mechanism was proposed for the formation of the composites. Highlights: Black-Right-Pointing-Pointer Ni-Al LDHs/C composites have been self-assembled by an in situ solvothermal method. Black-Right-Pointing-Pointer A possible growth mechanism to explain the composite is proposed. Black-Right-Pointing-Pointer Ni-Al LDHs/C composites display better electrochemical performance.

  4. Application of dissolvable layered double hydroxides as sorbent in dispersive solid-phase extraction and extraction by co-precipitation for the determination of aromatic acid anions.

    PubMed

    Tang, Sheng; Lee, Hian Kee

    2013-08-01

    Three types of magnesium-aluminum layered double hydroxides were synthesized and employed as solid-phase extraction (SPE) sorbents to extract several aromatic acids (protocatechuic acid, mandelic acid, phthalic acid, benzoic acid, and salicylic acid) from aqueous samples. An interesting feature of these sorbents is that they dissolve when the pH of the solution is lower than 4. Thus, the analyte elution step, as needed in conventional sorbent-based extraction, was obviated by dissolving the sorbent in acid after extraction and separation from the sample solution. The extract was then directly injected into a high-performance liquid chromatography-ultraviolet detection system for analysis. In the key adsorption process, both dispersive SPE and co-precipitation extraction with the sorbents were conducted and experimental parameters such as pH, temperature, and extraction time were optimized. The results showed that both extraction methods provided low limits of detection (0.03-1.47 μg/L) and good linearity (r(2) > 0.9903). The optimized extraction conditions were applied to human urine and sports drink samples. This new and interesting extraction approach was demonstrated to be a fast and efficient procedure for the extraction of organic anions from aqueous samples. PMID:23855757

  5. Anionic clay as the drug delivery vehicle: tumor targeting function of layered double hydroxide-methotrexate nanohybrid in C33A orthotopic cervical cancer model.

    PubMed

    Choi, Goeun; Piao, Huiyan; Alothman, Zeid A; Vinu, Ajayan; Yun, Chae-Ok; Choy, Jin-Ho

    2016-01-01

    Methotrexate (MTX), an anticancer agent, was successfully intercalated into the anionic clay, layered double hydroxides to form a new nanohybrid drug. The coprecipitation and subsequent hydrothermal method were used to prepare chemically, structurally, and morphologically well-defined two-dimensional drug-clay nanohybrid. The resulting two-dimensional drug-clay nanohybrid showed excellent colloidal stability not only in deionized water but also in an electrolyte solution of Dulbecco's Modified Eagle's Medium with 10% fetal bovine serum, in which the average particle size in colloid and the polydispersity index were determined to be around 100 and 0.250 nm, respectively. The targeting property of the nanohybrid drug was confirmed by evaluating the tumor-to-blood and tumor-to-liver ratios of the MTX with anionic clay carrier, and these ratios were compared to those of free MTX in the C33A orthotopic cervical cancer model. The biodistribution studies indicated that the mice treated with the former showed 3.5-fold higher tumor-to-liver ratio and fivefold higher tumor-to-blood ratio of MTX than those treated with the latter at 30 minutes postinjection. PMID:26855572

  6. Nanostructural drug-inorganic clay composites: Structure, thermal property and in vitro release of captopril-intercalated Mg Al-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zou, Kang; Guo, Shaohuan; Duan, Xue

    2006-06-01

    A nanostructural drug-inorganic clay composite involving a pharmaceutically active compound captopril (Cpl) intercalated Mg-Al-layered double hydroxides (Cpl-LDHs) with Mg/Al molar ratio of 2.06 has been assembled by coprecipitation method. Powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) and Raman spectra analysis indica