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Sample records for adsorbed dye molecules

  1. Evidence for photo-induced charge separation between dye molecules adsorbed to aluminium oxide surfaces

    PubMed Central

    Cappel, Ute B.; Moia, Davide; Bruno, Annalisa; Vaissier, Valerie; Haque, Saif A.; Barnes, Piers R. F.

    2016-01-01

    Excited state dynamics and photo-induced charge transfer of dye molecules have been widely studied due to their relevance for organic and dye-sensitised solar cells. Herein, we present a femtosecond transient absorption spectroscopy study of the indolene dye D131 when adsorbed to inert Al2O3 substrates for different surface concentration of the dye. Surprisingly, we find that at high surface concentrations, the first singlet excited state of the dye is converted into a new state with an efficiency of about 80%. We assign the absorption features of this state to the oxidised dye and discuss the possibility of photo-induced charge separation between neighboring dye molecules. Our study is the first to show that this process can be highly efficient without the use of donor and acceptor molecules of different chemical structures. PMID:26891851

  2. Evidence for photo-induced charge separation between dye molecules adsorbed to aluminium oxide surfaces

    NASA Astrophysics Data System (ADS)

    Cappel, Ute B.; Moia, Davide; Bruno, Annalisa; Vaissier, Valerie; Haque, Saif A.; Barnes, Piers R. F.

    2016-02-01

    Excited state dynamics and photo-induced charge transfer of dye molecules have been widely studied due to their relevance for organic and dye-sensitised solar cells. Herein, we present a femtosecond transient absorption spectroscopy study of the indolene dye D131 when adsorbed to inert Al2O3 substrates for different surface concentration of the dye. Surprisingly, we find that at high surface concentrations, the first singlet excited state of the dye is converted into a new state with an efficiency of about 80%. We assign the absorption features of this state to the oxidised dye and discuss the possibility of photo-induced charge separation between neighboring dye molecules. Our study is the first to show that this process can be highly efficient without the use of donor and acceptor molecules of different chemical structures.

  3. Charge transfer interactions of a Ru(II) dye complex and related ligand molecules adsorbed on Au(111)

    SciTech Connect

    Britton, Andrew J.; Weston, Matthew; O'Shea, James N.; Taylor, J. Ben; Rienzo, Anna; Mayor, Louise C.

    2011-10-28

    The interaction of the dye molecule, N3 (cis-bis(isothiocyanato)bis(2,2{sup '}-bipyridyl-4,4{sup '}-dicarboxylato) -ruthenium(II)), and related ligand molecules with a Au(111) surface has been studied using synchrotron radiation-based electron spectroscopy. Resonant photoemission spectroscopy (RPES) and autoionization of the adsorbed molecules have been used to probe the coupling between the molecules and the substrate. Evidence of charge transfer from the states near the Fermi level of the gold substrate into the lowest unoccupied molecular orbital (LUMO) of the molecules is found in the monolayer RPES spectra of both isonicotinic acid and bi-isonicotinic acid (a ligand of N3), but not for the N3 molecule itself. Calibrated x-ray absorption spectroscopy and valence band spectra of the monolayers reveals that the LUMO crosses the Fermi level of the surface in all cases, showing that charge transfer is energetically possible both from and to the molecule. A core-hole clock analysis of the resonant photoemission reveals a charge transfer time of around 4 fs from the LUMO of the N3 dye molecule to the surface. The lack of charge transfer in the opposite direction is understood in terms of the lack of spatial overlap between the {pi}*-orbitals in the aromatic rings of the bi-isonicotinic acid ligands of N3 and the gold surface.

  4. Enhanced photodegradation of organic dyes adsorbed on a clay.

    PubMed

    Tani, Seiji; Yamaki, Hiroshi; Sumiyoshi, Azumi; Suzuki, Yasutaka; Hasegawa, Shinya; Yamazaki, Suzuko; Kawamata, Jun

    2009-01-01

    The interaction of three photoactive organic dyes, Rhodamine B, Rhodamine 6G and a stilbazolium derivative 4'-dimethylamino-N-methyl-4-stilbazolium with synthetic sodium-saponite has been examined by UV-visible absorption spectroscopy. In all cases, bathochromic shifts and the reduction of peak absorbance for the dyes were observed in the absorption spectra at a low dye concentration (25% adsorption of the cation exchange capacity (CEC) of the clay), although the shape and the width of their absorption bands were similar to those in aqueous solution. This absorption behavior indicates that the organic dye molecules adsorbed onto the surface of the negatively charged clay particles and the adsorbed molecules were well dispersed. The photodegradation of the organic dyes in aqueous solution and in the clay suspension has been also examined by the irradiation of a laser beam at a wavelength of 532 nm. We have found that the hybridization of the organic dyes with the exfoliated clay particles largely enhanced a photodegradation. The clay particles acted as a catalyst even at a high concentration such as approximately 300% of CEC. PMID:19441365

  5. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  6. Size selective hydrophobic adsorbent for organic molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  7. Evaluation of adsorption potential of adsorbents: a case of uptake of cationic dyes.

    PubMed

    Maurya, Nityanand Singh; Mittal, Atul Kumar; Cornel, Peter

    2008-01-01

    Adsorption potential of a commercial activated carbon (FS300) has been evaluated for the uptake of cationic dyes namely methylene blue (MB) and rhodamine B (RB). Though, there are numerous studies in literature which report the sorption of MB (more than 40 studies) and RB (more than 10), however none of these use a common parameter to report the capacity of the sorbent. A protocol, based on the equilibrium dye concentration has been proposed to measure the sorption potential of a sorbent. The Langmuir model can very well describe the experimental equilibrium data for both dyes (coefficient of correlation > 0.999). MB (Qm = 312.5 mg g(-1)) is more adsorbable than the RB (Qm = 144.9 mg g(-1)). Molecular weight and chemical structure of dye molecules seem to affect the dye uptake. The effect of pH on dye uptake has also been evaluated by varyingpH from 3 to 11. Uptake of MB increases with pH, wherein RB removal decreases with pH. Dyes could not be desorbed either by distilled water (0.06 and 0.11% for MB and RB respectively), or by 0.1 NHCl (0.136 and 3.0% for MB and RB respectively) indicating, chemical adsorption type of adsorbent-adsorbate interactions. PMID:18831328

  8. Using Microcontact Printing as a Novel Method for Patterned Dyeing of Surface-adsorbed DNA

    NASA Astrophysics Data System (ADS)

    Shea, Emily; Budassi, Julia; Zhu, Ke; Sokolov, Jonathan

    2012-02-01

    We use microcontact printing (MCP)^1 to stain individual DNA molecules adsorbed and combed onto a polymer-coated silicon surface. Polydimethylsiloxane (PDMS) stamps with micron-sized features have been used to selectively stain lambda DNA molecules with SyBr Gold dye. DNA was deposited out of dilute solution onto polymethylmethacrylate (PMMA) layers, 70nm thick, spun-coated on Si wafers, producing linearly stretched and aligned molecules. The stamps were soaked in dye solutions for one minute, followed by wiping of excess solution with a swap. The stamp was pressed onto the surface, varying the pressure and time of application (typically 5-10 minutes) to control the staining. The DNA molecules were imaged with a fluorescence microscope equipped with a cooled CCD camera. Single molecules of DNA were successfully dyed and imaged with stamps having a grating pattern either parallel to or perpendicular to the DNA orientation. Supported by NSF-DMR MRSEC program.

  9. Imaging the wave functions of adsorbed molecules

    PubMed Central

    Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F. Stefan; Ramsey, Michael G.; Puschnig, Peter

    2014-01-01

    The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable. Regardless whether orbitals are observed in real space with scanning probe experiments, or in reciprocal space by photoemission, the phase information of the orbital is lost. Here, we show that the experimental momentum maps of angle-resolved photoemission from molecular orbitals can be transformed to real-space orbitals via an iterative procedure which also retrieves the lost phase information. This is demonstrated with images obtained of a number of orbitals of the molecules pentacene (C22H14) and perylene-3,4,9,10-tetracarboxylic dianhydride (C24H8O6), adsorbed on silver, which are in excellent agreement with ab initio calculations. The procedure requires no a priori knowledge of the orbitals and is shown to be simple and robust. PMID:24344291

  10. Modified durian seed as adsorbent for the removal of methyl red dye from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Ahmad, Mohd Azmier; Ahmad, Norhidayah; Bello, Olugbenga Solomon

    2015-12-01

    Mesoporous-activated carbon from durian seed (DSAC) was prepared; it was used as adsorbent for the removal of methyl red (MR) dye from aqueous solution. Textural and adsorptive characteristics of activated carbon prepared from raw durian seed (DS), char durian seed (char DS) and activated durian seed (DSAC) were studied using scanning electron microscopy, Fourier transform infra red spectroscopy, proximate analysis and adsorption of nitrogen techniques, respectively. Acidic condition favors the adsorption of MR dye molecule by electrostatic attraction. The maximum dye removal was 92.52 % at pH 6. Experimental data were analyzed by eight model equations: Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Radke-Prausnitz, Sips, Vieth-Sladek and Brouers-Sotolongo isotherms and it was found that the Freundlich isotherm model fitted the adsorption data most. Adsorption rate constants were determined using pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion and Avrami kinetic model equations. The results clearly showed that the adsorption of MR dye onto DSAC followed pseudo-second-order kinetic model. Both intraparticle and film diffusion were involved in the adsorption process. The mean energy of adsorption calculated from D-R isotherm confirmed the involvement of physical adsorption. Thermodynamic parameters were obtained and it was found that the adsorption of MR dye onto DSAC was an endothermic and spontaneous process at the temperatures under investigation.

  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. Morphology and structure of photosensitive dye J-aggregates adsorbed on AgBr microcrystals grown in gelatin.

    PubMed

    Saijo, H; Shiojiri, M

    1998-07-15

    Though the cyanine dye J-aggregates carry the role to sense the exposing light in the silver halide photographic system, little research on the morphology of the aggregates in adsorption has been made with modern surface analytical methods. In this paper, we describe the size, epitaxy, multi-layered array formation, nucleation and preferential adsorption, and irregular distribution of population between particles and the segregation on a particle, of J-aggregates adsorbed on AgBr grown in gelatin. We employed cathodoluminescence microscopy, low energy high resolution scanning electron microscopy, and atomic force microscopy. Dye molecules aggregate together near the surface of AgBr and adsorb on the surface. The growth of adsorbed aggregates is controlled by the diffusion of dye molecules from the surrounding solution. The population of J-aggregates adsorbed on an AgBr particle varies from almost none to full coverage. Each aggregate is about (20-30) x (30-50) nm in size and is 2.1 nm thick for thiacarbocyanine with sodium ion, 1.04 nm for thiacarbocyanine with tosyl ion, and 0.5 nm for an oxacarbocyanine. The aggregates connect their longer edges to each other to form arrays, and the arrays build up multi-layered stacks. The arrays align parallel and segregate to form terraces. The longer edges of J-aggregates align along [210] on AgBr (100) or [632] on AgBr (111). PMID:9728883

  13. Adsorbed molecules in external fields: Effect of confining potential.

    PubMed

    Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

    2016-12-01

    We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials. PMID:27387127

  14. Inhomogeneous distribution of organic molecules adsorbed in sol gel glasses

    NASA Astrophysics Data System (ADS)

    Meneses-Nava, M. A.; Chávez-Cerda, S.; Sánchez-Villicaña, V.; Sánchez-Mondragón, J. J.; King, T. A.

    1999-09-01

    The effects of the porous matrix upon the radiative characteristics of quinine sulphate doped sol-gel glasses are investigated. The broadenings of the absorption and fluorescence spectra are explained by the attachment of the molecules on distorted sites or in a non-planar fashion, creating an inhomogeneous distribution of adsorbed molecules. For this reason, each emitting center relaxes with its own characteristics. This inhomogeneous distribution is also supported by the non-exponential and the wavelength dependence of the fluorescence decay.

  15. Probing atomic positions of adsorbed ammonia molecules in zeolite.

    PubMed

    Ye, Lin; Lo, Benedict T W; Qu, Jin; Wilkinson, Ian; Hughes, Tim; Murray, Claire A; Tang, Chiu C; Tsang, Shik Chi Edman

    2016-02-25

    Atomic positions and interactions between adsorbed guest molecules, such as ammonia in H-ZSM-5 microporous solids, are for the first time revealed by making use of the change in the periodical scattering parameter using in situ synchrotron powder X-ray diffraction combined with refinement within experimental errors. PMID:26833032

  16. Hydrogen molecule on lithium adsorbed graphene: A DFT study

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Gupta, Shuchi; Gaganpreet, Dharamvir, Keya

    2016-05-01

    Electronic structure calculations for the adsorption of molecular hydrogen on lithium (Li) decorated and pristine graphene have been studied systematically using SIESTA code [1] within the framework of the first-principle DFT under the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA)[2], including spin polarization. The energy of adsorption of hydrogen molecule on graphene is always enhanced by the presence of co-adsorbed lithium. The most efficient adsorption configuration is when H2 is lying parallel to lithium adsorbed graphene which is in contrast to its adsorption on pristine graphene (PG) where it prefers perpendicular orientation.

  17. Natural Iraqi palygorskite clay as low cost adsorbent for the treatment of dye containing industrial wastewater.

    PubMed

    Nassir Taha, Dakhil; Sadi Samaka, Isra'a

    2012-01-01

    In this study, natural Iraqi low- cost locally available clay (palygorskite) was studied for its potential use as an adsorbent for removal Congo red from aqueous solutions. Batch type experiments were conducted to study the effect of contact time, initial pH of the dye solution, initial dye concentration, adsorbent dosage, and particle size of adsorbent on adsorption capacity of Congo red. The adsorption occurred very fast initially and attains equilibrium within 60 min. When the effect of pH of solution dye on the yield adsorption has been carried in a range of 2-10, the adsorption obtained was nearly the same with very slightly effect of pH and it was reported that above 49.07 mg/g of Cong red by palygorskite clay occurred in the pH range 2 to 10. It was observed that the removal of Congo red increase with increasing initial dye concentration and adsorbent dose, but, adsorption capacity decrease with increasing adsorbent dose. The adsorption capacity increase with decreasing particle size of adsorbent. The equilibrium adsorption data were interpreted using Langmuir and Freundlich isotherm models. The obtained results revealed that the equilibrium data closely followed both models, but the Langmuir isotherm fitted the data better. The maximum adsorption capacity was found to be 99 mg/g at ambient temperature. Results indicate that Iraqi palygorskite clay could be employed as a low cost alternative to commercial activated carbon in wastewater treatment for the removal of colour and dyes. PMID:23196874

  18. Cellulose based cationic adsorbent fabricated via radiation grafting process for treatment of dyes waste water.

    PubMed

    Goel, Narender Kumar; Kumar, Virendra; Misra, Nilanjal; Varshney, Lalit

    2015-11-01

    A cationized adsorbent was prepared from cellulosic cotton fabric waste via a single step-green-radiation grafting process using gamma radiation source, wherein poly[2-(methacryloyloxy) ethyl]trimethylammonium chloride (PMAETC) was covalently attached to cotton cellulose substrate. Radiation grafted (PMAETC-g-cellulose) adsorbent was investigated for removal of acid dyes from aqueous solutions using two model dyes: Acid Blue 25 (AB25) and Acid Blue 74 (AB74). The equilibrium adsorption data was analyzed by Langmuir and Freundlich isotherms, whereas kinetic data was analyzed by pseudo first order, pseudo second order, intra particle diffusion and Boyd's models. The PMAETC-g-cellulose adsorbent with 25% grafting yield exhibited equilibrium adsorption capacities of ∼ 540.0mg/g and ∼ 340.0mg/g for AB25 and AB74, respectively. Linear and nonlinear fitting of adsorption data suggested that the equilibrium adsorption process followed Langmuir adsorption isotherm model, whereas, the kinetic adsorption process followed pseudo-second order model. The multi-linearities observed in the intra-particle kinetic plots suggested that the intraparticle diffusion was not the only rate-controlling process in the adsorption of acid dyes on the adsorbent, which was further supported by Boyd's model. The adsorbent could be regenerated by eluting the adsorbed dye from the adsorbent and could be repeatedly used. PMID:26256369

  19. Candidate Source of Flux Noise in SQUIDs: Adsorbed Oxygen Molecules.

    PubMed

    Wang, Hui; Shi, Chuntai; Hu, Jun; Han, Sungho; Yu, Clare C; Wu, R Q

    2015-08-14

    A major obstacle to using superconducting quantum interference devices (SQUIDs) as qubits is flux noise. We propose that the heretofore mysterious spins producing flux noise could be O_{2} molecules adsorbed on the surface. Using density functional theory calculations, we find that an O_{2} molecule adsorbed on an α-alumina surface has a magnetic moment of ~1.8 μ_{B}. The spin is oriented perpendicular to the axis of the O-O bond, the barrier to spin rotations is about 10 mK. Monte Carlo simulations of ferromagnetically coupled, anisotropic XY spins on a square lattice find 1/f magnetization noise, consistent with flux noise in Al SQUIDs. PMID:26317742

  20. Preparation of Graphene Oxide-Based Hydrogels as Efficient Dye Adsorbents for Wastewater Treatment

    NASA Astrophysics Data System (ADS)

    Guo, Haiying; Jiao, Tifeng; Zhang, Qingrui; Guo, Wenfeng; Peng, Qiuming; Yan, Xuehai

    2015-06-01

    Graphene oxide (GO) sheets exhibit superior adsorption capacity for removing organic dye pollutants from an aqueous environment. In this paper, the facile preparation of GO/polyethylenimine (PEI) hydrogels as efficient dye adsorbents has been reported. The GO/PEI hydrogels were achieved through both hydrogen bonding and electrostatic interactions between amine-rich PEI and GO sheets. For both methylene blue (MB) and rhodamine B (RhB), the as-prepared hydrogels exhibit removal rates within about 4 h in accordance with the pseudo-second-order model. The dye adsorption capacity of the hydrogel is mainly attributed to the GO sheets, whereas the PEI was incorporated to facilitate the gelation process of GO sheets. More importantly, the dye-adsorbed hydrogels can be conveniently separated from an aqueous environment, suggesting potential large-scale applications of the GO-based hydrogels for organic dye removal and wastewater treatment.

  1. Preparation of Graphene Oxide-Based Hydrogels as Efficient Dye Adsorbents for Wastewater Treatment.

    PubMed

    Guo, Haiying; Jiao, Tifeng; Zhang, Qingrui; Guo, Wenfeng; Peng, Qiuming; Yan, Xuehai

    2015-12-01

    Graphene oxide (GO) sheets exhibit superior adsorption capacity for removing organic dye pollutants from an aqueous environment. In this paper, the facile preparation of GO/polyethylenimine (PEI) hydrogels as efficient dye adsorbents has been reported. The GO/PEI hydrogels were achieved through both hydrogen bonding and electrostatic interactions between amine-rich PEI and GO sheets. For both methylene blue (MB) and rhodamine B (RhB), the as-prepared hydrogels exhibit removal rates within about 4 h in accordance with the pseudo-second-order model. The dye adsorption capacity of the hydrogel is mainly attributed to the GO sheets, whereas the PEI was incorporated to facilitate the gelation process of GO sheets. More importantly, the dye-adsorbed hydrogels can be conveniently separated from an aqueous environment, suggesting potential large-scale applications of the GO-based hydrogels for organic dye removal and wastewater treatment. PMID:26123269

  2. Theory of raman scattering from molecules adsorbed at semiconductor surfaces

    NASA Astrophysics Data System (ADS)

    Ueba, H.

    1983-09-01

    A theory is presented to calculate the Raman polarizability of an adsorbed molecule at a semiconductor surface, where the electronic excitation in the molecular site interacts with excitons (elementary excitations in the semiconductor) through non-radiative energy transfer between them, in an intermediate state in the Raman scattering process. The Raman polarizability thus calculated is found to exhibit a peak at the energy corresponding to a resonant excitation of excitons, thereby suggesting the possibility of surface enhanced Raman scattering on semiconductor surfaces. The mechanism studied here can also give an explanation of a recent observation of the Raman excitation profiles of p-NDMA and p-DMAAB adsorbed on ZnO or TiO 2, where those profiles were best described by assuming a resonant intermediate state of the exciton transition in the semiconductors. It is also demonstrated that in addition to vibrational Raman scattering, excitonic Raman scattering of adsorbed molecules will occur in the coupled molecule-semiconductor system, where the molecular returns to its ground electronic state by leaving an exciton in the semiconductor. A spectrum of the excitonic Raman scattering is expected to appear in the background of the vibrational Raman band and to be characterized by the electronic structure of excitons. A desirable experiment is suggested for an examination of the theory.

  3. A simple model for electronic properties of surface adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Dhakal, Rajesh; Schwalm, William

    We adapt a minimal approximation to one electron quantum theory of molecules referred as Fast Accurate Kinetic Energy method. This in principle handles large complex molecular structures with less computational effort to compute electronic properties of adsorbed molecules. Kinetic energy integrals are calculated accurately but multi-electron potential energy integrals are approximated. The neighboring atom interactions are included also. For layers of isopthalic acids formed on pyrolytic graphite the configuration changes as a function of length of hydrocarbon tails. We study properties of this system as a function of tail length.

  4. Electronic structure and binding geometry of tetraphenylporphyrin-derived molecules adsorbed on metal and metal oxide surfaces

    NASA Astrophysics Data System (ADS)

    Coh, Senia

    Tetraphenylporphyrin (TPP)-derived molecules have been studied extensively as efficient photosensitizers when chemisorbed on the metal oxide substrates in dye-sensitized solar cells. Still, many fundamental electronic properties of the dye/oxide interface are not understood and need careful consideration. In this thesis we present a comprehensive study of the electronic structure, energy level alignment and the adsorption geometry of the TPP-derived dye molecules adsorbed on TiO2(110), ZnO(1120) and Ag(100) single crystal surfaces using ultra-high vacuum (UHV) based surface sensitive techniques. The alignment of the molecular energy levels with respect to the TiO 2 and ZnO band edges for all TPP-derived molecules we studied was found to be insensitive to either the nature of the functional groups located on the phenyl rings, presence of zinc as a central metal ion and different binding geometry of the molecules. Binding geometry, molecule-molecule interaction and the aggregation effects in the adsorbed layer, that were observed in the UV-visible spectra of the molecules adsorbed on ZnO substrate were not observed in the ultraviolet photoemission (UPS) and inverse photoemission (IPS) spectra of the occupied and unoccupied molecular states. Using near edge X-ray absorption fine structure (NEXAFS) and scanning tunneling microscopy (STM), binding geometry of the two representative TPP-derivatives was directly determined to be upright, with the porphyrin ring under large angle with respect to the surface for the p-ZnTCPP molecules and with the porphyrin ring parallel to the surface for the m-ZnTCPP molecules. We observe that the energies and the energy level alignment of the ZnTPP molecular levels measured in UPS and IPS depend on the substrate on which the molecules are adsorbed (Ag(100) or TiO2(110) single crystal surfaces). The differences are attributed to different charge screening properties of these two materials. Image charges created in the substrates during

  5. Removal of dyes using agricultural waste as low-cost adsorbents: a review

    NASA Astrophysics Data System (ADS)

    Bharathi, K. S.; Ramesh, S. T.

    2013-12-01

    Color removal from wastewater has been a matter of concern, both in the aesthetic sense and health point of view. Color removal from textile effluents on a continuous industrial scale has been given much attention in the last few years, not only because of its potential toxicity, but also mainly due to its visibility problem. There have been various promising techniques for the removal of dyes from wastewater. However, the effectiveness of adsorption for dye removal from wastewater has made it an ideal alternative to other expensive treatment methods. In this review, an extensive list of sorbent literature has been compiled. The review evaluates different agricultural waste materials as low-cost adsorbents for the removal of dyes from wastewater. The review also outlines some of the fundamental principles of dye adsorption on to adsorbents.

  6. SPR-MS: from identifying adsorbed molecules to image tissues

    NASA Astrophysics Data System (ADS)

    Masson, Jean-François; Breault-Turcot, Julien; Forest, Simon; Chaurand, Pierre

    2015-03-01

    Surface plasmon resonance (SPR) sensors have become valuable analytical sensors for biomolecule detection. While SPR is heralded with high sensitivity, label-free and real-time detection, nonspecific adsorption and detection of ultralow concentrations remain issues. Nonspecific adsorption can be minimized using adequate surface chemistry. For example, we have employed peptide monolayers to reduce nonspecific adsorption of crude serum or cell lysate. It is important to uncover the nature of molecules nonspecifically adsorbing to surfaces in these biofluids, to further improve understanding of the nonspecific adsorption processes. Mass spectrometry (MS) provides a complementary tool to SPR to identify biomolecule adsorbed to surface. Trypsic digestion of the proteins adsorbed to surfaces led to identification of characteristic peptides from the proteins involved in nonspecific adsorption. Nonspecific adsorption in crude cell lysate results mainly from lipids, as confirmed with SPR and MS but proteins were observed on some surfaces. In another application of SPR and MS, imaging SPR can be used in combination to imaging MS to image tissue sections. Thin sections of mouse liver were inserted in the fluidic chamber of a SPRi instrument and proteins were transferred to the SPRi chip. The SPR chip was then imaged using MALDI imaging MS to identify the biomolecules that were transferred to the SPRi chip.

  7. EDTA-Cross-Linked β-Cyclodextrin: An Environmentally Friendly Bifunctional Adsorbent for Simultaneous Adsorption of Metals and Cationic Dyes.

    PubMed

    Zhao, Feiping; Repo, Eveliina; Yin, Dulin; Meng, Yong; Jafari, Shila; Sillanpää, Mika

    2015-09-01

    The discharge of metals and dyes poses a serious threat to public health and the environment. What is worse, these two hazardous pollutants are often found to coexist in industrial wastewaters, making the treatment more challenging. Herein, we report an EDTA-cross-linked β-cyclodextrin (EDTA-β-CD) bifunctional adsorbent, which was fabricated by an easy and green approach through the polycondensation reaction of β-cyclodextrin with EDTA as a cross-linker, for simultaneous adsorption of metals and dyes. In this setting, cyclodextrin cavities are expected to capture dye molecules through the formation of inclusion complexes and EDTA units as the adsorption sites for metals. The adsorbent was characterized by FT-IR, elemental analysis, SEM, EDX, ζ-potential, and TGA. In a monocomponent system, the adsorption behaviors showed a monolayer adsorption capacity of 1.241 and 1.106 mmol g(-1) for Cu(II) and Cd(II), respectively, and a heterogeneous adsorption capacity of 0.262, 0.169, and 0.280 mmol g(-1) for Methylene Blue, Safranin O, and Crystal Violet, respectively. Interestingly, the Cu(II)-dye binary experiments showed adsorption enhancement of Cu(II), but no significant effect on dyes. The simultaneous adsorption mechanism was further confirmed by FT-IR, thermodynamic study, and elemental mapping. Overall, its facile and green fabrication, efficient sorption performance, and excellent reusability indicate that EDTA-β-CD has potential for practical applications in integrative and efficient treatment of coexistenting toxic pollutants. PMID:26237660

  8. PVDF membranes containing hybrid nanoparticles for adsorbing cationic dyes: physical insights and mechanism

    NASA Astrophysics Data System (ADS)

    Sharma, Maya; Madras, Giridhar; Bose, Suryasarathi

    2016-07-01

    In this study, Fe (iron) and Ag (silver) based adsorbents were synthesized using solution combustion and in situ reduction techniques. The synthesized adsorbents were comprehensively characterized by different techniques including electron microscopy, BET, XRD, Zeta potential etc. Three chlorinated cationic dyes used were malachite green, methyl violet and pyronin Y. These dyes were adsorbed on various synthesized adsorbents [iron III oxide (Fe2O3)], iron III oxide decorated silver nanoparticles by combustion synthesis technique [Fe2O3–Ag(C)] and iron III oxide decorated silver nanoparticles using in situ reduction, [Fe2O3–Ag (S)]. The isotherm and the adsorption kinetics have been studied systematically. The kinetic data can be explained by the pseudo second order model and the adsorption equilibrium followed Langmuir isotherm. The equilibrium and kinetics results suggest that Fe2O3–Ag(S) nanoparticles showed the maximum adsorption among all the adsorbents. Hence, Polyvinylidene fluoride based membranes containing Fe2O3–Ag(S) nanoparticles were prepared via phase inversion (precipitation immersion using DMF/water) technique. The adsorption kinetics were studied in detail and it was observed that the composite membrane showed synergistic improvement in dye adsorption. Such membranes can be used for water purification.

  9. Tunable surface charge of ZnS : Cu nano-adsorbent induced the selective preconcentration of cationic dyes from wastewater

    NASA Astrophysics Data System (ADS)

    Wang, Yongjing; Chen, Dagui; Wang, Yandi; Huang, Feng; Hu, Qichang; Lin, Zhang

    2012-05-01

    A novel environmentally friendly nano-adsorbent is developed by doping Cu+ cations into the lattice of ZnS microspheres. The adsorbent shows selective adsorbability for cationic dyes in low concentrations in wastewater. The adsorbed dye could be successfully eluted with alcohol, resulting in a 1000 fold enrichment of the dye solution.A novel environmentally friendly nano-adsorbent is developed by doping Cu+ cations into the lattice of ZnS microspheres. The adsorbent shows selective adsorbability for cationic dyes in low concentrations in wastewater. The adsorbed dye could be successfully eluted with alcohol, resulting in a 1000 fold enrichment of the dye solution. Electronic supplementary information (ESI) available: Synthesis, structural details of ZnS : Cu, adsorption isotherm of RhB on ZnS : Cu, control experiments for the adsorption measurements, pH effect on the adsorbability, and preliminary assessment of the adsorption efficiency for real industrial wastewater. See DOI: 10.1039/c2nr30689a

  10. Impact of local compressive stress on the optical transitions of single organic dye molecules

    NASA Astrophysics Data System (ADS)

    Stöttinger, Sven; Hinze, Gerald; Diezemann, Gregor; Oesterling, Ingo; Müllen, Klaus; Basché, Thomas

    2014-03-01

    The ability to mechanically control the optical properties of individual molecules is a grand challenge in nanoscience and could enable the manipulation of chemical reactivity at the single-molecule level. In the past, light has been used to alter the emission wavelength of individual molecules or modulate the energy transfer quantum yield between them. Furthermore, tensile stress has been applied to study the force dependence of protein folding/unfolding and of the chemistry and photochemistry of single molecules, although in these mechanical experiments the strength of the weakest bond limits the amount of applicable force. Here, we show that compressive stress modifies the photophysical properties of individual dye molecules. We use an atomic force microscope tip to prod individual molecules adsorbed on a surface and follow the effect of the applied force on the electronic states of the molecule by fluorescence spectroscopy. Applying a localized compressive force on an isolated molecule induces a stress that is redistributed throughout the structure. Accordingly, we observe reversible spectral shifts and even shifts that persist after retracting the microscope tip, which we attribute to transitions to metastable states. Using quantum-mechanical calculations, we show that these photophysical changes can be associated with transitions among the different possible conformers of the adsorbed molecule.

  11. Controlling spins in adsorbed molecules by a chemical switch

    PubMed Central

    Wäckerlin, Christian; Chylarecka, Dorota; Kleibert, Armin; Müller, Kathrin; Iacovita, Cristian; Nolting, Frithjof; Jung, Thomas A.; Ballav, Nirmalya

    2010-01-01

    The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning as an axial ligand of cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to nickel thin-film (Ni(001)). On NO addition, the coordination sphere of Co2+ is modified and a NO–CoTPP nitrosyl complex is formed, which corresponds to an off state of the Co spin. Thermal dissociation of NO from the nitrosyl complex restores the on state of the Co spin. The NO-induced reversible off–on switching of surface-adsorbed molecular spins observed here is attributed to a spin trans effect. PMID:20975713

  12. Plant-mediated synthesis of silver-nanocomposite as novel effective azo dye adsorbent

    NASA Astrophysics Data System (ADS)

    Satapathy, Mantosh Kumar; Banerjee, Priya; Das, Papita

    2015-01-01

    Toxicity of textile effluent is a globally alarming issue nowadays. In order to address this problem, a cost-effective and environment-friendly technique for adsorption of toxic dyes has been introduced in this research. Firstly in this study, green synthesis of silver nanoparticles (AgNPs) having antibacterial efficacy, had been carried out using leaf extracts of Azadirachta indica as reducing as well as capping agent. This research idea was further extended for the development and application of a novel method of preparation of silver-nanocomposite using synthesized microwave-assisted AgNPs with soil as a novel nanocomposite to adsorb hazardous dyes. However, this nanocomposite was found to possess higher efficiency and adsorption capacity in comparison to soil as adsorbent for the removal of crystal violet dye under same experimental conditions. Additionally, it was also observed that use of this Ag-nanocomposite as adsorbent helped in achieving about 97.2 % removal of crystal violet dye from the effluent solution.

  13. NiO(111) nanosheets as efficient and recyclable adsorbents for dye pollutant removal from wastewater

    NASA Astrophysics Data System (ADS)

    Song, Zhi; Chen, Lifang; Hu, Juncheng; Richards, Ryan

    2009-07-01

    Semiconductor single-crystalline polar NiO(111) nanosheets with well-defined hexagonal holes have been investigated for application in dye adsorption and combustion processes. With regard to adsorption technologies, high surface area metal oxides have an advantage over activated carbon in that the adsorbed species can be combusted and the adsorbent reused in the case of metal oxides while regeneration of activated carbon remains challenging and thus the adsorbent/adsorbate system must be disposed of. Here, three typical textile dyes, reactive brilliant red X-3B, congo red and fuchsin red, were studied for removal from wastewater with two NiO systems and activated carbon. These studies revealed that the NiO(111) nanosheets exhibited much more favorable adsorptive properties than conventionally prepared nickel oxide powder (CP-NiO) obtained from thermal decomposition of nickel nitrate. The maximum adsorption capabilities of the three dyes on NiO(111) nanosheets reached 30.4 mg g-1, 35.15 mg g-1 and 22 mg g-1 for reactive brilliant red X-3B, congo red and fuchsin acid, respectively, while the maximum adsorption capabilities of the three dyes on CP-NiO were only 8.4, 13.2 and 12 mg g-1 for reactive brilliant red X-3B, congo red and fuchsin acid. To simulate the adsorption isotherm, two commonly employed models, the Langmuir and the Freundlich isotherms, were selected to explicate the interaction of the dye and NiO(111). The isotherm evaluations revealed that the Langmuir model demonstrated better fit to experimental equilibrium data than the Freundlich model. The maximum predicted adsorption capacity was 36.1 mg g-1. In addition, adsorption kinetic data of NiO(111) followed a pseudo-second-order rate for congo red. These studies infer that NiO(111) nanosheets possess desirable properties for application in adsorption and combustion applications.

  14. Carboxymethyl cellulose-g-poly(2-(dimethylamino) ethyl methacrylate) hydrogel as adsorbent for dye removal.

    PubMed

    Salama, Ahmed; Shukry, Nadia; El-Sakhawy, Mohamed

    2015-02-01

    A novel adsorbent was prepared via crosslinking graft copolymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA) onto carboxymethyl cellulose (CMC) backbone. Ethylene glycol dimethacrylate and potassium persulphate were used as crosslinker and initiator, respectively. CMC-g-PDMAEMA hydrogel was used to remove methyl orange (MO) from aqueous solutions. The adsorption kinetics and isotherms were found to follow Pseudo-second-order kinetic model and Langmuir model, respectively. The high maximum adsorption capacity (1825 mg/g) implied that CMC-g-PDMAEMA can be used as promising adsorbent for the synthetic dyes removal from wastewater. PMID:25450049

  15. Surface-enhanced resonance hyper-Raman scattering and surface-enhanced resonance Raman scattering of dyes adsorbed on silver electrode and silver colloid: a comparison study

    NASA Astrophysics Data System (ADS)

    Li, Wu-Hu; Li, Xiao-Yuan; Yu, Nai-Teng

    1999-10-01

    Surface-enhanced resonance hyper-Raman scattering (SERHRS) and surface-enhanced resonance Raman scattering (SERRS) of three dyes, rhodamine 6G, crystal violet and basic fuchsin, are studied comparatively on electrochemically roughened silver electrode and silver colloid, respectively. All three dyes show a better SERHRS efficiency on the silver colloid than on the silver electrode, a phenomenon just opposite to what we have recently observed for pyridine and pyrazine [Chem. Phys. Lett. 305 (1999) 303]. These results suggest that the efficiency of SEHRS depends not only on the active surfaces employed (colloidal metals versus roughened electrodes) but also on the types of the adsorbed molecules.

  16. CuO embedded chitosan spheres as antibacterial adsorbent for dyes.

    PubMed

    Khan, Sher Bahadar; Ali, Fayaz; Kamal, Tahseen; Anwar, Yasir; Asiri, Abdullah M; Seo, Jongchul

    2016-07-01

    Chitosan/copper oxide (CS/CuO) composite spheres were prepared by simple mixing of CuO nanomaterials in CS solution followed by dropwise addition to NH4OH solution. The characterizations of all the prepared spheres were carried out by FESEM, EDS, XRD, XPS, and FTIR analyses while the thermal properties were analyzed by TGA. Further the ability of composite spheres was tested as an easily removable pollutant adsorbent from water containing different dyes and compared with pure CS. Composite spheres were found to be the best adsorbent when applied to remove indigo carmine (IC), congo red (CR) and methyl orange (MO) from water. Amongst the three dyes, CS/CuO composite spheres were more selective toward MO adsorption. CS/CuO composite spheres also displayed significant antibacterial activity by inhibiting Pseudomonas aeruginosa growth. Thus the fabricated composite spheres can be used as a biosorbent in the future. PMID:26993528

  17. Active manganese oxide: a novel adsorbent for treatment of wastewater containing azo dye.

    PubMed

    Chakrabarti, S; Dutta, B K; Apak, R

    2009-01-01

    A new variety of active manganese oxide was prepared, characterized, and tested for its potential of adsorbing Congo Red, a dis-azo dye, from aqueous solutions. Both equilibrium and kinetics were investigated over different values of process parameters such as temperature (25-45 degrees C), adsorbent loading (0.4-0.6%), initial dye concentration (50-500 mg/L), presence of salts (sodium sulphate, 500 mg/L) and the oxygen content (MnO(x), x=1.2, 1.33 and 2) of the adsorbent. The equilibrium adsorption data were fitted to Langmuir and Freundlich isotherms. Langmuir adsorption capacity of the sorbent (x=1.33) for Congo Red was 38.6 mg/g at room temperature which is substantially higher than those for commercial manganese dioxide, red mud, coir pith, activated carbon, and fly ash. The kinetic data were best interpreted using a pseudo-second order model. The results show that the active manganese oxide used in this work removes the dye by reversible adsorption and has the potential for practical use for remediation of textile industry effluents. PMID:19955624

  18. Dynamics of photoinduced electron transfer from adsorbed molecules into solids

    NASA Astrophysics Data System (ADS)

    Gundlach, L.; Ernstorfer, R.; Willig, F.

    2007-08-01

    Ultrafast interfacial electron transfer from the donor orbital of organic chromophores into empty electronic acceptor states of a semiconductor and of a metal was investigated by two-photon photoemission spectroscopy (2PPE). Experimental tools and procedures have been developed for carrying out wet-chemistry preparation of the molecule/solid interface. The organic chromophore perylene was investigated with several different bridge/anchor groups on TiO2(110). One perylene compound was investigated for comparison on Ag(110). Angle and polarization dependent 2PPE measurements revealed the orientation of the perylene chromophore on the surface as controlled by the adsorption geometry of the respective anchor group on TiO2. UPS measurements gave the position of the HOMO level of the chromophore with respect to the Fermi level of the solid. The donor level of each molecule was found high enough to fulfill the “wide band limit” of heterogeneous electron transfer dynamics. Time constants for heterogeneous electron transfer were extracted from 2PPE transients. A difference by a factor of four was found, 13 fs against 47 fs, when a conjugated bond was exchanged for a saturated bond in the otherwise identical bridge group. The two different contributions to the 2PPE transients arising firstly from the excited state of the chromophore and secondly from the injected electrons were separated by measuring the latter contribution separately in the case of instantaneous interfacial electron transfer realized with catechol as adsorbate. The time scales measured for the electron transfer step and for the subsequent electron escape process from the surface into the bulk of TiO2 showed both good agreement with recent theoretical predictions of other groups for these systems.

  19. Effective removal of Congo red dye from aqueous solution using modified xanthan gum/silica hybrid nanocomposite as adsorbent.

    PubMed

    Ghorai, Soumitra; Sarkar, Amit Kumar; Panda, A B; Pal, Sagar

    2013-09-01

    The aim of this work is to study the feasibility of XG-g-PAM/SiO2 nanocomposite towards its potential application as high performance adsorbent for removal of Congo red (CR) dye from aqueous solution. The surface area, average pore size and total pore volume of the developed nanocomposite has been determined. The efficiency of CR dye adsorption depends on various factors like pH, temperature of the solution, equilibrium time of adsorption, agitation speed, initial concentration of dye and adsorbent dosage. It has been observed that the nanocomposite is having excellent CR dye adsorption capacity (Q0=209.205 mg g(-1)), which is considerably high. The dye adsorption process is controlled by pseudo-second order and intraparticle diffusion kinetic models. The adsorption equilibrium data correlates well with Langmuir isotherm. Desorption study indicates the efficient regeneration ability of the dye loaded nanocomposite. PMID:23896441

  20. Pulsed electric linear dichroism of triphenylmethane dyes adsorbed on montmorillonite K10 in aqueous media

    SciTech Connect

    Yamaoka, Kiwamu; Sasai, Ryo

    2000-05-01

    Electric linear dichroism (ELD) spectra of two cationic triphenylmethane dyes, crystal violet (CV) and malachite green (MG), bound to sodium montmorillonite K10 (MK-10) were studied at 20 C in aqueous media at two mixing ratios, D/S, of 0.10 and 0.24 in the 700- to 400 nm wavelength region and in the applied electric field strength range between 0 and 3 kV/cm. The specific parallel and perpendicular dichroism ({Delta}A{sub {parallel}}/A and {Delta}A{sub {perpendicular}}/A) spectra of dye-adsorbed MK-10 suspension were measured at a fixed field strength with an apparatus equipped with a 512-channel photodiode array detector. By changing the field strength over a wide range, a series of the reduced dichroism values of the bound dyes were measured at a fixed wavelength. By fitting these dichroism values to theoretical orientation functions, the intrinsic reduced dichroism ({Delta}A/A){sub int} spectra at the limiting high fields (ELD spectrum) were determined for CV and MG bound to MK-10. No appreciable difference was observed at the two D/S values. The ELD spectra of these bound dyes are undulatory but never constant, throughout their absorption region; thus, the dye plane does not lie flatly either on the surface or between layers of MK-10 particle.

  1. Deterministically Polarized Fluorescence from Single Dye Molecules Aligned in Liquid Crystal Host

    SciTech Connect

    Lukishova, S.G.; Schmid, A.W.; Knox, R.; Freivald, P.; Boyd, R. W.; Stroud, Jr., C. R.; Marshall, K.L.

    2005-09-30

    We demonstrated for the first time to our konwledge deterministically polarized fluorescence from single dye molecules. Planar aligned nematic liquid crystal hosts provide deterministic alignment of single dye molecules in a preferred direction.

  2. The application of textile sludge adsorbents for the removal of Reactive Red 2 dye.

    PubMed

    Sonai, Gabriela G; de Souza, Selene M A Guelli U; de Oliveira, Débora; de Souza, Antônio Augusto U

    2016-03-01

    Sludge from the textile industry was used as a low-cost adsorbent to remove the dye Reactive Red 2 from an aqueous solution. Adsorbents were prepared through the thermal and chemical treatment of sludge originating from physical-chemical (PC) and biological (BIO) effluent treatment processes. The adsorbent characterization was carried out through physical-chemical analysis, X-ray fluorescence (XRF) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, pHPZC determination, Boehm titration method, Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy (SEM). Batch kinetic experiments and adsorption isotherm modeling were conducted under different pH and temperature conditions. The results for the kinetic studies indicate that the adsorption processes associated with these systems can be described by a pseudo-second-order model and for the equilibrium data the Langmuir model provided the best fit. The adsorption was strongly dependent on the pH but not on the temperature within the ranges studied. The maxima adsorption capacities were 159.3 mg g(-1) for the BIO adsorbent and 213.9 mg g(-1) for PC adsorbent at pH of 2 and 25 °C. PMID:26706227

  3. Electroluminescence from completely horizontally oriented dye molecules

    NASA Astrophysics Data System (ADS)

    Komino, Takeshi; Sagara, Yuta; Tanaka, Hiroyuki; Oki, Yuji; Nakamura, Nozomi; Fujimoto, Hiroshi; Adachi, Chihaya

    2016-06-01

    A complete horizontal molecular orientation of a linear-shaped thermally activated delayed fluorescent guest emitter 2,6-bis(4-(10Hphenoxazin-10-yl)phenyl)benzo[1,2-d:5,4-d'] bis(oxazole) (cis-BOX2) was obtained in a glassy host matrix by vapor deposition. The orientational order of cis-BOX2 depended on the combination of deposition temperature and the type of host matrix. Complete horizontal orientation was obtained when a thin film with cis-BOX2 doped in a 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) host matrix was fabricated at 200 K. The ultimate orientation of guest molecules originates from not only the kinetic relaxation but also the kinetic stability of the deposited guest molecules on the film surface during film growth. Utilizing the ultimate orientation, a highly efficient organic light-emitting diode with the external quantum efficiency of 33.4 ± 2.0% was realized. The thermal stability of the horizontal orientation of cis-BOX2 was governed by the glass transition temperature (Tg) of the CBP host matrix; the horizontal orientation was stable unless the film was annealed above Tg.

  4. Polarizabilities of Adsorbed and Assembled Molecules: Measuring the Conductance through Buried Contacts

    PubMed Central

    2010-01-01

    We have measured the polarizabilities of four families of molecules adsorbed to Au{111} surfaces, with structures ranging from fully saturated to fully conjugated, including single-molecule switches. Measured polarizabilities increase with increasing length and conjugation in the adsorbed molecules and are consistent with theoretical calculations. For single-molecule switches, the polarizability reflects the difference in substrate−molecule electronic coupling in the ON and OFF conductance states. Calculations suggest that the switch between the two conductance states is correlated with an oxidation state change in a nitro functional group in the switch molecules. PMID:21077677

  5. Utilization of ground eggshell waste as an adsorbent for the removal of dyes from aqueous solution.

    PubMed

    Tsai, Wen-Tien; Hsien, Kuo-Jong; Hsu, Hsin-Chieh; Lin, Chien-Ming; Lin, Keng-Yu; Chiu, Chun-Hsiang

    2008-04-01

    The adsorption of cationic basic blue 9 and anionic acid orange 51 from aqueous solution onto the calcified eggshell (ES) and its ground eggshell powder (ESP) was carried out by varying the process parameters such as agitation speed, initial dye concentration, adsorbent mass and temperature. The adsorption potential for basic blue 9 onto ESP is far lower than that for acid orange 51, mainly due to the ionic interaction between the acid dye with the sulfonate groups and the positively charged sites on the surface of ESP. The adsorption capacity of acid orange 51 onto ES is significantly smaller than that onto ESP, which is in line with their pore properties (i.e., 1 vs. 21 m(2)/g). The experimental results showed that the adsorption process can be well described with a simple model, the pseudo-second-order model. According to the equilibrium adsorption capacity from the fitting of pseudo-second order reaction model, it was further found that the Freundlich model yields a somewhat better fit than the Langmuir model in the adsorption of acid orange 51 onto ESP. In addition, an increase in adsorption temperature from 15 to 45 degrees C significantly enhances the adsorption capacity of acid orange 51 onto ESP, revealing that the adsorption should be an endothermic or chemisorption process. From the results, it is feasible to utilize the ground eggshell waste as an effective adsorbent for removal of anionic dye from aqueous solution. PMID:17543519

  6. Low-cost adsorbents from bio-waste for the removal of dyes from aqueous solution.

    PubMed

    Manoj Kumar Reddy, P; Mahammadunnisa, Sk; Ramaraju, B; Sreedhar, B; Subrahmanyam, Ch

    2013-06-01

    Activated carbons (ACs) were developed from bio-waste materials like rice husk and peanut shell (PS) by various physicochemical activation methods. PS char digested in nitric acid followed by treatment at 673 K resulted in high surface area up to ∼585 m(2)/g. The novelty of the present study is the identification of oxygen functional groups formed on the surface of activated carbons by infrared and X-ray photoelectron spectroscopy and quantification by using temperature programmed decomposition (TPD). Typical TPD data indicated that each activation method may lead to varying amounts of acidic and basic functional groups on the surface of the adsorbent, which may be a crucial factor in determining the adsorption capacity. It was shown that ACs developed during the present study are good adsorbents, especially for the removal of a model textile dye methylene blue (MB) from aqueous solution. As MB is a basic dye, H(2)O(2)-treated rice husk showed the best adsorption capacity, which is in agreement with the acidic groups present on the surface. Removal of the dye followed Langmuir isotherm model, whereas MB adsorption on ACs followed pseudo-second-order kinetics. PMID:23233187

  7. Chitosan/Graphene Oxide Composite as an Effective Adsorbent for Reactive Red Dye Removal.

    PubMed

    Guo, Xiaoqing; Qu, Lijun; Tian, Mingwei; Zhu, Shifeng; Zhang, Xiansheng; Tang, Xiaoning; Sun, Kaikai

    2016-07-01

    Chitosan, modified with different dosages of graphene oxide (GO) and reduced graphene oxide (rGO), was first prepared, and its adsorption capacity for reactive red (RR) dye in aqueous solutions was investigated, in this paper. The structure and morphology of the adsorbents were characterized by FT-IR, XRD, SEM, EDX, BET, and TGA. The effect of varying parameters (pH, temperature, adsorbent loading, and contact time) was also investigated. The maximum adsorption capacity based on the Langmuir model was found to be 32.16 mg/g. In addition, experimental kinetic data were analyzed by the psuedo-first order and psuedo-second order equation models. The psuedo-second order model proved to be the best model for the adsorption system, which suggested that adsorption might be controlled by the chemical rate-limiting step through sharing of electrons or by covalent forces. PMID:27329054

  8. Geopolymeric adsorbents from fly ash for dye removal from aqueous solution

    SciTech Connect

    Li, L.; Wang, S.B.; Zhu, Z.H.

    2006-08-01

    Adsorbents from coal fly ash treated by a solid-state fusion method using NaOH were prepared. It was found that amorphous aluminosilicate, geopolymers would be formed. These fly ash-derived inorganic polymers were assessed as potential adsorbents for removal of some basic dyes, methylene blue and crystal violet, from aqueous solution. It was found that the adsorption capacity of the synthesised adsorbents depends on the preparation conditions such as NaOH:fly-ash ratio and fusion temperature with the optimal conditions being at 1.2:1 weight ratio of Na:fly-ash at 250-350{sup o}C. The synthesised materials exhibit much higher adsorption capacity than fly ash itself and natural zeolite. The adsorption isotherm can be fitted by Langmuir and Freundlich models while the two-site Langmuir model produced the best results. It was also found that the fly ash derived geopolymeric adsorbents show higher adsorption capacity for crystal violet than methylene blue and the adsorption temperature influences the adsorption capacity. Kinetic studies show that the adsorption process follows the pseudo second-order kinetics.

  9. The optical properties of molecules and chromogenic aggregates of xanthene dyes

    NASA Astrophysics Data System (ADS)

    Mikheev, Yu. A.; Guseva, L. N.; Ershov, Yu. A.

    2009-05-01

    The UV absorption spectra of rhodamine B and G molecules isolated from industrial dye samples were obtained. Two procedures were used. In one of them, rhodamine B molecules were displaced with water into a heptane layer from a solution of the dye in an alcohol-heptane mixture. The second procedure involved heating of the dye introduced into cellulose triacetate films. Individual rhodamine molecules (namely, dye cation-chlorine anion ion pairs) prepared by both methods did not absorb visible light. The spectra of individual rhodamine molecules coincided with the spectra of so-called pseudoleucobases of xanthene dyes reported in the literature. The conclusion was drawn that the chromaticity property in the series of xanthene dyes appeared because of the formation of supramolecular dimeric and larger aggregates, as was earlier established for triphenylmethane dyes (TPMDs) and copper phthalocyanine (CuPc). At the same time, individual xanthene dye molecules, like TPMD and CuPc molecules, are not chromogens.

  10. Quasielastic neutron scattering from adsorbed water molecules on pyrogenic silica surfaces

    NASA Astrophysics Data System (ADS)

    Tumanov, A. A.; Zarko, V. I.

    1994-04-01

    Quasielastic neutron scattering (QNS) from hydrated samples of high dispersion (Aerosil) and of porous dioxide silicon was investigated. The broadening of the QNS peak analysis permits one to obtain the effective diffusion coefficient D of adsorbed water molecules. It was obtained that the D-value increases with silica hydration. The mean square displacement of the water molecules from equilibrium < x2> equals approximately 0.1 Å 2 and does not depend on the quantity of adsorbed water.

  11. A small-molecule dye for NIR-II imaging

    NASA Astrophysics Data System (ADS)

    Antaris, Alexander L.; Chen, Hao; Cheng, Kai; Sun, Yao; Hong, Guosong; Qu, Chunrong; Diao, Shuo; Deng, Zixin; Hu, Xianming; Zhang, Bo; Zhang, Xiaodong; Yaghi, Omar K.; Alamparambil, Zita R.; Hong, Xuechuan; Cheng, Zhen; Dai, Hongjie

    2016-02-01

    Fluorescent imaging of biological systems in the second near-infrared window (NIR-II) can probe tissue at centimetre depths and achieve micrometre-scale resolution at depths of millimetres. Unfortunately, all current NIR-II fluorophores are excreted slowly and are largely retained within the reticuloendothelial system, making clinical translation nearly impossible. Here, we report a rapidly excreted NIR-II fluorophore (~90% excreted through the kidneys within 24 h) based on a synthetic 970-Da organic molecule (CH1055). The fluorophore outperformed indocyanine green (ICG)--a clinically approved NIR-I dye--in resolving mouse lymphatic vasculature and sentinel lymphatic mapping near a tumour. High levels of uptake of PEGylated-CH1055 dye were observed in brain tumours in mice, suggesting that the dye was detected at a depth of ~4 mm. The CH1055 dye also allowed targeted molecular imaging of tumours in vivo when conjugated with anti-EGFR Affibody. Moreover, a superior tumour-to-background signal ratio allowed precise image-guided tumour-removal surgery.

  12. A small-molecule dye for NIR-II imaging.

    PubMed

    Antaris, Alexander L; Chen, Hao; Cheng, Kai; Sun, Yao; Hong, Guosong; Qu, Chunrong; Diao, Shuo; Deng, Zixin; Hu, Xianming; Zhang, Bo; Zhang, Xiaodong; Yaghi, Omar K; Alamparambil, Zita R; Hong, Xuechuan; Cheng, Zhen; Dai, Hongjie

    2016-02-01

    Fluorescent imaging of biological systems in the second near-infrared window (NIR-II) can probe tissue at centimetre depths and achieve micrometre-scale resolution at depths of millimetres. Unfortunately, all current NIR-II fluorophores are excreted slowly and are largely retained within the reticuloendothelial system, making clinical translation nearly impossible. Here, we report a rapidly excreted NIR-II fluorophore (∼90% excreted through the kidneys within 24 h) based on a synthetic 970-Da organic molecule (CH1055). The fluorophore outperformed indocyanine green (ICG)-a clinically approved NIR-I dye-in resolving mouse lymphatic vasculature and sentinel lymphatic mapping near a tumour. High levels of uptake of PEGylated-CH1055 dye were observed in brain tumours in mice, suggesting that the dye was detected at a depth of ∼4 mm. The CH1055 dye also allowed targeted molecular imaging of tumours in vivo when conjugated with anti-EGFR Affibody. Moreover, a superior tumour-to-background signal ratio allowed precise image-guided tumour-removal surgery. PMID:26595119

  13. Development of organovermiculite-based adsorbent for removing anionic dye from aqueous solution.

    PubMed

    Yu, Xubiao; Wei, Chaohai; Ke, Lin; Hu, Yun; Xie, Xiaoqi; Wu, Haizhen

    2010-08-15

    This paper reports on the development of organovermiculite-based adsorbent for removing Congo Red (CR), a model anionic dye, from aqueous solution. The organovermiculite was prepared using hexadecyl trimethylammonium bromide (HDTMAB) with variations in cation exchange capacity (CEC) and was then characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results from the adsorption experiments showed that with the organic modification of 50, 100, and 200% CEC, the adsorption capacity of vermiculite towards CR was greatly improved from 2.6 to 74.07, 175.44 and 192.31 mg/g, respectively, at 298 K. The adsorption isotherm experiment was conducted at different temperatures (298, 308 and 318 K), and it was found that the uptake of CR increased with increasing temperature. Langmuir and Freundlich isotherm models were applied and the Langmuir model was found to fit the equilibrium data better. The adsorption kinetics was found to follow the pseudo-second-order model. In addition, various thermodynamic parameters such as changes in enthalpy, entropy, and the Gibbs free energy were calculated, showing adsorption to be an endothermic yet spontaneous process. The results indicated that the organovermiculite may be an effective adsorbent for the removal of anionic dyes from wastewater. PMID:20466486

  14. Microscopic observation of dye molecules for solar cells on a titania surface

    NASA Astrophysics Data System (ADS)

    Koshiya, Shogo; Yamashita, Shunsuke; Kimoto, Koji

    2016-04-01

    The lateral distribution and coverage of Ru-based dye molecules, which are used for dye-sensitized solar cells (DSCs), were directly examined on a titania surface using high-resolution scanning transmission electron microscopy (STEM). The clean surface of a free-standing titania nanosheet was first confirmed with atomic resolution, and then, the nanosheet was used as a substrate. A single dye molecule on the titania nanosheet was visualized for the first time. The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules. The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies.

  15. Microscopic observation of dye molecules for solar cells on a titania surface

    PubMed Central

    Koshiya, Shogo; Yamashita, Shunsuke; Kimoto, Koji

    2016-01-01

    The lateral distribution and coverage of Ru-based dye molecules, which are used for dye-sensitized solar cells (DSCs), were directly examined on a titania surface using high-resolution scanning transmission electron microscopy (STEM). The clean surface of a free-standing titania nanosheet was first confirmed with atomic resolution, and then, the nanosheet was used as a substrate. A single dye molecule on the titania nanosheet was visualized for the first time. The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules. The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies. PMID:27087005

  16. Microscopic observation of dye molecules for solar cells on a titania surface.

    PubMed

    Koshiya, Shogo; Yamashita, Shunsuke; Kimoto, Koji

    2016-01-01

    The lateral distribution and coverage of Ru-based dye molecules, which are used for dye-sensitized solar cells (DSCs), were directly examined on a titania surface using high-resolution scanning transmission electron microscopy (STEM). The clean surface of a free-standing titania nanosheet was first confirmed with atomic resolution, and then, the nanosheet was used as a substrate. A single dye molecule on the titania nanosheet was visualized for the first time. The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules. The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies. PMID:27087005

  17. Characterization of chitosan/montmorillonite membranes as adsorbents for Bezactiv Orange V-3R dye.

    PubMed

    Nesic, Aleksandra R; Velickovic, Sava J; Antonovic, Dusan G

    2012-03-30

    The synthesis, characterization and environmental application of chitosan/montmorillonite membrane for adsorption Bezactiv Orange V-3R were investigated. Chitosan/montmorillonite membranes were synthesized in different ratios, containing 10-50% of montmorillonite (MMT) in membrane. These membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy (SEM). The adsorption kinetics were investigated using three different concentrations of Bezactiv Orange dye (30, 50 and 80 mg/L). The adsorption capacity increases with increasing amount of MMT in membranes. These membranes show the highest adsorption capacity when the initial dye concentration was 80 mg/L. The results show that the optimum condition for adsorption of Bezactiv Orange is pH 6. A comparison of kinetic models was evaluated for the pseudo-first and pseudo-second order and intra-particle diffusion. The experimental data were fitted to the pseudo-second order kinetic model, and also followed by intra-particle diffusion. Intra-particle diffusion is not the only rate-controlling step. The Langmuir and Freundlich adsorption isotherms were applied to experimental equilibrium data at different concentration of dye solution. The results indicated the competency of chitosan/MMT membranes adsorbent for Bezactiv Orange adsorption. PMID:22305598

  18. Novel synthesis of a versatile magnetic adsorbent derived from corncob for dye removal.

    PubMed

    Ma, Huan; Li, Jia-Bao; Liu, Wei-Wei; Miao, Miao; Cheng, Bei-Jiu; Zhu, Su-Wen

    2015-08-01

    Corncob, an agricultural waste, was successfully converted into a novel magnetic adsorbent by a low-temperature hydrothermal method (453K), including carbonization under saline conditions and magnetization using iron (III) salt. The resultant magnetic carbonaceous adsorbent (MCA) exhibited a porous structure with a higher specific surface area and more oxygen-containing functional groups than its carbonaceous precursor (CP), which can be attributed to the catalytic effect of Fe (III). The adsorption behaviors of both MCA and CP could be described well by Langmuir isotherm and pseudo-second-order model. The adsorption capacity for Methylene blue (MB) revealed by adsorption isotherms were 163.93mg/g on MCA and 103.09mg/g on CP, respectively. Moreover, MCA was demonstrated as a versatile adsorbent for removal of both anionic and cationic dyes, and it showed good reusability in regeneration studies. This work provides an alternative approach for effective conversion of biomass waste and application of them in pollutant removal. PMID:25919932

  19. Novel tannin-based adsorbent in removing cationic dye (Methylene Blue) from aqueous solution. Kinetics and equilibrium studies.

    PubMed

    Sánchez-Martín, J; González-Velasco, M; Beltrán-Heredia, J; Gragera-Carvajal, J; Salguero-Fernández, J

    2010-02-15

    Natural tannin-based adsorbent has been prepared on the basis of the gelification of Quebracho bark extract. The resulting product, Quebracho Tannin Gel (QTG) was tested as cationic dye adsorbent with Methylene Blue (MB). Kinetics of adsorption process were studied out and a period of 15 days was determined for reaching equilibrium. The influences of pH and temperature were evaluated. As pH or temperature raise q capacity of QTG increases. Theoretical modelization of dye-QTG adsorption was carried out by multiparametric adjustment according to Langmuir's hypothesis. Values of the k(l1), k(l2) and activation energies were calculated. PMID:19782466

  20. Electronic structure of Fe- vs. Ru-based dye molecules

    SciTech Connect

    Johnson, Phillip S.; Himpsel, F. J.; Cook, Peter L.; Zegkinoglou, Ioannis; Garcia-Lastra, J. M.; Rubio, Angel; Ruther, Rose E.; Hamers, Robert J.

    2013-01-28

    In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold, octahedral N cage, such as tris(bipyridines) and tris(phenanthrolines), exhibit a systematic downward shift of the N 1s-to-{pi}* transition when Ru is replaced by Fe. This shift is explained by an extra transfer of negative charge from the metal to the N ligands in the case of Fe, which reduces the binding energy of the N 1s core level. The C 1s-to-{pi}* transitions show the opposite trend, with an increase in the transition energy when replacing Ru by Fe. Molecules with the metal in a fourfold, planar N cage (porphyrins) exhibit a more complex behavior due to a subtle competition between the crystal field, axial ligands, and the 2+ vs. 3+ oxidation states.

  1. Resonance Raman Spectra of o-Safranin Dye, Free and Adsorbed on Silver Nanoparticles: Experiment and Density Functional Theory Calculation.

    PubMed

    Ricci, Marilena; Platania, Elena; Lofrumento, Cristiana; Castellucci, Emilio M; Becucci, Maurizio

    2016-07-14

    The properties of o-Safranin (SO) dye in the first electronic excited state were studied with combined experimental and theoretical methods. The electronic absorption spectra of SO molecules are measured in water solution and in the presence of silver nanoparticles. The normal Raman (NRS) and resonance Raman (RR) spectra of solid SO and the surface enhanced Raman (SERS) and surface enhanced resonance Raman (SE[R]RS) spectra of SO adsorbed on silver nanoparticles are measured at different excitation energies. The enhancement factors for selected vibrational bands of the RR, SERS, and SE[R]RS spectra of SO have been obtained with respect to the NRS spectra of the solid after a careful evaluation of the experimental conditions. The data furnished useful information on the excited electronic states and the interactions of SO with silver nanoparticles. The experimental results are discussed on the basis of DFT and TD-DFT calculations (B3LYP/6-311+G(d,p)) on the isolated SO molecule. PMID:27139691

  2. Relaxation dynamics of surface-adsorbed water molecules in nanoporous silica probed by terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Ru; Liu, Kao-Hsiang; Mou, Chung-Yuan; Sun, Chi-Kuang

    2015-08-01

    Relaxation dynamics of an exclusively adsorbed water molecule in mesoporous silica MCM-41-S was studied by using terahertz spectroscopy. With the temperature controlled from 0 to 50 °C, we observed strongly frequency- and temperature-dependent dielectric relaxation responses, implying that, unlike ice, surface-adsorbed water molecules retained flourishing picosecond dynamics. Based on the Debye relaxation model, a relaxation time constant was found to increase from 1.77 to 4.83 ps when the water molecule was cooled from 50 to 0 °C. An activation energy of ˜15 kJ/mol, which was in close agreement with a hydrogen-bonding energy, was further extracted from the Arrhenius analysis. Combined with previous molecular dynamics simulations, our results indicate that the reorientation relaxation originated from the "flip-flop" rotation of a three hydrogen-bonded surface-adsorbed water molecule.

  3. Laser electrospray mass spectrometry of adsorbed molecules at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Brady, John J.; Judge, Elizabeth J.; Simon, Kuriakose; Levis, Robert J.

    2010-02-01

    Atmospheric pressure mass analysis of solid phase biomolecules is performed using laser electrospray mass spectrometry (LEMS). A non-resonant femtosecond duration laser pulse vaporizes native samples at atmospheric pressure for subsequent electrospray ionization and transfer into a mass spectrometer. LEMS was used to detect a complex molecule (irinotecan HCl), a complex mixture (cold medicine formulation with active ingredients: acetaminophen, dextromethorphan HBr and doxylamine succinate), and a biological building block (deoxyguanosine) deposited on steel surfaces without a matrix molecule.

  4. Textile dyes removal from aqueous solution using Opuntia ficus-indica fruit waste as adsorbent and its characterization.

    PubMed

    Peláez-Cid, A A; Velázquez-Ugalde, I; Herrera-González, A M; García-Serrano, J

    2013-11-30

    For this research, three different adsorbents, one untreated and two chemically activated, were prepared from Opuntia ficus-indica fruit waste. By the construction of adsorption isotherms, its adsorption capabilities and the viability of its use in the removal of textile basic and direct type dyes were determined. It was found that the adsorbent with the most adsorption capacity for basic dyes was the one activated with NaClO, and, for direct dyes, it was the one activated with NaOH. Langmuir and Freundlich equations isotherms were applied for the analysis of the experimental data. It was found that the Freundlich model best described the adsorption behavior. The adsorption capacity was improved when the pH of the dye solution had an acid value. The specific surface area of the adsorbents was calculated by means of methylene blue adsorption at 298 K to stay within a range between 348 and 643 m(2) g(-1). The FTIR spectroscopic characterization technique, the SEM, the point of zero charge, and the elemental analysis show the chemical and physical characteristics of the studied adsorbents, which confirm the adsorption results obtained. PMID:24071717

  5. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  6. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.

    1993-10-01

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  7. Pyridinium molten salts as co-adsorbents in dye-sensitized solar cells

    SciTech Connect

    Chang, Jui-Cheng; Sun, I-Wen; Yang, Cheng-Hsien; Yang, Hao-Hsun; Hsueh, Mao-Lin; Ho, Wen-Yueh; Chang, Jia-Yaw

    2011-01-15

    The influence of using pyridinium molten salts as co-adsorbents to modify the monolayer of a TiO{sub 2} semiconductor on the performance of a dye-sensitized solar cell is studied. The current-voltage characteristics are measured under AM 1.5 (100 mW cm{sup -2}). The pyridinium molten salts significantly enhance the open-circuit photovoltage (V{sub oc}), the short circuit photocurrent density (J{sub sc}) as well as the solar energy conversion efficiency ({eta}). 1-Ethyl-3-carboxypyridinium iodide ([ECP][I]) is applied successfully to prepare an insulating molecular layer with N719, and achieve high energy conversion efficiency as high as 4.49% at 100 mW cm{sup -2} and AM 1.5. The resulting efficiency is 20% higher than that of a non-additive device. This enhancement of conversion efficiency is attributed to the negative shift of the conduction band (CB) edge and the abundant concentration of I{sup -} on the surface of the electrode when using [ECP][I] as the co-adsorbent. (author)

  8. Transient magnetization of core excited organic molecules adsorbed on graphene

    NASA Astrophysics Data System (ADS)

    Ravikumar, Abhilash; Baby, Anu; Lin, He; Brivio, Gian Paolo; Fratesi, Guido

    This work presents a density functional theory based computational investigation of electronic and magnetic properties of physisorbed and chemisorbed organic molecules on graphene in the ground state and core excited one at low molecular coverage. For physisorbed molecules, where the interaction with graphene is dominated by van der Waals forces and the system is non-magnetic in the ground state, it is found that the valence electrons relax towards a spin polarized configuration upon excitation of a core-level electron. The magnetism depends on efficient electron transfer from graphene on the femtosecond time scale. On the contrary, when graphene is covalently functionalized, the system is magnetic in the ground state presenting two spin dependent mid gap states localized around the adsorption site. At variance with the physisorbed case upon core-level excitation, the LUMO of the molecule and the mid gap states of graphene hybridize and the relaxed valence shell is not magnetic anymore. This project has received funding from the European Union Seventh Framework Programme under grant agreement n∘ 607232 [THINFACE].

  9. Rotational Spectromicroscopy: Imaging the Orbital Interaction between Molecular Hydrogen and an Adsorbed Molecule

    NASA Astrophysics Data System (ADS)

    Li, Shaowei; Yuan, Dingwang; Yu, Arthur; Czap, Gregory; Wu, Ruqian; Ho, W.

    2015-05-01

    A hydrogen molecule can diffuse freely on the surface and be trapped above an adsorbed molecule within the junction of a scanning tunneling microscope. The trapped dihydrogen exhibits the properties of a free rotor. Here we show that the intermolecular interaction between dihydrogen and Mg-porphyrin (MgP) can be visualized by imaging j =0 to 2 rotational excitation of dihydrogen. The interaction leads to a weakened H-H bond and modest electron donation from the dihydrogen to the lowest unoccupied molecular orbital of MgP, a process similarly observed for the interaction between dihydrogen and an adsorbed Au atom.

  10. Rotational Spectromicroscopy: Imaging the Orbital Interaction between Molecular Hydrogen and an Adsorbed Molecule.

    PubMed

    Li, Shaowei; Yuan, Dingwang; Yu, Arthur; Czap, Gregory; Wu, Ruqian; Ho, W

    2015-05-22

    A hydrogen molecule can diffuse freely on the surface and be trapped above an adsorbed molecule within the junction of a scanning tunneling microscope. The trapped dihydrogen exhibits the properties of a free rotor. Here we show that the intermolecular interaction between dihydrogen and Mg-porphyrin (MgP) can be visualized by imaging j=0 to 2 rotational excitation of dihydrogen. The interaction leads to a weakened H-H bond and modest electron donation from the dihydrogen to the lowest unoccupied molecular orbital of MgP, a process similarly observed for the interaction between dihydrogen and an adsorbed Au atom. PMID:26047242

  11. Dynamics of Molecules Adsorbed in Zeolitic Systems: Neutron Scattering and MD Simulation Studies

    SciTech Connect

    Mitra, S.; Sharma, V. K.; Mukhopadhyay, R.

    2011-07-15

    Zeolites represent a class of technologically important materials because of their characteristic properties of molecular sieving and catalysis, which makes them indispensable in the petroleum industries. While the catalytic properties depend upon many factors, a major role is played by the dynamics of hydrocarbon gases. In order to be able to tailor make these materials for use in industry for catalytic and sieving purposes, it is important to understand the dynamical properties of the guest molecules adsorbed in the zeolitic materials. It is of interest to study the effects of size and shape of guest molecules and also the host zeolitic structure, governing the diffusion mechanism of the adsorbed species. Here we report the results of Quasielastic Neutron Scattering (QENS) and classical molecular dynamics (MD) simulation studies of two hydrocarbons namely acetylene and propylene adsorbed in two structurally different zeolites Na-Y and ZSM-5.

  12. Method and apparatus for passive optical dosimeter comprising caged dye molecules

    DOEpatents

    Sandison, David R.

    2001-07-03

    A new class of ultraviolet dosimeters is made possible by exposing caged dye molecules, which generate a dye molecule on exposure to ultraviolet radiation, to an exterior environment. Applications include sunburn monitors, characterizing the UV exposure history of UV-sensitive materials, especially including structural plastics, and use in disposable `one-use` optical equipment, especially medical devices.

  13. Giant Hysteresis of Single-Molecule Magnets Adsorbed on a Nonmagnetic Insulator.

    PubMed

    Wäckerlin, Christian; Donati, Fabio; Singha, Aparajita; Baltic, Romana; Rusponi, Stefano; Diller, Katharina; Patthey, François; Pivetta, Marina; Lan, Yanhua; Klyatskaya, Svetlana; Ruben, Mario; Brune, Harald; Dreiser, Jan

    2016-07-01

    TbPc2 single-molecule magnets adsorbed on a magnesium oxide tunnel barrier exhibit record magnetic remanence, record hysteresis opening, perfect out-of-plane alignment of the magnetic easy axes, and self-assembly into a well-ordered layer. PMID:27159732

  14. Dynamics of water molecules adsorbed by silica and resin SGK-7

    NASA Astrophysics Data System (ADS)

    Lisichkin, Yu. V.; Sakharova, L. A.; Tumanov, A. A.

    2014-01-01

    This paper has presented neutron spectroscopy data on the dynamics of light water molecules adsorbed in the cation exchanger (ion-exchange resin) SGK-7 and on the surface of aerosils (highly dispersed pyrogenic silica) with different levels of hydration. The measurements have been performed on a DIN-2PI spectrometer (Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research, Dubna, Russia). The characteristics of the diffusive and vibrational motions of adsorbed water molecules have been determined from the experimental neutron scattering spectra. The data obtained in the quasi-elastic neutron scattering region have been analyzed using a model accounting for the effects of restricted translational and rotational diffusion. The results have demonstrated a significant decrease in the diffusion mobility of adsorbed water molecules as compared to conventional (bulk) water. In particular, the self-diffusion coefficient decreases several times, and the diffusion rate is the lower, the smaller is the thickness of the hydration layer. The dependences of the intensity and half-width of the quasi-elastic scattering peak on the magnitude of the neutron momentum transfer q in the scattering process exhibit a nonmonotonic character. This indicates manifestation of the effects of restricted translational diffusion, rotational diffusion, and jump diffusion. The partial distributions of vibrational frequencies of hydrogen atoms of water molecules adsorbed by the cation exchanger and aerosils have been obtained from the inelastic neutron scattering data.

  15. Novel stimuli responsive gellan gum-graft-poly(DMAEMA) hydrogel as adsorbent for anionic dye.

    PubMed

    Karthika, J S; Vishalakshi, B

    2015-11-01

    In this study, gellan gum-grafted-poly((2-dimethylamino) ethyl methacrylate) (GG-g-poly(DMAEMA)) hydrogel was made by free radical polymerization in aqueous media employing microwave irradiation technique. Ammonium persulfate (APS)/N,N,N',N'-tetramethylethylenediamine (TMEDA) were used as initiator-accelerator pair. N,N'-methylenebisacrylamide (MBA) has been used as crosslinker. The gel was characterized by FTIR, XRD, TGA, DSC and SEM techniques. The characteristic peaks at 1724, 2630, 1147, 1650 and 1535cm(-1) in the IR spectrum confirms grafting and gel formation. The TGA data reveals that synthesized gels were thermally more stable than gellan gum. The XRD studies confirm the crystalline nature of the synthesized material. Swelling behaviour of the hydrogel under different temperatures and pH conditions was investigated. The results indicated drastic changes in swelling around pH 7.0 and 50°C. The gels were evaluated as an adsorbent to remove an anionic dye, methyl orange (MO), from aqueous solution. The pH conditions for maximum adsorption were optimized, the adsorption data is observed to fit best to the Freundlich isotherm model and the maximum adsorption capacity was found to be 25.8mgg(-1). The kinetic analysis revealed a second-order adsorption process. The thermodynamic parameters showed the adsorption to be exothermic and non-spontaneous at high temperatures. PMID:26325677

  16. Metal oxide-encapsulated dye-sensitized photoanodes for dye-sensitized solar cells

    DOEpatents

    Hupp, Joseph T.; Son, Ho-Jin

    2016-01-12

    Dye-sensitized semiconducting metal oxide films for photoanodes, photoanodes incorporating the films and DSCs incorporating the photoanodes are provided. Also provided are methods for making the dye sensitized semiconducting metal oxide films. The methods of making the films are based on the deposition of an encapsulating layer of a semiconducting metal oxide around the molecular anchoring groups of photosensitizing dye molecules adsorbed to a porous film of the semiconducting metal oxide. The encapsulating layer of semiconducting metal oxide is formed in such a way that it is not coated over the chromophores of the adsorbed dye molecules and, therefore, allows the dye molecules to remain electrochemically addressable.

  17. Activated carbon prepared from yerba mate used as a novel adsorbent for removal of tannery dye from aqueous solution.

    PubMed

    Linhares, Bruno; Weber, Caroline Trevisan; Foletto, Edson Luiz; Paz, Diego Silva; Mazutti, Marcio A; Collazzo, Gabriela Carvalho

    2013-01-01

    Activated carbon prepared from yerba mate (Ilex paraguariensis) was used as adsorbent for the removal of tannery dye from aqueous solution. The activated carbon was characterized, and it showed a mesoporous texture, with surface area of 537.4 m2 g(-1). The initial dye concentration, contact time and pH influenced the adsorption capacity. The equilibrium data were in good agreement with both Langmuir and Freundlich isotherms. The adsorption kinetics of the tannery dye on activated carbon prepared from yerba mate followed a pseudo-second-order model. The adsorption process was found to be controlled by both external mass-transfer and intraparticle diffusion, but the external diffusion was the dominating process. This work highlights the potential application of activated carbon produced from yerba mate in the field of adsorption. PMID:24350496

  18. Vibrational dynamics of fullerene molecules adsorbed on metal surfaces studied with synchrotron infrared radiation

    SciTech Connect

    P. Rudolf; R. Raval; P. Dumas; Gwyn P. Williams

    2002-04-01

    Infrared (IR) spectroscopy of chemisorbed C{sub 60} on Ag (111), Au (110) and Cu (100) reveals that a non-IR-active mode becomes active upon adsorption, and that its frequency shifts proportionally with the charge transferred from the metal to the molecule by about 5 cm{sup -1} per electron. The temperature dependence of the frequency and the width of this IR feature have also been followed for C{sub 60>}/Cu (100) and were found to agree well with a weak anharmonic coupling (dephasing) to a low-frequency mode, which we suggest to be the frustrated translational mode of the adsorbed molecules.

    Additionally, the adsorption is accompanied by a broadband reflectance change, which is interpreted as due to the scattering of conduction electrons of the metal surface by the adsorbate. The reflectance change allows determination of the friction coefficient of the C{sub 60} molecules, which results in rather small values ({approx}2 x 10{sup 9}s{sup -1} for Ag and Au, and {approx}1.6 x 10{sup 9}s{sup -1} for Cu), consistent with a marked metallic character of the adsorbed molecules.

    Pre-dosing of alkali atoms onto the metal substrates drastically changes the IR spectra recorded during subsequent C{sub 60} deposition: anti-absorption bands, as well as an increase of the broadband reflectance, occur and are interpreted as due to strong electron-phonon coupling with induced surface states.

  19. Physical description of the impregnation mechanism of dye molecules in contact with porous electrodes

    NASA Astrophysics Data System (ADS)

    Shahzad, N.; Alexe-Ionescu, A. L.; Tresso, E.; Barbero, G.

    2013-05-01

    We propose and discuss two models that take into account the decreasing of the bulk density of dyes molecules in contact with a porous electrode. We show that the models based on the standard adsorption phenomenon have to be considered just as fitting models, of limited physical significance. A more physical model has to take into account the diffusion of dye molecules into the channels present in the porous electrode and also the adsorption of dye molecules on the lateral surfaces of these channels. The agreement between the theoretical prediction of such a model and the experimental data is reasonably good.

  20. Rod-like cyanophenyl probe molecules nanoconfined to oxide particles: Density of adsorbed surface species

    NASA Astrophysics Data System (ADS)

    Frunza, Stefan; Frunza, Ligia; Ganea, Constantin Paul; Zgura, Irina; Brás, Ana Rita; Schönhals, Andreas

    2016-02-01

    Surface layers have already been observed by broadband dielectric spectroscopy for composite systems formed by adsorption of rod-like cyanophenyl derivates as probe molecules on the surface of oxide particles. In this work, features of the surface layer are reported; samples with different amounts of the probe molecules adsorbed onto oxide (nano) particles were prepared in order to study their interactions with the surface. Thermogravimetric analysis (TGA) was applied to analyze the amount of loaded probe molecules. The density of the surface species ns was introduced and its values were estimated from quantitative Fourier transform infrared spectroscopy (FTIR) coupled with TGA. This parameter allows discriminating the composites into several groups assuming a similar interaction of the probe molecules with the hosts of a given group. An influence factor H is further proposed as the ratio of the number of molecules in the surface layer showing a glassy dynamics and the number of molecules adsorbed tightly on the surface of the support: It was found for aerosil composites and used for calculating the maximum filling degree of partially filled silica MCM-41 composites showing only one dielectric process characteristic for glass-forming liquids and a bulk behavior for higher filling degrees.

  1. Orientation and electronic structure of ion exchanged dye molecules on mica: An X-ray absorption study

    SciTech Connect

    Fischer, D.; Caseri, W.R.; Haehner, G.

    1998-02-15

    Dye molecules are frequently used to determine the specific surface area and the ion exchange capacity of high-surface-area materials such as mica. The organic molecules are often considered to be planar and to adsorb in a flat orientation. In the present study the authors have investigated the orientation and electronic structure of crystal violet (CV) and malachite green (MG) on muscovite mica, prepared by immersing the substrates for extended periods into aqueous solutions of the dyes of various concentrations. The K{sup +} ions of the mica surface are replaced by the organic cations via ion exchange. X-ray photoelectron spectroscopy reveals that only one amino group is involved in the interaction of CV and MG with the muscovite surface, i.e., certain resonance structures are abolished upon adsorption. With near edge X-ray absorption fine structure spectroscopy a significant tilt angle with respect to the surface was found for all investigated species. A flat orientation, as has often been proposed before, can effectively be ruled out. Hence, results are in marked contrast to the often quoted orientation and suggest that the specific surface areas determined with dyes may, in general, be overestimated.

  2. Modeling the binding of fulvic acid by goethite: the speciation of adsorbed FA molecules

    NASA Astrophysics Data System (ADS)

    Filius, Jeroen D.; Meeussen, Johannes C. L.; Lumsdon, David G.; Hiemstra, Tjisse; van Riemsdijk, Willem H.

    2003-04-01

    Under natural conditions, the adsorption of ions at the solid-water interface may be strongly influenced by the adsorption of organic matter. In this paper, we describe the adsorption of fulvic acid (FA) by metal(hydr)oxide surfaces with a heterogeneous surface complexation model, the ligand and charge distribution (LCD) model. The model is a self-consistent combination of the nonideal competitive adsorption (NICA) equation and the CD-MUSIC model. The LCD model can describe simultaneously the concentration, pH, and salt dependency of the adsorption with a minimum of only three adjustable parameters. Furthermore, the model predicts the coadsorption of protons accurately for an extended range of conditions. Surface speciation calculations show that almost all hydroxyl groups of the adsorbed FA molecules are involved in outer sphere complexation reactions. The carboxylic groups of the adsorbed FA molecule form inner and outer sphere complexes. Furthermore, part of the carboxylate groups remain noncoordinated and deprotonated.

  3. Adsorbed Oxygen Molecules as a Possible Source of Flux Noise in SQUIDs

    NASA Astrophysics Data System (ADS)

    Shi, Chuntai; Wang, Hui; Hu, Jun; Yu, Clare; Wu, Ruqian

    2015-03-01

    One of the dominant source of flux noise in SQUIDs is flux noise which has been attributed to mysterious fluctuating magnetic spins on the surface. We propose that the spins producing flux noise could be adsorbed O2 molecules that have a magnetic moment of about 2 μB. Using density functional calculations, we studied O2 molecules adsorbed on a sapphire surface. We find that the barrier for spin rotation is small enough to allow almost free spin reorientation due to thermal excitations at low temperatures. Monte Carlo simulations of a 2D XY spin model yields 1 / f noise where f is frequency. This work was supported by 1000 Talent Program of China through Fudan University. Work at UCI was supported by DOE-BES (Grant No. DE-FG02-05ER46237) and the Army Research Office (Grant No. W911NF-10-1-0494).

  4. Graphene-catalyzed photoreduction of dye molecules revealed by graphene enhanced Raman spectroscopy.

    PubMed

    Lee, Bora; Kang, Jin Hyoun; Jo, Insu; Shin, Dongha; Hong, Byung Hee

    2016-02-01

    The unique electrical and optical properties of graphene have enabled its application in various photocatalysis reactions. However, graphene needs to be combined with photosensitizing co-catalysts such as TiO2 due to its negligible visible light absorption. Here, we report that the single layer graphene by itself is capable of catalyzing the photoreduction of dye molecules, which has been revealed by graphene-enhanced Raman spectroscopy studies. The proposed mechanism involves the electron transfer from graphene to temporarily empty HOMO states of photoexcited dye molecules, which can be interpreted as ultrafast hole transfer from dyes to graphene. We also confirm that graphene-encapsulated nitrobenzene dyes show less photoreduction, implying that the ambient hydrogen molecules are the important source of photoreduction into aniline dyes. The photocatalytic reactivity of graphene would find numerous energy and environmental applications in the future. PMID:26784530

  5. Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

    NASA Astrophysics Data System (ADS)

    Katoch, Neha; Kapoor, Pooja; Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2016-05-01

    We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G0 to 2G0 suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

  6. Ammonium-Functionalized Hollow Polymer Particles As a pH-Responsive Adsorbent for Selective Removal of Acid Dye.

    PubMed

    Qin, Yan; Wang, Li; Zhao, Changwen; Chen, Dong; Ma, Yuhong; Yang, Wantai

    2016-07-01

    In this work, a novel type of ammonium-functionalized hollow polymer particles (HPP-NH3(+)) with a high density of ammonium groups in the shell has been specially designed and synthesized. Benefiting from both the high surface area and from the high density of positively charged ammonium groups, the as-prepared HPP-NH3(+) can serve as a selective adsorbent for the removal of negatively charged acid dye (e.g., methyl blue a-MB). The equilibrium adsorption data of a-MB on the HPP-NH3(+) were evaluated using Freundlich and Langmuir isotherm models, and Langmuir isotherm exhibited a better fit with a maximum adsorption capacity of 406 mg/g. Most importantly, because of the presence of dual functional groups (ammonium and carboxyl groups), the HPP-NH3(+) showed a significant pH-dependent equilibrium adsorption capacity, which increased dramatically from 59 mg/g to 449 mg/g as the solution pH decreased from 9 to 2. This uniqueness makes the dye-adsorbed HPP-NH3(+) can be facilely regenerated under mild condition (in weak alkaline solution, pH 10) to recover both a-MB and the HPP-NH3(+), whereas the recovery of conventional adsorbents is commonly performed under particularly severe conditions. The regenerated HPP-NH3(+) can be reused for dye removal and the dye removal efficiency remained above 98% even after five adsorption-desorption cycles. Because of its high adsorption capacity, pH-sensitivity, easy regeneration, and good reusability, the HPP-NH3(+) has great potential for the application in the field of water treatment, controlled drug release, and pH-responsive delivery. PMID:27302068

  7. Orientation and heat capacity of horizontally adsorbed molecules in electric fields

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Yen

    2014-02-01

    The orientation and the heat capacity of horizontally adsorbed molecules are investigated in static electric fields. We evaluate the energy spectrum and the wave function to probe the rotational characteristics of the molecule. Numerical results indicate that the electric field and the effect of quantum confinement lead to anticrossing behaviors in the energy levels. The orientation reveals a stepped feature due to the anticrossing in the ground state. Moreover, the heat capacity displays two peaks near the anticrossing. By means of comparison, each peak of the heat capacity corresponds to a particular degree of orientation.

  8. Imposed Orientation of Dye Molecules by Liquid Crystals and an Electric Field.

    ERIC Educational Resources Information Center

    Sadlej-Sosnowska, Nina

    1980-01-01

    Describes experiments using dye solutions in liquid crystals in which polar molecules are oriented in an electrical field and devices are constructed to change their color in response to an electric signal. (CS)

  9. Polypyrrole-coated magnetic nanoparticles as an efficient adsorbent for RB19 synthetic textile dye: Removal and kinetic study.

    PubMed

    Shanehsaz, Maryam; Seidi, Shahram; Ghorbani, Yousefali; Shoja, Seyed Mohammad Reza; Rouhani, Shohre

    2015-10-01

    The present work deals with the first attempt to study the removal of synthetic textile dye, reactive blue 19 (RB19), using the magnetic Fe3O4 nanoparticles modified by pyrrole (PPy@Fe3O4 MNPs) as an efficient adsorbent. The nanoadsorbent was synthesized using chemical co-precipitation. Scanning electron microscopy and FT-IR were used to characterize nanoparticles. Factors affecting the dye adsorption including the pH of the dye solution, amount of adsorbent and contact time were also further investigated. Sorption of the RB19 on PPy@Fe3O4 MNPs reached to equilibrium at contact time less than 10 min and fitted well to the Langmuir adsorption model with a maximum adsorption capacity of 112.36 mg g(-1). Experiments for adsorption kinetic were carried out and the data fitted well according to a pseudo-second-order kinetic model. Moreover, the MNPs were recovered with over than 90% efficiency using methanol as elution agent. PMID:25978015

  10. Preparation and performance of chitosan encapsulated activated charcoal (ACCB) adsorbents for small molecules.

    PubMed

    Chandy, T; Sharma, C P

    1993-01-01

    A technique is described to encapsulate activated charcoal for haemoperfusion to be used in an artificial liver support. Activated charcoal was encapsulated within chitosan matrix (ACCB) in different concentrations, and was used as the supports for perfusion of a mixture of solutes, having molecular weight ranges from 60 to 69,000; under a flow rate of 8 ml/min. It seems the ACCB may be a good adsorbent system for the removal of toxic uric acid, creatinine, bilirubin, etc., from solutions; while larger molecules such as albumin are adsorbed less. The encapsulated charcoal did not leach out from the matrix during perfusion, and the system may be useful for detoxification of blood. The haemolytic potential of ACCB has been compatible with polystyrene control tubes. However, further studies are needed to determine their behaviour under clinical conditions. PMID:8263676

  11. Low cost CaCl₂ pretreatment of sugarcane bagasse for enhancement of textile dyes adsorption and subsequent biodegradation of adsorbed dyes under solid state fermentation.

    PubMed

    Kadam, Avinash A; Lade, Harshad S; Patil, Swapnil M; Govindwar, Sanjay P

    2013-03-01

    Pretreatments to sugarcane bagasse (SCB) such as CaCl2, alkali, ammonia, steam and milling showed 91%, 46%, 47%, 42% and 56% adsorption of Solvent Red 5B (SR5B); 92%, 57%, 58%, 56% and 68% adsorption of simulated dyes mixture (SDM), and 86%, 45%, 49%, 44% and 56% adsorption of a real textile effluent (RTE), respectively. However, the untreated SCB showed 32%, 38% and 30% adsorption of SR5B, SDM and RTE, respectively. Adsorption of SR5B on CaCl2 pretreated SCB follows pseudo-second order kinetics. SEM and FTIR analysis reveals the delignification of CaCl2 pretreated SCB. SR5B, SDM and RTE adsorbed on CaCl2, alkali, ammonia, steam and milling pretreated SCB were decolorized under solid state fermentation using isolated Providencia staurti strain EbtSPG. Tray bioreactor study showed 86% American Dye Manufacturers Institute (ADMI) removal of RTE in 72h. Biodegradation of adsorbed SR5B was confirmed using FTIR, HPLC and HPTLC. PMID:23411459

  12. Homeotropic orientation of a nematic liquid crystal by bent-core molecules adsorbed on its surface

    NASA Astrophysics Data System (ADS)

    Hwang, Jiyong; Yang, Seungbin; Lee, Hyojin; Kim, Jongyoon; Lee, Ji-Hoon; Kang, Shin-Woong; Choi, E.-Joon

    2015-06-01

    We reported the promotion of a homeotropic alignment of a nematic liquid crystal (NLC) by bent-core liquid-crystal (BLC) Molecules adsorbed its surface. The BLC was mixed at various concentrations with the NLC, and the mixtures were injected into an empty cell with a cell gap of 13 μm. Although the pure NLC showed a heterogeneous orientation, the BLC-NLC mixture was gradually transformed to a homeotropic alignment with increasing concentration of the BLC. We investigated the surface topography of the samples by using an atomic force microscopy (AFM) and found that the BLC molecules were segregated into a polyimide (PI) surface and formed protrusion domains with diameters of 50-100 nm. The BLC protrusions might promote the homeotropic orientation of the NLC molecules.

  13. Ultra-sensitive fluorescence spectroscopy of isolated surface-adsorbed molecules using an optical nanofiber.

    PubMed

    Stiebeiner, A; Rehband, O; Garcia-Fernandez, R; Rauschenbeutel, A

    2009-11-23

    The strong radial confinement and the pronounced evanescent field of the guided light in optical nanofibers yield favorable conditions for ultra-sensitive surface spectroscopy of molecules deposited on the fiber. Using the guided mode of the nanofiber for both excitation and fluorescence collection, we present spectroscopic measurements on 3,4,9,10-perylenetetracarboxylic dianhydride molecules (PTCDA) at ambient conditions. Surface coverages as small as 1 per thousand of a compact monolayer still give rise to fluorescence spectra with a good signal to noise ratio. Moreover, we analyze and quantify the self-absorption effects due to reabsorption of the emitted fluorescence light by circumjacent surface-adsorbed molecules distributed along the fiber waist. PMID:19997412

  14. Structure formation in adsorbed overlayers comprising functional cross-shaped molecules: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Kasperski, Adam; Nieckarz, Damian; Szabelski, Paweł

    2015-11-01

    Surface confined self-assembly of functional star-shaped organic molecules is a promising method to create nanoporous networks with tailorable structure and functions. In this work we use the Monte Carlo simulation method to demonstrate how the morphology of these supramolecular assemblies can be tuned by manipulating intrinsic parameters of the building blocks and modified by the presence of co-adsorbed metal atoms. To that purpose we study the 2D self-assembly of planar cruciform molecules modeled as collections of interconnected segments, some of which were activated to represent discrete interaction centers. We consider a few exemplary adsorbed systems in which the molecules with different size, aspect ratio and intramolecular distribution of active centers form superstructures stabilized by short-range segment-segment interactions or by metal-segment interactions. These two situations correspond to supramolecular assemblies sustained by, for example, hydrogen bonding and metal-organic ligand coordination, respectively. The simulated results show that proper encoding of intramolecular interactions into the cruciform building bricks allows for directing the self-assembly towards largely diversified structures ranging from nanoclusters to porous grids. The obtained findings can facilitate designing and optimization of molecular networks comprising cross-shaped units including functionalized porphyrins and phthalocyanines and they can be helpful in preliminary selection of these building blocks.

  15. Thermal and Electronic Fluctuations of Flexible Adsorbed Molecules: Azobenzene on Ag(111)

    NASA Astrophysics Data System (ADS)

    Maurer, Reinhard J.; Liu, Wei; Poltavsky, Igor; Stecher, Thomas; Oberhofer, Harald; Reuter, Karsten; Tkatchenko, Alexandre

    2016-04-01

    We investigate the thermal and electronic collective fluctuations that contribute to the finite-temperature adsorption properties of flexible adsorbates on surfaces on the example of the molecular switch azobenzene C12 H10 N2 on the Ag(111) surface. Using first-principles molecular dynamics simulations, we obtain the free energy of adsorption that accurately accounts for entropic contributions, whereas the inclusion of many-body dispersion interactions accounts for the electronic correlations that govern the adsorbate binding. We find the adsorbate properties to be strongly entropy driven, as can be judged by a kinetic molecular desorption prefactor of 1024 s-1 that largely exceeds previously reported estimates. We relate this effect to sizable fluctuations across structural and electronic observables. A comparison of our calculations to temperature-programed desorption measurements demonstrates that finite-temperature effects play a dominant role for flexible molecules in contact with polarizable surfaces, and that recently developed first-principles methods offer an optimal tool to reveal novel collective behavior in such complex systems.

  16. Thermal and Electronic Fluctuations of Flexible Adsorbed Molecules: Azobenzene on Ag(111).

    PubMed

    Maurer, Reinhard J; Liu, Wei; Poltavsky, Igor; Stecher, Thomas; Oberhofer, Harald; Reuter, Karsten; Tkatchenko, Alexandre

    2016-04-01

    We investigate the thermal and electronic collective fluctuations that contribute to the finite-temperature adsorption properties of flexible adsorbates on surfaces on the example of the molecular switch azobenzene C_{12}H_{10}N_{2} on the Ag(111) surface. Using first-principles molecular dynamics simulations, we obtain the free energy of adsorption that accurately accounts for entropic contributions, whereas the inclusion of many-body dispersion interactions accounts for the electronic correlations that govern the adsorbate binding. We find the adsorbate properties to be strongly entropy driven, as can be judged by a kinetic molecular desorption prefactor of 10^{24}  s^{-1} that largely exceeds previously reported estimates. We relate this effect to sizable fluctuations across structural and electronic observables. A comparison of our calculations to temperature-programed desorption measurements demonstrates that finite-temperature effects play a dominant role for flexible molecules in contact with polarizable surfaces, and that recently developed first-principles methods offer an optimal tool to reveal novel collective behavior in such complex systems. PMID:27104719

  17. Excitation laser energy dependence of surface-enhanced fluorescence showing plasmon-induced ultrafast electronic dynamics in dye molecules

    NASA Astrophysics Data System (ADS)

    Itoh, Tamitake; Yamamoto, Yuko S.; Tamaru, Hiroharu; Biju, Vasudevanpillai; Murase, Norio; Ozaki, Yukihiro

    2013-06-01

    We find unique properties accompanying surface-enhanced fluorescence (SEF) from dye molecules adsorbed on Ag nanoparticle aggregates, which generate surface-enhanced Raman scattering. The properties are observed in excitation laser energy dependence of SEF after excluding plasmonic spectral modulation in SEF. The unique properties are large blue shifts of fluorescence spectra, deviation of ratios between anti-Stokes SEF intensity and Stokes from those of normal fluorescence, super-broadening of Stokes spectra, and returning to original fluorescence by lower energy excitation. We elucidate that these properties are induced by electromagnetic enhancement of radiative decay rates exceeding the vibrational relaxation rates within an electronic excited state, which suggests that molecular electronic dynamics in strong plasmonic fields can be largely deviated from that in free space.

  18. Alignment and assembly of adsorbed collagen molecules induced by anisotropic chemical nanopatterns.

    PubMed

    Denis, Frédéric A; Pallandre, Antoine; Nysten, Bernard; Jonas, Alain M; Dupont-Gillain, Christine C

    2005-10-01

    Collagen, a protein widely used to control cell-material interactions, is known to self-assemble in solution. Supramolecular structures also form on material surfaces following collagen adsorption. Herein, we report the use of anisotropic, flat, surface chemical nanopatterns, which consist of alkyl-terminated tracks drawn in an oligo(ethylene glycol)-terminated matrix, to direct collagen adsorption. As revealed by atomic force microscopy, the spontaneous collagen adsorption performed on such patterned substrates results in the accumulation of collagen on the hydrophobic tracks. Moreover, the width of the tracks (30-90 nm), which is much smaller than the length of the collagen molecule (approximately 300 nm), is the origin of preferential alignment of the molecules and of their assembly into continuous bundles of adsorbed collagen. This chemical guidance effect due to self-confinement of proteins upon adsorption may bring novel and valuable applications, specifically in biomaterials science and cell growth control. PMID:17193383

  19. Molecular resonant dissociation of surface-adsorbed molecules by plasmonic nanoscissors

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenglong; Sheng, Shaoxiang; Zheng, Hairong; Xu, Hongxing; Sun, Mengtao

    2014-04-01

    The ability to break individual bonds or specific modes in chemical reactions is an ardently sought goal by chemists and physicists. While photochemistry based methodologies are very successful in controlling e.g. photocatalysis, photosynthesis and the degradation of plastic, it is hard to break individual molecular bonds for those molecules adsorbed on the surface because of the weak light-absorption in molecules and the redistribution of the resulting vibrational energy both inside the molecule and to its surrounding environment. Here we show how to overcome these obstacles with a plasmonic hot-electron mediated process and demonstrate a new method that allows the sensitive control of resonant dissociation of surface-adsorbed molecules by `plasmonic' scissors. To that end, we used a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) setup to dissociate resonantly excited NC2H6 fragments from Malachite green. The surface plasmons (SPs) excited at the sharp metal tip not only enhance the local electric field to harvest the light incident from the laser, but crucially supply `hot electrons' whose energy can be transferred to individual bonds. These processes are resonant Raman, which result in some active chemical bonds and then weaken these bonds, followed by dumping in lots of indiscriminant energy and breaking the weakest bond. The method allows for sensitive control of both the rate and probability of dissociation through their dependence on the density of hot electrons, which can be manipulated by tuning the laser intensity or tunneling current/bias voltage in the HV-TERS setup, respectively. The concepts of plasmonic scissors open up new versatile avenues for the deep understanding of in situ surface-catalyzed chemistry.The ability to break individual bonds or specific modes in chemical reactions is an ardently sought goal by chemists and physicists. While photochemistry based methodologies are very successful in controlling e.g. photocatalysis

  20. Aggregation of dye molecules and its influence on the spectral luminescent properties of solutions

    NASA Astrophysics Data System (ADS)

    Yuzhakov, V. I.

    1992-06-01

    The principal results of studies carried out in recent years on the molecular aggregation of organic dyes and pigments in solutions are examined and surveyed in the present review. Attention is concentrated on the influence of association on the photoenergetics of the dye molecules. Theoretical studies on the spectral-luminescent spectroscopic characteristics of the molecular aggregates are briefly considered. Studies on the anisotropy of the absorption and on the emission from the associated species are described. Investigations of the concentration depolarisation and concentration quenching of the fluorescence of dye solutions are subjected to a critical analysis. The results of studies of the mixed association of dye molecules and of its influence on the lasing characteristics of the solutions are presented. The physicochemical conditions affecting the efficiency of the association process are examined. The bibliography includes 251 references.

  1. Synthesis of highly phosphonic acid functionalized benzene-bridged periodic mesoporous organosilicas for use as efficient dye adsorbents.

    PubMed

    Deka, Juti Rani; Liu, Chia-Ling; Wang, Tzu-Hua; Chang, Wei-Chieh; Kao, Hsien-Ming

    2014-08-15

    Periodic mesoporous organosilicas (PMOs) with benzene bridging groups in the silica wall were functionalized with a tunable content of phosphonic acid groups. These bifunctional materials were synthesized by co-condensation of two different organosilane precursors, that is, 1,4-bis(triethoxysilyl)benzene (BTEB) and sodium 3-(trihydroxysilyl)propyl methyl phosphate (SPMP), under acidic conditions using nonionic surfactant Brij-S10 as template. The materials exhibited well-ordered mesostructures and were characterized by X-ray diffraction, nitrogen sorption, TEM, TGA, FTIR, and solid-state NMR measurements. The materials thus obtained were employed as adsorbents to remove different types of dyes, for example, cationic dyes methylene blue and phenosafranine, anionic orange II, and amphoteric rhodamine B, from aqueous solutions. The materials exhibited a remarkably high adsorption capacity than activated carbon due to their ordered mesostructures, a large number of phosphonic acid groups, and high surface areas. The adsorption was mainly governed by electrostatic interaction, but also involved π-π stacking interaction as well as hydrogen bonding. The adsorption kinetics can be better fitted by the pseudo-second order model. The adsorption process was controlled by the mechanisms of external mass transfer and intraparticle diffusion. The materials retained more than 97% dye removal efficiency after use for five consecutive cycles. PMID:25010459

  2. Mechanism of charge transfer and its impacts on Fermi-level pinning for gas molecules adsorbed on monolayer WS2.

    PubMed

    Zhou, Changjie; Yang, Weihuang; Zhu, Huili

    2015-06-01

    Density functional theory calculations were performed to assess changes in the geometric and electronic structures of monolayer WS2 upon adsorption of various gas molecules (H2, O2, H2O, NH3, NO, NO2, and CO). The most stable configuration of the adsorbed molecules, the adsorption energy, and the degree of charge transfer between adsorbate and substrate were determined. All evaluated molecules were physisorbed on monolayer WS2 with a low degree of charge transfer and accept charge from the monolayer, except for NH3, which is a charge donor. Band structure calculations showed that the valence and conduction bands of monolayer WS2 are not significantly altered upon adsorption of H2, H2O, NH3, and CO, whereas the lowest unoccupied molecular orbitals of O2, NO, and NO2 are pinned around the Fermi-level when these molecules are adsorbed on monolayer WS2. The phenomenon of Fermi-level pinning was discussed in light of the traditional and orbital mixing charge transfer theories. The impacts of the charge transfer mechanism on Fermi-level pinning were confirmed for the gas molecules adsorbed on monolayer WS2. The proposed mechanism governing Fermi-level pinning is applicable to the systems of adsorbates on recently developed two-dimensional materials, such as graphene and transition metal dichalcogenides. PMID:26049513

  3. Single-Molecule Magnets: Giant Hysteresis of Single-Molecule Magnets Adsorbed on a Nonmagnetic Insulator (Adv. Mater. 26/2016).

    PubMed

    Wäckerlin, Christian; Donati, Fabio; Singha, Aparajita; Baltic, Romana; Rusponi, Stefano; Diller, Katharina; Patthey, François; Pivetta, Marina; Lan, Yanhua; Klyatskaya, Svetlana; Ruben, Mario; Brune, Harald; Dreiser, Jan

    2016-07-01

    In Tb(Pc)2 single-molecule magnets, where Pc is phthalocyanine, adsorbed on magnesium oxide, the fluctuations of the terbium magnetic moment are strongly suppressed in contrast to the adsorption on silver. On page 5195, J. Dreiser and co-workers investigate that the molecules are perfectly organized by self-assembly, as seen in the scanning tunnelling microscopy image (top part of the design). The molecules are probed by circularly polarized X-rays depicted as green spirals. PMID:27383020

  4. Imaging the wave functions of adsorbed molecules using angle-resolved photoemmision data

    NASA Astrophysics Data System (ADS)

    Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F. Stefan; Ramsey, Michael G.; Puschnig, Peter

    2014-03-01

    The frontier electronic orbitals of molecules are the prime determinants of the respective compounds' chemical, electronic, and optical properties. Although orbitals are very powerful concepts, experimentally only the electron densities and energy levels are directly observable. As has been shown in recent publications, angle-resolved photoemission (ARPES) intensity maps of organic molecular layers are related to the absolute value of the Fourier transform of the initial state molecular orbital. However, the lost phase information impedes the back-transformation of the orbital into real space. Here, we show how molecular orbital images as well as the absent phase information can be retrieved by applying an iterative procedure which takes experimental ARPES maps as input and only assumes spatial confinement of the orbital. The method is demonstrated for several molecular orbitals of two proto-typical pi-conjugated molecules: the LUMO, HOMO, and HOMO-1 of pentacene, and the LUMO and HOMO of PTCDA. The technique is simple and robust and further emphasizes the capabilities of ARPES looking at spatial distributions of wave functions of adsorbed molecules thereby complementing data obtained from scanning probe methods.

  5. Room temperature differential conductance measurements of triethylamine molecules adsorbed on Si(001).

    PubMed

    Naitabdi, Ahmed; Rochet, François; Carniato, Stéphane; Bournel, Fabrice; Gallet, Jean-Jacques

    2016-08-17

    We have measured the differential conductance of the triethylamine molecule (N(CH2CH3)3) adsorbed on Si(001)-2 × 1 at room temperature using scanning tunneling spectroscopy. Triethylamine can be engaged in a dative bonding with a silicon dimer, forming a Si-Si-N(CH2CH3)3 unit. We have examined the datively bonded adduct, either as an isolated molecule, or within an ordered molecular domain (reconstructed 4 × 2). The differential conductance curves, supported by DFT calculations, show that in the explored energy window (±2.5 near the Fermi level) the main features stem from the uncapped dangling bonds of the reacted dimer and of the adjacent unreacted ones that are electronically coupled The formation of a molecular domain, in which one dimer in two is left unreacted, is reflected in a shift of the up dimer atom occupied level away from the Fermi level, likely due to an increased π-bonding strength. In stark contrast with the preceding, pairs of dissociated molecule (a minority species) are electronically decoupled from the dimer dangling bond states. DFT calculation show that the lone-pair of the Si-N(CH2CH3)2 is a shallow level, that is clearly seen in the differential conductance curve. PMID:27499070

  6. Preparation of dye-adsorbing ZnO thin films by electroless deposition and their photoelectrochemical properties.

    PubMed

    Nagaya, Satoshi; Nishikiori, Hiromasa

    2013-09-25

    Dye-adsorbing ZnO thin films were prepared on ITO films by electroless deposition. The films were formed in an aqueous solution containing zinc nitrate, dimethylamine-borane, and eosin Y at 328 K. The film thickness was 1.2-2.0 μm. Thinner and larger-plane hexagonal columns were produced from the solution containing a higher concentration of eosin Y. A photocurrent was observed in the electrodes containing such ZnO films during light irradiation. The photoelectrochemical performance of the film was improved by increasing the concentration of eosin Y because of increases in the amount of absorbed photons and the electronic conductivity of ZnO. PMID:24020721

  7. Effect of resonance dipole-dipole interaction on spectra of adsorbed SF6 molecules.

    PubMed

    Dobrotvorskaia, Anna N; Kolomiitsova, Tatiana D; Petrov, Sergey N; Shchepkin, Dmitriy N; Smirnov, Konstantin S; Tsyganenko, Alexey A

    2015-09-01

    Adsorption of SF6 on zinc oxide and on silicalite-1 was investigated by a combination of IR spectroscopy with the calculations of spectra by means of a modernized model, developed previously for liquids. Comparison of the experimental spectra and the results of modeling shows that the complex band shapes in spectra of adsorbed molecules with extremely high absorbance are due to the strong resonance dipole-dipole interaction (RDDI) rather that the surface heterogeneity or the presence of specific surface sites. Perfect agreement between calculated and observed spectra was found for ZnO, while some dissimilarity in band intensities for silicalite-1 was attributed to complicated geometry of molecular arrangement in the channels. PMID:25897721

  8. Cooperative Emission of Dye Molecules at High Dephasing Rates

    NASA Astrophysics Data System (ADS)

    Klochkov, V. P.; Verkhovskiĭ, E. B.

    2000-05-01

    The dependence of the emission of a concentrated (˜1019 cm-3 solution of Rhodamine C on the power density Φ of exciting laser radiation was studied. The emission intensity for the power density of exciting radiation above ˜1025 cm-2 s-1 was found to have a nearly quadratic dependence on the power density Φ, and this emission was interpreted as the cooperative spontaneous emission of a Dicke type. For Φ≲1025 cm-2 s-1, the emission intensity increased with increasing Φ according to the exponential law. This emission was interpreted as the amplified spontaneous emission. The spectra of cooperative emission depended on the pump radiation power only weakly. The absence of lasing in dye solutions at high concentrations, which is a well-known phenomenon, was shown to be caused by the development of the cooperative spontaneous emission and not by the concentration quenching, and the former process is more rapid than the latter.

  9. Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control

    NASA Astrophysics Data System (ADS)

    Das, Sujoy K.; Khan, Md. Motiar R.; Parandhaman, T.; Laffir, Fathima; Guha, Arun K.; Sekaran, G.; Mandal, Asit Baran

    2013-05-01

    A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology. The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π-π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes.A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through

  10. Benzene carboxylic acid derivatized graphene oxide nanosheets on natural zeolites as effective adsorbents for cationic dye removal.

    PubMed

    Yu, Yang; Murthy, Bandaru N; Shapter, Joseph G; Constantopoulos, Kristina T; Voelcker, Nicolas H; Ellis, Amanda V

    2013-09-15

    Graphene oxide (GO) nanosheets were grafted to acid-treated natural clinoptilolite-rich zeolite powders followed by a coupling reaction with a diazonium salt (4-carboxybenzenediazoniumtetrafluoroborate) to the GO surface. Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) revealed successful grafting of GO nanosheets onto the zeolite surface. The application of the adsorbents for the adsorption of rhodamine B from aqueous solutions was then demonstrated. After reaching adsorption equilibrium the maximum adsorption capacities were shown to be 50.25, 55.56 and 67.56 mg g(-1) for pristine natural zeolite, GO grafted zeolite (GO-zeolite) and benzene carboxylic acid derivatized GO-zeolite powders, respectively. The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. Further, a relationship between surface functional groups, pH and adsorption efficiency was established. Results indicate that benzene carboxylic acid derivatized GO-zeolite powders are environmentally favorable adsorbents for the removal of cationic dyes from aqueous solutions. PMID:23778259

  11. Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control.

    PubMed

    Das, Sujoy K; Khan, Md Motiar R; Parandhaman, T; Laffir, Fathima; Guha, Arun K; Sekaran, G; Mandal, Asit Baran

    2013-06-21

    A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology. The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π-π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes. PMID:23680871

  12. Does Moisture Influence the Chemical Detection of Gas Molecules Adsorbed on Single-Wall Carbon Nanotubes?

    NASA Astrophysics Data System (ADS)

    Yu, Ming; Tian, W. Q.; Jayanthi, C. S.; Wu, S. Y.

    2009-03-01

    In this work, the role of water in the detection of hydrazine (N2H4) by a single-wall carbon nanotube (SWCNT) is investigated using first principles electronic structure calculations (DFT/GGA--USPP)[1]. This calculation is undertaken to interpret the experimental resistivity measurements for N2H4 adsorbed on SWCNT that reveal an n-type behavior [2]. Our preliminary theoretical studies of the adsorption of N2H4 on SWCNT revealed physisorption for N2H4 and an unaltered band structure for the SWCNT [3]. This prompted us to look into the role of water on the bonding of N2H4 to the SWCNT. We found that, by introducing a monolayer of water film on the (8,0) SWCNT, the adsorption of N2H4 can introduce occupied states near the Fermi level, exhibiting an n-type behavior. However, the introduction of just few water molecules was not sufficient to influence the electronic structure of N2H4/SWCNT. Presently, we are studying the influence of water films on the chemical detection of a variety of other gas molecules (N2, NH3, etc.) by SWCNTs, and the results from such studies will also be reported. [1]. G. Kresse et al. Phys. Rev. B 54, 11169 (1996). [2]. S. Desai, et al. (APS, March 2008). [3]. M. Yu, et al. (APS, March 2008).

  13. Hierarchical Porous and High Surface Area Tubular Carbon as Dye Adsorbent and Capacitor Electrode.

    PubMed

    Chen, Long; Ji, Tuo; Brisbin, Logan; Zhu, Jiahua

    2015-06-10

    Hierarchically porous tubular carbon (HPTC) with large surface area of 1094 m(2)/g has been successfully synthesized by selectively removing lignin from natural wood. No templates or chemicals are involved during the process. By further KOH activation, surface area of activated HPTC reaches up to 2925 m(2)/g. These materials show unprecedented high adsorption capacity toward organic dyes (methylene blue, 838 mg/g; methyl orange, 264 mg/g) and large electrochemical capacitance of >200 F/g. The sustainable feature of the wood precursor and demonstrated superior adsorption and energy storage properties allow promising applications of the processed materials in energy and environmental related fields. PMID:25980528

  14. The analysis of surface-adsorbed organic molecules by alkali-assisted MIES combined with UPS(He I)

    NASA Astrophysics Data System (ADS)

    Günster, J.; Ochs, D.; Dieckhoff, S.; Kempter, V.

    1996-12-01

    Metastable impact electron spectroscopy (MIES) in combination with UPS(He I) is applied to the study of s-triazine and triethoxytriazine molecules adsorbed on Si(100) either alone or in combination with cesium atoms. It is demonstrated that the presence of the Cs atoms facilitates the identification of the adsorbed species considerably. It is concluded that (i) non-dissociative adsorption of the studied organic molecules occurs whereby the basal rings of the molecules lie flat on the silicon surface, in accordance with previous studies by Bu and Lin, (ii) the binding of the molecules to the surface is mainly via the lone pair orbitals of the nitrogen in the ring, and (iii) s-triazine reacts strongly with oxygen which bonds to the carbon atoms of the triazine ring.

  15. Superresolution imaging of single DNA molecules using stochastic photoblinking of minor groove and intercalating dyes.

    PubMed

    Miller, Helen; Zhou, Zhaokun; Wollman, Adam J M; Leake, Mark C

    2015-10-15

    As proof-of-principle for generating superresolution structural information from DNA we applied a method of localization microscopy utilizing photoblinking comparing intercalating dye YOYO-1 against minor groove binding dye SYTO-13, using a bespoke multicolor single-molecule fluorescence microscope. We used a full-length ∼49 kbp λ DNA construct possessing oligo inserts at either terminus allowing conjugation of digoxigenin and biotin at opposite ends for tethering to a glass coverslip surface and paramagnetic microsphere respectively. We observed stochastic DNA-bound dye photoactivity consistent with dye photoblinking as opposed to binding/unbinding events, evidenced through both discrete simulations and continuum kinetics analysis. We analyzed dye photoblinking images of immobilized DNA molecules using superresolution reconstruction software from two existing packages, rainSTORM and QuickPALM, and compared the results against our own novel home-written software called ADEMS code. ADEMS code generated lateral localization precision values of 30-40 nm and 60-70 nm for YOYO-1 and SYTO-13 respectively at video-rate sampling, similar to rainSTORM, running more slowly than rainSTORM and QuickPALM algorithms but having a complementary capability over both in generating automated centroid distribution and cluster analyses. Our imaging system allows us to observe dynamic topological changes to single molecules of DNA in real-time, such as rapid molecular snapping events. This will facilitate visualization of fluorescently-labeled DNA molecules conjugated to a magnetic bead in future experiments involving newly developed magneto-optical tweezers combined with superresolution microscopy. PMID:25637032

  16. Optical orientation of azo dye molecules in a thin solid film upon nonlinear excitation by femtosecond laser pulses

    SciTech Connect

    Yongseok, Jung; Kozenkov, V M; Magnitskiy, Sergey A; Nagorskiy, Nikolay M

    2006-11-30

    The orientation of molecules in an amorphous pure azo dye film upon nonlinear excitation is detected for the first time. The simultaneous increase and decrease in the film transmission by a factor of 2.5 for orthogonal polarisations of probe radiation indicated the appearance of orientation order in the film caused by the reorientation of azo dye molecules. Due to a high photostability of the AD-1 azo dye demonstrated in single-photon experiments and a high efficiency of nonlinear orientation obtained in experiments with femtosecond pulses, this dye can be widely used in three-dimensional nanophotonic devices such as photonic crystals, optical computers, and optical memory. (letters)

  17. An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: A novel reusable adsorbent

    NASA Astrophysics Data System (ADS)

    Haldorai, Yuvaraj; Shim, Jae-Jin

    2014-02-01

    We report a novel multi-functional magnesium oxide (MgO) immobilized chitosan (CS) composite was prepared by chemical precipitation method. The CS-MgO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and zeta potential. The composite was applied as a novel adsorbent for removal of methyl orange model dye and the effect of adsorbent dosage, pH and contact time were studied. The adsorption kinetics followed a pseudo second order reaction. The adsorbent efficiency was unaltered even after five cycles of reuse. In addition, the composite exhibited a superior antibacterial efficacy of 93% within 24 h against Escherichia coli as measured by colony forming units. Based on the data of present investigation the composite being a biocompatible, eco-friendly and low-cost adsorbent with antibacterial activity could find potential applications in variety of fields and in particular environmental applications.

  18. Barriers to intramolecular rotation determined from the temperature dependence of the Henry constant in the region of adsorbed molecule rigidity failure

    NASA Astrophysics Data System (ADS)

    Dolgonosov, A. M.; Prudkovskii, A. G.

    2008-05-01

    A distribution for the rigid and nonrigid adsorbed molecule forms was found. Adsorbed molecule rigidity failure was shown to be accompanied by a weak nonlinear effect, which manifested itself as a temperature dependence of the Henry constant. A method for the determination of the barrier to intramolecular rotation from the temperature dependence of the molecule adsorption constant was suggested. Barriers to rotation about the C-C and C-O bonds were determined for several molecules.

  19. Application of acidic treated pumice as an adsorbent for the removal of azo dye from aqueous solutions: kinetic, equilibrium and thermodynamic studies

    PubMed Central

    2012-01-01

    Colored effluents are one of the important environment pollution sources since they contain unused dye compounds which are toxic and less-biodegradable. In this work removal of Acid Red 14 and Acid Red 18 azo dyes was investigated by acidic treated pumice stone as an efficient adsorbent at various experimental conditions. Removal of dye increased with increase in contact time and initial dye concentration, while decreased for increment in solution temperature and pH. Results of the equilibrium study showed that the removal of AR14 and AR18 followed Freundlich (r2>0.99) and Langmuir (r2>0.99) isotherm models. Maximum sorption capacities were 3.1 and 29.7 mg/g for AR 14 and AR18, namely significantly higher than those reported in the literature, even for activated carbon. Fitting of experimental data onto kinetic models showed the relevance of the pseudo-second order (r2>0.99) and intra-particle diffusion (r2>0.98) models for AR14 and AR18, respectively. For both dyes, the values of external mass transfer coefficient decreased for increasing initial dye concentrations, showing increasing external mass transfer resistance at solid/liquid layer. Desorption experiments confirmed the relevance of pumice stone for dye removal, since the pH regeneration method showed 86% and 89% regeneration for AR14 and AR18, respectively. PMID:23369579

  20. Application of acidic treated pumice as an adsorbent for the removal of azo dye from aqueous solutions: kinetic, equilibrium and thermodynamic studies.

    PubMed

    Samarghandi, Mohammad Reza; Zarrabi, Mansur; Sepehr, Mohammad Noori; Amrane, Abdeltif; Safari, Gholam Hossein; Bashiri, Saied

    2012-01-01

    Colored effluents are one of the important environment pollution sources since they contain unused dye compounds which are toxic and less-biodegradable. In this work removal of Acid Red 14 and Acid Red 18 azo dyes was investigated by acidic treated pumice stone as an efficient adsorbent at various experimental conditions. Removal of dye increased with increase in contact time and initial dye concentration, while decreased for increment in solution temperature and pH. Results of the equilibrium study showed that the removal of AR14 and AR18 followed Freundlich (r2>0.99) and Langmuir (r2>0.99) isotherm models. Maximum sorption capacities were 3.1 and 29.7 mg/g for AR 14 and AR18, namely significantly higher than those reported in the literature, even for activated carbon. Fitting of experimental data onto kinetic models showed the relevance of the pseudo-second order (r2>0.99) and intra-particle diffusion (r2>0.98) models for AR14 and AR18, respectively. For both dyes, the values of external mass transfer coefficient decreased for increasing initial dye concentrations, showing increasing external mass transfer resistance at solid/liquid layer. Desorption experiments confirmed the relevance of pumice stone for dye removal, since the pH regeneration method showed 86% and 89% regeneration for AR14 and AR18, respectively. PMID:23369579

  1. Functionalization of boron-doped nanocrystalline diamond with N3 dye molecules.

    PubMed

    Yeap, W S; Liu, X; Bevk, D; Pasquarelli, A; Lutsen, L; Fahlman, M; Maes, W; Haenen, K

    2014-07-01

    N3 dye molecules [cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(II)] are covalently attached to boron-doped nanocrystalline diamond (B:NCD) thin films through a combination of coupling chemistries, i.e., diazonium, Suzuki, and EDC-NHS. X-ray and ultraviolet photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy are used to verify the covalent bonding of the dye on the B:NCD surface (compared to a hydrogen-terminated reference). The spectroscopic results confirm the presence of a dense N3 chromophore layer, and the positions of the frontier orbitals of the dye relative to the band edge of the B:NCD thin film are inferred as well. Proof-of-concept photoelectrochemical measurements show a strong increase in the photocurrent compared to non-dye-functionalized B:NCD films. This study opens up the possibility of applying N3-sensitized B:NCD thin films as hole conductors in dye-sensitized solar cells. PMID:24915549

  2. Direct comparison of the electronic coupling efficiency of sulfur and selenium alligator clips for molecules adsorbed onto gold electrodes

    NASA Astrophysics Data System (ADS)

    Patrone, L.; Palacin, S.; Bourgoin, J. P.

    2003-05-01

    Scanning tunneling microscopy experiments have been performed to compare the electronic coupling provided by S and by Se used as alligator clips for bisthiol- and biselenol-terthiophene molecules adsorbed onto gold. The molecules were inserted in a dodecanethiol (DT) self-assembled monolayer. Their apparent height above the dodecanethiol matrix was used as a measure of the electronic coupling strength corresponding to S and Se, respectively. We show that the insertion behaviors of the two molecules are qualitatively the same, and that Se provides systematically a better coupling link than S, whatever the tunneling conditions.

  3. Direct comparison of the electronic coupling efficiency of sulfur and selenium anchoring groups for molecules adsorbed onto gold electrodes

    NASA Astrophysics Data System (ADS)

    Patrone, L.; Palacin, S.; Bourgoin, J. P.; Lagoute, J.; Zambelli, T.; Gauthier, S.

    2002-08-01

    We performed air and ultra-high vacuum scanning tunneling microscopy experiments in order to compare the electronic coupling provided by S and by Se used as alligator clips for bisthiol- and biselenol-terthiophene molecules adsorbed onto gold. The molecules were inserted in a dodecanethiol self-assembled monolayer. Their apparent height above the dodecanethiol matrix was used as a measure of the electronic coupling strength corresponding to S and Se, respectively. We show that the insertion behaviors of the two molecules are qualitatively the same, and that Se provides systematically a better coupling link than S whatever the tunneling conditions.

  4. Detection of smectites in ppm and sub-ppm concentrations using dye molecule sensors

    NASA Astrophysics Data System (ADS)

    Lofaj, Marcel; Bujdák, Juraj

    2012-03-01

    Methylene blue and rhodamine 6G were used as molecular sensors for the spectrophotometric titrations of the aqueous colloids of clay minerals (montmorillonite, illite and kaolinite). The dyes adsorbed on colloid particles form molecular aggregates, which exhibit spectral properties significantly different from those of dye solutions. Spectrophotometric titrations provide the most sensitive detection of smectites in aqueous colloids (sub-ppm concentrations); and the sensitivity further increases using second derivative spectroscopy. The endpoint of spectrophotometric titrations can be used for the determination of exchange capacity of the mineral in colloids and in this way to estimate its amount. The method is selective only to expandable clays, which was proven by experiments with kaolinite and illite. Spectrophotometric titrations have promising future in the analysis of clays and can be applied in many fields of geology, mineralogy, chemistry, material sciences or in industry. Its application may expand to the analysis of other nanomaterials built from charged particles and exhibiting metachromasy in the systems with organic dyes.

  5. Tunneling Spectroscopy Studies of Urea, Thiourea, and Selected Phosphonate Molecules Adsorbed on Aluminum Oxide

    NASA Astrophysics Data System (ADS)

    Crowder, Charles D.

    Experimental and calculated inelastic electron tunneling intensities were compared for several of the vibrational modes of thiourea adsorbed on aluminum oxide. The partial charge model of Kirtley, Scalapino, and Hansma was used to compute the theoretical intensities of each mode. The required partial charges were determined using a method developed by Momany. Essentially, the Coulomb potential resulting from point charges located at atom sites was fitted to the quantum mechanical electrostatic potential of a molecule calculated from Hartree-Fock theory. The effect of a vibrational mode pattern on the electrostatic potential of a molecule was investigated. This effect could not be acceptably modeled with a single point charge located on each atom, so one charge was used to represent the positive nucleus of each atom and a second charge was used to represent the valence cloud. The valence charge was allowed to move independently of the nuclear charge during a molecular vibration, and the motions of the two charges were found to be very different for hydrogen atoms. This model gave very reasonable agreement between the theoretical and observed relative intensities for the in plane vibrational modes of thiourea. An acceptable set of out of plane force constants could not be found. This caused problems in the interpretation of the out of plane relative intensities. Based on the in plane modes, it was concluded that thiourea bonded to aluminum oxide with the sulfur atom near the oxide and the sulfur-carbon bond perpendicular to the aluminum oxide surface. Quantum mechanical electrostatic potentials were also calculated for urea, phosphoric acid (PA), methylphosphonic acid (MPA), hydroxymethylphosphonic acid (HMP), and nitrotrismethylphosphonic acid (NTMP). Electron tunneling spectra were taken for PA, HMP and NTMP, and the observed frequencies were compared to values obtained from Fourier transform infrared, infrared and Raman spectroscopy. Upward shifts in the P=O and P

  6. In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO₂ Surface of Dye-Sensitized Solar Cells.

    PubMed

    Voïtchovsky, Kislon; Ashari-Astani, Negar; Tavernelli, Ivano; Tétreault, Nicolas; Rothlisberger, Ursula; Stellacci, Francesco; Grätzel, Michael; Harms, Hauke A

    2015-05-27

    Amphiphilic sensitizers are central to the function of dye-sensitized solar cells. It is known that the cell's performance depends on the molecular arrangement and the density of the dye on the semiconductor surface, but a molecular-level picture of the cell-electrolyte interface is still lacking. Here, we present subnanometer in situ atomic force microscopy images of the Z907 dye at the surface of TiO2 in a relevant liquid. Our results reveal changes in the conformation and the lateral arrangement of the dye molecules, depending on their average packing density on the surface. Complementary quantitative measurements on the ensemble of the film are obtained by the quartz-crystal microbalance with dissipation technique. An atomistic picture of the dye coverage-dependent packing, the effectiveness of the hydrophobic alkyl chains as blocking layer, and the solvent accessibility is obtained from molecular dynamics simulations. PMID:25936429

  7. Optical devices based on dye-coated superconductor junctions: An example of a composite molecule-superconductor device

    SciTech Connect

    Zhao, J.; Jurbergs, D.; Yamazi, B.; McDevitt, J.T.

    1992-03-25

    High-temperature superconductors provide new opportunities as materials used in the construction of hybrid molecule-superconductor components. Here, the authors describe fabrication methods for and operation of optical sensors based on molecular dye-coated superconductor junctions. Devices prepared from yttrium barium cuprates and using octaethylporphyrin, phthalocyanine, and rhodamine 6G as dyes have been prepared. 9 refs., 1 fig.

  8. Effects of molecule-insulator interaction on geometric property of a single phthalocyanine molecule adsorbed on an ultrathin NaCl film

    NASA Astrophysics Data System (ADS)

    Miwa, Kuniyuki; Imada, Hiroshi; Kawahara, Shota; Kim, Yousoo

    2016-04-01

    The adsorption structure and orientation of a metal-free phthalocyanine (H2Pc ) and a magnesium phthalocyanine (MgPc) on a bilayer of NaCl films were investigated both theoretically and experimentally by means of first-principles calculations based on density functional theory and by scanning tunneling microscopy. H2Pc is adsorbed with its center over the sodium cation, and H-N bonds in the molecule are aligned with the [100] or [010] surface direction of a bilayer (001)-terminated NaCl film. The most stable structures of MgPc on the NaCl film show two kinds of orientations corresponding to the molecule rotated by ±7∘ relative to the [110] surface direction, with the Mg cation positioned over the chlorine anion in both cases. The energetic barrier for switching between these orientations is as low as 9.0 meV, and during an STM measurement, an orientational change of MgPc can be observed. The interaction between the adsorbed molecule and the NaCl film were analyzed in terms of dispersion interaction, Mg-Cl chemical bonding, and electrostatic interaction. It is found that the small electrostatic interaction between the molecule and the film gives a dominant contribution to determining the molecular orientation. Our detailed and comprehensive studies of the molecule-insulator interaction will provide knowledge to understand and control the properties of molecules on an insulating material.

  9. Highly Fluorescent dye-nanoclay Hybrid Materials Made from Different Dye Classes.

    PubMed

    Grabolle, Markus; Starke, Marian; Resch-Genger, Ute

    2016-04-12

    Nanoclays like laponites, which are commercially avaible in large quantities for a very moderate price, provide a facile solubilization strategy for hydrophobic dyes without the need for chemical functionalization and can act as a carrier for a high number of dye molecules. This does not require reactive dyes, amplifies fluorescence signals from individual emitters due to the high number of dyes molecules per laponite disk, and renders hydrophobic emitters applicable in aqueous environments. Aiming at the rational design of bright dye-loaded nanoclays as a new class of fluorescent reporters for bioanalysis and material sciences and the identification of dye structure-property relationships, we screened a series of commercial fluorescent dyes, differing in dye class, charge, and character of the optical transitions involved, and studied the changes of their optical properties caused by clay adsorption at different dye loading concentrations. Upon the basis of our dye loading density-dependent absorption and fluorescence measurements with S2105 and Lumogen F Yellow 083, we could identify two promising dye-nanoclay hybrid materials that reveal high fluorescence quantum yields of the nanoclay-adsorbed dyes of at least 0.20 and low dye self-quenching even at high dye-loading densities of up to 50 dye molecules per laponite platelet. PMID:27007448

  10. Encapsulation of dye molecules and nanoparticles in hollow organogel fibers of a nonchiral polyurethane model compound.

    PubMed

    Khan, Mostofa Kamal; Sundararajan, Pudupadi

    2011-01-24

    We present the case of a nonchiral organogelator that forms hollow fibers and encapsulates silver nanoparticles (SNP) and a dye molecule. The biscarbamate molecule (a model compound for polyurethanes), which has two hydrogen-bonding motifs symmetrically attached to n-dodecyl side chains (C(12)), gels benzonitrile with hollow fibrillar morphology. The C(12) molecules form sheets that eventually wrap into hollow fibers to form the gel network. Herein, two-component gels were prepared with C(12) as one component and SNP, phthalocyanine (Pc), or perylene (Pe) as the other. Microscopic analysis and partial melting experiments confirmed the inclusion of the silver nanoparticles and phthalocyanine into the hollow fibers. On the other hand, Pe molecules tend to form crystals at the outer surface of the C(12) fibers, which results in a significant increase in the width of the gel fibers. This difference in the behavior of Pc and Pe molecules were accounted for by their crystal geometry and significantly different crystal growth rate compared with that of C(12) fiber formation in the gels. Pc crystallizes in a needle shape that facilitates occlusion in the gel fibers, whereas Pe forms large platelets. X-ray diffraction and spectroscopic analysis of the two-component gels along with their neat components confirmed that there was no change in the packing behavior of the Pc and Pe molecules in the gels. Therefore, these are examples of two-component physical gels in which the Pc crystals are occluded within the hollow fibers of C(12) by physical mixing of the components without the aid of any inter-molecular interactions between the different components. We have thus shown that lumen-loaded gel fibers with nanoparticles and dye molecules can be prepared by the two-component gel route, provided that the above growth rate, shape, and size conditions are satisfied. PMID:21243684

  11. X-ray absorption spectroscopy of biomimetic dye molecules for solar cells

    SciTech Connect

    Cook, Peter L.; Liu Xiaosong; Himpsel, F. J.; Yang Wanli

    2009-11-21

    Dye-sensitized solar cells are potentially inexpensive alternatives to traditional semiconductor solar cells. In order to optimize dyes for solar cells we systematically investigate the electronic structure of a variety of porphyrins and phthalocyanines. As a biological model system we use the heme group in cytochrome c which plays a role in biological charge transfer processes. X-ray absorption spectroscopy of the N 1s and C 1s edges reveals the unoccupied molecular orbitals and the orientation of the molecules in thin films. The transition metal 2p edges reflect the oxidation state of the central metal atom, its spin state, and the ligand field of the surrounding N atoms. The latter allows tuning of the energy position of the lowest unoccupied orbital by several tenths of an eV by tailoring the molecules and their deposition. Fe and Mn containing phthalocyanines oxidize easily from +2 to +3 in air and require vacuum deposition for obtaining a reproducible oxidation state. Chlorinated porphyrins, on the other hand, are reduced from +3 to +2 during vacuum deposition at elevated temperatures. These findings stress the importance of controlled thin film deposition for obtaining photovoltaic devices with an optimum match between the energy levels of the dye and those of the donor and acceptor electrodes, together with a molecular orientation for optimal overlap between the {pi} orbitals in the direction of the carrier transport.

  12. Lifetime of fluorescent dye molecules in dense aqueous suspensions of polystyrene nanoparticles.

    PubMed

    Scalia, Giuseppe; Scheffold, Frank

    2015-11-16

    We study the lifetime of two common fluorescent dye molecules from the Alexa Fluor NHS Ester family dissolved in water in an opaque aqueous dispersion of dielectric polystyrene nanoparticles. We investigate the role of the dispersion composition by varying the particle concentration and adding SDS (sodium dodecyl sulfate) surfactant molecules. The observed strong changes in lifetime of Alexa 430 can be attributed to the relative contribution of radiative and non-radiative decay channels while the lifetime of the Alexa 488 dye depends only weakly on the sample composition. For Alexa 430, a dye with a rather low quantum yield in aqueous solution, the addition of polystyrene nanoparticles leads to a significant enhancement in quantum yield and an associated increase of the fluorescent lifetime by up to 55 %. We speculate that the increased quantum yield can be attributed to the hydrophobic effect on the structure of water in the boundary layer around the polystyrene particles in suspension. Adding SDS acts as a quencher. Over a range of particle concentrations the particle induced increase of the lifetime can be completely compensated by adding SDS. PMID:26698418

  13. Thermodynamic Driving Forces for Dye Molecule Position and Orientation in Nanoconfined Solvents.

    PubMed

    Harvey, Jacob A; Thompson, Ward H

    2015-07-23

    The results of replica exchange molecular dynamics simulations of a coumarin 153 (C153) dye molecule dissolved in ethanol confined within a 2.4 nm hydrophilic amorphous silica pore are presented. The C153 dye position and orientation distributions provide insight into time-dependent fluorescence measurements in nanoconfined solvents as well as general features of chemistry in mesoporous materials. In addition to the distributions themselves, the free energy, internal energy, and entropic contributions have been calculated to explore the factors determining the distributions. The most likely location of C153 is found to be near the pore surface, but two possible hydrogen-bonding structures lead to differing orientations. Internal energy and entropy are found to be competing forces within the pore, with entropy playing a significant role with unexpected consequences. These results represent a crucial step in determining how the nanoconfining framework can affect measurements of solvation dynamics. PMID:25295835

  14. Evaluation of thermodynamic and photophysical properties of tricarbocyanine near-IR dyes in organized media using single-molecule monitoring

    NASA Astrophysics Data System (ADS)

    Soper, Steven A.; Legendre, Benjamin L., Jr.; Huang, Jiping

    1995-05-01

    Detection of single NIR fluorescent dye molecules in the organized media sodium dodecyl sulfate (SDS) and triton X-100 surfactnts above their critical micelle concentrations was used to determine partition coefficients and photophysical properties of dye molecules resident within the micelle aggregate. Inspection of the filtered data showed evidence of large amplitude photon bursts arising from single molecular events in these organized media. In pure H 2O containing dye, no bursts were observed. The results indicate that only molecules resident within the hydrophobic core of the micelle were detected. From the number of events observed and the number of events expected, partition coefficients ( Kp) for IR-132 in SDS and triton X-100 solutions were calculated. In addition, the photon yield per molecule associated with only those molecules resident within the hydrophobic cavity of the micelle was determined.

  15. Playing with dye molecules at the inner and outer surface of zeolite L

    NASA Astrophysics Data System (ADS)

    Calzaferri, Gion; Brühwiler, Dominik; Megelski, Silke; Pfenniger, Michel; Pauchard, Marc; Hennessy, Brian; Maas, Huub; Devaux, André; Graf, Urs

    2000-06-01

    Plants are masters of transforming sunlight into chemical energy. In the ingenious antenna system of the leaf, the energy of the sunlight is transported by chlorophyll molecules for the purpose of energy transformation. We have succeeded in reproducing a similar light transport in an artificial system on a nano scale. In this artificial system, zeolite L cylinders adopt the antenna function. The light transport is made possible by specifically organized dye molecules, which mimic the natural function of chlorophyll. Zeolites are crystalline materials with different cavity structures. Some of them occur in nature as a component of the soil. We are using zeolite L crystals of cylindrical morphology which consist of a continuous one-dimensional tube system and we have succeeded in filling each individual tube with chains of joined but noninteracting dye molecules. Light shining on the cylinder is first absorbed and the energy is then transported by the dye molecules inside the tubes to the cylinder ends. We expect that our system can contribute to a better understanding of the important light harvesting process which plants use for the photochemical transformation and storage of solar energy. We have synthesized nanocrystalline zeolite L cylinders ranging in length from 300 to 3000 nm. A cylinder of 800 nm diameter, e.g. consists of about 150 000 parallel tubes. Single red emitting dye molecules (oxonine) were put at each end of the tubes filled with a green emitting dye (pyronine). This arrangement made the experimental proof of efficient light transport possible. Light of appropriate wavelength shining on the cylinder is only absorbed by the pyronine and the energy moves along these molecules until it reaches the oxonine. The oxonine absorbs the energy by a radiationless energy transfer process, but it is not able to send it back to the pyronine. Instead it emits the energy in the form of red light. The artificial light harvesting system makes it possible to

  16. Strength of interactions between immobilized dye molecules and sol-gel matrices.

    PubMed

    Ismail, Fanya; Schoenleber, Monika; Mansour, Rolan; Bastani, Behnam; Fielden, Peter; Goddard, Nicholas J

    2011-02-21

    In this paper we present a new theory to re-examine the immobilization technique of dye doped sol-gel films, define the strength and types of possible bonds between the immobilized molecule and sol-gel glass, and show that the immobilized molecule is not free inside the pores as was previously thought. Immobilizing three different pH sensitive dyes with different size and functional groups inside the same sol-gel films revealed important information about the nature of the interaction between the doped molecule and the sol-gel matrix. The samples were characterized by means of ultraviolet-visible spectrophotometer (UV-VIS), thermal gravimetric analysis (TGA), mercury porosimetry (MP), nuclear magnetic resonance spectroscopy ((29)Si NMR) and field-emission environmental scanning electron microscopy (ESEM-FEG). It was found that the doped molecule itself has a great effect on the strength and types of the bonds. A number of factors were identified, such as number and types of the functional groups, overall charge, size, pK(a) and number of the silanol groups which surround the immobilized molecule. These results were confirmed by the successful immobilization of bromocresol green (BCG) after a completely polymerized sol-gel was made. The sol-gel consisted of 50% tetraethoxysilane (TEOS) and 50% methyltriethoxysilane (MTEOS) (w/w). Moreover, the effect of the immobilized molecule on the structure of the sol-gel was studied by means of a leaky waveguide (LW) mode for doped films made before and after polymerization of the sol-gel. PMID:21120245

  17. Large pi-aromatic molecules as potential sensitizers for highly efficient dye-sensitized solar cells.

    PubMed

    Imahori, Hiroshi; Umeyama, Tomokazu; Ito, Seigo

    2009-11-17

    Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. Thus far, ruthenium(II) bipyridyl complexes have proven to be the most efficient TiO(2) sensitizers in dye-sensitized solar cells. However, a gradual increment in the highest power conversion efficiency has been recognized in the past decade. More importantly, considering that ruthenium is a rare metal, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. Large pi-aromatic molecules, such as porphyrins, phthalocyanines, and perylenes, are important classes of potential sensitizers for highly efficient dye-sensitized solar cells, owing to their photostability and high light-harvesting capabilities that can allow applications in thinner, low-cost dye-sensitized solar cells. Porphyrins possess an intense Soret band at 400 nm and moderate Q bands at 600 nm. Nevertheless, the poor light-harvesting properties relative to the ruthenium complexes have limited the cell performance of porphyrin-sensitized TiO(2) cells. Elongation of the pi conjugation and loss of symmetry in porphyrins cause broadening and a red shift of the absorption bands together with an increasing intensity of the Q bands relative to that of the Soret band. On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved intensively by the enhanced light absorption. Actually, some push-pull-type porphyrins have disclosed a remarkably high power conversion efficiency (6-7%) that was close to that of the ruthenium complexes. Phthalocyanines exhibit strong absorption around 300 and 700 nm and redox features that are similar to porphyrins. Moreover, phthalocyanines are transparent over a large region of the visible spectrum, thereby enabling the possibility of using them as "photovoltaic windows". However, the cell performance was poor, owing to strong aggregation and lack of directionality in the

  18. Third order optical nonlinearities characteristics of Disperse Red1 organic dye molecules inside of polymeric nanocapsules

    NASA Astrophysics Data System (ADS)

    Sharifimehr, Mohammad Reza; Ayoubi, Kazem; Mohajerani, Ezeddin

    2015-11-01

    Measuring nonlinear optical response of a specific material in a mixture, not only leads to investigate the behavior of a particular component in various circumstances, but also can be a way to select suitable combination and optimum concentration of additives and therefore obtaining the maximum nonlinear optical signals. In this work, by using dual-arm Z-scan technique, the nonlinear refractive index of Disperse Red1 (DR1) organic dye molecules inside the core of prepared polymeric nanocapsules was measured among various materials which prepared nanocapsules were made of them. Then the measured value was compared with nonlinear refractive index of DR1 solved in dichloromethane.

  19. Synthesis of magnetic oxidized multiwalled carbon nanotube-κ-carrageenan-Fe3O4 nanocomposite adsorbent and its application in cationic Methylene Blue dye adsorption.

    PubMed

    Duman, Osman; Tunç, Sibel; Polat, Tülin Gürkan; Bozoğlan, Bahar Kancı

    2016-08-20

    In this study, magnetic oxidized multiwalled carbon nanotube (OMWCNT)-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were synthesized and used as adsorbent for the removal of Methylene Blue (MB) from aqueous solution. Magnetic nanocomposites were characterized by using of specific surface area, Fourier transform infrared, X-ray diffraction, vibrating sample magnetometry, thermal gravimetric analysis, scanning electron microscope and transmission electron microscope measurements. The results of characterization analyses exhibited that OMWCNT was successfully modified with κ-carrageenan. Furthermore, OMWCNT-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were of a super-paramagnetic property. Adsorption studies revealed that the data of adsorption kinetics and isotherm were well fitted by the pseudo second-order kinetic model and Langmuir isotherm model, respectively. The adsorption amounts of magnetic adsorbents increased with contact time and initial dye concentration. Compared with magnetic OMWCNT-Fe3O4 nanocomposite, magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite showed a better adsorption performance for the removal of MB from aqueous solution. Therefore, OMWCNT-κ-carrageenan-Fe3O4 nanocomposite may be used as a magnetic adsorbent to remove the cationic dyes from wastewaters. PMID:27178911

  20. Synthesis, photophysical and electrochemical properties of two novel carbazole-based dye molecules

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Zhu, Weiju; Fang, Min; Yin, Fangfang; Li, Cun

    2015-01-01

    Two carbazole-based dye molecules: 3-(6-benzothiazol-2-yl-9H-hexylcarbazole-3-yl)-2-cyano-acylic acid (D3) and 3-[5-(6-benzothiazol-2-yl-9H-hexylcarbazole-3-yl)-thiophen-2-yl]-2-cyan-acylic acid (D4) were synthesized by an approach from carbazole derivate using Vilsmeier-Haack, Suzuki cross-coupling and Knoevenagel reactions. Their physical and electrochemical properties were investigated. D3 and D4 exhibit different optical properties, such as UV absorption, photoluminescence, fluorescence quantum yield and fluorescence lifetime in different solvents. Compared with D3 without a thiophene unit, the maximum absorption wavelength of D4 red-shift obviously and its fluorescence intensity is also enhanced. A shift of the EHOMO and ELUMO is observed for D3 (EHOMO = 2.06 V, ELUMO = -1.39 V vs. NHE) and D4 (EHOMO = 1.73 V, ELUMO = -1.33 V vs. NHE). D3 and D4 can be used as dyes for dye-sensitized solar cells (DSSCs) with TiO2 nanomaterial because their EHOMO are lower than the conduction band edge of TiO2 [-0.5 V (vs. NHE)] and their ELUMO are higher than the I3-/I- redox potential [0.42 V (vs. NHE)].

  1. Synthesis, photophysical and electrochemical properties of two novel carbazole-based dye molecules.

    PubMed

    Zhang, Qing; Zhu, Weiju; Fang, Min; Yin, Fangfang; Li, Cun

    2015-01-25

    Two carbazole-based dye molecules: 3-(6-benzothiazol-2-yl-9H-hexylcarbazole-3-yl)-2-cyano-acylic acid (D3) and 3-[5-(6-benzothiazol-2-yl-9H-hexylcarbazole-3-yl)-thiophen-2-yl]-2-cyan-acylic acid (D4) were synthesized by an approach from carbazole derivate using Vilsmeier-Haack, Suzuki cross-coupling and Knoevenagel reactions. Their physical and electrochemical properties were investigated. D3 and D4 exhibit different optical properties, such as UV absorption, photoluminescence, fluorescence quantum yield and fluorescence lifetime in different solvents. Compared with D3 without a thiophene unit, the maximum absorption wavelength of D4 red-shift obviously and its fluorescence intensity is also enhanced. A shift of the EHOMO and ELUMO is observed for D3 (EHOMO=2.06 V, ELUMO=-1.39 V vs. NHE) and D4 (EHOMO=1.73 V, ELUMO=-1.33 V vs. NHE). D3 and D4 can be used as dyes for dye-sensitized solar cells (DSSCs) with TiO2 nanomaterial because their EHOMO are lower than the conduction band edge of TiO2 [-0.5 V (vs. NHE)] and their ELUMO are higher than the I(3-)/I(-) redox potential [0.42 V (vs. NHE)]. PMID:25104283

  2. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    SciTech Connect

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  3. Determining the exact number of dye molecules attached to colloidal CdSe/ZnS quantum dots in Förster resonant energy transfer assemblies

    NASA Astrophysics Data System (ADS)

    Kaiser, Uwe; Jimenez de Aberasturi, Dorleta; Vázquez-González, Margarita; Carrillo-Carrion, Carolina; Niebling, Tobias; Parak, Wofgang J.; Heimbrodt, Wolfram

    2015-01-01

    Semiconductor quantum dots functionalized with organic dye molecules are important tools for biological sensor applications. Energy transfer between the quantum dot and the attached dyes can be utilized for sensing. Though important, the determination of the real number of dye molecules attached per quantum dot is rather difficult. In this work, a method will be presented to determine the number of ATTO-590 dye molecules attached to CdSe/ZnS quantum dots based on time resolved spectral analysis. The energy transfer from the excited quantum dot to the attached ATTO-590 dye leads to a reduced lifetime of the quantum dot's excitons. The higher the concentration of dye molecules, the shorter the excitonic lifetime becomes. However, the number of dye molecules attached per quantum dot will vary. Therefore, for correctly explaining the decay of the luminescence upon photoexcitation of the quantum dot, it is necessary to take into account the distribution of the number of dyes attached per quantum dot. A Poisson distribution of the ATTO-590 dye molecules not only leads to excellent agreement between experimental and theoretical decay curves but also additionally yields the average number of dye molecules attached per quantum dot. In this way, the number of dyes per quantum dot can be conveniently determined.

  4. Determining the exact number of dye molecules attached to colloidal CdSe/ZnS quantum dots in Förster resonant energy transfer assemblies

    SciTech Connect

    Kaiser, Uwe; Jimenez de Aberasturi, Dorleta; Vázquez-González, Margarita; Carrillo-Carrion, Carolina; Niebling, Tobias; Parak, Wofgang J.; Heimbrodt, Wolfram

    2015-01-14

    Semiconductor quantum dots functionalized with organic dye molecules are important tools for biological sensor applications. Energy transfer between the quantum dot and the attached dyes can be utilized for sensing. Though important, the determination of the real number of dye molecules attached per quantum dot is rather difficult. In this work, a method will be presented to determine the number of ATTO-590 dye molecules attached to CdSe/ZnS quantum dots based on time resolved spectral analysis. The energy transfer from the excited quantum dot to the attached ATTO-590 dye leads to a reduced lifetime of the quantum dot's excitons. The higher the concentration of dye molecules, the shorter the excitonic lifetime becomes. However, the number of dye molecules attached per quantum dot will vary. Therefore, for correctly explaining the decay of the luminescence upon photoexcitation of the quantum dot, it is necessary to take into account the distribution of the number of dyes attached per quantum dot. A Poisson distribution of the ATTO-590 dye molecules not only leads to excellent agreement between experimental and theoretical decay curves but also additionally yields the average number of dye molecules attached per quantum dot. In this way, the number of dyes per quantum dot can be conveniently determined.

  5. Understanding and controlling laser-matter interactions: From solvated dye molecules to polyatomic molecules in gas phase

    NASA Astrophysics Data System (ADS)

    Konar, Arkaprabha

    The goal of my research is to obtain a better understanding of the various processes that occur during and following laser-matter interactions from both the physical and chemical point of view. In particular I focused my research on understanding two very important aspects of laser-matter interaction; 1) Intense laser-matter interactions for polyatomic molecules in the gas phase in order to determine to what extent processes like excitation, ionization and fragmentation can be controlled by modifying the phase and amplitude of the laser field according to the timescales for electronic, vibrational and rotational energy transfer. 2) Developing pulse shaping based single beam methods aimed at studying solvated molecules in order to elucidate processes like inhomogeneous broadening, solvatochromic shift and to determine the electronic coherence lifetimes of solvated molecules. The effect of the chirped femtosecond pulses on fluorescence and stimulated emission from solvated dye molecules was studied and it was observed that the overall effect depends quadratically on pulse energy, even where excitation probabilities range from 0.02 to 5%, in the so-called "linear excitation regime". The shape of the chirp dependence is found to be independent of the energy of the pulse. It was found that the chirp dependence reveals dynamics related to solvent rearrangement following excitation and also depends on electronic relaxation of the chromophore. Furthermore, the chirped pulses were found to be extremely sensitive to solvent environment and that the complementary phases having the opposite sign provide information about the electronic coherence lifetimes. Similar to chirped pulses, the effects of a phase step on the excitation spectrum and the corresponding changes to the stimulated emission spectrum were also studied and it was found that the coherent feature on the spectrum is sensitive to the dephasing time of the system. Therefore a single phase scanning method can

  6. Investigating the Energy Transfer from Dye Molecules to DNA Stabilized Au Nanoparticles.

    PubMed

    Patel, Arun Singh; Sahoo, Harekrushna; Mohanty, T

    2016-09-01

    Double-stranded DNA stabilized gold nanoparticles (Au NPs) are synthesized by chemical reduction method and characterized with different spectroscopic techniques such as UV-Visible absorption, Fourier transform infrared (FTIR), & circular-dichroism (CD) as well as transmission electron microscopy (TEM). These NPs show absorption maximum at 520 nm and size of most of the particles are of the order of 3.5 ± 1.0 nm. These Au NPs show crystalline nature as confirmed from electron diffraction pattern. The effect of formation of Au NPs on the macromolecule has been studied using infrared and circular dichroism spectroscopy. Formation of NPs causes conformational changes in the DNA molecules. These Au NPs are further used as resonant energy acceptor of fluorescence emission from dye molecules (Rhodamine 6G). The fluorescence intensity of Rhodamine 6G (R6G) is quenched in presence of Au NPs. The effect of DNA molecules on the fluorescence quenching and the rate of energy transfer from R6G molecules to Au NPs have been explored. PMID:27422695

  7. Influence of the layer thickness and concentration of dye molecules on the emission amplification in cholesteric liquid crystals

    SciTech Connect

    Alaverdyan, R B; Gevorgyan, A A; Chilingaryan, A D; Chilingaryan, Yu S

    2008-05-31

    The propagation of light through a planar layer of a cholesteric liquid crystal doped with dye molecules is considered. The features of the emission spectra of the crystal are studied both in the absence and presence of dielectric boundaries. The increase in the emission intensity is investigated for different layer thicknesses and different concentrations of dye molecules. It is shown that an anomalously strong increase in the emission intensity with the diffraction intrinsic polarisation takes place in the case of a comparatively small crystal thickness and a relatively low concentration of dye molecules. The obtained results can be used for the development of miniature lasers with the circular polarisation of the fundamental radiation mode. (laser applications and other topics in quantum electronics)

  8. Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

    SciTech Connect

    Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr., C.R.; Schmid, A.W.; Marshall, K.L.

    2006-08-18

    This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time.

  9. Charge-transfer photodissociation of adsorbed molecules via electron image states

    SciTech Connect

    Jensen, E. T.

    2008-01-28

    The 248 and 193 nm photodissociations of submonolayer quantities of CH{sub 3}Br and CH{sub 3}I adsorbed on thin layers of n-hexane indicate that the dissociation is caused by dissociative electron attachment from subvacuum level photoelectrons created in the copper substrate. The characteristics of this photodissociation-translation energy distributions and coverage dependences show that the dissociation is mediated by an image potential state which temporarily traps the photoelectrons near the n-hexane-vacuum interface, and then the charge transfers from this image state to the affinity level of a coadsorbed halomethane which then dissociates.

  10. Decolourization of aqueous dye solutions by a novel adsorbent: application of statistical designs and surface plots for the optimization and regression analysis.

    PubMed

    Ravikumar, K; Deebika, B; Balu, K

    2005-06-30

    Adsorption of Neolan Blue 2G (Acid Blue 158) and Basic Methylene Blue (Basic Blue 9) was investigated using a hybrid adsorbent that was prepared by pyrolysing a mixture of carbon and flyash at 1:1 ratio. A 2(4) full factorial central composite design with nine replicates at the center point and thus a total of 31 experiments were successfully employed for batch experimental design and analysis of the results. The combined effect of pH, temperature, particle size and time on the dye adsorption was studied. An empirical model was developed and validated applying ANOVA analysis incorporating interaction effects of all parameters and optimized using response surface methodology. The optimum pH, temperature, particle size and time were found to be 2.20, 27.85 degrees C, 0.0565 mm, 245 min, respectively, for Acid Blue 158 and those for Basic Blue 9 were 13.40, 28.45 degrees C, 0.0555 mm and 230 min, respectively. Complete removal (100%) was observed for both the dyes using the hybrid adsorbent. PMID:15943929

  11. Adsorbed states of chlorophenol on Cu(110) and controlled switching of single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Okuyama, H.; Kitaguchi, Y.; Hattori, T.; Ueda, Y.; Ferrer, N. G.; Hatta, S.; Aruga, T.

    2016-06-01

    A molecular junction of substituted benzene (chlorophenol) is fabricated and controlled by using a scanning tunneling microscope (STM). Prior to the junction formation, the bonding geometry of the molecule on the surface is characterized by STM and electron energy loss spectroscopy (EELS). EELS shows that the OH group of chlorophenol is dissociated on Cu(110) and that the molecule is bonded nearly flat to the surface via an O atom, with the Cl group intact. We demonstrate controlled contact of an STM tip to the "available" Cl group and lift-up of the molecule while it is anchored to the surface via an O atom. The asymmetric bonding motifs of the molecule to the electrodes allow for reversible control of the junction.

  12. Adsorbed states of chlorophenol on Cu(110) and controlled switching of single-molecule junctions.

    PubMed

    Okuyama, H; Kitaguchi, Y; Hattori, T; Ueda, Y; Ferrer, N G; Hatta, S; Aruga, T

    2016-06-28

    A molecular junction of substituted benzene (chlorophenol) is fabricated and controlled by using a scanning tunneling microscope (STM). Prior to the junction formation, the bonding geometry of the molecule on the surface is characterized by STM and electron energy loss spectroscopy (EELS). EELS shows that the OH group of chlorophenol is dissociated on Cu(110) and that the molecule is bonded nearly flat to the surface via an O atom, with the Cl group intact. We demonstrate controlled contact of an STM tip to the "available" Cl group and lift-up of the molecule while it is anchored to the surface via an O atom. The asymmetric bonding motifs of the molecule to the electrodes allow for reversible control of the junction. PMID:27369529

  13. How hottest geometries and adsorptive parameters influence the SER(R)S spectra of Methylene Blue molecules adsorbed on nanocolloidal gold particles of varied sizes?

    PubMed

    Roy, Sannak Dutta; Ghosh, Manash; Chowdhury, Joydeep

    2015-12-01

    The SER(R)S spectra of Methylene Blue (MB) molecule adsorbed on gold nanocolloidal particles (AuNCs) have been investigated. The adsorptive parameters of the molecule adsorbed on AuNCs have been evaluated with the aid of Fluorescence Spectroscopy study. Fluorescence spectroscopic studies have been further applied to understand the concentration of probe molecule actually adsorbed on AuNC surfaces. Gigantic enhancements ∼10(6)-10(16) orders of magnitude have been recorded for the enhanced Raman bands in the SER(R)S spectra. Three-dimensional Finite Difference Time Domain (3D-FDTD) simulations studies have been carried out to predict the distributions of electric fields around the possible nanoaggregated hot geometries considered to be responsible for the huge enhancements of SER(R)S bands of the MB molecule. PMID:26172467

  14. A Research Module for the Organic Chemistry Laboratory: Multistep Synthesis of a Fluorous Dye Molecule.

    PubMed

    Slade, Michael C; Raker, Jeffrey R; Kobilka, Brandon; Pohl, Nicola L B

    2014-01-14

    A multi-session research-like module has been developed for use in the undergraduate organic teaching laboratory curriculum. Students are tasked with planning and executing the synthesis of a novel fluorous dye molecule and using it to explore a fluorous affinity chromatography separation technique, which is the first implementation of this technique in a teaching laboratory. Key elements of the project include gradually introducing students to the use of the chemical literature to facilitate their searching, as well as deliberate constraints designed to force them to think critically about reaction design and optimization in organic chemistry. The project also introduces students to some advanced laboratory practices such as Schlenk techniques, degassing of reaction mixtures, affinity chromatography, and microwave-assisted chemistry. This provides students a teaching laboratory experience that closely mirrors authentic synthetic organic chemistry practice in laboratories throughout the world. PMID:24501431

  15. Pulsed laser induced birefringence switching in a biopolymer matrix containing azo-dye molecules

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Ziemienczuk, Marta; Miniewicz, Andrzej

    2011-07-01

    All optical switching has been studied using the Optical Kerr Effect (OKE) configuration in a biopolymer matrix containing an azo-dye: the Disperse Orange 3 (DO3). The biopolymer system consisted of a deoxyribonucleic acid blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride is suitable for optical quality thin film fabrication. The excitation beams inducing birefringence were delivered from a continuous wave laser at 532 nm and another nanosecond pulsed Nd: YAG laser. The birefringence was instantaneously monitored under crossed polarizer system by a weak non-absorbed light from a cw He-Ne laser working at 632.8 nm. Fast all optical switching process (in the range of microseconds) and excellent reversibility have been observed.

  16. 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

  17. Dye-Binding Assays for Evaluation of the Effects of Small Molecule Inhibitors on Amyloid (Aβ) Self-Assembly

    PubMed Central

    2012-01-01

    Dye-binding assays, such as those utilizing Congo red and thioflavin T, are among the most widely used tools to probe the aggregation of amyloidogenic biomolecules and for the evaluation of small molecule inhibitors of amyloid aggregation and fibrillization. A number of recent reports have indicated that these dye-binding assays could be prone to false positive effects when assessing inhibitors’ potential toward Aβ peptides, species involved in Alzheimer’s disease. Specifically, this review focuses on the application of thioflavin T for determining the efficiency of small molecule inhibitors of Aβ aggregation and addresses potential reasons that might be associated with the false positive effects in an effort to increase reliability of dye-binding assays. PMID:23173064

  18. Mechanism of charge transfer and its impacts on Fermi-level pinning for gas molecules adsorbed on monolayer WS{sub 2}

    SciTech Connect

    Zhou, Changjie; Zhu, Huili; Yang, Weihuang

    2015-06-07

    Density functional theory calculations were performed to assess changes in the geometric and electronic structures of monolayer WS{sub 2} upon adsorption of various gas molecules (H{sub 2}, O{sub 2}, H{sub 2}O, NH{sub 3}, NO, NO{sub 2}, and CO). The most stable configuration of the adsorbed molecules, the adsorption energy, and the degree of charge transfer between adsorbate and substrate were determined. All evaluated molecules were physisorbed on monolayer WS{sub 2} with a low degree of charge transfer and accept charge from the monolayer, except for NH{sub 3}, which is a charge donor. Band structure calculations showed that the valence and conduction bands of monolayer WS{sub 2} are not significantly altered upon adsorption of H{sub 2}, H{sub 2}O, NH{sub 3}, and CO, whereas the lowest unoccupied molecular orbitals of O{sub 2}, NO, and NO{sub 2} are pinned around the Fermi-level when these molecules are adsorbed on monolayer WS{sub 2}. The phenomenon of Fermi-level pinning was discussed in light of the traditional and orbital mixing charge transfer theories. The impacts of the charge transfer mechanism on Fermi-level pinning were confirmed for the gas molecules adsorbed on monolayer WS{sub 2}. The proposed mechanism governing Fermi-level pinning is applicable to the systems of adsorbates on recently developed two-dimensional materials, such as graphene and transition metal dichalcogenides.

  19. Effects of non-local exchange on core level shifts for gas-phase and adsorbed molecules

    SciTech Connect

    Van den Bossche, M.; Grönbeck, H.; Martin, N. M.; Gustafson, J.; Lundgren, E.; Hakanoglu, C.; Weaver, J. F.

    2014-07-21

    Density functional theory calculations are often used to interpret experimental shifts in core level binding energies. Calculations based on gradient-corrected (GC) exchange-correlation functionals are known to reproduce measured core level shifts (CLS) of isolated molecules and metal surfaces with reasonable accuracy. In the present study, we discuss a series of examples where the shifts calculated within a GC-functional significantly deviate from the experimental values, namely the CLS of C 1s in ethyl trifluoroacetate, Pd 3d in PdO and the O 1s shift for CO adsorbed on PdO(101). The deviations are traced to effects of the electronic self-interaction error with GC-functionals and substantially better agreements between calculated and measured CLS are obtained when a fraction of exact exchange is used in the exchange-correlation functional.

  20. Hindered and modulated rotational states and spectra of adsorbed diatomic molecules

    SciTech Connect

    Shih, Y.T.; Chuu, D.S.; Mei, W.N.

    1996-10-01

    Both vertical and horizontal adsorption configurations of a diatomic molecule were modeled as the rigid rotor with which the spatial motion was confined by a finite conical well. In addition to the polar hindering potential, a sinusoidal azimuthal modulation, which bears the local symmetry of the adsorption site, was incorporated. Eigenfunctions for different models were expressed analytically in terms of the hypergeometric functions, and eigenvalues were solved numerically. We found that the rotational energy levels exhibit oscillatory behavior when plotted as functions of the hindrance angle. This particular phenomenon was interpreted as the occurrence of resonance transmission of the rotor wave function at certain hindrance condition. We also found that the rotational levels were grouped into bands when the azimuthal modulation strength was increased. The solutions were used to calculate the rotational-state distribution of desorbed molecules, and agreement with the previous experiment was obtained. {copyright} {ital 1996 The American Physical Society.}

  1. Simultaneous utilization of soju industrial waste for silica production and its residue ash as effective cationic dye adsorbent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soju industrial waste is an important biomass resource. The present study is aimed to utilize soju industrial waste for silica extraction, and residual ash as a low cost adsorbent for the removal of Methylene Blue (MB) from aqueous solution. High percentage of pure amorphous nanosilica was obtained ...

  2. Quantitative Structure of an Acetate Dye Molecule Analogue at the TiO2–Acetic Acid Interface

    PubMed Central

    2016-01-01

    The positions of atoms in and around acetate molecules at the rutile TiO2(110) interface with 0.1 M acetic acid have been determined with a precision of ±0.05 Å. Acetate is used as a surrogate for the carboxylate groups typically employed to anchor monocarboxylate dye molecules to TiO2 in dye-sensitized solar cells (DSSC). Structural analysis reveals small domains of ordered (2 × 1) acetate molecules, with substrate atoms closer to their bulk terminated positions compared to the clean UHV surface. Acetate is found in a bidentate bridge position, binding through both oxygen atoms to two 5-fold titanium atoms such that the molecular plane is along the [001] azimuth. Density functional theory calculations provide adsorption geometries in excellent agreement with experiment. The availability of these structural data will improve the accuracy of charge transport models for DSSC. PMID:27110318

  3. Switching orientation of adsorbed molecules: Reverse domino on a metal surface

    NASA Astrophysics Data System (ADS)

    Braatz, C. R.; Esat, T.; Wagner, C.; Temirov, R.; Tautz, F. S.; Jakob, P.

    2016-01-01

    A thus far unknown phase of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) on Ag(111), characterized by an all perpendicular orientation of the planar molecules and bound to the Ag substrate through the carboxyl oxygen atoms has been identified using infrared absorption spectroscopy and scanning tunneling microscopy. Its formation process requires second layer NTCDA to squeeze into empty spaces between relaxed monolayer NTCDA molecules. Remarkably, this process causes initially parallel oriented NTCDA to likewise adopt the new, highly inclined adsorption geometry. According to our SPA-LEED and STM findings, the new phase displays a distinct long range order and shows a pronounced tendency to form 1D rows or narrow islands. We suggest that extra NTCDA preferentially transforms into the upright configuration close to existing islands and attaches to them, i.e. the transformation process proceeds in a directed and recurrent manner (reverse domino scenario). Identical processing starting with a compressed NTCDA/Ag(111) monolayer leads to a purely parallel oriented bilayer, that is, the NTCDA monolayer phase is retained and merely acts as a passive template for bilayer NTCDA. The new vertical NTCDA phase represents an unusual molecular system with π-orbitals oriented parallel to a metal surface. A substantially reduced coupling of these orbitals to Ag(111) electronic levels is conjectured, which will have a major impact on intermolecular couplings and electronically excited state lifetimes.

  4. Molecular orientation of rhodamine dyes on surfaces of layered silicates.

    PubMed

    Bujdák, Juraj; Iyi, Nobuo

    2005-03-17

    Films of the layered silicates fluorohectorite (FH) and saponite (Sap) with various rhodamine dyes were prepared. The dyes with acidic as well as large hydrophobic groups in their molecule were not adsorbed on the surface of FH, which was interpreted in terms of high charge density on the surface of this silicate. All adsorbed dyes formed similar forms, such as isolated cations and H-type molecular aggregates, which were characterized by different spectral properties. Polarized ultraviolet-visible (UV-vis) spectroscopy was used for the characterization of the molecular orientation of dye chromophores on the silicate surface. The isolated dye cations and species, which absorbed light at the low energy part of the spectra, were only slightly tilted with respect to the plane of the silicate surface. The cations forming H-aggregates and absorbing light at low wavelengths were oriented in a nearly perpendicular fashion. The nearly perpendicular orientation was observed as a strong increase of dichroic ratio with film tilting. The orientation of the cations in H-aggregates depends partially on the structure of the dye molecule, namely, on the type of amino group (primary, secondary, or tertiary) in the dye molecule. The type of amino groups probably plays a role in the suitable orientation of dye cations for effective electrostatic interaction between the cations and the negatively charged siloxane surface. X-ray powder diffraction could not distinguish dye phases of dye monomers and molecular aggregates. PMID:16851539

  5. Tribochemical synthesis of nano-lubricant films from adsorbed molecules at sliding solid interface: Tribo-polymers from α-pinene, pinane, and n-decane

    NASA Astrophysics Data System (ADS)

    He, Xin; Barthel, Anthony J.; Kim, Seong H.

    2016-06-01

    The mechanochemical reactions of adsorbed molecules at sliding interfaces were studied for α-pinene (C10H16), pinane (C10H18), and n-decane (C10H22) on a stainless steel substrate surface. During vapor phase lubrication, molecules adsorbed at the sliding interface could be activated by mechanical shear. Under the equilibrium adsorption condition of these molecules, the friction coefficient of sliding steel surfaces was about 0.2 and a polymeric film was tribochemically produced. The synthesis yield of α-pinene tribo-polymers was about twice as much as pinane tribo-polymers. In contrast to these strained bicyclic hydrocarbons, n-decane showed much weaker activity for tribo-polymerization at the same mechanical shear condition. These results suggested that the mechanical shear at tribological interfaces could induce the opening of the strained ring structure of α-pinene and pinane, which leads to polymerization of adsorbed molecules at the sliding track. On a stainless steel surface, such polymerization reactions of adsorbed molecules do not occur under typical surface reaction conditions. The mechanical properties and boundary lubrication efficiency of the produced tribo-polymer films are discussed.

  6. Infrared spectroscopy of water clusters co-adsorbed with hydrogen molecules on a sodium chloride film

    NASA Astrophysics Data System (ADS)

    Yamakawa, Koichiro; Fukutani, Katsuyuki

    2016-06-01

    Hydrogen gas containing a trace of water vapor was dosed on a vacuum-evaporated sodium chloride film at 13 K, and water clusters formed on the substrate were investigated by infrared absorption spectroscopy. Absorption bands due to (H2O)n clusters with n = 3-6 and an induced absorption band due to hydrogen were clearly observed. With increasing gas dosage, the intensities of the cluster bands increased linearly while the intensity of the hydrogen band was constant. This suggests that the water clusters were formed in two-dimensional matrices of hydrogen. We found that the water clusters did exist on the surface upon heating even after the hydrogen molecules had desorbed. A further rise of the substrate temperature up to 27 K yielded the formation of larger clusters, (H2O)n with n > 6 . We also discuss the origins of the two bands of the trimer in terms of pseudorotation and a metastable isomer.

  7. Application of longan shell as non-conventional low-cost adsorbent for the removal of cationic dye from aqueous solution

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Zhu, Lin; Jiang, Haitao; Hu, Fang; Shen, Xiangqian

    2016-04-01

    With simple physical treatment, adsorption potential of longan shell for the methylene blue (MB) from aqueous solution was studied as a low-cost material under the conditions of adsorbent dosage (1-6 g/L), initial solution pH (2-12), contact time (5-180 min), temperature (293, 313, 313 K) and initial dye concentration (100-500 mg/L). The SEM images and FTIR spectra of longan shell before and after dye adsorption were analyzed to understand the adsorption process of MB onto longan shell. The kinetic data and the equilibrium data were simulated by different kinetic and isotherm models, respectively. The results showed that the adsorption process was well described by the pseudo-second-order kinetic model, and the experimental equilibrium data were better fit to Langmuir equation than Freundlich equation with the maximum adsorption capacity of 141.04 mg/g. In addition, main activation parameters (Ea, ΔH#, ΔS# and ΔG#) and thermodynamic parameters (ΔG°, ΔH° and ΔS°) of the absorption process were also determined.

  8. Application of longan shell as non-conventional low-cost adsorbent for the removal of cationic dye from aqueous solution.

    PubMed

    Wang, Ya; Zhu, Lin; Jiang, Haitao; Hu, Fang; Shen, Xiangqian

    2016-04-15

    With simple physical treatment, adsorption potential of longan shell for the methylene blue (MB) from aqueous solution was studied as a low-cost material under the conditions of adsorbent dosage (1-6 g/L), initial solution pH (2-12), contact time (5-180 min), temperature (293, 313, 313 K) and initial dye concentration (100-500 mg/L). The SEM images and FTIR spectra of longan shell before and after dye adsorption were analyzed to understand the adsorption process of MB onto longan shell. The kinetic data and the equilibrium data were simulated by different kinetic and isotherm models, respectively. The results showed that the adsorption process was well described by the pseudo-second-order kinetic model, and the experimental equilibrium data were better fit to Langmuir equation than Freundlich equation with the maximum adsorption capacity of 141.04 mg/g. In addition, main activation parameters (E(a), ΔH(#), ΔS(#) and ΔG(#)) and thermodynamic parameters (ΔG°, ΔH° and ΔS°) of the absorption process were also determined. PMID:26878356

  9. Liquid phase adsorptions of Rhodamine B dye onto raw and chitosan supported mesoporous adsorbents: isotherms and kinetics studies

    NASA Astrophysics Data System (ADS)

    Inyinbor, A. A.; Adekola, F. A.; Olatunji, G. A.

    2016-04-01

    Irvingia gabonensis endocarp waste was charred (DNc) and subsequently coated with chitosan (CCDNc). Physicochemical characteristics of the two adsorbents were established, while Fourier transform infrared (FTIR), Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area methods were further employed for characterization. Efficiencies of the prepared adsorbents in the uptake of Rhodamine B (RhB) from aqueous effluent were investigated and adsorption data were tested using four isotherms and four kinetics models. The BET surface areas of the prepared adsorbent were 0.0092 and 4.99 m2/g for DNc and CCDNc, respectively, and maximum adsorption was recorded at pH between 3 and 4, respectively. While monolayer adsorption dominates the uptake of RhB onto DNc, uptake of RhB onto CCDNc was onto heterogeneous surface. The maximum monolayer adsorption capacities (q max) obtained from the Langmuir equation are 52.90 and 217.39 mg/g for DNc and CCDNc, respectively. Pseudo second order and Elovich kinetic models well described the kinetics of the two adsorption processes. The mean sorption energy (E) calculated from the D-R model and desorption efficiencies suggests that while the uptake of RhB onto DNc was physical in nature, for RhB-CCDNc system chemisorption dominates.

  10. A linewidth-narrowed and frequency-stabilized dye laser for application in laser cooling of molecules.

    PubMed

    Dai, D P; Xia, Y; Yin, Y N; Yang, X X; Fang, Y F; Li, X J; Yin, J P

    2014-11-17

    We demonstrate a robust and versatile solution for locking the continuous-wave dye laser for applications in laser cooling of molecules which need linewidth-narrowed and frequency-stabilized lasers. The dye laser is first stabilized with respect to a reference cavity by Pound-Drever-Hall (PDH) technique which results in a single frequency with the linewidth 200 kHz and short-term stabilization, by stabilizing the length of the reference cavity to a stabilized helium-neon laser we simultaneously transfer the ± 2 MHz absolute frequency stability of the helium-neon laser to the dye laser with long-term stabilization. This allows the dye laser to be frequency chirped with the maximum 60 GHz scan range while its frequency remains locked. It also offers the advantages of locking at arbitrary dye laser frequencies, having a larger locking capture range and frequency scanning range to be implemented via software. This laser has been developed for the purpose of laser cooling a molecular magnesium fluoride beam. PMID:25402105

  11. Photon-exposure-dependent photon-stimulated desorption for obtaining photolysis cross section of molecules adsorbed on surface by monochromatic soft x-ray photons.

    PubMed

    Chou, L-C; Jang, C-Y; Wu, Y-H; Tsai, W-C; Wang, S-K; Chen, J; Chang, S-C; Liu, C-C; Shai, Y; Wen, C-R

    2008-12-01

    Photon-exposure-dependent positive- and negative-ion photon-stimulated desorption (PSD) was proposed to study the photoreactions and obtain the photolysis cross sections of molecules adsorbed on a single-crystal surface by monochromatic soft x-ray photons with energy near the core level of adsorbate. The changes in the F(+) and F(-) PSD ion yields were measured from CF(3)Cl molecules adsorbed on Si(111)-7x7 at 30 K (CF(3)Cl dose=0.3x10(15) molecules/cm(2), approximately 0.75 monolayer) during irradiation of monochromatic soft x-ray photons near the F(1s) edge. The PSD ion yield data show the following characteristics: (a) The dissociation of adsorbed CF(3)Cl molecules is due to a combination of direct photodissociation via excitation of F(1s) core level and substrate-mediated dissociation [dissociative attachment and dipolar dissociation induced by the photoelectrons emitting from the silicon substrate]. (b) the F(+) ion desorption is associated with the bond breaking of the surface CF(3)Cl, CF(2)Cl, CFCl, and SiF species. (c) the F(-) yield is mainly due to DA and DD of the adsorbed CF(3)Cl molecules. (d) The surface SiF is formed by reaction of the surface Si atom with the neutral fluorine atom, F(+), or F(-) ion produced by scission of C-F bond of CF(3)Cl, CF(2)Cl, or CFCl species. A kinetic model was proposed for the explanation of the photolysis of this submonolayer CF(3)Cl-covered surface. Based on this model and the variation rates of the F(+)F(-) signals during fixed-energy monochromatic photon bombardment at 690.2 and 692.6 eV [near the F(1s) edge], the photolysis cross section was deduced as a function of energy. PMID:19063541

  12. Highly ordered Ti-SBA-15: Efficient H{sub 2} adsorbent and photocatalyst for eco-toxic dye degradation

    SciTech Connect

    Das, Swapan K.; Bhunia, Manas K.; Bhaumik, Asim

    2010-06-15

    Highly ordered 2D-hexagonal mesoporous titanium silicate Ti-SBA-15 materials (space group p6mm) have been synthesized hydrothermally in acidic medium employing amphiphilic tri-block copolymer, Pluronic F127 as structure directing agent. Samples are characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, FT IR spectroscopy, UV-visible diffuse reflectance measurements, N{sub 2} adsorption/desorption and TG-DTA analysis. XRD and TEM results suggested the presence of highly ordered mesophase with hexagonal pore arrangements. BET surface area for Ti-SBA-15 (924 m{sup 2} g{sup -1}) is considerably higher than the pure silica SBA-15 (611 m{sup 2} g{sup -1}) prepared following the same synthetic route. UV-visible and FT-IR studies suggested the incorporation of mostly tetrahedral titanium (IV) species, along with some six-coordinated sites in the silicate network. This material shows very good H{sub 2} adsorption capacity at higher pressure and excellent catalytic activity in the photocatalytic degradation of ecologically abundant dye methylene blue. - Graphical abstract: Highly ordered 2D-hexagonal mesoporous Ti-SBA-15 materials are synthesized hydrothermally, which show high H{sub 2} adsorption capacity and excellent activity in the photocatalytic degradation of ecologically abundant dye methylene blue.

  13. Antibacterial nanocomposites based on chitosan/Co-MCM as a selective and efficient adsorbent for organic dyes.

    PubMed

    Khan, Shahid Ali; Khan, Sher Bahadar; Kamal, Tahseen; Yasir, Muhammad; Asiri, Abdullah M

    2016-10-01

    Chitosan/cobalt-silica (Co-MCM) nanocomposites were synthesized for the purification of effluent by adding 5, 15 and 25mL of Co-MCM solution to the aqueous chitosan solution for the formation of chitosan/Co-MCM-5, chitosan/Co-MCM-15 and chitosan/Co-MCM-25, respectively. These different nanocomposites were characterized by FESEM, EDS, X-ray crystallography and IR spectrophotometer and employed for the adsorption of various dyes (methyl orange, acridine orange, indigo carmine and congo red). The respective nanocomposites showed good adsorption toward methyl orange, indigo carmine and congo red while all nanocomposites were inactive for acridine orange dye. Among the nanocomposites, chitosan/Co-MCM-15 showed the highest adsorption performance which might be due to ideal dispersion of Co-MCM inside the chitosan polymer host. Chitosan/Co-MCM-15 exhibited high adsorption for methyl orange as compared to indigo carmine. We have further checked the biological potential of chitosan/Co-MCM nanocomposites against gram positive and negative bacteria as well as multi drug resistant bacteria. The results favor the strongest bioactivities of chitosan/Co-MCM-15 against various gram positive and gram negative bacteria as well as multi drug resistant bacteria, which further suggest the ideal dispersion of Co-MCM in chitosan polymer host and is responsible for the improvement of both adsorption as well as biological performance. PMID:27287771

  14. Concentration quenching of rhodamine 6G fluorescence in the adsorbed state

    SciTech Connect

    Zemskii, V.I.; Meshkovskii, I.K.; Sokolov, I.A.

    1985-08-01

    Porous glass to which molecules of organic dyes have been added is a promising active solid medium for tunable lasers. The spectroluminescent characteristics of samples of porous glass activated with rhodamine 6G molecules have been studied. It is shown that molecules of rhodamine 6G adsorbed in porus glass retain their capacity for fluorescence with a high quantum yield. Fixation of rhodamine 6G molecules on the pore walls interferes with their association in the concentration range up to 10/sup 19/ cm/sup -3/. Concentration quenching of fluorescence is observed starting with a concentration of dye molecules of 5 x 10/sup 15/ cm/sup -3/; this is explained by inductive-resonance energy transfer between monomeric molecules under conditions of inhomogeneous broadening of the electronic spectra of the adsorbed molecules.

  15. Spectroscopic studies of interactions between dyes and model molecules of Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Elhaddaoui, A.; Delacourte, A.; Turrell, S.

    1993-06-01

    Raman, FTIR, fluorescence, and UV-visible spectra are used to study interactions between amuloid-labelling dyes and poly-L-lysine and bovine insulin, two proteins which play the role of models of (beta) amyloid of Alzheimers disease. It is found that though the (beta) conformation of the peptide is not essential, it helps to encourage binding which appears to be stable and specific in nature, involving SO3- groups of the dyes and NH2 groups of the proteins.

  16. Highly ordered Ti-SBA-15: Efficient H 2 adsorbent and photocatalyst for eco-toxic dye degradation

    NASA Astrophysics Data System (ADS)

    Das, Swapan K.; Bhunia, Manas K.; Bhaumik, Asim

    2010-06-01

    Highly ordered 2D-hexagonal mesoporous titanium silicate Ti-SBA-15 materials (space group p6 mm) have been synthesized hydrothermally in acidic medium employing amphiphilic tri-block copolymer, Pluronic F127 as structure directing agent. Samples are characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, FT IR spectroscopy, UV-visible diffuse reflectance measurements, N 2 adsorption/desorption and TG-DTA analysis. XRD and TEM results suggested the presence of highly ordered mesophase with hexagonal pore arrangements. BET surface area for Ti-SBA-15 (924 m 2 g -1) is considerably higher than the pure silica SBA-15 (611 m 2 g -1) prepared following the same synthetic route. UV-visible and FT-IR studies suggested the incorporation of mostly tetrahedral titanium (IV) species, along with some six-coordinated sites in the silicate network. This material shows very good H 2 adsorption capacity at higher pressure and excellent catalytic activity in the photocatalytic degradation of ecologically abundant dye methylene blue.

  17. Influence of silver nanoparticles on relaxation processes and efficiency of dipole - dipole energy transfer between dye molecules in polymethylmethacrylate films

    NASA Astrophysics Data System (ADS)

    Bryukhanov, V. V.; Konstantinova, E. I.; Borkunov, R. Yu; Tsarkov, M. V.; Slezhkin, V. A.

    2015-10-01

    The fluorescence and phosphorescence of dyes in thin polymethylmethacrylate (PMMA) films in the presence of ablated silver nanoparticles has been investigated in a wide temperature range by methods of femtosecond and picosecond laser photoexcitation. The fluorescence and phosphorescence times, as well as spectral and kinetic characteristics of rhodamine 6G (R6G) molecules in PMMA films are measured in a temperature range of 80 - 330 K. The temperature quenching activation energy of the fluorescence of R6G molecules in the presence of ablated silver nanoparticles is found. The vibrational relaxation rate of R6G in PMMA films is estimated, the efficiency of the dipole - dipole electron energy transfer between R6G and brilliant green molecules (enhanced by plasmonic interaction with ablated silver nanoparticles) is analysed, and the constants of this energy transfer are determined.

  18. Photon-exposure-dependent photon-stimulated desorption for obtaining photolysis cross section of molecules adsorbed on surface by monochromatic soft x-ray photons

    SciTech Connect

    Chou, L.-C.; Jang, C.-Y.; Wu, Y.-H.; Tsai, W.-C.; Wang, S.-K.; Chen, J.; Chang, S.-C.; Liu, C.-C.; Shai, Y.; Wen, C.-R.

    2008-12-07

    Photon-exposure-dependent positive- and negative-ion photon-stimulated desorption (PSD) was proposed to study the photoreactions and obtain the photolysis cross sections of molecules adsorbed on a single-crystal surface by monochromatic soft x-ray photons with energy near the core level of adsorbate. The changes in the F{sup +} and F{sup -} PSD ion yields were measured from CF{sub 3}Cl molecules adsorbed on Si(111)-7x7 at 30 K (CF{sub 3}Cl dose=0.3x10{sup 15} molecules/cm{sup 2}, {approx}0.75 monolayer) during irradiation of monochromatic soft x-ray photons near the F(1s) edge. The PSD ion yield data show the following characteristics: (a) The dissociation of adsorbed CF{sub 3}Cl molecules is due to a combination of direct photodissociation via excitation of F(1s) core level and substrate-mediated dissociation [dissociative attachment and dipolar dissociation induced by the photoelectrons emitting from the silicon substrate]. (b) the F{sup +} ion desorption is associated with the bond breaking of the surface CF{sub 3}Cl, CF{sub 2}Cl, CFCl, and SiF species. (c) the F{sup -} yield is mainly due to DA and DD of the adsorbed CF{sub 3}Cl molecules. (d) The surface SiF is formed by reaction of the surface Si atom with the neutral fluorine atom, F{sup +}, or F{sup -} ion produced by scission of C-F bond of CF{sub 3}Cl, CF{sub 2}Cl, or CFCl species. A kinetic model was proposed for the explanation of the photolysis of this submonolayer CF{sub 3}Cl-covered surface. Based on this model and the variation rates of the F{sup +}/F{sup -} signals during fixed-energy monochromatic photon bombardment at 690.2 and 692.6 eV[near the F(1s) edge], the photolysis cross section was deduced as a function of energy.

  19. Continuous-time core-level photon-stimulated desorption spectroscopy for monitoring soft x-ray-induced reactions of molecules adsorbed on a single-crystal surface

    SciTech Connect

    Chou, L.-C.; Wen, C.-R.

    2006-05-15

    Continuous-time core-level photon-stimulated desorption (PSD) spectroscopy was proposed for monitoring the soft x-ray-induced reactions of molecules adsorbed on a single-crystal surface. Monochromatic synchrotron radiation was used as a soft x-ray light source in the photon-induced reactions of CF{sub 3}Cl adsorbed on a Si(111)-7x7 surface at 30 K and also as a probe for studying the produced fluorination states of the bonding surface Si atom in the positive-ion PSD spectroscopy. The F{sup +} PSD spectrum was obtained by monitoring the F{sup +} signal as a function of incident photon energy near the Si(2p) edge (98-110 eV). Sequential F{sup +} PSD spectra were measured as a function of photon exposure at four adsorbate coverages (the first dose=0.3x10{sup 15} molecules/cm{sup 2}, the second dose=0.8x10{sup 15} molecules/cm{sup 2}, the third dose=2.2x10{sup 15} molecules/cm{sup 2}, and the fourth dose=3.2x10{sup 15} molecules/cm{sup 2}). For the first and second CF{sub 3}Cl-dosed surfaces, the sequential F{sup +} PSD spectra show the variation of their shapes with photon exposure and indicate the formation of surface SiF species. The sequential F{sup +} PSD spectra for the third and fourth CF{sub 3}Cl-dosed surfaces also show the variation of their shapes with photon exposure and depict the production of surface SiF and SiF{sub 3} species.

  20. Intracavity Dye-Laser Absorption Spectroscopy (IDLAS) for application to planetary molecules

    NASA Technical Reports Server (NTRS)

    Lang, Todd M.; Allen, John E., Jr.

    1990-01-01

    Time-resolved, quasi-continuous wave, intracavity dye-laser absorption spectroscopy is applied to the investigation of absolute absorption coefficients for vibrational-rotational overtone bands of water at visible wavelengths. Emphasis is placed on critical factors affecting detection sensitivity and data analysis. Typical generation-time dependent absorption spectra are given.

  1. Spectral Inspections on Molecular Configurations of Nile Blue A Adsorbed on the Elementary Clay Sheets.

    PubMed

    Huang, Mei; He, Shuai; Liu, Wenhong; Yao, Yunjin; Miao, Shiding

    2015-10-22

    Studies on the configuration of dye molecules are of great importance in revealing origins of the electronic bands as well as understanding their transitions. In this work, we utilized dye molecules named Nile blue A, which are a type of oxazine dyes, to study the molecular configurations when they are transferred from solutions to a solid surface. The Langmuir-Blodgett (LB) technique was employed to construct such an interface where the interaction between the dye molecules and solid supports can be pursued. Hybrid films were prepared via the LB depositions, and the dye molecules were assembled on the elementary clay sheets (laponite, saponite). The configuration of Nb reflected by the molecular orientation, packing density, phase behavior, and variances of the surface tension has been derived. The ex situ spectroscopy characterizations such as UV-vis absorption, fluorescence emission, and excitation spectra were carried out on these LB films to reveal the fact that the adsorbed Nb molecules are mainly assembled in two types of configurations. Adsorbed state I was found to be achieved at high concentrations (1-10 ppm) of clay dispersions and low surface pressure (∼5 mN/m). In this state the anionic oxazine rings of Nb are adsorbed on clay sheets sharing a large lift-off area. This configuration gives allowable fluorescence (λ = 550 nm). Lower clay concentration (<1 ppm) and high surface pressure (10-30 mN/m) yield the adsorbed state II in which the oxazine chromophores were arranged in a side-by-side style, and the dye molecules stand perpendicularly to the clay sheets. This conformation exhibits no photoluminescence. PMID:26436823

  2. Infrared Spectroscopy and Catalysis Research: Infrared spectra of adsorbed molecules provide important information in the study of catalysis.

    PubMed

    Eischens, R P

    1964-10-23

    The examples discussed here represent only a small part of the published work relating to infrared spectra of adsorbed molecules. The publications in this field indicate that infrared spectroscopy is being used for surface chemistry research in about 50 laboratories throughout the world. This effort is mainly devoted to problems related to catalysis, and in this field infrared spectroscopy is the most widely used physical tool for surface chemistry studies. The general acceptance of infrared spectroscopy is primarily due to the fact that it provides information which is pertinent to the understanding of surface reactions on an atomic scale. During the last decade significant progress has also been made in the classical chemical techniques of catalysis study and in utilization of physical tools which depend on phenomena of magnetism, conductivity, low-energy electron diffraction, and electron emission. Probably the most important progress has been in the field of inorganic chemistry, where dramatic advances have been made in knowledge of metal coordination compounds. Such knowledge is vital to the understanding of catalysis on metal surfaces. I believe this progress has produced an attitude of sophisticated optimism among catalysis researchers with regard to eventual understanding of heterogeneous catalysis. This attitude is closely related to the realization that there is no "secret of catalysis" which places catalytic action beyond the limits of ordinary chemical knowledge (22). This view implies that the chemical aspects of heterogeneous catalysis are not unique and that the use of solid catalysts merely provides a highly effective exposure of catalytic atoms and facilitates separation of the products from the catalyst. Many capable catalysis researchers believe that studies of homogeneous catalysis provide the most direct route for the study of heterogeneous catalysis. Obviously homogeneous reactions catalyzed by compounds containing only one or two metal atoms

  3. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    NASA Astrophysics Data System (ADS)

    Dey, S.; Banik, M.; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2016-01-01

    Surface-enhanced Raman scattering (SERS) from bipyridyl ethylene adsorbed on gold dumbbells shows Fano-like spectra at high incident light intensity. This is accompanied by an increased electronic temperature, while no vibrational anti-Stokes scattering is observed. Theory indicates that interference between vibrational and electronic Raman scattering can yield such asymmetric scattering lineshapes. The best fit to observations is however obtained by disregarding this coupling and accounting for the detailed lineshape of the continuous electronic component of the SERS.

  4. Dependence of Purcell effect on fluorescence wavelength in dye molecules on metal-dielectric multilayer hyperbolic metamaterials

    NASA Astrophysics Data System (ADS)

    Tsurumachi, Noriaki; Izawa, Hayato; Tomioka, Ryo; Sakata, Tomohiro; Suzuki, Makoto; Tanaka, Yasuhiro; Shimokawa, Fusao; Nakanishi, Shunsuke

    2016-02-01

    Recently, the enhancement of spontaneous emission, i.e., broadband Purcell effect, has been achieved using hyperbolic metamaterials. Hyperbolic metamaterials, which can be realized using a metal-dielectric multilayer structure, have an extremely large optical anisotropy of permittivity in both the parallel and perpendicular directions to the propagation of light, especially when the signs of permittivities in both directions differ. In this study, we investigated the conditions for realizing the broadband Purcell effect using dye molecules with different fluorescence wavelengths. Our fabricated metal-dielectric multilayer structure exhibited hyperbolic dispersion at wavelengths beyond 500 nm. In the case of coumarin 500 whose fluorescence peak is located at 500 nm, no broadband Purcell effect was observed. However, in the case of pyridine 1 whose fluorescence peak is located at 650 nm, we observed the successfull fluorescence lifetime shortening, i.e., the broadband Purcell effect.

  5. Dye-sensitized solar cells using natural dyes as sensitizers from Malaysia local fruit `Buah Mertajam'

    NASA Astrophysics Data System (ADS)

    Hambali, N. A. M. Ahmad; Roshidah, N.; Hashim, M. Norhafiz; Mohamad, I. S.; Saad, N. Hidayah; Norizan, M. N.

    2015-05-01

    We experimentally demonstrate the high conversion efficiency, low cost, green technology and easy to fabricate dye-sensitized solar cells (DSSCs) using natural anthocyanin dyes as sensitizers. The DSSCs was fabricated by using natural anthocyanin dyes which were extracted from different parts of the plants inclusive `Buah Mertajam', `Buah Keriang Dot', `Bunga Geti', Hibiscus, Red Spinach and Henna. The natural anthocyanin dyes that found in flower, leaves and fruits were extracted by the simple procedures. This anthocyanin dye is used to replace the expensive chemical synthetic dyes due to its ability to effectively attach into the surface of Titanium dioxide (TiO2). A natural anthocyanin dyes molecule adsorbs to each particle of the TiO2 and acts as the absorber of the visible light. A natural anthocyanin dye from Buah Mertajam shows the best performance with the conversion efficiency of 5.948% and fill factor of 0.708 followed by natural anthocyanin dyes from `Buah Keriang Dot', `Bunga Geti', Hibiscus, Red Spinach and Henna. Buah Mertajam or scientifically known as eriglossum rubiginosum is a local Malaysia fruit.

  6. Towards the coupling of single photons from dye molecules to a photonic waveguide

    NASA Astrophysics Data System (ADS)

    Polisseni, Claudio; Kho, Kiang Wei; Major, Kyle; Grandi, Samuele; Boisser, Sebastien; Hwang, Jaesuk; Clark, Alex; Hinds, Edward

    Single photons are very attractive for quantum information processing given their long coherence time and their ability to carry information in many degrees of freedom. A current challenge is the efficient generation of single photons in a photonic chip in order to scale up the complexity of quantum operations. We have proposed that a dibenzoterrylene (DBT) molecule inside an anthracene (AC) crystal could couple lifetime-limited indistinguishable single photons into a photonic waveguide if deposited in its vicinity. In this talk I describe the recent progress towards the realization of this proposal. A new method has been developed for evaporating AC and DBT to produce crystals that are wide and thin. The crystals are typically several microns across and have remarkably uniform thickness, which we control between 20 and 150 nm. The crystal growth is carried out in a glove bag in order to exclude oxygen, which improves the photostability of the DBT molecules by orders of magnitude. We image the fluorescence of single DBT molecules using confocal microscopy and analyse the polarization of this light to determine the alignment of the molecules. I will report on our efforts to control the alignement of the molecules by aligning the host matrix with the substrate.

  7. Dye adsorption of cotton fabric grafted with PPI dendrimers: Isotherm and kinetic studies.

    PubMed

    Salimpour Abkenar, Samera; Malek, Reza Mohammad Ali; Mazaheri, Firouzmehr

    2015-11-01

    In this research, the cotton fabrics grafted with two generations of the poly(propylene imine) dendrimers were applied to adsorb textile dyes from aqueous solutions. Direct Red 80 (anionic dye), Disperse Yellow 42 (nonionic dye) and Basic Blue 9 (cationic dye) were selected as model dyes. The effect of various experimental parameters such as initial concentration of dyes, charge of dyes molecule, salt and pH was investigated on the adsorption process. Furthermore, kinetics and equilibrium of the adsorption process on the grafted samples were studied. It was found that maximum adsorption of anionic and disperse dyes took place at around pH 3, while cationic dye could be adsorbed at around pH 11. The Langmuir equation was able to describe the mechanism of dyes adsorption. In addition, the second-order equation was found to be fit with the kinetics data. Interestingly, it seems that the dye adsorption of the grafted fabrics is strongly pH dependent. PMID:26292774

  8. Can the state of platinum species be unambiguously determined by the stretching frequency of an adsorbed CO probe molecule?

    PubMed

    Aleksandrov, Hristiyan A; Neyman, Konstantin M; Hadjiivanov, Konstantin I; Vayssilov, Georgi N

    2016-08-10

    The paper addresses possible ambiguities in the determination of the state of platinum species by the stretching frequency of a CO probe, which is a common technique for characterization of platinum-containing catalytic systems. We present a comprehensive comparison of the available experimental data with our theoretical modeling (density functional) results of pertinent systems - platinum surfaces, nanoparticles and clusters as well as reduced or oxidized platinum moieties on a ceria support. Our results for CO adsorbed on-top on metallic Pt(0), with C-O vibrational frequencies in the region 2018-2077 cm(-1), suggest that a decrease of the coordination number of the platinum atom, to which CO is bound, by one lowers the CO frequency by about 7 cm(-1). This trend corroborates the Kappers-van der Maas correlation derived from the analysis of the experimental stretching frequency of CO adsorbed on platinum-containing samples on different supports. We also analyzed the effect of the charge of platinum species on the CO frequency. Based on the calculated vibrational frequencies of CO in various model systems, we concluded that the actual state of the platinum species may be mistaken based only on the measured value of the C-O vibrational frequency due to overlapping regions of frequencies corresponding to different types of species. In order to identify the actual state of platinum species one has to combine this powerful technique with other approaches. PMID:27444400

  9. Fully resonant four-wave mixing spectroscopy of pentacene and dye molecules in condensed phases

    SciTech Connect

    Chang, T.C.

    1985-01-01

    Four-wave mixing spectroscopy (FWM) including coherent antistokes Raman spectroscopy (CARS) and coherent stokes Raman spectroscopy (CSRS) have been studied for pentacene doped in naphthalene crystals at low temperatures (4.5 to 35 K) in order to investigate nonlinear optical behavior of the third-order nonlinear susceptibility, X/sup (3)/. Further, its application to study of cresyl violet perchlorate embedded in polyacrylic acid and in polyvinyl carbazole has been examined. The theoretical basis for line narrowing has been established for fully resonant four wave mixing for a four-level system. A careful line-narrowing study for the pentacene 755 cm/sup -1/ resonance in naphthalene illustrates that line narrowing is operative. Temperature dependent studies indicate that the excited state population mechanism for negative detuning involves phonon hotband absorption. Power broadening data are discussed in terms of dynamic Stark shifts resulting from the site inhomogeneous line broadening of vibronic transitions. Cresyl violet perchlorate in polyacrylic acid shows that the CARS intensity of the excited state resonance at 585 cm/sup -1/ depends on the location of the omega/sub 1/-field within the severely inhomogeneously broadened absorption profile of the dye. It is argued that the linear electron-phonon interaction is an important mechanism for the intensity of the excited state resonance.

  10. Spectrally resolved analysis of fluorescence blinking of single dye molecules in polymers at low temperatures

    NASA Astrophysics Data System (ADS)

    Orlov, S. V.; Naumov, A. V.; Vainer, Yu. G.; Kador, Lothar

    2012-11-01

    We present a method for the spectrally resolved analysis of fluorescence blinking of single quantum emitters. It is based on the well-known technique of repeated recording of single-molecule (SM) fluorescence excitation spectra. The potential of our approach is presented for the example of single tetra-tert-butylterrylene molecules in an amorphous polymer matrix (polyisobutylene), which exhibit fluorescence blinking at cryogenic temperatures. Measuring the spectral dependence of the blinking statistics improves the possibility to clarify the microscopic nature of the dark state(s) of the emitters. We demonstrate how the blinking statistics can be definitely attributed to conformational changes in the local environment of a SM and how the parameters of the corresponding elementary excitations can be measured. The analysis of the blinking statistics as a function of the optical excitation frequency allows us to discriminate between photo-induced and spontaneous transitions into a dark state.

  11. Fluorescent styryl dyes of the RH series affect a potential drop on the membrane/solution boundary.

    PubMed

    Malkov, D Y; Sokolov, V S

    1996-01-31

    The effects of the adsorption of the fluorescent potential-sensitive dyes RH-421, RH-237 and RH-160 on the bilayer lipid membrane were studied. It was shown that a dipole potential drop, positive in the hydrophobic part of the membrane, arose due to the dye adsorption. The dye adsorption led to a considerable increase of the rate constant of hydrophobic anion translocation through the membrane, but did not affect their partition coefficient between membrane and water. It implies that the region of the membrane where the potential drops is located deeper than the adsorption plane of hydrophobic ions. The values of boundary potential differences were estimated by two independent methods with unilateral and bilateral application of the dyes to lipid bilayer membranes. The results suggest that RH dye molecules penetrate through the lipid bilayers. The values of zeta-potential in liposomes did not change on dye adsorption. Hence, dye molecules are adsorbed in a form that does not change the surface charge. We estimated the effects of electric field of dye dipole layer on an individual dipole located in the same layer and on ion transport through a membrane protein Na+/K+-ATPase. It turned out that the local electric field of each dye dipole decayed so rapidly that a neighbouring dye molecule did not feel it. It also appeared that RH dyes could have but a minor effect on the electrogenic transport performed by the sodium pump in the examined range of dye concentrations. PMID:8593277

  12. N-acetylation of three aromatic amine hair dye precursor molecules eliminates their genotoxic potential.

    PubMed

    Zeller, Andreas; Pfuhler, Stefan

    2014-01-01

    N-acetylation has been described as a detoxification reaction for aromatic amines; however, there is only limited data available showing that this metabolic conversion step changes their genotoxicity potential. To extend this database, three aromatic amines, all widely used as precursors in oxidative hair dye formulations, were chosen for this study: p-phenylenediamine (PPD), 2,5-diaminotoluene (DAT) and 4-amino-2-hydroxytoluene (AHT). Aiming at a deeper mechanistic understanding of the interplay between activation and detoxification for this chemical class, we compared the genotoxicity profiles of the parent compounds with those of their N-acetylated metabolites. While PPD, DAT and AHT all show genotoxic potential in vitro, their N-acetylated metabolites completely lack genotoxic potential as shown in the Salmonella typhimurium reversion assay, micronucleus test with cultured human lymphocytes (AHT), chromosome aberration assay with V79 cells (DAT) and Comet assay performed with V79 cells. For the bifunctional aromatic amines studied (PPD and DAT), monoacetylation was sufficient to completely abolish their genotoxic potential. Detoxification through N-acetylation was further confirmed by comparing PPD, DAT and AHT in the Comet assay using standard V79 cells (N-acetyltransferase (NAT) deficient) and two NAT-proficient cell lines,V79NAT1*4 and HaCaT (human keratinocytes). Here we observed a clear shift of dose-response curves towards decreased genotoxicity of the parent aromatic amines in the NAT-proficient cells. These findings suggest that genotoxic effects will only be found at concentrations where the N-acetylation (detoxifying) capacity of the cells is overwhelmed, indicating that a 'first-pass' effect in skin could be taken into account for risk assessment of these topically applied aromatic amines. The findings also indicate that the use of liver S-9 preparations, which generally underestimate Phase II reactions, contributes to the generation of irrelevant

  13. Single-molecule imaging at high fluorophore concentrations by local activation of dye.

    PubMed

    Geertsema, Hylkje J; Schulte, Aartje C; Spenkelink, Lisanne M; McGrath, William J; Morrone, Seamus R; Sohn, Jungsan; Mangel, Walter F; Robinson, Andrew; van Oijen, Antoine M

    2015-02-17

    Single-molecule fluorescence microscopy is a powerful tool for observing biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Making use of short-distance energy-transfer mechanisms, only the fluorescence from those proteins that bind to their substrate is activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease on DNA in the presence of a background of hundreds of nanomolar Cy5 fluorophore. PMID:25692599

  14. Single-molecule imaging at high fluorophore concentrations by local activation of dye

    SciTech Connect

    Geertsema, Hylkje J.; Mangel, Walter F.; Schulte, Aartje C.; Spenkelink, Lisanne M.; McGrath, William J.; Morrone, Seamus R.; Sohn, Jungsan; Robinson, Andrew; van Oijen, Antoine M.

    2015-02-17

    Single-molecule fluorescence microscopy is a powerful approach to observe biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual, labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Then, making use of short-distance energy-transfer mechanisms, the fluorescence from only those proteins bound to their substrate are selectively activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 (IFI16) with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease (pVIc-AVP) on DNA in the presence of a background of hundreds of nM Cy5 fluorophore.

  15. Single-molecule imaging at high fluorophore concentrations by local activation of dye

    DOE PAGESBeta

    Geertsema, Hylkje J.; Mangel, Walter F.; Schulte, Aartje C.; Spenkelink, Lisanne M.; McGrath, William J.; Morrone, Seamus R.; Sohn, Jungsan; Robinson, Andrew; van Oijen, Antoine M.

    2015-02-17

    Single-molecule fluorescence microscopy is a powerful approach to observe biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual, labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Then, making use ofmore » short-distance energy-transfer mechanisms, the fluorescence from only those proteins bound to their substrate are selectively activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 (IFI16) with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease (pVIc-AVP) on DNA in the presence of a background of hundreds of nM Cy5 fluorophore.« less

  16. Single-Molecule Imaging at High Fluorophore Concentrations by Local Activation of Dye

    PubMed Central

    Geertsema, Hylkje J.; Schulte, Aartje C.; Spenkelink, Lisanne M.; McGrath, William J.; Morrone, Seamus R.; Sohn, Jungsan; Mangel, Walter F.; Robinson, Andrew; van Oijen, Antoine M.

    2015-01-01

    Single-molecule fluorescence microscopy is a powerful tool for observing biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Making use of short-distance energy-transfer mechanisms, only the fluorescence from those proteins that bind to their substrate is activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease on DNA in the presence of a background of hundreds of nanomolar Cy5 fluorophore. PMID:25692599

  17. Conformations of polyaniline molecules adsorbed on Au(111) probed by in situ STM and ex situ XPS and NEXAFS.

    PubMed

    Lee, YiHui; Chang, ChinZen; Yau, ShuehLin; Fan, LiangJen; Yang, YawWen; Yang, LiangYueh Ou; Itaya, Kingo

    2009-05-13

    In situ scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) have been used to examine the conformation of a monolayer of polyaniline (PAN) molecules produced on a Au(111) single-crystal electrode by anodization at 1.0 V [vs reversible hydrogen electrode (RHE)] in 0.10 M H(2)SO(4) containing 0.030 M aniline. The as-produced PAN molecules took on a well-defined linear conformation stretching for 500 A or more, as shown by in situ and ex situ STM. The XPS and NEXAFS results indicated that the linear PAN seen at 1.0 V assumed the form of an emeraldine salt made of PAN chains and (bi)sulfate anions. Shifting the potential from 1.0 to 0.7 V altered the shape of the PAN molecules from straight to crooked, which was ascribed to restructuring of the Au(111) electrified interface on the basis of voltammetric and XPS results. In situ STM showed that further decreasing the potential to 0.5 V transformed the crooked PAN threads into a mostly linear form again, with preferential alignment and formation of some locally ordered structures. PAN molecules could be reduced from emeraldine to leucoemeraldine as the potential was decreased to 0.2 V or less. In situ STM showed that the fully reduced PAN molecules were straight but mysteriously shortened to approximately 50 A in length. The conformation of PAN did not recuperate when the potential was shifted positively to 1.0 V. PMID:19361217

  18. Enhance the performance of co-sensitized solar cell by a series efficient pyridine-anchor co-adsorbents of N,N‧-bis((pyridin-2-yl)methylene)-p-phenylenediimine and a ruthenium dye of N719

    NASA Astrophysics Data System (ADS)

    Wei, Liguo; Yang, Yulin; Fan, Ruiqing; Wang, Ping; Dong, Yuwei; Zhou, Wei; Luan, Tianzhu

    2015-10-01

    A pyridine-anchor co-adsorbent N,N‧-bis((pyridin-2-yl)methylene)-p-phenyl- lenediimine (named L1) and its derivatives N,N‧-bis((6-methoxylpyridin-2-yl)methylene)- p-phenylenediimine (named L2) and N,N‧-bis((pyridin-2-yl) (methyl)methylene)-p-phenyl- enediimine (named L3) are synthesized and employed in combination with a ruthenium complex N719 in dye sensitized solar cells (DSSCs). The prepared co-adsorbent can overcome the deficiency of N719 absorption in the low wavelength region of visible spectrum, offset competitive visible light absorption of I3-, suppress the charge recombination and prolong the electron lifetime. The introduction of methyl or methoxyl substituent also has some effect on the performance of DSSCs. A short circuit current density of 14.60 mA cm-2, an open circuit voltage of 0.75 V and a fill factor of 0.63 corresponding to an overall conversion efficiency of 6.92% under AM 1.5G solar irradiation are achieved when L2 is used as co-adsorbent, which is 30% higher than that for DSSCs only sensitized by N719 (5.31%) under the same condition. Mechanistic investigations are carried out by various spectral and electrochemical characterizations.

  19. David Adler Lectureship Award Talk: Friction and energy dissipation mechanisms in adsorbed molecules and molecularly thin films

    NASA Astrophysics Data System (ADS)

    Krim, Jacqueline

    2015-03-01

    Studies of the fundamental origins of friction have undergone rapid progress in recent years, with the development of new experimental and computational techniques for measuring and simulating friction at atomic length and time scales. The increased interest has sparked a variety of discussions and debates concerning the nature of the atomic-scale and quantum mechanisms that dominate the dissipative process by which mechanical energy is transformed into heat. Measurements of the sliding friction of physisorbed monolayers and bilayers can provide information on the relative contributions of these various dissipative mechanisms. Adsorbed films, whether intentionally applied or present as trace levels of physisorbed contaminants, moreover are ubiquitous at virtually all surfaces. As such, they impact a wide range of applications whose progress depends on precise control and/or knowledge of surface diffusion processes. Examples include nanoscale assembly, directed transport of Brownian particles, material flow through restricted geometries such as graphene membranes and molecular sieves, passivation and edge effects in carbon-based lubricants, and the stability of granular materials associated with frictional and frictionless contacts. Work supported by NSFDMR1310456.

  20. Conductivity Measurements of Pyrrole Molecules Incorporated into Chemically Adsorbed Monolayer by Conducting Probe Technique in Atomic Force Microscope

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shin‑ichi; Ogawa, Kazufumi

    2006-03-01

    A monomolecular layer containing pyrrolyl groups at the surface was prepared between two parallel Pt electrodes on a glass substrate by a chemical adsorption technique using N-[11-(trichlorosilyl)undecyl] pyrrole (PNN). Then, the pyrrolyl was polymerized with pure water by applying a DC voltage of 10 V between the two Pt electrodes. It was confirmed using an optical microscope that many electric paths were formed between the two Pt electrodes by a decoration technique using electrochemical polymerization in an aqueous medium containing pyrrole after the polymerization. Next, a conductive probe of an atomic force microscope (AFM) was used to examine an electrical polymerized path through the surface of the polypyrrolyl group in a chemically adsorbed monomolecular layer. The resistance of one electric path in the monomolecular layer was measured using an AFM with an attached Au-covered tip at room temperature. With a measurement volume of about 0.2 nm (the thickness of the electric path in the monomolecular layer) × 200 μm (the average width of the electric path) × 100 μm (the distance between the Pt electrode and the Au-covered AFM tip), the resistance at room temperature of one electric path was 4 k Ω under ambient conditions. From the results in the atmosphere, the conductivity of a super long conjugated polypyrrolyl group without any dopant in a lateral direction was ohmically estimated to be at least 6.0 × 105 S/m.

  1. On the widths of Stokes lines in Raman scattering from molecules adsorbed at metal surfaces and in molecular conduction junctions

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Galperin, Michael; Nitzan, Abraham

    2016-06-01

    Within a generic model we analyze the Stokes linewidth in surface enhanced Raman scattering (SERS) from molecules embedded as bridges in molecular junctions. We identify four main contributions to the off-resonant Stokes signal and show that under zero voltage bias (a situation pertaining also to standard SERS experiments) and at low bias junctions only one of these contributions is pronounced. The linewidth of this component is determined by the molecular vibrational relaxation rate, which is dominated by interactions with the essentially bosonic thermal environment when the relevant molecular electronic energy is far from the metal(s) Fermi energy(ies). It increases when the molecular electronic level is close to the metal Fermi level so that an additional vibrational relaxation channel due to electron-hole (eh) exciton in the molecule opens. Other contributions to the Raman signal, of considerably broader linewidths, can become important at larger junction bias.

  2. Self-assembly in the mixtures of surfactant and dye molecule controlled via temperature and β-cyclodextrin recognition.

    PubMed

    Wang, Dong; Long, Panfeng; Dong, Renhao; Hao, Jingcheng

    2012-10-01

    A new ternary system of tetradecyldimethylamine oxide (C(14)DMAO)/4-phenylazo benzoic acid (AzoH)/H(2)O was first investigated, and it was found that the self-assembly can be regulated via temperature and β-cyclodextrin (β-CD) recognition. In the temperature regulated self-assembly, the self-assembled phase structural transition between wormlike micelles and multilamellar vesicles (onions) were determined by cryogenic-transmission electron microscopy (cryo-TEM) images and (2)H nuclear magnetic resonance ((2)H NMR) spectra. The phase structural transition temperatures (PSTT) controlled by changing the amount of AzoH were measured by differential scanning calorimetry analysis. The self-assembled phase structural transition mechanism was discussed. It is argued that the self-assembled phase structural transition is the synergetic balance among the hydrophilic headgroup, steric structures of the hydrophobic chain, and membrane charge. β-CD molecules were used as controlling hands to modulate the phase structural transition of self-assembly of the C(14)DMAO/AzoH/H(2)O system in solution via snatching C(14)DMAO molecules. The phase structural transitions from the threadlike micellar phase to the lamellar phase and from the lamellar phase to the vesicular phase can each be controlled because of the β-CD molecular recognition. The phase structural transitions were confirmed by cryo-TEM observations and (2)H NMR measurements. The rheological properties were also investigated to display the importance in the phase structural transition. It was found that the dye molecule, AzoH, is harder to enclose by β-CD than by C(14)DMAO because of the lower complex stability constant (i.e., K(C(14)DMAO@β-CD) ≫ K(AzoH@β-CD). Therefore, the phase structural transition is mainly controlled by the inclusion of C(14)DMAO into the hydrophobic cavity of β-CD molecules. The phase structural transition controlled via temperature and β-CD may find potential applications such as in

  3. Impact of the different electron-releasing subunits on the dye-sensitized solar cell performance of new triphenylamine-benzimidazole based molecules

    NASA Astrophysics Data System (ADS)

    Dinçalp, Haluk; Saltan, Gözde Murat; Aykut, Deniz; Zafer, Ceylan

    2015-10-01

    New triphenylamine-benzimidazole type small molecules with different electron-releasing groups were designed and synthesized to investigate their photovoltaic performances in dye sensitized solar cells (DSSCs). Their good visible absorptions covering the 400-535 nm in addition to suitable lowest unoccupied molecular orbital (LUMO) energy levels between -3.03 and -3.11 eV make good candidates them for DSSC devices. Fluorescence quenching studies of the dyes with pristine titania support the good electron injection to conduction band of TiO2. Time resolved measurements of the dyes in solutions indicate the occurence of charge generation during the excited state. One of the used dyes in DSSC devices, TPA5a, carrying a methoxy group in triphenylamine part of the structure, gave much higher power conversion efficiency (PCE) value of 4.31% as compared to the other derivatives. Device fabricated from TPA5a dye gives good external quantum efficiency (EQE) value above 70% at 460 nm. Also, electron impedance spectroscopy (EIS) analysis of the devices gives a good explanation of the understanding of the cell performances.

  4. Orbital tomography: Molecular band maps, momentum maps and the imaging of real space orbitals of adsorbed molecules

    PubMed Central

    Offenbacher, Hannes; Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Puschnig, Peter; Ramsey, Michael G.

    2015-01-01

    The frontier orbitals of molecules are the prime determinants of their chemical, optical and electronic properties. Arguably, the most direct method of addressing the (filled) frontier orbitals is ultra-violet photoemission spectroscopy (UPS). Although UPS is a mature technique from the early 1970s on, the angular distribution of the photoemitted electrons was thought to be too complex to be analysed quantitatively. Recently angle resolved UPS (ARUPS) work on conjugated molecules both, in ordered thick films and chemisorbed monolayers, has shown that the angular (momentum) distribution of the photocurrent from orbital emissions can be simply understood. The approach, based on the assumption of a plane wave final state is becoming known as orbital tomography. Here we will demonstrate, with selected examples of pentacene (5A) and sexiphenyl (6P), the potential of orbital tomography. First it will be shown how the full angular distribution of the photocurrent (momentum map) from a specific orbital is related to the real space orbital by a Fourier transform. Examples of the reconstruction of 5A orbitals will be given and the procedure for recovering the lost phase information will be outlined. We then move to examples of sexiphenyl where we interrogate the original band maps of thick sexiphenyl in the light of our understanding of orbital tomography that has developed since then. With comparison to theoretical simulations of the molecular band maps, the molecular conformation and orientation will be concluded. New results for the sexiphenyl monolayer on Al(1 1 0) will then be presented. From the band maps it will be concluded that the molecule is planarised and adopts a tilted geometry. Finally the momentum maps down to HOMO-11 will be analysed and real space orbitals reconstructed. PMID:26752804

  5. Optical and electronic properties of SO2 molecule adsorbed on Si-doped (8, 0) boron nitride nanotube

    NASA Astrophysics Data System (ADS)

    Guo, Shuang-Shuang; Wei, Xiu-Mei; Zhang, Jian-Min; Zhu, Gang-Qiang; Guo, Wan-Jin

    2016-09-01

    The study of the optical properties of pristine BNNT, Si-doped BNNTs and SO2 molecule adsorption on Si-doped BNNTs is that, to our knowledge, few relevant research have ever been found. In this paper, the adsorption behaviors of Sulfur dioxide (SO2) molecule on Si-doped Boron nitride nanotubes (BNNTs) are investigated applying the first-principles calculations. The main contribution of this paper is that the foremost investigation for the optical properties of the pristine BNNT, Si-doped BNNTs and SO2 adsorption on Si-doped BNNTs. Additionally, the electronic properties and the structural properties are also presented. In our calculations of optical properties, the dielectric constant, the refractive index and the absorption coefficient are obtained. Comparing the pristine BNNT, our results indicate that, the blue-shifts (in the main peaks of the dielectric constant of SiB -BNNT and SO2-SiB -BNNT), and the red-shifts (in the main peaks of the refractive index of SiN -BNNT and SO2-SiN -BNNT) are appeared. Under these conditions, Si-doped BNNT and Si-doped BNNT with SO2 adsorption, the gaps are reduced both for the speculated optical band gaps and the electronic structure band gaps.

  6. Electron transfer in the quenching of protonated triplet methylene blue by ground-state molecules of the dye

    SciTech Connect

    Kamat, P.V.; Lichtin, N.N.

    1981-04-02

    A Q-switched pulsed ruby laser emitting at 694.3 nm was used in an investigation by means of flash photolysis-kinetic spectrophotometry of the mechanism of quenching of the monoprotonated lowest triplet state of methylene blue, /sup 3/MBH/sup 2 +/, by the ground state of the dye, MB/sup +/. Quenching in 0.01 N acid is accompanied by electron transfer to give the half-oxidized and half-reduced ion radicals, MB/sup 2 +/. and MBH/sup +/.. The absorption spectrum of MB/sup 2 +/. has been characterized in several media from 360 to 600 nm. The rate constant for quenching, k/sub q/, varies with solvent, ionic strength, and nature of anions with values around 1 x 10/sup 8/ M/sup -1/ s/sup -1/ in water, aqueous CH/sub 3/CN, and aqueous EtOH. The efficiency of net electron transfer in quenching, F/sub 1/(= k/sub et//k/sub q/), varies with solvent but is independent of the ionic strength or the nature of the anions. F/sub 1/ varies inversely with polarity of the solvent from 0.055 in water to 0.48 in 90% (vol/vol) aqueous CH/sub 3/CN. On the basis of analogy to the behavior of a number of other quenchers and the observed linear variation of the function ln ((1/F/sub 1/)-1) with Kosower's polarity parameter Z, it is suggested that reversible electron transfer is the only significant mechanism of quenching of /sup 3/MBH/sup 2 +/ by MB/sup +/(S/sub 0/). Both MBH/sup +/. and MB/sup 2 +/. decay by second-order processes in solvents containing 75% (vol/vol) or less of organic component but the specific rates are different for the two species in most media. It is suggested that in the latter media both cross reaction of MBH/sup +/. with MB/sup 2 +/. and biomolecular reaction of two molecules of the same radical occur. This study shows that ground-state quenching can significantly reduce the sunlight engineering efficency of photogalvanic conversion in systems incorporating relatively concentrated dyes.

  7. THE APPLICATION OF HIGH RESOLUTION ELECTRON ENERGY LOSS SPECTROSCOPY TO THE CHARACTERIZATION OF ADSORBED MOLECULES ON RHODIUM SINGLE CRYSTAL SURFACES

    SciTech Connect

    Dubois, L.H.; Somorjai, G.A.

    1980-01-01

    The scattering of low energy electrons by metal surfaces has been studied for many years now. The electron's ease of generation and detection and high surface sensitivity (low penetration depth) make it an ideal probe for surface scientists. The impinging electron can interact with the surface in basically two ways: it can either elastically reflect (or diffract) from the surface without losing energy or lose a portion of it's incident energy and inelastically scatter. In this paper we will be concerned with only one of many possible inelastic scattering processes: the loss of the electron's energy to the vibrational modes of atoms and molecules chemisorbed on the surface. This technique is known as high resolution electron energy loss spectroscopy (or ELS, EELS, HRELS, HREELS, etc.).

  8. Scrutinizing individual CoTPP molecule adsorbed on coinage metal surfaces from the interplay of STM experiment and theory

    NASA Astrophysics Data System (ADS)

    Houwaart, Torsten; Le Bahers, Tangui; Sautet, Philippe; Auwärter, Willi; Seufert, Knud; Barth, Johannes V.; Bocquet, Marie-Laure

    2015-05-01

    The cobalt tetraphenyl porphyrin (CoTPP) molecule and its adsorption on clean Cu and Ag surfaces are comparatively analyzed within the Density Functional Theory (DFT) framework. Different sets of exchange-correlation functionals - the Local Density Approximation (LDA) and the Gradient Generalized Approximation (along with the PBE functional and the semi-empirical Grimme's corrections of dispersion) - are compared. Two prominent structural adsorption properties are disclosed in all sets of calculations: an asymmetric saddle deformation of CoTPP with an enhanced tilting of the upwards bent pyrroles and a single adsorption site where the Co center occupies a bridge position and one molecular axis (along the direction of the lowered pair of opposite pyrroles) is aligned with the dense-packed < 1 1 bar 0 > substrate direction. The similarities between Cu(111) and Ag(111) surfaces extend to the interfacial electronic structure with similar electronic redistribution and molecular charging. However subtle differences between the two substrates are revealed with bias-dependent STM simulations, especially in the low-bias imaging range. The STM calculations underline the difficulty for the commonly used GGA + D2 DFT framework to quantitatively predict the energy positions of the frontier molecular orbitals (MOs).

  9. New physicochemical interpretations for the adsorption of food dyes on chitosan films using statistical physics treatment.

    PubMed

    Dotto, G L; Pinto, L A A; Hachicha, M A; Knani, S

    2015-03-15

    In this work, statistical physics treatment was employed to study the adsorption of food dyes onto chitosan films, in order to obtain new physicochemical interpretations at molecular level. Experimental equilibrium curves were obtained for the adsorption of four dyes (FD&C red 2, FD&C yellow 5, FD&C blue 2, Acid Red 51) at different temperatures (298, 313 and 328 K). A statistical physics formula was used to interpret these curves, and the parameters such as, number of adsorbed dye molecules per site (n), anchorage number (n'), receptor sites density (NM), adsorbed quantity at saturation (N asat), steric hindrance (τ), concentration at half saturation (c1/2) and molar adsorption energy (ΔE(a)) were estimated. The relation of the above mentioned parameters with the chemical structure of the dyes and temperature was evaluated and interpreted. PMID:25308634

  10. Localization microscopy of DNA in situ using Vybrant(®) DyeCycle™ Violet fluorescent probe: A new approach to study nuclear nanostructure at single molecule resolution.

    PubMed

    Żurek-Biesiada, Dominika; Szczurek, Aleksander T; Prakash, Kirti; Mohana, Giriram K; Lee, Hyun-Keun; Roignant, Jean-Yves; Birk, Udo J; Dobrucki, Jurek W; Cremer, Christoph

    2016-05-01

    Higher order chromatin structure is not only required to compact and spatially arrange long chromatids within a nucleus, but have also important functional roles, including control of gene expression and DNA processing. However, studies of chromatin nanostructures cannot be performed using conventional widefield and confocal microscopy because of the limited optical resolution. Various methods of superresolution microscopy have been described to overcome this difficulty, like structured illumination and single molecule localization microscopy. We report here that the standard DNA dye Vybrant(®) DyeCycle™ Violet can be used to provide single molecule localization microscopy (SMLM) images of DNA in nuclei of fixed mammalian cells. This SMLM method enabled optical isolation and localization of large numbers of DNA-bound molecules, usually in excess of 10(6) signals in one cell nucleus. The technique yielded high-quality images of nuclear DNA density, revealing subdiffraction chromatin structures of the size in the order of 100nm; the interchromatin compartment was visualized at unprecedented optical resolution. The approach offers several advantages over previously described high resolution DNA imaging methods, including high specificity, an ability to record images using a single wavelength excitation, and a higher density of single molecule signals than reported in previous SMLM studies. The method is compatible with DNA/multicolor SMLM imaging which employs simple staining methods suited also for conventional optical microscopy. PMID:26341267

  11. Applications of Metal Oxide Materials in Dye Sensitized Photoelectrosynthesis Cells for Making Solar Fuels: Let the Molecules do the Work

    SciTech Connect

    Alibabaei, Leila; Luo, Hanlin; House, Ralph L.; Hoertz, Paul G.; Lopez, Rene; Meyer, Thomas J.

    2013-01-01

    Solar fuels hold great promise as a permanent, environmentally friendly, long-term renewable energy source, that would be readily available across the globe. In this account, an approach to solar fuels is described based on Dye Sensitized Photoelectrosynthesis Cells (DSPEC) that mimic the configuration used in Dye Sensitized Solar Cells (DSSC), but with the goal of producing oxygen and a high energy solar fuel in the separate compartments of a photoelectrochemical cell rather than a photopotential and photocurrent.

  12. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    NASA Astrophysics Data System (ADS)

    Meng, Qingyong; Meyer, Hans-Dieter

    2015-10-01

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  13. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    SciTech Connect

    Meng, Qingyong; Meyer, Hans-Dieter

    2015-10-28

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  14. Orientation Difference of Chemically Immobilized and Physically Adsorbed Biological Molecules on Polymers Detected at the Solid/Liquid Interfaces in Situ

    PubMed Central

    Ye, Shuji; Nguyen, Khoi Tan; Boughton, Andrew P.; Mello, Charlene M.; Chen, Zhan

    2009-01-01

    A surface sensitive second order nonlinear optical technique, sum frequency generation (SFG) vibrational spectroscopy, was applied to study peptide orientation on polymer surfaces, supplemented by a linear vibrational spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Using the antimicrobial peptide Cecropin P1 as a model system, we have quantitatively demonstrated that chemically immobilized peptides on polymers adopt a more ordered orientation than less tightly bound physically adsorbed peptides. These differences were also observed in different chemical environments, e.g., air versus water. Although numerous studies have reported a direct correlation between the choice of immobilization method and the performance of an attached biological molecule, the lack of direct biomolecular structure and orientation data has made it difficult to elucidate the relationship between structure, orientation and function at a surface. In this work, we directly studied the effect of chemical immobilization method on biomolecular orientation/ordering, an important step for future studies of biomolecular activity. The methods for orientation analysis described within are also of relevance to understanding biosensors, biocompatibility, marine-antifouling, membrane protein functions, and antimicrobial peptide activities. PMID:19961170

  15. X-ray photoelectron and optical absorption spectroscopic studies on the dye chlorodiane blue, used as a carrier generation molecule in organic photoconductors

    SciTech Connect

    Pacansky, J.; Waltman, R.J.

    1992-07-01

    The dye chlorodiane blue, used as a carrier generation molecule in organic photoconductors, is characterized via optical absorption and X-ray photoelectron spectroscopy, and the results are interpreted on the basis of ab initio quantum mechanical molecular models. These data indicate that chlorodiane blue exists as azo-enol and hydrazone-quinone chemical structures and it is the hydrazone-quinone form that provides the higher xerographic gain in electrophotographic applications. Optimized geometries, atomic charges, and molecular orbital plots and energies are reported for both the azo-enol and hydrazone-quinone forms of chlorodiane blue. The two structural forms of the dye are experimentally distinguishable via both optical absorption and X-ray photoelectron spectroscopy, and the wavelength and chemical shifts, respectively, are interpreted via the theoretical results. 29 refs., 9 figs., 4 tabs.

  16. In situ spectroelectrochemical and theoretical study on the oxidation of a 4H-imidazole-ruthenium dye adsorbed on nanocrystalline TiO2 thin film electrodes.

    PubMed

    Zhang, Ying; Kupfer, Stephan; Zedler, Linda; Schindler, Julian; Bocklitz, Thomas; Guthmuller, Julien; Rau, Sven; Dietzek, Benjamin

    2015-11-28

    Terpyridine 4H-imidazole-ruthenium(II) complexes are considered promising candidates for use as sensitizers in dye sensitized solar cells (DSSCs) by displaying broad absorption in the visible range, where the dominant absorption features are due to metal-to-ligand charge transfer (MLCT) transitions. The ruthenium(III) intermediates resulting from photoinduced MLCT transitions are essential intermediates in the photoredox-cycle of the DSSC. However, their photophysics is much less studied compared to the ruthenium(II) parent systems. To this end, the structural alterations accompanying one-electron oxidation of the RuIm dye series (including a non-carboxylic RuIm precursor, and, carboxylic RuImCOO in solution and anchored to a nanocrystalline TiO2 film) are investigated via in situ experimental and theoretical UV-Vis absorption and resonance Raman (RR) spectroelectrochemistry. The excellent agreement between the experimental and the TDDFT spectra derived in this work allows for an in-depth assignment of UV-Vis and RR spectral features of the dyes. A concordant pronounced wavelength dependence with respect to the charge transfer character has been observed for the model system RuIm, and both RuImCOO in solution and attached on the TiO2 surface. Excitation at long wavelengths leads to the population of ligand-to-metal charge transfer states, i.e. photoreduction of the central ruthenium(III) ion, while high-energy excitation features an intra-ligand charge transfer state localized on the 4H-imidazole moiety. Therefore, these 4H-imidazole ruthenium complexes investigated here are potential multi-photoelectron donors. One electron is donated from MLCT states, and additionally, the 4H-imidazole ligand reveals electron-donating character with a significant contribution to the excited states of the ruthenium(III) complexes upon blue-light irradiation. PMID:26478575

  17. Multilayer Dye Adsorption in Activated Carbons-Facile Approach to Exploit Vacant Sites and Interlayer Charge Interaction.

    PubMed

    Hadi, Pejman; Guo, Jiaxin; Barford, John; McKay, Gordon

    2016-05-17

    Altering the textural properties of activated carbons (ACs) via physicochemical techniques to increase their specific surface area and/or to manipulate their pore size is a common practice to enhance their adsorption capacity. Instead, this study proposes the utilization of the vacant sites remaining unoccupied after dye uptake saturation by removing the steric hindrance and same-charge repulsion phenomena via multilayer adsorption. Herein, it has been shown that the adsorption capacity of the fresh AC is a direct function of the dye molecular size. As the cross-sectional area of the dye molecule increases, the steric hindrance effect exerted on the neighboring adsorbed molecules increases, and the geometrical packing efficiency is constrained. Thus, ACs saturated with larger dye molecules render higher concentrations of vacant adsorption sites which can accommodate an additional layer of dye molecules on the exhausted adsorbent through interlayer attractive forces. The second layer adsorption capacity (60-200 mg·g(-1)) has been demonstrated to have a linear relationship with the uncovered surface area of the exhausted AC, which is, in turn, inversely proportional to the adsorbate molecular size. Unlike the second layer adsorption, the third layer adsorption is a direct function of the charge density of the second layer. PMID:27088796

  18. Novel durable bio-photocatalyst purifiers, a non-heterogeneous mechanism: accelerated entrapped dye degradation into structural polysiloxane-shield nano-reactors.

    PubMed

    Dastjerdi, Roya; Montazer, Majid; Shahsavan, Shadi; Böttcher, Horst; Moghadam, M B; Sarsour, Jamal

    2013-01-01

    This research has designed innovative Ag/TiO(2) polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO(2) were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity. PMID:23010055

  19. Microchip electrophoresis with background electrolyte containing polyacrylic acid and high content organic solvent in cyclic olefin copolymer microchips for easily adsorbed dyes.

    PubMed

    Wei, Xuan; Sun, Ping; Yang, Shenghong; Zhao, Lei; Wu, Jing; Li, Fengyun; Pu, Qiaosheng

    2016-07-29

    Plastic microchips can significantly reduce the fabrication cost but the adsorption of some analytes limits their application. In this work, background electrolyte containing ionic polymer and high content of organic solvent was adopted to eliminate the analyte adsorption and achieve highly efficient separation in microchip electrophoresis. Two dyes, rhodamine 6G (Rh6G) and rhodamine B (RhB) were used as the model analytes. By using methanol as the organic solvent and polyacrylic acid (PAA) as a multifunctional additive, successful separation of the two dyes within 75μm id. microchannels was realized. The role of PAA is multiple, including viscosity regulator, selectivity modifier and active additive for counteracting analyte adsorption on the microchannel surface. The number of theoretical plate of 7.0×10(5)/m was attained within an effective separation distance of 2cm using background electrolyte consisting 80% methanol, 0.36% PAA and 30mmol/L phosphate at pH 5.0. Under optimized conditions, relative standard deviations of Rh6G and RhB detection (n=5) were no more than 1.5% for migration time and 2.0% for peak area, respectively. The limit of detection (S/N=3) was 0.1nmol/L for Rh6G. The proposed technique was applied in the determination of both Rh6G and RhB in chilli powder and lipstick samples with satisfactory recoveries of 81.3-103.7%. PMID:27371017

  20. Adsorption and trace detection of pharmacologically significant 5-methylthio-1, 3, 4-thiadiazole-2-thiol molecule adsorbed on silver nanocolloids and understanding the role of Albrecht's “A” and Herzberg-Teller contributions in the SERS spectra

    NASA Astrophysics Data System (ADS)

    Chowdhury, Joydeep; Chandra, Subhendu; Ghosh, Manash

    2015-01-01

    The surface enhanced Raman scattering (SERS) spectra of biologically and industrially significant 5-methylthio-1, 3, 4-thiadiazole 2-thiol molecule have been investigated. The SERS spectra at various concentrations of the adsorbate are compared with the Fourier transform Infrared (FTIR) and normal Raman spectra (NRS) of the probe molecule recorded in different environmental conditions. The optimized molecular structures of the most probable thione and the thiol forms of the molecule have been estimated from the density functional theory (DFT) calculations. The vibrational signatures of the molecule have been assigned from the potential energy distributions (PEDs). The detail vibrational analyses reveal that ∼54% of the thione form of the molecule is prevalent in the solid state and its population increases to ∼65% in ACN solvent medium. Concentration dependent SERS, together with the 2-dimensional correlation spectra (2D-COS), corroborate the presence of both the thione and the thiol forms of the molecule even in the surface adsorbed state. The orientations of the thione and the thiol forms of the molecule on the nanocolloidal silver surface have been predicted from the surface selection rule. The selective enhancement of Raman bands in the SERS spectra have been explored from the view of the Albrecht's "A" and Herzberg-Teller (HT) charge transfer (CT) contribution.

  1. Adsorption and trace detection of pharmacologically significant 5-methylthio-1, 3, 4-thiadiazole-2-thiol molecule adsorbed on silver nanocolloids and understanding the role of Albrecht's "A" and Herzberg-Teller contributions in the SERS spectra.

    PubMed

    Chowdhury, Joydeep; Chandra, Subhendu; Ghosh, Manash

    2015-01-25

    The surface enhanced Raman scattering (SERS) spectra of biologically and industrially significant 5-methylthio-1, 3, 4-thiadiazole 2-thiol molecule have been investigated. The SERS spectra at various concentrations of the adsorbate are compared with the Fourier transform Infrared (FTIR) and normal Raman spectra (NRS) of the probe molecule recorded in different environmental conditions. The optimized molecular structures of the most probable thione and the thiol forms of the molecule have been estimated from the density functional theory (DFT) calculations. The vibrational signatures of the molecule have been assigned from the potential energy distributions (PEDs). The detail vibrational analyses reveal that ∼54% of the thione form of the molecule is prevalent in the solid state and its population increases to ∼65% in ACN solvent medium. Concentration dependent SERS, together with the 2-dimensional correlation spectra (2D-COS), corroborate the presence of both the thione and the thiol forms of the molecule even in the surface adsorbed state. The orientations of the thione and the thiol forms of the molecule on the nanocolloidal silver surface have been predicted from the surface selection rule. The selective enhancement of Raman bands in the SERS spectra have been explored from the view of the Albrecht's "A" and Herzberg-Teller (HT) charge transfer (CT) contribution. PMID:25168230

  2. A novel biosorbent for dye removal: extracellular polymeric substance (EPS) of Proteus mirabilis TJ-1.

    PubMed

    Zhang, Zhiqiang; Xia, Siqing; Wang, Xuejiang; Yang, Aming; Xu, Bin; Chen, Ling; Zhu, Zhiliang; Zhao, Jianfu; Jaffrezic-Renault, Nicole; Leonard, Didier

    2009-04-15

    This paper deals with the extracellular polymeric substance (EPS) of Proteus mirabilis TJ-1 used as a novel biosorbent to remove dye from aqueous solution in batch systems. As a widely used and hazardous dye, basic blue 54 (BB54) was chosen as the model dye to examine the adsorption performance of the EPS. The effects of pH, initial dye concentration, contact time and temperature on the sorption of BB54 to the EPS were examined. At various initial dye concentrations (50-400 mg/L), the batch sorption equilibrium can be obtained in only 5 min. Kinetic studies suggested that the sorption followed the internal transport mechanism. According to the Langmuir model, the maximum BB54 uptake of 2.005 g/g was obtained. Chemical analysis of the EPS indicated the presence of protein (30.9%, w/w) and acid polysaccharide (63.1%, w/w). Scanning electron microscopy (SEM) images showed that the EPS with a crystal-linear structure was whole enwrapped by adsorbed dye molecules. FTIR spectrum result revealed the presence of adsorbing groups such as carboxyl, hydroxyl and amino groups in the EPS. High-molecular weight of the EPS with more binding-sites and stronger van der Waals forces together with its specific construct leads to the excellent performance of dye adsorption. The EPS shows potential board application as a biosorbent for both environmental protection and dye recovery. PMID:18718709

  3. Removal of dyes from aqueous solutions using activated carbon prepared from rice husk residue.

    PubMed

    Li, Yaxin; Zhang, Xian; Yang, Ruiguang; Li, Guiying; Hu, Changwei

    2016-01-01

    The treatment of dye wastewater by activated carbon (AC) prepared from rice husk residue wastes was studied. Batch adsorption studies were conducted to investigate the effects of contact time, initial concentration (50-450 mg/L), pH (3-11) and temperature (30-70 °C) on the removal of methylene blue (MB), neutral red, and methyl orange. Kinetic investigation revealed that the adsorption of dyes followed pseudo-second-order kinetics. The results suggested that AC was effective to remove dyes, especially MB, from aqueous solutions. Desorption studies found that chemisorption by the adsorbent might be the major mode of dye removal. Fourier transform infrared results suggested that dye molecules were likely to combine with the O-H and P=OOH groups of AC. PMID:26942535

  4. A simple approach for the synthesis of Ag-coated Ni@TiO{sub 2} nanocomposites as recyclable photocatalysts and SERS substrate to monitor catalytic degradation of dye molecules

    SciTech Connect

    Ding, Qianqian; Zhang, Li; Yang, Liangbao

    2014-05-01

    Graphical abstract: - Highlights: • A simple approach was used to synthesize Ag-coated Ni@TiO{sub 2} nanocomposites. • The nanocomposites can be the convenient and effective SERS substrate. • The nanocomposites can be a self-cleaning SERS substrate. • The nanocomposites can monitor the catalytic degradation of dye molecules. - Abstract: In this work, we demonstrate an extremely simple and speedy approach to synthesis Ag-coated Ni@TiO{sub 2} nanocomposites, which can be a convenient and effective substrate for surface enhanced Raman spectroscopy (SERS) observation. Due to possessing the excellent magnetic properties and stable catalytic properties at room temperature, the nanocomposites can clean themselves by photocatalytic degradation of dye molecules under irradiation with UV light into inorganic small molecules for the self-cleaning SERS detection. Furthermore, the nanocomposites can be used as the SERS substrate for monitoring the catalytic degradation of dye molecules.

  5. Enhanced stability of Zn2SnO4 with N719, N3 and eosin Y dye molecules for DSSC application.

    PubMed

    Pratim Das, Partha; Roy, Anurag; Das, Sumita; Devi, Parukuttyamma Sujatha

    2016-01-21

    In view of the increased prospects of Zn2SnO4 as an alternative photoanode for dye sensitized solar cells (DSSCs), we synthesized phase pure Zn2SnO4 nanostructures by a cost effective sonochemical technique. In order to establish the stability of this alternative photoanode in DSSCs, we further explored the interaction of the synthesized Zn2SnO4 with commonly used photosensitizers in DSSCs, such as N3, N719 and eosin Y. Based on the time dependent optical studies we could establish the prominence of anchoring groups in controlling the dye loading. Optical studies confirmed an enhanced stable interaction of Zn2SnO4 with all the studied sensitizers which could be beneficial in designing DSSC devices in future. In addition, we also established contact angle measurement as an indirect tool to understand the surface characteristics and thereby optimize the dye loading and stability of the photoanode surface. With the help of contact angle data, we could unequivocally establish the stability of the Zn2SnO4 photoanode surface modified with N3 and N719 dye molecules. Our studies further suggest the enhanced and superior stability of the prepared Zn2SnO4 compared to ZnO in different chemical environments. The quenching of the fluorescence and the abrupt decrease in the contact angle owing to an increase in the surface roughness further strengthen the above conclusion. To our best knowledge, this probably is the first report on the synthesis of Zn2SnO4 by a sonochemical process and its interaction with various photosensitizers. An exceptionally high open circuit voltage of >0.8 V was observed for all the devices fabricated with the synthesized ZTO as a photoanode. Our studies could pave way to future developments in the area of DSSCs using Zn2SnO4 as a photoanode. PMID:26498509

  6. Enhanced photostability of an anthracene-based dye due to supramolecular encapsulation: a new type of photostable fluorophore for single-molecule study.

    PubMed

    Mitsui, Masaaki; Higashi, Koji; Takahashi, Ryoya; Hirumi, Yohei; Kobayashi, Kenji

    2014-08-01

    For single-molecule fluorescence studies, highly photostable fluorophores are absolutely imperative, because photo-induced degradation (i.e., photobleaching) limits the observation time of individual molecules. Herein, the photophysics and photostability of a highly fluorescent 9,10-bis(phenylethynyl)anthracene derivative (G) and its self-assembled boronic ester encapsulation complex (G@Cap) embedded in a glassy polymer matrix are investigated by single-molecule fluorescence spectroscopy (SMFS). The heterogeneity of the fluorescence emission wavelength and triplet blinking kinetics of the guest G are significantly decreased by supramolecular encapsulation due to conformational restriction and reduced heterogeneity in the local environment. A nearly 10-fold increase in the photostability of G due to encapsulation is quantitatively confirmed by evaluating the photobleaching yields of G and G@Cap. In addition, it is found that the G@Cap is >30-fold more photostable than rhodamine 6G, a widely used fluorescent dye in single-molecule studies. These results demonstrate that the G@Cap can serve as a very bright, long-lasting fluorescent probe for single-molecule studies. PMID:24887756

  7. Adsorbent phosphates

    NASA Technical Reports Server (NTRS)

    Watanabe, S.

    1983-01-01

    An adsorbent which uses as its primary ingredient phosphoric acid salts of zirconium or titanium is presented. Production methods are discussed and several examples are detailed. Measurements of separating characteristics of some gases using the salts are given.

  8. Aggregate formation of eosin-Y adsorbed on nanocrystalline TiO2 films

    NASA Astrophysics Data System (ADS)

    Yaguchi, Kaori; Furube, Akihiro; Katoh, Ryuzi

    2012-11-01

    We have studied the adsorption of eosin-Y on nanocrystalline TiO2 films with two different solvents namely acetonitrile (ACN) and ethanol (EtOH). A Langmuir-type adsorption isotherm was observed with ACN. In contrast, a Freundlich-type adsorption isotherm was observed with EtOH, suggesting that EtOH molecules co-adsorbed on TiO2 surface. Absorption spectra of the dye adsorbed films clearly show aggregate formation at high concentrations of dye in the solutions. From the analysis of the spectra, we conclude that head-to-tail type aggregates are observed with ACN, whereas various types of aggregates, including H-type and head-to-tail type aggregates, are observed with EtOH.

  9. Extending the range of low energy electron diffraction (LEED) surface structure determination: Co-adsorbed molecules, incommensurate overlayers and alloy surface order studied by new video and electron counting LEED techniques

    SciTech Connect

    Ogletree, D.F.

    1986-11-01

    LEED multiple scattering theory is briefly summarized, and aspects of electron scattering with particular significance to experimental measurements such as electron beam coherence, instrument response and phonon scattering are analyzed. Diffuse LEED experiments are discussed. New techniques that enhance the power of LEED are described, including a real-time video image digitizer applied to LEED intensity measurements, along with computer programs to generate I-V curves. The first electron counting LEED detector using a ''wedge and strip'' position sensitive anode and digital electronics is described. This instrument uses picoampere incident beam currents, and its sensitivity is limited only by statistics and counting times. Structural results on new classes of surface systems are presented. The structure of the c(4 x 2) phase of carbon monoxide adsorbed on Pt(111) has been determined, showing that carbon monoxide molecules adsorb in both top and bridge sites, 1.85 +- 0.10 A and 1.55 +- 0.10 A above the metal surface, respectively. The structure of an incommensurate graphite overlayer on Pt(111) is analyzed. The graphite layer is 3.70 +- 0.05 A above the metal surface, with intercalated carbon atoms located 1.25 +- 0.10 A above hollow sites supporting it. The (2..sqrt..3 x 4)-rectangular phase of benzene and carbon monoxide coadsorbed on Pt(111) is analyzed. Benzene molecules adsorb in bridge sites parallel to and 2.10 +- 0.10 A above the surface. The carbon ring is expanded, with an average C-C bond length of 1.72 +- 0.15 A. The carbon monoxide molecules also adsorb in bridge sites. The structure of the (..sqrt..3 x ..sqrt..3) reconstruction on the (111) face of the ..cap alpha..-CuAl alloy has been determined.

  10. Momentum resolved electron stimulated desorption ion angular distribution, a new technique, probing the low frequency motion of adsorbed molecules on single crystal surfaces

    SciTech Connect

    Ahner, J.; Mocuta, D.; Yates, J.T. Jr.

    1999-07-01

    A new technique, momentum resolved electron stimulated desorption ion angular distribution (ESDIAD), provides a method for taking snapshots of the zero-point position and lateral momentum of particles adsorbed on crystalline surfaces. By employing state-of-the-art electronics and computer technology it is possible to record for each desorbing particle the desorption direction together with the flight time. High momentum and directional resolved images are obtained, with time-of-flight resolution in the picosecond range and data acquisition rates up to 100 kHz. This enables us to deconvolute spatial and momentum contributions to the ESDIAD pattern and to map the low frequency motion of the adsorbed particles. These maps reflect the adsorbate interactions with the substrate and with neighboring species on the substrate. For selected examples it is demonstrated that by measuring the three dimensional momentum vector for each desorbing particle it is possible to probe the lowest energy states of adsorbed species, as well as to measure the momentum distribution when the adsorbed species gains thermal energy. Such information can be used as a basis for thinking about anisotropies in lateral motion of particles on surfaces. One major opportunity involves the study of dissimilar chemisorbed species which, when imaged together in momentum and real space, give new insights into the first stages of interaction between the species, leading ultimately to a chemical reaction. {copyright} {ital 1999 American Vacuum Society.}

  11. J-aggregates of organic dye molecules complexed with iron oxide nanoparticles for imaging-guided photothermal therapy under 915-nm light.

    PubMed

    Song, Xuejiao; Gong, Hua; Liu, Teng; Cheng, Liang; Wang, Chao; Sun, Xiaoqi; Liang, Chao; Liu, Zhuang

    2014-11-12

    Recently, the development of nano-theranostic agents aiming at imaging guided therapy has received great attention. In this work, a near-infrared (NIR) heptamethine indocyanine dye, IR825, in the presence of cationic polymer, polyallylamine hydrochloride (PAH), forms J-aggregates with red-shifted and significantly enhanced absorbance. After further complexing with ultra-small iron oxide nanoparticles (IONPs) and the followed functionalization with polyethylene glycol (PEG), the obtained IR825@PAH-IONP-PEG composite nanoparticles are highly stable in different physiological media. With a sharp absorbance peak, IR825@PAH-IONP-PEG can serve as an effective photothermal agent under laser irradiation at 915 nm, which appears to be optimal in photothermal therapy application considering its improved tissue penetration compared with 808-nm light and much lower water heating in comparison to 980-nm light. As revealed by magnetic resonance (MR) imaging, those nanoparticles after intravenous injection exhibit high tumor accumulation, which is then harnessed for in vivo photothermal ablation of tumors, achieving excellent therapeutic efficacy in a mouse tumor model. This study demonstrates for the first time that J-aggregates of organic dye molecules are an interesting class of photothermal material, which when combined with other imageable nanoprobes could serve as a theranostic agent for imaging-guided photothermal therapy of cancer. PMID:24976309

  12. Quasiparticle excitations of adsorbates on doped graphene

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Wickenburg, Sebastian; Wong, Dillon; Karrasch, Christoph; Wang, Yang; Lu, Jiong; Omrani, Arash A.; Brar, Victor; Tsai, Hsin-Zon; Wu, Qiong; Corsetti, Fabiano; Mostofi, Arash; Kawakami, Roland K.; Moore, Joel; Zettl, Alex; Louie, Steven G.; Crommie, Mike

    Adsorbed atoms and molecules can modify the electronic structure of graphene, but in turn it is also possible to control the properties of adsorbates via the graphene substrate. In my talk, I will discuss the electronic structure of F4-TCNQ molecules on doped graphene and present a first-principles based theory of quasiparticle excitations that captures the interplay of doping-dependent image charge interactions between substrate and adsorbate and electron-electron interaction effects on the molecule. The resulting doping-dependent quasiparticle energies will be compared to experimental scanning tunnelling spectra. Finally, I will also discuss the effects of charged adsorbates on the electronic structure of doped graphene.

  13. Dynamic polarization grating based on a dye-doped liquid crystal controllable by a single beam in a homeotropic-planar geometry.

    PubMed

    Kim, Hak-Rin; Jang, Eunje; Kim, Jiyoon; Joo, Kyung-Il; Lee, Sin-Doo

    2012-12-20

    We present a dynamic polarization grating based on a dye-doped liquid crystal cell that is controllable by a single pump beam in a binary homeotropic-planar configuration produced through selective rubbing. Upon single pump beam irradiation, the azo dyes in the liquid-crystal (LC) layer diffuse and adsorb onto the planar LC-anchoring surface due to trans-cis photo-isomerization. It is found that the dynamic polarization grating effect results mainly from the photo-induced easy axis reorientation by the amount of dye molecules adsorbed on the planar LC-alignment surface in a single-beam control scheme. The initial LC-anchoring conditions and the dynamic behavior of the dye adsorption strongly influence the repetitive writing-erasing processes by the single pump beam. PMID:23262590

  14. Enhancement of Spectral Response of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Chang, Shuai

    Dye-Sensitized solar cell (DSSC) is a class of third-generation solar devices. A notable feature of DSSC is that it can be manufactured by solution-based approach; this non-vacuum processing renders significant reduction in manufacturing costs. Different from conventional solar cells, in a DSSC, mesoporous semiconductor film with large surface areas is utilized for anchoring dye molecules, serving as light absorbing layer. Dye sensitizers play an important role in determining the final performance in DSSCs. Since the first highly-efficient DSSC was reported in 1991 sensitized by a ruthenium-based dye, numerous researchers have been focused on the development and characterization of various kinds of dyes for the applications in DSSCs. These include mainly metal complexes dyes, organic dyes, porphyrins and phthalocyanines dyes. The first part of my thesis work is to develop and test new dyes for DSSCs and a series of phenothiazine-based organic dyes and new porphyrin dyes are reported during the process. It has been realized that extending the response of dye sensitizers to a wider range of the solar spectrum is a key step in further improving the device efficiency. Typically, there are two ways for expanding the strong spectral response of DSSCs from visible to far red/NIR region. One approach is called co-sensitization. Herein, we demonstrate a new co-sensitization concept where small molecules is used to insert the interstitial site of between the pre-adsorbed large molecules. In this case, the co-adsorbed small ones is found to improve the light response and impede the back recombination, finally leading to the power conversion efficiency over 10% in conventional DSSC devices and a record-equaling efficiency of 9.2% in quasi-solid-state devices. I also implemented graphene sheets in the anode films for better charge transfer efficiency and break the energy conversion limit of co-sensitization in DSSCs. The optimal configuration between porphyrin dyes and

  15. Investigation into Photoconductivity in Single CNF/TiO2-Dye Core-Shell Nanowire Devices

    NASA Astrophysics Data System (ADS)

    Li, Zhuangzhi; Rochford, Caitlin; Javier Baca, F.; Liu, Jianwei; Li, Jun; Wu, Judy

    2010-09-01

    A vertically aligned carbon nanofiber array coated with anatase TiO2 (CNF/TiO2) is an attractive possible replacement for the sintered TiO2 nanoparticle network in the original dye-sensitized solar cell (DSSC) design due to the potential for improved charge transport and reduced charge recombination. Although the reported efficiency of 1.1% in these modified DSSC’s is encouraging, the limiting factors must be identified before a higher efficiency can be obtained. This work employs a single nanowire approach to investigate the charge transport in individual CNF/TiO2 core-shell nanowires with adsorbed N719 dye molecules in dark and under illumination. The results shed light on the role of charge traps and dye adsorption on the (photo) conductivity of nanocrystalline TiO2 CNF’s as related to dye-sensitized solar cell performance.

  16. Voltage-sensitive styryl dyes as singlet oxygen targets on the surface of bilayer lipid membrane.

    PubMed

    Sokolov, V S; Gavrilchik, A N; Kulagina, A O; Meshkov, I N; Pohl, P; Gorbunova, Yu G

    2016-08-01

    Photosensitizers are widely used as photodynamic therapeutic agents killing cancer cells by photooxidation of their components. Development of new effective photosensitive molecules requires profound knowledge of possible targets for reactive oxygen species, especially for its singlet form. Here we studied photooxidation of voltage-sensitive styryl dyes (di-4-ANEPPS, di-8-ANEPPS, RH-421 and RH-237) by singlet oxygen on the surface of bilayer lipid membranes commonly used as cell membrane models. Oxidation was induced by irradiation of a photosensitizer (aluminum phthalocyanine tetrasulfonate) and monitored by the change of dipole potential on the surface of the membrane. We studied the drop of the dipole potential both in the case when the dye molecules were adsorbed on the same side of the lipid bilayer as the photosensitizer (cis-configuration) and in the case when they were adsorbed on the opposite side (trans-configuration). Based on a simple model, we determined the rate of oxidation of the dyes from the kinetics of change of the potential during and after irradiation. This rate is proportional to steady-state concentration of singlet oxygen in the membrane under irradiation. Comparison of the oxidation rates of various dyes reveals that compounds of ANEPPS series are more sensitive to singlet oxygen than RH type dyes, indicating that naphthalene group is primarily responsible for their oxidation. PMID:27236238

  17. Swelling induced regeneration of TiO2-impregnated chitosan adsorbents under visible light.

    PubMed

    Yang, Limin; Jiang, Lei; Hu, Di; Yan, Qingyun; Wang, Zhi; Li, Sisi; Chen, Cheng; Xue, Qi

    2016-04-20

    Since only the molecules that are in direct contact with the TiO2 surface undergo photosensitization, it is challenging to regenerate the TiO2-impregnated chitosan (TIC) adsorbent beads under visible light. This study focused on the role of chitosan swelling properties. It was found that dye-loaded TIC adsorbent exhibited a pH-dependent swelling owing to protonation/deprotonation of free amino groups on chitosan chains. In the acidic medium (pH<6.0), the adsorbent underwent a 'smart' phase transition from a dry contracted state to a hydrated swollen state, and its physicochemical properties were also significantly changed, which eventually enabled the photosensitized oxidation of dye. This swelling induced regeneration was further confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The involvement of oxygen radical species (O2(-)/HOO and OH) was also confirmed with electron spin resonance (ESR) spectroscopy. Moreover, the adsorption effectiveness of TIC adsorbent was mostly recovered after six regeneration cycles. PMID:26876871

  18. Electronic structure of p-type perylene monoimide-based donor-acceptor dyes on the nickel oxide (100) surface: a DFT approach.

    PubMed

    Kontkanen, O V; Niskanen, M; Hukka, T I; Rantala, T T

    2016-05-25

    A p-type dye-sensitized solar cell, where the dye injects a hole into the semiconductor, could be combined with a typical Grätzel cell to create an efficient tandem device. However, the current p-type devices suffer from low efficiency. Here, geometries and electronic structures of four perylenemonoimide-based dyes () both as free and adsorbed on the NiO(100) semiconductor surface have been investigated to gain a better understanding of the p-type devices. In particular, the electronic transitions relevant to charge transfer between the dye and the surface have been identified. Excitations have been evaluated using the time-dependent DFT calculations, and the roles of frontier orbitals and band edges in transitions have been assessed. The adsorbed dyes can adopt either upright or slightly tilted geometries depending on the structure of the anchoring group and the binding mode of the dye. The adsorption slightly lowers the NiO band gap, from 4.06 eV to 3.90-3.96 eV, depending on the surface-adsorbate system and the band gaps of the dye molecules by 0.1-0.2 eV. Additionally, the adsorption mode of dye moves the LUMO+1 level down by 0.5 eV. The effective mass of charge carrier holes is significantly smaller at the NiO surface than in the bulk indicating the importance of surface conductivity. We also found that the potential drop, i.e. the driving force for charge transfer from NiO to the dye molecule, depends on the adsorption mode of . PMID:27224900

  19. Synergistic effect of dual interfacial modifications with room-temperature-grown epitaxial ZnO and adsorbed indoline dye for ZnO nanorod array/P3HT hybrid solar cell.

    PubMed

    Chen, Dian-Wei; Wang, Ting-Chung; Liao, Wen-Pin; Wu, Jih-Jen

    2013-09-11

    ZnO nanorod (NR)/poly(3-hexylthiophene) (P3HT) hybrid solar cells with interfacial modifications are investigated in this work. The ZnO NR arrays are modified with room-temperature (RT)-grown epitaxial ZnO shells or/and D149 dye molecules prior to the P3HT infiltration. A synergistic effect of the dual modifications on the efficiency of the ZnO NR/P3HT solar cell is observed. The open-circuit voltage and fill factor are considerable improved through the RT-grown ZnO and D149 modifications in sequence on the ZnO NR array, which brings about a 2-fold enhancement of the efficiency of the ZnO NR/P3HT solar cell. We suggested that the more suitable surface of RT-grown ZnO for D149 adsorption, the chemical compatibility of D149 and P3HT, and the elevated conduction band edge of the RT-grown ZnO/D149-modified ZnO NR array construct the superior interfacial morphology and energetics in the RT-grown ZnO/D149-modified ZnO NR/P3HT hybrid solar cell, resulting in the synergistic effect on the cell efficiency. An efficiency of 1.16% is obtained in the RT-grown ZnO/D149-modified ZnO NR/P3HT solar cell. PMID:23937447

  20. Direct visual evidence for chemical mechanism of SERRS of the S-complex of pyrimidine molecule adsorbed on silver nanoparticle via charge transfer.

    PubMed

    Zhang, Xin; Wang, Peijie; Sheng, Shaoxiang; Zhang, Lisheng; Fang, Yan

    2014-01-01

    In this paper, the S-complex of pyrimidine molecule absorbed on silver clusters was employed as a model molecule to study the enhancement mechanism in surface-enhanced resonance Raman scattering (SERRS). We described the chemical enhancement of SERRS through charge transfer (CT) from Ag20 to pyrimidine on resonance excitation, and electromagnetic enhancement through intracluster charge redistribution (CR) on the electronic intracluster collective oscillation excitation. It is shown that SERRS process of the pyrimidine molecule absorbed on silver clusters with different incident wavelength are dominated by different enhancement mechanisms. Both experimental and theoretical works have been performed to understand the CT process in SERRS. PMID:24287052

  1. Influence of the glass transition on rotational dynamics of dyes in thin polymer films: single-molecule and ensemble experiments.

    PubMed

    Araoz, Beatriz; Carattino, Aquiles; Täuber, Daniela; von Borczyskowski, Christian; Aramendia, Pedro F

    2014-11-13

    We performed polarized fluorescence emission studies of Nile Red (NR) in poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(butyl methacrylate) (PBMA) at the single molecule (SM) and at the ensemble level to study the in cage movements of the ground-state molecule in polymer films of nanometric thickness at room temperature. Experiments were performed with wide field irradiation. At the ensemble level, the linearly polarized irradiation was used to induce a photoselection by bleaching, which is compensated by rotational diffusion. Both results show an appreciable difference in mobility of NR in the films that is correlated with the different glass-transition temperatures of the films, particularly in PEMA, which displays a clearly distinct behavior between the 200 nm films, representing a rigid environment, and the 25 nm ones, showing much higher mobility. We developed a model of broad application for polarized photobleaching that allows obtaining rotational diffusion coefficients and photobleaching quantum yields in an easy way from ensemble experiments. The parameters obtained from ensemble measurements correlate well with the results from SM experiments. PMID:24870555

  2. Targeted adsorption of molecules in the colon with the novel adsorbent-based medicinal product, DAV132: A proof of concept study in healthy subjects.

    PubMed

    de Gunzburg, Jean; Ducher, Annie; Modess, Christiane; Wegner, Danilo; Oswald, Stefan; Dressman, Jennifer; Augustin, Violaine; Feger, Céline; Andremont, Antoine; Weitschies, Werner; Siegmund, Werner

    2015-01-01

    During antibiotic treatments, active residuals reaching the colon profoundly affect the bacterial flora resulting in the emergence of resistance. To prevent these effects, we developed an enteric-coated formulated activated-charcoal based product, DAV132, meant to deliver its adsorbent to the ileum and neutralize antibiotic residues in the proximal colon. In a randomized, control, crossover study, the plasma pharmacokinetics of the probe drugs amoxicillin (500 mg) absorbed in the proximal intestine, and sulfapyridine (25 mg) metabolized from sulfasalazine in the cecum and rapidly absorbed, were compared after a single administration in 18 healthy subjects who had received DAV132, uncoated formulated activated charcoal (FAC) or water 16 and 8 hours before, concomitantly with the probe drugs, and 8 hours thereafter. The AUC0-96 h of amoxicillin was reduced by more than 70% when it was taken with FAC, but bioequivalent when it was taken with water or DAV132. By contrast, the AUC0-96 h of sulfapyridine was reduced by more than 90% when administered with either FAC or DAV132 in comparison with water. The results show that DAV132 can selectively adsorb drug compounds in the proximal colon, without interfering with drug absorption in the proximal small intestine, thereby constituting a proof of concept that DAV132 actually functions in humans. PMID:25042595

  3. Photophysics of new photostable rylene derivatives: applications in single-molecule studies and membrane labelling.

    PubMed

    Davies, Melari; Jung, Christophe; Wallis, Philipp; Schnitzler, Tobias; Li, Chen; Müllen, Klaus; Bräuchle, Christoph

    2011-06-01

    Three new photostable rylene dyes for applications in single molecule studies and membrane labelling have been synthesized and their photophysical properties were characterized. These dyes differ in the number of polyethylene glycol (PEG) chains attached to the core structure which is either a perylene derivate or a terrylene derivate. One perylene and one terrylene dye is modified with two PEG chains, and another terrylene derivate has four PEG chains. The results show that the terrylene dye with four PEG chains (4-PEG-TDI) forms soluble nonfluorescing H-aggregates in water, so that the absorption bands are blue-shifted with respect to those of the fluorescing monomeric form. The presence of a surfactant such as Pluronic P123 leads to the disruption of the aggregates due to the formation of monomers in micelles and a strong increase in fluorescence. Application for labelling cell membranes can be considered for this dye since it adsorbs in a similar way as monomer to a lipid bilayer. Furthermore a single-molecule study of all three rylene dyes in polymeric films of PMMA showed excellent photostability with respect to photobleaching, far above the photostability of other common water-soluble dyes, such as Oxazine-1, Atto647N, Cy5, Alexa647 and Rhodamin6G. Especially 4-PEG-TDI seems to be a promising dye for membrane labelling with its high photostability. PMID:21154947

  4. Effectiveness and mechanisms of dye adsorption on a straw-based biochar.

    PubMed

    Qiu, Yuping; Zheng, Zhenzhi; Zhou, Zunlong; Sheng, G Daniel

    2009-11-01

    A biochar (BC) generated from straw as a cost-effective substitute for activated carbon (AC) was tested for its adsorptive ability toward reactive brilliant blue (KNR) and rhodamine B (RB). BC and AC had similar surface areas but differed in porosity, surface acidity and point of zero surface charge. The two carbons were highly effective adsorbents for both dyes at pH 3.0 and 6.5. BC was slightly more effective than AC to adsorb RB due to the RB-BC electrostatic interactions and RB protonation at low pH. The two carbons reversed in their effectiveness to adsorb KNR for similar reasons. The pi-pi interactions between dye molecules and graphene layers of BC, the direct dye-BC electrostatic attraction/repulsion and the intermolecular hydrogen bonding are proposed to be the combined mechanisms for dye adsorption. Rich phenolic hydroxyls on the surface of BC are expected to enhance the pi-pi interactions. PMID:19540756

  5. 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

  6. Enhanced Raman spectroscopy of molecules adsorbed on carbon-doped TiO₂ obtained from titanium carbide: a visible-light-assisted renewable substrate.

    PubMed

    Kiran, Vankayala; Sampath, Srinivasan

    2012-08-01

    Titanium carbide (TiC) is an electrically conducting material with favorable electrochemical properties. In the present studies, carbon-doped TiO(2) (C-TiO(2)) has been synthesized from TiC particles, as well as TiC films coated on stainless steel substrate via thermal annealing under various conditions. Several C-TiO(2) substrates are synthesized by varying experimental conditions and characterized by UV-visible spectroscopy, photoluminescence, X-ray diffraction, and X-ray photoelectron spectroscopic techniques. C-TiO(2) in the dry state (in powder form as well as in film form) is subsequently used as a substrate for enhancing Raman signals corresponding to 4-mercaptobenzoic acid and 4-nitrothiophenol by utilizing chemical enhancement based on charge-transfer interactions. Carbon, a nonmetal dopant in TiO(2), improves the intensities of Raman signals, compared to undoped TiO(2). Significant dependence of Raman intensity on carbon doping is observed. Ameliorated performance obtained using C-TiO(2) is attributed to the presence of surface defects that originate due to carbon as a dopant, which, in turn, triggers charge transfer between TiO(2) and analyte. The C-TiO(2) substrates are subsequently regenerated for repetitive use by illuminating an analyte-adsorbed substrate with visible light for a period of 5 h. PMID:22738214

  7. Enhancement of the fluorescence of triphenylmethane dyes caused by their interaction with nanoparticles from β-diketonate complexes

    NASA Astrophysics Data System (ADS)

    Sveshnikova, E. B.; Ermolaev, V. L.

    2014-08-01

    We have studied the absorption and fluorescence spectra of Malachite Green and Crystal Violet in aqueous and alcoholic-aqueous solutions in which nanoparticles from Ln(III) and Sc(III) diketonates are formed at concentrations of complexes in a solution of 5-30 μM. We have shown that, if the concentrations of the dyes in the solution are lower than 0.5 μM, dye molecules are incorporated completely into nanoparticles or are precipitated onto their surface. The fluorescence intensity of these incorporated and adsorbed Malachite Green and Crystal Violet molecules increases by several orders of magnitude compared to the solution, which takes place because of a sharp increase in the fluorescence quantum yields of these dyes and at the expense of the sensitization of their fluorescence upon energy transfer from β-diketonate complexes entering into the composition of nanoparticles. We have shown that, if there is no concentration quenching, the values of the fluorescence quantum yield of the Crystal Violet dye incorporated into nanoparticles and adsorbed on their surface vary from 0.06 to 0.13, i.e., are close to the fluorescence quantum yield of this dye in solid solutions of sucrose acetate at room temperature. The independence of the fluorescence quantum yield of Crystal Violet on the morphology of nanoparticles testifies to a high binding constant of complexes and the dye. The considerable fluorescence quantum yields of triphenylmethane dyes in nanoparticles and sensitization of their fluorescence by nanoparticle-forming complexes make it possible to determine the concentration of these dyes in aqueous solutions by the luminescent method in the range of up to 1 nM.

  8. Observing single molecule chemical reactions on metal nanoparticles.

    SciTech Connect

    Emory, S. R.; Ambrose, W. Patrick; Goodwin, P. M.; Keller, Richard A.

    2001-01-01

    We report the study of the photodecomposition of single Rhodamine 6G (R6G) dye molecules adsorbed on silver nanoparticles. The nanoparticles were immobilized and spatially isolated on polylysine-derivatized glass coverslips, and confocal laser microspectroscopy was used to obtain surface-enhanced Raman scattering (SERS) spectra from individual R6G molecules. The photodecomposition of these molecules was observed with 150-ms temporal resolution. The photoproduct was identified as graphitic carbon based on the appearance of broad SERS vibrational bands at 1592 cm{sup -1} and 1340 cm{sup -1} observed in both bulk and averaged single-molecule photoproduct spectra. In contrast, when observed at the single-molecule level, the photoproduct yielded sharp SERS spectra. The inhomogeneous broadening of the bulk SERS spectra is due to a variety of photoproducts in different surface orientations and is a characteristic of ensemble-averaged measurements of disordered systems. These single-molecule studies indicate a photodecomposition pathway by which the R6G molecule desorbs from the metal surface, an excited-state photoreaction occurs, and the R6G photoproduct(s) readsorbs to the surface. A SERS spectrum is obtained when either the intact R6G or the R6G photoproduct(s) are adsorbed on a SERS-active site. This work further illustrates the power of single-molecule spectroscopy (SMS) to reveal unique behaviors of single molecules that are not discernable with bulk measurements.

  9. Efficient and selective removal of dyes using imidazolium-based supramolecular gels.

    PubMed

    Cheng, Ni; Hu, Qiongzheng; Guo, Yongxian; Wang, Yong; Yu, Li

    2015-05-20

    A supramolecular gel was constructed by using an imidazolium-based surfactant, N-cetyl-N'-carboxymethyl imidazolium bromide ([N-C16, N'-CO2H-Im]Br), in the DMSO/H2O binary solvent mixtures and investigated as an adsorbent for removing dyes from aqueous solution. The self-assembled gel displays a morphology of microplatelets stacked in bilayer units with interdigitated hydrocarbon tails, and the structure remains unchanged below the sol-gel transition temperature. The gel also exhibits a strong birefringence property and excellent mechanical strength. In particular, the gels show superior performance in removal of anionic dye molecules, for example, removing 80% of eosin Y within 10 min, The constructed gels also present excellent salinity tolerance, even when the concentration of NaCl is 1000 times higher than that of the dye, and can maintain their high efficiency after 25 cycles, indicative of their promise in water treatment. PMID:25938635

  10. Graphene oxide supported copper oxide nanoneedles: An efficient hybrid material for removal of toxic azo dyes.

    PubMed

    Rajesh, Rajendiran; Iyer, Sahithya S; Ezhilan, Jayabal; Kumar, S Senthil; Venkatesan, Rengarajan

    2016-09-01

    Herein, we report a simple, one step synthesis of hybrid copper oxide nanoneedles on graphene oxide sheets (GO-CuONNs) through sonochemical method. The present method affords a facile mean for controlling effective concentration of the active CuO nanoneedles on the graphene oxide sheets, and also offers the necessary stability to the resulting GO-CuONNs structure for adsorption transformations.Furthermore, this hybrid GO-CuONNs is successfully employed in the removal of a series of hazardous ionic organic dyes namely coomassie brilliant blue, methylene blue, congo red and amidoblack 10B. Through careful investigation of the material, we found that the synergetic effect between CuONNs and GO play a significant role in the adsorption of all the dyes studied. The prepared hybrid material contains both hydrophobic and hydrophilic environment which is expected to enhance the electrostatic interaction between the adsorbent and the dye molecules, consequently favouring the adsorption process. PMID:27208759

  11. Graphene oxide supported copper oxide nanoneedles: An efficient hybrid material for removal of toxic azo dyes

    NASA Astrophysics Data System (ADS)

    Rajesh, Rajendiran; Iyer, Sahithya S.; Ezhilan, Jayabal; Kumar, S. Senthil; Venkatesan, Rengarajan

    2016-09-01

    Herein, we report a simple, one step synthesis of hybrid copper oxide nanoneedles on graphene oxide sheets (GO-CuONNs) through sonochemical method. The present method affords a facile mean for controlling effective concentration of the active CuO nanoneedles on the graphene oxide sheets, and also offers the necessary stability to the resulting GO-CuONNs structure for adsorption transformations.Furthermore, this hybrid GO-CuONNs is successfully employed in the removal of a series of hazardous ionic organic dyes namely coomassie brilliant blue, methylene blue, congo red and amidoblack 10B. Through careful investigation of the material, we found that the synergetic effect between CuONNs and GO play a significant role in the adsorption of all the dyes studied. The prepared hybrid material contains both hydrophobic and hydrophilic environment which is expected to enhance the electrostatic interaction between the adsorbent and the dye molecules, consequently favouring the adsorption process.

  12. Surfactant induced aggregation behavior of Merocyanine-540 adsorbed on polymer coated positively charged gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Das, K.; Uppal, A.; Saini, R. K.

    2016-01-01

    Surfactant induced aggregation behavior of Merocyanine 540 adsorbed on polymer (PDD) coated gold nanoparticles (AuNP) is reported. The absorption band of the dye shifts to higher energy in the presence of free polymer and polymer coated AuNP implying aggregation. Addition of a negatively charged surfactant (SDS) induces multiple bands in the extinction spectrum of the dye adsorbed on nanoparticle surface. The highest (460 nm) and lowest (564 nm) energy bands of the dye become prominent at 10 and >50 μM SDS concentrations respectively (dye: 10 μM; AuNP: 100-200 pM). Based on earlier results the high energy band is likely to originate from dye aggregates and the low energy band is likely to originate from dye monomers. This is attributed to the interplay between polymer-surfactant and polymer-dye interactions at the AuNP surface. The extinction spectra of dye adsorbed at AuNP surface remain unaffected in the presence of a positively charged (CTAB) or a neutral surfactant (Tx-100), at low surfactant concentrations. However at higher surfactant concentrations (>60 μM) dye aggregation takes place which is attributed to dye-surfactant interactions. The fluorescence intensity of the dye quenched significantly but its lifetime increased in the presence of polymer coated AuNP. This is attributed to aggregation and reduction in the photoisomerization rate of the dye adsorbed on AuNP surface.

  13. Fluorescence dynamics of microsphere-adsorbed sunscreens

    NASA Astrophysics Data System (ADS)

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  14. A study of the role played by the Hartree-Fock orbital exchange in the formation of the energy of the first singlet charge-transfer excited state by the example of JK-62 and JK-201 sensitizing dye molecules

    NASA Astrophysics Data System (ADS)

    Baryshnikov, G. V.; Minaev, B. F.; Slepets, A. A.; Minaeva, V. A.

    2014-03-01

    Based on the time-dependent density functional theory with the use of the functionals B3LYP, B97-2, BHandHLYP, BMK, MPWB1K, PBE1W, PBE1PBE, τ-HCTHh, and TPSS in the 6-31G(d) basis set of atomic orbitals, we have performed a quantum-chemical investigation of electronic and spectral properties of JK-62 and JK-201 bis-dimethylfluorenyl dye sensitizers for Grätzel photoelectric converters. In terms of the Bader theory, we have done a complete analysis of the electron-density distribution function in the dye molecules under study, which proves the occurrence of intramolecular nonvalent interactions, which, in turn, stabilize a planar mutual arrangement of structural fragments of dye molecules. The role that the Hartree-Fock orbital exchange plays in the energy formation of the first and most intense electronic transition, which is responsible for the primary current generation in a solar cell, has been elucidated.

  15. Pyrocatechol as a surface capping molecule on rutile TiO 2 (110)

    NASA Astrophysics Data System (ADS)

    Syres, K. L.; Thomas, A. G.; Cant, D. J. H.; Hardman, S. J. O.; Preobrajenski, A.

    2012-02-01

    A 'cap and dip' method of adsorbing ruthenium di-2,2‧-bipyridyl-4,4‧-dicarboxylic acid diisocyanate (N3 dye) on a rutile TiO2 (110) surface was investigated using pyrocatechol as a capping molecule. This method involves cleaning the rutile surface in ultra-high vacuum (UHV), depositing pyrocatechol onto the surface to 'cap' the adsorption sites, removing from vacuum, 'dipping' in an N3 dye solution and returning to vacuum. Photoemission measurements following the return of the crystal to vacuum suggest that the pyrocatechol keeps the surface free from contamination on exposure to atmosphere. Photoemission spectra also indicate that the pyrocatechol capping molecules are replaced by the N3 dye in solution and that the N3 dye is adsorbed intact on the rutile TiO2 (110) surface. This technique may allow other large molecules, which are thermally unstable to evaporation in UHV, to be easily deposited onto TiO2 surfaces.

  16. Sunflower stalks as adsorbents for color removal from textile wastewater

    SciTech Connect

    Sun, G.; Xu, X.

    1997-03-01

    Sunflower stalks as adsorbents for two basic dyes (Methylene Blue and Basic Red 9) and two direct dyes (Congo Red and Direct Blue 71) in aqueous solutions were studied with equilibrium isotherms and kinetic adsorptions. The maximum adsorptions of two basic dyes on sunflower stalks are very high, i.e., 205 and 317 mg/g for Methylene Blue and Basic Red 9, respectively. The two direct dyes have relatively lower adsorption on sunflower stalks. The adsorptive behaviors of sunflower stalk components are different. The pith, which is the soft and porous material in the center of stalks, has twice the adsorptive capacity of the skin. Particle sizes of sunflower stalks also affect the adsorption of dyes. The adsorption rates of two basic dyestuffs are much higher than that of the direct dyes. Within 30 min about 80% basic dyes were removed from the solutions.

  17. Modified optical absorption of molecules on metallic nanoparticles at sub-monolayer coverage

    NASA Astrophysics Data System (ADS)

    Darby, Brendan L.; Auguié, Baptiste; Meyer, Matthias; Pantoja, Andres E.; Le Ru, Eric C.

    2016-01-01

    Enhanced optical absorption of molecules in the vicinity of metallic nanostructures is key to a number of surface-enhanced spectroscopies and of great general interest to the fields of plasmonics and nano-optics. However, experimental access to this absorbance has long proven elusive. Here, we present direct measurements of the surface absorbance of dye molecules adsorbed onto silver nanospheres and, crucially, at sub-monolayer concentrations where dye-dye interactions become negligible. With a large detuning from the plasmon resonance, distinct shifts and broadening of the molecular resonances reveal the intrinsic properties of the dye in contact with the metal colloid, in contrast to the often studied strong-coupling regime where the optical properties of the dye molecules cannot be isolated. The observation of these shifts together with the ability to routinely measure them has broad implications in the interpretation of experiments involving resonant molecules on metallic surfaces, such as surface-enhanced spectroscopies and many aspects of molecular plasmonics.

  18. Assessment of dye distribution in sensitized solar cells by microprobe techniques

    NASA Astrophysics Data System (ADS)

    Barreiros, M. A.; Corregidor, V.; Alves, L. C.; Guimarães, F.; Mascarenhas, J.; Torres, E.; Brites, M. J.

    2015-04-01

    Dye sensitized solar cells (DSCs) have received considerable attention once this technology offers economic and environmental advantages over conventional photovoltaic (PV) devices. The PV performance of a DSC relies on the characteristics of its photoanode, which typically consists of a nanocrystalline porous TiO2 film, enabled with a large adsorptive surface area. Dye molecules that capture photons from light during device operation are attached to the film nanoparticles. The effective loading of the dye in the TiO2 electrode is of paramount relevance for controlling and optimizing solar cell parameters. Relatively few methods are known today for quantitative evaluation of the total dye adsorbed on the film. In this context, microprobe techniques come out as suitable tools to evaluate the dye surface distribution and depth profile in sensitized films. Electron Probe Microanalysis (EPMA) and Ion Beam Analytical (IBA) techniques using a micro-ion beam were used to quantify and to study the distribution of the Ru organometallic dye in TiO2 films, making use of the different penetration depth and beam sizes of each technique. Different 1D nanostructured TiO2 films were prepared, morphologically characterized by SEM, sensitized and analyzed by the referred techniques. Dye load evaluation in different TiO2 films by three different techniques (PIXE, RBS and EPMA/WDS) provided similar results of Ru/Ti mass fraction ratio. Moreover, it was possible to assess dye surface distribution and its depth profile, by means of Ru signal, and to visualize the dye distribution in sample cross-section through X-ray mapping by EPMA/EDS. PIXE maps of Ru and Ti indicated an homogeneous surface distribution. The assessment of Ru depth profile by RBS showed that some films have homogeneous Ru depth distribution while others present different Ru concentration in the top layer (2 μm thickness). These results are consistent with the EPMA/EDS maps obtained.

  19. Reactive Fluorescent Dyes For Urethane Coatings

    NASA Technical Reports Server (NTRS)

    Willis, Paul B.; Cuddihy, Edward F.

    1991-01-01

    Molecules of fluorescent dyes chemically bound in urethane conformal-coating materials to enable nondestructive detection of flaws in coats through inspection under ultraviolet light, according to proposal. Dye-bonding technique prevents outgassing of dyes, making coating materials suitable for use where flaw-free coats must be assured in instrumentation or other applications in which contamination by outgassing must be minimized.

  20. Anchoring strength of o-, m-, and p-methyl red-dye-doped nematics on rubbed and unrubbed polyimide surfaces

    NASA Astrophysics Data System (ADS)

    Statman, David; Wozniak, Kaitlin; Potuzko, Marci

    2011-10-01

    It is demonstrated that the photoinduced gliding of the easy axis for nematics doped with various azo dyes on rubbed polyimide involves the formation of a second easy axis on the polyimide surface. While some azo dyes, such as disperse orange 3, do not exhibit large surface induced nonlinear effects, other dyes, such as methyl red, do. The amount of reorientation of the easy axis on rubbed polyimide is determined by the relative anchoring strengths of the easy axis formed from adsorbed dye and that formed from rubbing. One question of interest is what is the source of the anchoring strength? In this paper, we discuss the formation of easy axes via the photo-induced adsorption of azo dye. We will compare the anchoring strengths between dyed nematic liquid crystals and the easy axes formed by photoinduced adsorption of three isomers of the methyl red azo dye, ortho, meta, and para, as well as disperse orange 3. We will also discuss the impact of the carboxyl group position in the dye molecule on the anchoring strength.

  1. Strategies for modulating the luminescence properties of pyronin Y dye-clay films: an experimental and theoretical study.

    PubMed

    Epelde-Elezcano, Nerea; Martínez-Martínez, Virginia; Duque-Redondo, Eduardo; Temiño, Inés; Manzano, Hegoi; López-Arbeloa, Iñigo

    2016-03-28

    The aggregation process, particularly the type and extent of pyronin Y (PY) laser dye intercalated into supported thin films of two different trioctahedral clay minerals, LAPONITE® (Lap) and saponite (Sap), at different dye loadings is studied: (i) experimentally by means of electronic absorption and fluorescence spectroscopy and (ii) theoretically by modeling the distribution of the dye into the interlayer space of these layered silicates. According to the results, H-type aggregates of the PY dye are favoured in Lap even at very low dye loading while a much lower molecular aggregation tendency in J-type geometry is found in Sap films. The aggregation state of PY in each clay mineral is likely attributed to different strengths of the electrostatic interactions between the dye and the layered silicate in the interlayer space due to their distinctive charge localization on the TOT clay layer (i.e. net negative charge in octahedral layers for Lap vs. in tetrahedral layers for Sap), as well as the interlaminar water distribution in each clay mineral, although other factors such as their CEC and particle size cannot be discarded. To reduce the huge aggregation processes of PY dye into Lap films, surfactant molecules (DDTAB) are co-adsorbed in the interlayer space of the clay. At an optimized surfactant concentration, the aggregation tendency of PY dye in Lap is considerably reduced enormously improving the fluorescence efficiency of the PY/Lap films. Finally, by means of anisotropic response from the hybrid films to the plane of the polarized light, the orientation of the PY molecules with respect to the normal axis of the clay layer is determined for all films (with and without surfactant) at different dye loadings. PMID:26954470

  2. Dye Painting!

    ERIC Educational Resources Information Center

    Johnston, Ann

    This resource provides practical instructions for applying color and design directly to fabric. Basic information about the dye painting process is given. The guide addresses the technical aspects of fabric dye and color use and offers suggestions for fabric manipulation and dye application in order to achieve various design effects. This…

  3. Dye adsorption onto activated carbons from tyre rubber waste using surface coverage analysis.

    PubMed

    Mui, Edward L K; Cheung, W H; Valix, Marjorie; McKay, Gordon

    2010-07-15

    Two types of activated carbons from tyre char (with or without sulphuric acid treatment) were produced via carbon dioxide activation with BET surface areas in the range 59-1118 m(2)/g. Other characterisation tests include micropore and mesopore surface areas and volumes, pH, and elemental compositions, particularly heteroatoms such as nitrogen and sulphur. They were correlated to the adsorption capacity which were in the range of 0.45-0.71 mmol/g (untreated) and 0.62-0.84 mmol/g (acid-treated) for Acid Blue 25. In the case of larger-sized molecules like Acid Yellow 117, capacities were in the range of 0.23-0.42 mmol/g (untreated) and 0.29-0.40 mmol/g (acid-treated). Some tyre carbons exhibit a more superior performance than a microporous, commercial activated carbon (Calgon F400). By modelling the dye adsorption equilibrium data, the Redlich-Peterson isotherm is adopted as it has the lowest SSE. Based on the surface coverage analysis, a novel molecular orientation modelling of adsorbed dyes has been proposed and correlated with surface area and surface charge. For the acid dyes used in this study, molecules were likely to be adsorbed by the mesopore areas. PMID:20416883

  4. Environmental photochemistry on semiconductor surfaces. Visible light induced degradation of a textile diazo dye, naphthol blue black, on TiO{sub 2} nanoparticles

    SciTech Connect

    Nasr, C.; Hotchandani, S.; Vinodgopal, K.; Fisher, L.; Chattopadhyay, A.K.; Kamat, P.V.

    1996-05-16

    Visible light induced degradation of the textile diazo dye Naphthol Blue Black (NBB) has been carried out on TiO{sub 2} semiconductor nanoparticles. Diffuse reflectance transient absorption and FTIR techniques have been used to elucidate the mechanistic details of the dye degradation. The failure of the dye to degrade on insulator surfaces such as Al{sub 2}O{sub 3} or in the absence of oxygen further highlights the importance of semiconducting properties of support material in controlling the surface photochemical processes. The primary event following visible light excitation is the charge injection from the excited dye molecule into the conduction band of the semiconductor TiO{sub 2}, producing the dye cation radical. This was confirmed by diffuse reflectance laser flash photolysis. The surface-adsorbed oxygen plays an important role in scavenging photogenerated electrons, thus preventing the recombination between the dye cation radical and photoinjected electrons. Diffuse reflectance FTIR study facilitated identification of reaction intermediates and end products of dye degradation. By comparison with the degradation products from other azo dyes such as Chromotrope 2B and Chromotrope 2R we conclude that the NBB is degraded to a colorless naphthaquinone-like end product. 41 refs., 9 figs.

  5. Properties of N-Type Conductivity Material in Electrical Power Conversion of p-CuI|Dye|n-TiO2 Dye-Sensitized Solid-State Solar Cell

    NASA Astrophysics Data System (ADS)

    Rusop, M.

    2010-03-01

    The properties of n-type conductivity titanium dioxide have been characterized. The optical band gap excitation of nano-structured titanium dioxide (TiO2) in power output of p-CuI|dye|n-TiO2 cells were also studied. An efficient charge generation was observed through the illumination of the TiO2 layer of the fabricated p-CuI/dye|n-TiO2 cells. The band gap excitation of TiO2 was observed only under illumination through TiO2 layer. Adsorbed dye molecules to the TiO2 surface act as a relay, especially under illumination through TiO2 layer in the wave range region of 300-400 nm.

  6. Adsorbed Water Illustration

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Thermal and Electrical Conductivity Probe on NASA's Phoenix Mars Lander detected small and variable amounts of water in the Martian soil.

    In this schematic illustration, water molecules are represented in red and white; soil minerals are represented in green and blue. The water, neither liquid, vapor, nor solid, adheres in very thin films of molecules to the surfaces of soil minerals. The left half illustrates an interpretation of less water being adsorbed onto the soil-particle surface during a period when the tilt, or obliquity, of Mars' rotation axis is small, as it is in the present. The right half illustrates a thicker film of water during a time when the obliquity is greater, as it is during cycles on time scales of hundreds of thousands of years. As the humidity of the atmosphere increases, more water accumulates on mineral surfaces. Thicker films behave increasingly like liquid water.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  7. Nanovalved Adsorbents for CH4 Storage.

    PubMed

    Song, Zhuonan; Nambo, Apolo; Tate, Kirby L; Bao, Ainan; Zhu, Minqi; Jasinski, Jacek B; Zhou, Shaojun J; Meyer, Howard S; Carreon, Moises A; Li, Shiguang; Yu, Miao

    2016-05-11

    A novel concept of utilizing nanoporous coatings as effective nanovalves on microporous adsorbents was developed for high capacity natural gas storage at low storage pressure. The work reported here for the first time presents the concept of nanovalved adsorbents capable of sealing high pressure CH4 inside the adsorbents and storing it at low pressure. Traditional natural gas storage tanks are thick and heavy, which makes them expensive to manufacture and highly energy-consuming to carry around. Our design uses unique adsorbent pellets with nanoscale pores surrounded by a coating that functions as a valve to help manage the pressure of the gas and facilitate more efficient storage and transportation. We expect this new concept will result in a lighter, more affordable product with increased storage capacity. The nanovalved adsorbent concept demonstrated here can be potentially extended for the storage of other important gas molecules targeted for diverse relevant functional applications. PMID:27124722

  8. Control over the charge transfer in dye-nanoparticle decorated graphene

    NASA Astrophysics Data System (ADS)

    Bongu, Sudhakara Reddy; Veluthandath, Aneesh V.; Nanda, B. R. K.; Ramaprabhu, Sundara; Bisht, Prem B.

    2016-01-01

    Charge transfer interaction between silver decorated graphene and three differently charged dyes, cationic (rhodamine 6G), neutral (rhodamine B) and anionic (fluorescein 27) has been studied. The ground state association constants have been evaluated and changes in the fluorescence intensity and lifetimes have been obtained in two solvents. Strength of complex-formation has been found to be higher with the cationic molecule in water. In a higher viscosity solvent, the ground state complex formation is restricted. Local field of localized surface plasmons of nanoparticles adsorbed on the graphene sheets leads to enhanced absorption and fluorescence of fluorescein 27.

  9. Dye-sensitized solar cells

    DOEpatents

    Skotheim, T.A.

    1980-03-04

    A low-cost dye-sensitized Schottky barrier solar cell is comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent. 3 figs.

  10. Dye-sensitized solar cells

    DOEpatents

    Skotheim, Terje A. [Berkeley, CA

    1980-03-04

    A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

  11. Optimization of nanoparticle structure for improved conversion efficiency of dye solar cell

    SciTech Connect

    Mohamed, Norani Muti; Zaine, Siti Nur Azella

    2014-10-24

    Heavy dye loading and the ability to contain the light within the thin layer (typically ∼12 μm) are the requirement needed for the photoelectrode material in order to enhance the harvesting efficiency of dye solar cell. This can be realized by optimizing the particle size with desirable crystal structure. The paper reports the investigation on the dependency of the dye loading and light scattering on the properties of nanostructured photoelectrode materials by comparing 4 different samples of TiO{sub 2} in the form of nanoparticles and micron-sized TiO{sub 2} aggregates which composed of nanocrystallites. Their properties were evaluated by using scanning electron microscopy, X-ray diffraction and UVVis spectroscopy while the performance of the fabricated test cells were measured using universal photovoltaic test system (UPTS) under 1000 W/cm{sup 2} intensity of radiation. Nano sized particles provide large surface area which allow for greater dye adsorption but have no ability to retain the incident light in the TiO{sub 2} film. In contrast, micron-sized particles in the form of aggregates can generate light scattering allowing the travelling distance of the light to be extended and increasing the interaction between the photons and dye molecules adsorb on TiO{sub 2}nanocrystallites. This resulted in an improvement in the conversion efficiency of the aggregates that demonstrates the close relation between light scattering effect and the structure of the photolectrode film.

  12. Effect of photoanode thickness on electrochemical performance of dye sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Khatani, Mehboob; Mohamed, Norani Muti; Hamid, Nor Hisham; Muhsan, Ali Samer; Sahmer, Ahmed Zahrin

    2015-07-01

    The thickness of photoanode is crucial as it adsorbed a large amount of dye molecules that provide electrons for generation of electricity in dye sensitized solar cell (DSC). Thus, in order to realize the practical application of DSC, study on various thickness of photoanode need to be carried out to analyze its effect on the electrochemical behavior of dye sensitized solar cell. To enhance the conversion efficiency, an additional layer of TiO2 using TiCl4 treatment was deposited prior to the deposition of the photoanode (active area of 1cm2) with the thickness of 6, 12, 18, 24, and 30 µm on fluorine doped tin oxide (FTO) glass substrate. The resulting photoanode after the soak in N719 dye for more than 12hrs were used to be assembled in a test cell in combination with liquid electrolyte and counter electrode. The fabricated cells were characterized by solar simulator, ultraviolet-visible spectroscopy (UV-VIS), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was used to approximate the thickness of photoanode. An optimum power conversion efficiency of 4.54% was obtained for the cell fabricated with 18 µm photoanode thickness. This is attributed to the reduced resistance related to electron transport in the TiO2/dye/electrolyte interface as proven by the EIS result. This led to the reduction of internal resistance, the increase in the electron life time and the improvement in the conversion efficiency.

  13. Molecule-Based Water-Oxidation Catalysts (WOCs): Cluster-Size-Dependent Dye-Sensitized Polyoxometalates for Visible-Light-Driven O2 Evolution

    PubMed Central

    Gao, Junkuo; Cao, Shaowen; Tay, Qiuling; Liu, Yi; Yu, Lingmin; Ye, Kaiqi; Mun, Peter Choon Sze; Li, Yongxin; Rakesh, Ganguly; Loo, Say Chye Joachim; Chen, Zhong; Zhao, Yang; Xue, Can; Zhang, Qichun

    2013-01-01

    From atomic level to understand the cluster-size-dependant behavior of dye-sensitized photocatalysts is very important and helpful to design new photocatalytic materials. Although the relationship between the photocatalytic behaviors and particles' size/shape has been widely investigated by theoretical scientists, the experimental evidences are much less. In this manuscript, we successfully synthesized three new ruthenium dye-sensitized polyoxometalates (POM-n, n relate to different size clusters) with different-sized POM clusters. Under visible-light illumination, all three complexes show the stable O2 evolution with the efficient order POM-3 > POM-2 > POM-1. This cluster-size-dependent catalytic behavior could be explained by the different numbers of M = Ot (terminal oxygen) bonds in each individual cluster because it is well-known that Mo = Ot groups are the catalytically active sites for photooxidation reaction. The proposed mechanism of water oxidation for the dye-sensitized POMs is radical reaction process. This research could open up new perspectives for developing new POM-based WOCs. PMID:23676701

  14. First principles modeling of eosin-loaded ZnO films: a step toward the understanding of dye-sensitized solar cell performances.

    PubMed

    Labat, Frédéric; Ciofini, Ilaria; Hratchian, Hrant P; Frisch, Mike; Raghavachari, Krishnan; Adamo, Carlo

    2009-10-14

    A theoretical investigation of eosin-Y (EY) loaded ZnO thin films, the basic components of a dye-sensitized solar cell (DSSC), is presented. The EY/ZnO wurtzite (10-10) system has been fully described within a periodic approach using density functional theory (DFT) and a hybrid exchange-correlation functional. Reduced systems were also analyzed to simulate an electron transfer from the dye to the substrate. Injection times from dye to the semiconductor were calculated using the Newns-Anderson approach. Finally, the UV-visible spectra of EY/ZnO films were simulated using a time-dependent DFT approach and compared to that of the EY molecule computed in solution. The results obtained highlight that EY strongly adsorbs on the ZnO substrate contributing significantly to the electronic structure of the adsorbed system. The UV-visible spectral signature of the isolated EY molecule is still found when adsorbed on ZnO but the analysis of Gamma-point crystalline orbitals reveals that a direct HOMO-->LUMO excitation cannot lead to a direct electron injection into the semiconductor, the first unoccupied orbital with contributions from the ZnO substrate being the LUMO + 1. As a consequence, a two photon injection mechanism is proposed explaining the low efficiency of the EY/ZnO solar cells. On this basis, possible strategies for enhancing the cell efficiency are presented and discussed. PMID:19761184

  15. Investigation of the influence of coadsorbent dye upon the interfacial structure of dye-sensitized solar cells

    SciTech Connect

    Honda, M. Miyano, K.; Yanagida, M.; Han, L.

    2014-11-07

    The interface between Ru(tcterpy)(NCS){sub 3}TBA{sub 2} [black dye (BD); tcterpy = 4,4{sup ′},4{sup ″}-tricarboxy-2,2{sup ′}:6{sup ′},2{sup ″}-terpyridine, NCS = thiocyanato, TBA = tetrabutylammonium cation] and nanocrystalline TiO{sub 2}, as found in dye-sensitized solar cells, is investigated by soft-X-ray synchrotron radiation and compared with the adsorption structure of cis-Ru(Hdcbpy){sub 2}(NCS){sub 2}TBA{sub 2} (N719; dcbpy = 4,4{sup ′}-dicarboxy-2,2{sup ′}-bipyridine) on TiO{sub 2} to elucidate the relationship between the adsorption mode of BD and the photocurrent with and without coadsorbed indoline dye D131. The depth profile is characterized with X-ray photoelectron spectroscopy and S K-edge X-ray absorption fine structure using synchrotron radiation. Both datasets indicate that one of the isothiocyanate groups of BD interacts with TiO{sub 2} via its S atom when the dye is adsorbed from a single-component solution. In contrast, the interaction is slightly suppressed when D131 is coadsorbed, indicated by the fact that the presence of D131 changes the adsorption mode of BD. Based upon these results, the number of BD dye molecules interacting with the substrate is shown to decrease by 10% when D131 is coadsorbed, and the dissociation is shown to be related to the short-circuit photocurrent in the 600–800 nm region. The design of a procedure to promote the preferential adsorption of D131 therefore leads to an improvement of the short-circuit current and conversion efficiency.

  16. Adsorption behavior of natural anthocyanin dye on mesoporous silica

    NASA Astrophysics Data System (ADS)

    Kohno, Yoshiumi; Haga, Eriko; Yoda, Keiko; Shibata, Masashi; Fukuhara, Choji; Tomita, Yasumasa; Maeda, Yasuhisa; Kobayashi, Kenkichiro

    2014-01-01

    Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability.

  17. Functionalization of cubic mesoporous silica SBA-16 with carboxylic acid via one-pot synthesis route for effective removal of cationic dyes.

    PubMed

    Tsai, Cheng-Hsun; Chang, Wei-Chieh; Saikia, Diganta; Wu, Cheng-En; Kao, Hsien-Ming

    2016-05-15

    In this work, we demonstrate that a high density of −COOH groups loading, up to 60 mol% based on silica, is successfully incorporated into SBA-16 via a one-pot synthesis route, which involves co-condensation of carboxyethylsilanetriol sodium salt (CES) and tetraethylorthosilicate (TEOS) templated by Pluronic F127 and P123 in an acidic medium. A variety of characterization techniques are performed to confirm quantitative incorporation of carboxylic groups into ordered cubic mesostructures. These functionalized materials are used to effectively remove two cationic dyes methylene blue (MB) and phenosafranine (PF) with the maximum adsorption capacities of 561 and 519 mg g(-1), respectively, at pH 9. The zeta potential results reveal that the electrostatic interactions between cationic dye molecule and negatively charged surface of the adsorbent play a crucial role in their high adsorption capacities. For a binary component system consisting of MB and PF, competitive adsorption of these two dyes is observed with adsorption capacity values slightly lower than those of the corresponding single dye systems. The dye adsorbed material can be easily regenerated by simple acid washing and be reused for five times with MB removal efficiency still up to 98.6%, showing its great potentials in environmental remediation. PMID:26906434

  18. Separation of the attractive and repulsive contributions to the adsorbate-adsorbate interactions of polar adsorbates on Si(100)

    NASA Astrophysics Data System (ADS)

    Lin, Ying-Hsiu; Jeng, Horng-Tay; Lin, Deng-Sung

    2015-11-01

    Dissociative adsorption of H2O, NH3, CH3OH and CH3NH2 polar molecules on the Si(100) surface results in a 1:1 mixture of two adsorbates (H and multi-atomic fragment A = OH, NH2, CH3O, CH3NH, respectively) on the surface. By using density functional theory (DFT) calculations, the adsorption geometry, the total energies and the charge densities for various possible ordered structures of the mixed adsorbate layer have been found. Analyzing the systematic trends in the total energies unveils concurrently the nearest-neighbor interactions ENN and the next nearest-neighbor interactions ENNN between two polar adsorbates A. In going from small to large polar adsorbates, ENN's exhibit an attractive-to-repulsive crossover behavior, indicating that they include competing attractive and repulsive contributions. Exploration of the charge density distributions allows the estimation of the degree of charge overlapping between immediately neighboring A's, the resulting contribution of the steric repulsions, and that of the attractive interactions to the corresponding ENN's. The attractive contributions to nearest neighboring adsorbate-adsorbate interactions between the polar adsorbates under study are shown to result from hydrogen bonds or dipole-dipole interactions.

  19. Real-time monitoring of single-molecule reactions in aqueous solution

    SciTech Connect

    Hong, Xiao; Xu, N.; Yeung, E.S. |

    1997-12-31

    Direct measurement of dynamics of single molecules, e.g., rhodamine 6G (R-6G) and single R-6G tagged with single biological molecules in aqueous solution, was achieved by using thin-layer laser-induced total internal reflection fluorescence microscopy (TLTIRFM). Single-molecule reactions can be directly and simultaneously monitored with spatial resolution down to 0.2 {mu}m and temporal resolution down to 0.2 ms. Dynamics of single-molecule reactions, for example, single dye molecules reacting with a proton and single proteins adsorbing on an active surface, are investigated and evident by monitoring their reaction environment, e.g., temperature and pH. Novel approaches and applications of these studies will be prospected in this presentation.

  20. Dye-sensitized solar cells using double-oxide electrodes: a brief review

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshikazu; Okamoto, Yuji; Ishii, Natsumi

    2015-04-01

    Dye-sensitized solar cells (DSC or DSSC) have been widely investigated because of their potentially high cost performance compared with Si-based solar cells and of their fascinating appearance. DSC with photoelectric conversion efficiency of >10 % (or even 12 %) have been reported, where porous TiO2 films are generally used as semi-conductor electrodes. Such porous TiO2 films usually have high specific surface area, and thus, they adsorb plenty of dye molecules, resulting in high photocurrent density. Recently, some double oxides have been examined as alternative photoanode materials, mainly in order to improve photovoltage. Here, studies on DSC using double-oxide electrodes, i.e., perovskite, spinel, ilmenite, wolframite, scheelite and pseudobrookite-types, are briefly reviewed.

  1. Examining Adsorbed Polymer Conformations with Fluorescence Imaging

    NASA Astrophysics Data System (ADS)

    Parkes, Maria; Chennaoui, Mourad; Wong, Janet; Tribology Group, Dept. of Mechanical Engineering Team

    2011-03-01

    The conformation of adsorbed polymers can have significant impact on their properties such as dynamics and elasticity as well as their ability to take part in reactions with other molecules. Experimental research to determine adsorbed polymer conformation has relied mainly on atomic force microscopy (AFM) studies. During an AFM scan, the contact between the scanning probe and the polymer could affect the polymer conformation, particularly where parts of the polymer might have formed projected loops and tails. In this work, conformations of model polymers are examined with total internal reflection fluorescence microscopy (TIRFM). The advantage of TIRFM over AFM is that TIRFM is a non contact technique. Lambda DNA labelled along its length with fluorescent probes was adsorbed in a projected 2D -- 3D state. With TIRFM, the relationship between intensity and depth was used as a basis to determine how the conformation of the adsorbed polymers evolved with time using our custom algorithm.

  2. Biosorption of water-soluble dyes on magnetically modified Saccharomyces cerevisiae subsp. uvarum cells.

    PubMed

    Safaríková, M; Ptácková, L; Kibriková, I; Safarík, I

    2005-05-01

    Brewer's yeast (bottom yeast, Saccharomyces cerevisiae subsp. uvarum) cells were magnetically modified using water based magnetic fluid stabilized with perchloric acid. Magnetically modified yeast cells efficiently adsorbed various water soluble dyes. The dyes adsorption can be described by the Langmuir adsorption model. The maximum adsorption capacity of the magnetic cells differed substantially for individual dyes; the highest value was found for aniline blue (approx. 220 mg per g of dried magnetic adsorbent). PMID:15811411

  3. Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  4. Dye removal using modified copper ferrite nanoparticle and RSM analysis.

    PubMed

    Mahmoodi, Niyaz Mohammad; Soltani-Gordefaramarzi, Sajjad; Sadeghi-Kiakhani, Moosa

    2013-12-01

    In this paper, copper ferrite nanoparticle (CFN) was synthesized, modified by cetyl trimethylammonium bromide, and characterized. Dye removal ability of the surface modified copper ferrite nanoparticle (SMCFN) from single system was investigated. The physical characteristics of SMCFN were studied using Fourier transform infrared, scanning electron microscopy, and X-ray diffraction. Acid Blue 92, Direct Green 6, Direct Red 23, and Direct Red 80 were used as model compounds. The effect of operational parameters (surfactant concentration, adsorbent dosage, dye concentration, and pH) on dye removal was evaluated. Response surface methodology (RSM) was used for the analysis of the dye removal data. The experimental checking in these optimal conditions confirms good agreements with RSM results. The results showed that the SMCFN being a magnetic adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions. PMID:23852534

  5. Structure and properties of water film adsorbed on mica surfaces

    NASA Astrophysics Data System (ADS)

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-01

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  6. Biological construction of single-walled carbon nanotube electron transfer pathways in dye-sensitized solar cells.

    PubMed

    Inoue, Ippei; Watanabe, Kiyoshi; Yamauchi, Hirofumi; Ishikawa, Yasuaki; Yasueda, Hisashi; Uraoka, Yukiharu; Yamashita, Ichiro

    2014-10-01

    We designed and mass-produced a versatile protein supramolecule that can be used to manufacture a highly efficient dye-sensitized solar cell (DSSC). Twelve single-walled carbon-nanotube (SWNT)-binding and titanium-mineralizing peptides were genetically integrated on a cage-shaped dodecamer protein (CDT1). A process involving simple mixing of highly conductive SWNTs with CDT1 followed by TiO2 biomineralization produces a high surface-area/weight TiO2 -(anatase)-coated intact SWNT nanocomposite under environmentally friendly conditions. A DSSC with a TiO2 photoelectrode containing 0.2 wt % of the SWNT-TiO2 nanocomposite shows a current density improvement by 80% and a doubling of the photoelectric conversion efficiency. The SWNT-TiO2 nanocomposite transfers photon-generated electrons from dye molecules adsorbed on the TiO2 to the anode electrode swiftly. PMID:25111295

  7. Hydrothermal Fabrication of Hierarchically Anatase TiO2 Nanowire arrays on FTO Glass for Dye-sensitized Solar Cells

    PubMed Central

    Wu, Wu-Qiang; Lei, Bing-Xin; Rao, Hua-Shang; Xu, Yang-Fan; Wang, Yu-Fen; Su, Cheng-Yong; Kuang, Dai-Bin

    2013-01-01

    Hierarchical anatase TiO2 nano-architecture arrays consisting of long TiO2 nanowire trunk and numerous short TiO2 nanorod branches on transparent conductive fluorine-doped tin oxide glass are successfully synthesized for the first time through a facile one-step hydrothermal route without any surfactant and template. Dye-sensitized solar cells based on the hierarchical anatase TiO2 nano-architecture array photoelectrode of 18 μm in length shows a power conversion efficiency of 7.34% because of its higher specific surface area for adsorbing more dye molecules and superior light scattering capacity for boosting the light-harvesting efficiency. The present photovoltaic performance is the highest value for the reported TiO2 nanowires array photoelectrode. PMID:23443301

  8. Exciton annihilation in dye-sensitized nanocrystalline semiconductor films

    NASA Astrophysics Data System (ADS)

    Namekawa, Akihiro; Katoh, Ryuzi

    2016-08-01

    Exciton annihilation in dye-sensitized nanocrystalline semiconductor (Al2O3) films has been studied through laser-induced fluorescence spectroscopy. The relative quantum yield of the fluorescence decreases with increasing excitation light intensity, the indication being that exciton annihilation occurred. The rate constants of the annihilation were estimated for three dyes, N719, D149, and MK2, that are known to be sensitizing dyes for efficient dye-sensitized solar cells. The hopping time between dye molecules and the diffusion length of excitons within their lifetime were also estimated to facilitate discussion of the relevance of exciton annihilation to primary processes in dye-sensitized solar cells.

  9. Standoff Spectroscopy of Surface Adsorbed Chemicals

    SciTech Connect

    Van Neste, Charles W; Senesac, Larry R; Thundat, Thomas George

    2009-01-01

    Despite its immediate applications, selective detection of trace quantities of surface adsorbed chemicals, such as explosives, without physically collecting the sample molecules is a challenging task. Standoff spectroscopic techniques offer an ideal method of detecting chemicals without using a sample collection step. Though standoff spectroscopic techniques are capable of providing high selectivity, their demonstrated sensitivities are poor. Here we describe standoff detection of trace quantities of surface adsorbed chemicals using two quantum cascade lasers operated simultaneously, with tunable wavelength windows that match with absorption peaks of the analytes. This standoff method is a variation of photoacoustic spectroscopy, where scattered light from the sample surface is used for exciting acoustic resonance of the detector. We demonstrate a sensitivity of 100 ng/cm{sup 2} and a standoff detection distance of 20 m for surface adsorbed analytes such as explosives and tributyl phosphate.

  10. Dye energy transfer in xerogel matrices and application to solid-state dye lasers

    NASA Astrophysics Data System (ADS)

    Nhung, Tran Hong; Canva, Michael; Chaput, Frédéric; Goudket, Hélène; Roger, Gisèle; Brun, Alain; Manh, Dang Duc; Hung, Nguyen Dai; Boilot, Jean-Pierre

    2004-03-01

    Laser dyes Rhodamine B and Perylene Red were incorporated at different relative concentrations into hybrid matrices synthesized using the sol-gel process. Energy transfer from Rhodamine B-donor to Perylene Red-acceptor molecules was observed. Using the different co-doped samples, solid-state dye laser systems were achieved with tuning band position control and increased efficiency with respect to the materials using solely one type of dye.

  11. Stability and efficiency of dye-sensitized solar cells based on papaya-leaf dye

    NASA Astrophysics Data System (ADS)

    Suyitno, Suyitno; Saputra, Trisma Jaya; Supriyanto, Agus; Arifin, Zainal

    2015-09-01

    The present article reports on the enhancement of the performance and stability of natural dye-based dye-sensitized solar cells (DSSCs). Natural dyes extracted from papaya leaves (PL) were investigated as sensitizers in TiO2-based DSSCs and evaluated in comparison with N719 dye. The acidity of the papaya-leaf extract dyes was tuned by adding benzoic acid. The TiO2 film-coated fluorine-doped tin oxide glass substrates were prepared using the doctor-blade method, followed by sintering at 450 °C. The counter electrode was coated by chemically deposited catalytic platinum. The working electrodes were immersed in N719 dye and papaya dye solutions with concentrations of 8 g/100 mL. The absorbance spectra of the dyes were obtained by ultra-violet-visible spectroscopy. The energy levels of the dyes were measured by the method of cyclic voltammetry. In addition, Fourier transform infrared spectroscopy was used to determine the characteristic functionalities of the dye molecules. The DSSC based on the N719 dye displayed a highest efficiency of 0.87% whereas those based on papaya-leaf dye achieved 0.28% at pH 3.5. The observed improved efficiency of the latter was attributed to the increased current density value. Furthermore, the DSSCs based on papaya-leaf dye with pH 3.5-4 exhibited better stability than those based on N719 dye. However, further studies are required to improve the current density and stability of natural dye-based DSSCs, including the investigation of alternative dye extraction routes, such as isolating the pure chlorophyll from papaya leaves and stabilizing it.

  12. Stability and efficiency of dye-sensitized solar cells based on papaya-leaf dye.

    PubMed

    Suyitno, Suyitno; Saputra, Trisma Jaya; Supriyanto, Agus; Arifin, Zainal

    2015-09-01

    The present article reports on the enhancement of the performance and stability of natural dye-based dye-sensitized solar cells (DSSCs). Natural dyes extracted from papaya leaves (PL) were investigated as sensitizers in TiO2-based DSSCs and evaluated in comparison with N719 dye. The acidity of the papaya-leaf extract dyes was tuned by adding benzoic acid. The TiO2 film-coated fluorine-doped tin oxide glass substrates were prepared using the doctor-blade method, followed by sintering at 450 °C. The counter electrode was coated by chemically deposited catalytic platinum. The working electrodes were immersed in N719 dye and papaya dye solutions with concentrations of 8 g/100 mL. The absorbance spectra of the dyes were obtained by ultra-violet-visible spectroscopy. The energy levels of the dyes were measured by the method of cyclic voltammetry. In addition, Fourier transform infrared spectroscopy was used to determine the characteristic functionalities of the dye molecules. The DSSC based on the N719 dye displayed a highest efficiency of 0.87% whereas those based on papaya-leaf dye achieved 0.28% at pH 3.5. The observed improved efficiency of the latter was attributed to the increased current density value. Furthermore, the DSSCs based on papaya-leaf dye with pH 3.5-4 exhibited better stability than those based on N719 dye. However, further studies are required to improve the current density and stability of natural dye-based DSSCs, including the investigation of alternative dye extraction routes, such as isolating the pure chlorophyll from papaya leaves and stabilizing it. PMID:25875031

  13. Ultrasound energy to accelerate dye uptake and dye-fiber interaction of reactive dye on knitted cotton fabric at low temperatures.

    PubMed

    Tissera, Nadeeka D; Wijesena, Ruchira N; de Silva, K M Nalin

    2016-03-01

    Acoustic cavitation formed due to propagation of ultrasound wave inside a dye bath was successfully used to dye cotton fabric with a reactive dye at lower temperatures. The energy input to the system during sonication was 0.7 W/cm(2). This was within the energy range that contributes towards forming cavitation during ultra-sonication. The influence of ultrasound treatment on dye particle size and fiber morphology is discussed. Particle size analysis of the dye bath revealed ultra-sonication energy was capable of de-agglomeration of hydrolyzed dye molecules during dyeing. SEM micrograph and AFM topographical image of the fiber surface revealed fiber morphology remains unchanged after the sonication. The study was extended in understanding the contribution of ultrasound method of dyeing towards achieving good color strength on the fabric, compared to the normal heating method of dyeing. Study showed color strength obtained using ultra sound method of dyeing is higher compared to normal heating dyeing. Ultrasound energy was able to achieve the good color strength on cotton fabric at very low temperature such as 30 °C, which was approximately 230% more than the color strength achieved in normal heating method of dyeing. This indicates that energy input to the system using ultrasound was capable of acting as an effective alternative method of dyeing knitted cotton fabrics with reactive dye. PMID:26585007

  14. Surface modifications of photoanodes in dye sensitized solar cells: enhanced light harvesting and reduced recombination

    NASA Astrophysics Data System (ADS)

    Saxena, Vibha; Aswal, D. K.

    2015-06-01

    In a quest to harvest solar power, dye-sensitized solar cells (DSSCs) have potential for low-cost eco-friendly photovoltaic devices. The major processes which govern the efficiency of a DSSC are photoelectron generation, injection of photo-generated electrons to the conduction band (CB) of the mesoporous nanocrystalline semiconductor (nc-SC); transport of CB electrons through nc-SC and subsequent collection of CB electrons at the counter electrode (CE) through the external circuit; and dye regeneration by redox couple or hole transport layer (HTL). Most of these processes occur at various interfaces of the photoanode. In addition, recombination losses of photo-generated electrons with either dye or redox molecules take place at the interfaces. Therefore, one of the key requirements for high efficiency is to improve light harvesting of the photoanode and to reduce the recombination losses at various interfaces. In this direction, surface modification of the photoanode is the simplest method among the various other approaches available in the literature. In this review, we present a comprehensive discussion on surface modification of the photoanode, which has been adopted in the literature for not only enhancing light harvesting but also reducing recombination. Various approaches towards surface modification of the photoanode discussed are (i) fluorine-doped tin oxide (FTO)/nc-SC interface modified via a compact layer of semiconductor material which blocks exposed sites of FTO to electrolyte (or HTL), (ii) nc-SC/dye interface modification either through acid treatment resulting in enhanced dye loading due to a positively charged surface or by depositing insulating/semiconducting blocking layer on the nc-SC surface, which acts as a tunneling barrier for recombination, (iii) nc-SC/dye interface modified by employing co-adsorbents which helps in reducing the dye aggregation and thereby recombination, and (iv) dye/electrolyte (or dye/HTL) interface modification using

  15. Black Molecular Adsorber Coatings for Spaceflight Applications

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  16. Regenerative adsorbent heat pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  17. Influence of structural fluctuations on lifetimes of adsorbate states at hybrid organic-semiconductor interfaces

    NASA Astrophysics Data System (ADS)

    Müller, M.; Sánchez-Portal, D.; Lin, H.; Fratesi, G.; Brivio, G. P.; Selloni, A.

    On the road towards a more realistic description of charge transfer processes at hybrid organic-semiconductor interfaces for photovoltaic applications we extend our first-principles scheme for the extraction of elastic linewidths to include the effects of structural fluctuations. Based on snapshots obtained from Car-Parinello molecular dynamics simulations at room temperature, we set up geometries in which dye molecules at interfaces are attached to a semi-infinite TiO2 substrate. The elastic linewidths are computed using a Green's function method. This effectively introduces the coupling to a continuum of states in the substrate. In particular we investigate catechol and isonicotinic acid on rutile(110) and anatase(101) at the level of semi-local density functional theory. We perform multiple calculations of linewidths and peak-positions associated with the adsorbate's frontier orbitals for different geometric configurations to obtain a time-averaged analysis of such physical properties. We compare the results from the considered systems to understand the effects of dynamics onto interfacial charge transfer and systematically assess the dependence of the extracted elastic lifetimes on the relative alignment between adsorbate and substrate states. This project has received funding from the European Union Seventh Framework Programme under Grant Agreement No. 607323 [THINFACE].

  18. Computer simulations of adsorbed liquid crystal films

    NASA Astrophysics Data System (ADS)

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  19. Dye-sensitized Schottky barrier solar cells

    DOEpatents

    Skotheim, Terje A.

    1978-01-01

    A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

  20. Dye laser amplifier

    DOEpatents

    Moses, Edward I.

    1992-01-01

    An improved dye laser amplifier is disclosed. The efficiency of the dye lr amplifier is increased significantly by increasing the power of a dye beam as it passes from an input window to an output window within the dye chamber, while maintaining the intensity of the dye beam constant.

  1. Dye laser amplifier

    DOEpatents

    Moses, E.I.

    1992-12-01

    An improved dye laser amplifier is disclosed. The efficiency of the dye laser amplifier is increased significantly by increasing the power of a dye beam as it passes from an input window to an output window within the dye chamber, while maintaining the intensity of the dye beam constant. 3 figs.

  2. Adsorbent and adsorbent bed for materials capture and separation processes

    SciTech Connect

    Liu, Wei

    2011-01-25

    A method device and material for performing adsorption wherein a fluid mixture is passed through a channel in a structured adsorbent bed having a solid adsorbent comprised of adsorbent particles having a general diameter less than 100 um, loaded in a porous support matrix defining at least one straight flow channel. The adsorbent bed is configured to allow passage of a fluid through said channel and diffusion of a target material into said adsorbent under a pressure gradient driving force. The targeted molecular species in the fluid mixture diffuses across the porous support retaining layer, contacts the adsorbent, and adsorbs on the adsorbent, while the remaining species in the fluid mixture flows out of the channel.

  3. Dye adsorption behavior of Luffa cylindrica fibers.

    PubMed

    Demir, H; Top, A; Balköse, D; Ulkü, S

    2008-05-01

    Using natural Luffa cylindrica fibers as adsorbent removal of methylene blue dye from aqueous solutions at different temperatures and dye concentrations was investigated in this study. Thermodynamics and kinetics of adsorption were also investigated. The adsorption isotherms could be well defined with Langmuir model instead of Freundlich model. The thermodynamic parameters of methylene blue (MB) adsorption indicated that the adsorption is exothermic and spontaneous. The average MB adsorption capacity was found out as 49 mg/g and average BET surface area of fibers was calculated as 123 m(2)/g. PMID:17919814

  4. Preparation of Nanoporous TiO2 for Dye-Sensitized Solar Cell (DSSC) Using Various Dyes

    NASA Astrophysics Data System (ADS)

    Yuliarto, Brian; Fanani, Fahiem; Fuadi, M. Kasyful; Nugraha

    2010-10-01

    This article reports the development of organic dyes as an attempt to reduce material costs of Dye-Sensitized Solar Cell (DSSC). Indonesia, a country with variety and considerable number of botanical resources, is suitable to perform the research. Indonesian black rice, curcuma, papaya leaf, and the combination were chosen as organic dyes source. Dyes were extracted using organic solvent and adsorbed on mesoporous Titanium Dioxide (TiO2) which has been optimized in our laboratory. The best dyes light absorbance and performance obtained from papaya leaf as chlorophyll dyes that gives two peaks at 432 nm and 664 nm from UV-Vis Spectrophotometry and performance under 100 mW/cm2 Xenon light solar simulator gives VOC = 0.566 Volt, JSC = 0.24 mA/cm2, Fill Factor = 0.33, and efficiency of energy conversion 0,045%.

  5. Effect of photoanode thickness on electrochemical performance of dye sensitized solar cell

    SciTech Connect

    Khatani, Mehboob Hamid, Nor Hisham Sahmer, Ahmed Zahrin; Mohamed, Norani Muti Muhsan, Ali Samer

    2015-07-22

    The thickness of photoanode is crucial as it adsorbed a large amount of dye molecules that provide electrons for generation of electricity in dye sensitized solar cell (DSC). Thus, in order to realize the practical application of DSC, study on various thickness of photoanode need to be carried out to analyze its effect on the electrochemical behavior of dye sensitized solar cell. To enhance the conversion efficiency, an additional layer of TiO{sub 2} using TiCl{sub 4} treatment was deposited prior to the deposition of the photoanode (active area of 1cm{sup 2}) with the thickness of 6, 12, 18, 24, and 30 µm on fluorine doped tin oxide (FTO) glass substrate. The resulting photoanode after the soak in N719 dye for more than 12hrs were used to be assembled in a test cell in combination with liquid electrolyte and counter electrode. The fabricated cells were characterized by solar simulator, ultraviolet-visible spectroscopy (UV-VIS), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was used to approximate the thickness of photoanode. An optimum power conversion efficiency of 4.54% was obtained for the cell fabricated with 18 µm photoanode thickness. This is attributed to the reduced resistance related to electron transport in the TiO{sub 2}/dye/electrolyte interface as proven by the EIS result. This led to the reduction of internal resistance, the increase in the electron life time and the improvement in the conversion efficiency.

  6. Adsorption of a Textile Dye on Commercial Activated Carbon: A Simple Experiment to Explore the Role of Surface Chemistry and Ionic Strength

    ERIC Educational Resources Information Center

    Martins, Angela; Nunes, Nelson

    2015-01-01

    In this study, an adsorption experiment is proposed using commercial activated carbon as adsorbent and a textile azo dye, Mordant Blue-9, as adsorbate. The surface chemistry of the activated carbon is changed through a simple oxidation treatment and the ionic strength of the dye solution is also modified, simulating distinct conditions of water…

  7. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    SciTech Connect

    Weinelt, M.; Nilsson, A.; Wassdahl, N.

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  8. New insights into perfluorinated adsorbents for analytical and bioanalytical applications.

    PubMed

    Marchetti, Nicola; Guzzinati, Roberta; Catani, Martina; Massi, Alessandro; Pasti, Luisa; Cavazzini, Alberto

    2015-01-01

    Perfluorinated (F-) adsorbents are generally prepared by bonding perfluoro-functionalized silanes to silica gels. They have been employed for a long time essentially as media for solid-phase extraction of F-molecules or F-tagged molecules in organic chemistry and heterogeneous catalysis. More recently, this approach has been extended to proteomics and metabolomics. Owing to their unique physicochemical properties, namely fluorophilicity and proteinophilicity, and a better understanding of some fundamental aspects of their behavior, new applications of F-adsorbents in the field of environmental science and bio-affinity studies can be envisaged. In this article, we revisit the most important features of F-adsorbents by focusing, in particular, on some basic information that has been recently obtained through (nonlinear) chromatographic studies. Finally, we try to envisage new applications and possibilities that F-adsorbents will allow in the near future. PMID:25358910

  9. Accurate simulation of optical properties in dyes.

    PubMed

    Jacquemin, Denis; Perpète, Eric A; Ciofini, Ilaria; Adamo, Carlo

    2009-02-17

    Since Antiquity, humans have produced and commercialized dyes. To this day, extraction of natural dyes often requires lengthy and costly procedures. In the 19th century, global markets and new industrial products drove a significant effort to synthesize artificial dyes, characterized by low production costs, huge quantities, and new optical properties (colors). Dyes that encompass classes of molecules absorbing in the UV-visible part of the electromagnetic spectrum now have a wider range of applications, including coloring (textiles, food, paintings), energy production (photovoltaic cells, OLEDs), or pharmaceuticals (diagnostics, drugs). Parallel to the growth in dye applications, researchers have increased their efforts to design and synthesize new dyes to customize absorption and emission properties. In particular, dyes containing one or more metallic centers allow for the construction of fairly sophisticated systems capable of selectively reacting to light of a given wavelength and behaving as molecular devices (photochemical molecular devices, PMDs).Theoretical tools able to predict and interpret the excited-state properties of organic and inorganic dyes allow for an efficient screening of photochemical centers. In this Account, we report recent developments defining a quantitative ab initio protocol (based on time-dependent density functional theory) for modeling dye spectral properties. In particular, we discuss the importance of several parameters, such as the methods used for electronic structure calculations, solvent effects, and statistical treatments. In addition, we illustrate the performance of such simulation tools through case studies. We also comment on current weak points of these methods and ways to improve them. PMID:19113946

  10. Monitoring the dye impregnation time of nanostructured photoanodes for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shahzad, N.; Pugliese, D.; Lamberti, A.; Sacco, A.; Virga, A.; Gazia, R.; Bianco, S.; Shahzad, M. I.; Tresso, E.; Pirri, C. F.

    2013-06-01

    Dye-sensitized solar cells (DSSCs) are getting increasing attention as low-cost, easy-to-prepare and colored photovoltaic devices. In the current work, in view of optimizing the fabrication procedures and understanding the mechanisms of dye attachment to the semiconductor photoanode, absorbance measurements have been performed at different dye impregnation times ranging from few minutes to 24 hours using UV-Vis spectroscopy. In addition to the traditional absorbance experiments, based on diffuse and specular reflectance on dye impregnated thin films and on the desorption of dye molecules from the photoanodes by means of a basic solution, an alternative in-situ solution depletion measurement, which enables fast and continuous evaluation of dye uptake, is presented. Photoanodes have been prepared with two different nanostructured semiconducting films: mesoporous TiO2, using a commercially available paste from Solaronix, and sponge-like ZnO obtained in our laboratory from sputtering and thermal annealing. Two different dyes have been analyzed: Ruthenizer 535-bisTBA (N719), which is widely used because it gives optimal photovoltaic performances, and a new metal-free organic dye based on a hemisquaraine molecule (CT1). Dye sensitized cells were fabricated using a customized microfluidic architecture. The results of absorbance measurements are presented and discussed in relation to the obtained solar energy conversion efficiencies and the incident photon-to-electron conversion efficiencies (IPCE).

  11. Oil palm biomass-based adsorbents for the removal of water pollutants--a review.

    PubMed

    Ahmad, Tanweer; Rafatullah, Mohd; Ghazali, Arniza; Sulaiman, Othman; Hashim, Rokiah

    2011-07-01

    This article presents a review on the role of oil palm biomass (trunks, fronds, leaves, empty fruit bunches, shells, etc.) as adsorbents in the removal of water pollutants such as acid and basic dyes, heavy metals, phenolic compounds, various gaseous pollutants, and so on. Numerous studies on adsorption properties of various low-cost adsorbents, such as agricultural wastes and its based activated carbons, have been reported in recent years. Studies have shown that oil palm-based adsorbent, among the low-cost adsorbents mentioned, is the most promising adsorbent for removing water pollutants. Further, these bioadsorbents can be chemically modified for better efficiency and can undergo multiple reuses to enhance their applicability at an industrial scale. It is evident from a literature survey of more than 100 recent papers that low-cost adsorbents have demonstrated outstanding removal capabilities for various pollutants. The conclusion is been drawn from the reviewed literature, and suggestions for future research are proposed. PMID:21929380

  12. Reverse micelles for the removal of dyes from aqueous solutions.

    PubMed

    Majhi, S; Sharma, Y C; Upadhyay, S N

    2009-08-01

    The ability of reverse micelles to solvate organic dyes in the aqueous core was investigated with methyl orange (MO) and methylene blue (MB) using hexadecyl trimethyl ammonium bromide (HTAB) and sodium dodecyl benzene sulphonate (SDBS) surfactants in a polar amyl alcohol medium. The removal trend of the dyes from water was studied with different concentrations of the dyes. The effects of NaCl and CaCl2 salts on removal efficiency of the surfactants were investigated and results were compared. It was observed that the separation of dyes from the aqueous phase to the organic phase depends on the electrostatic interaction between the dye molecule and surfactant head groups. In the case of NaCl, with increasing salt concentration, the removal (%) of dye decreases. For CaCl2, removal of methyl orange shows a gradual increase with increasing dye concentration, whereas, for methylene blue, its removal decreases with increasing dye concentration. PMID:19803326

  13. Adsorption of dyes using different types of clay: a review

    NASA Astrophysics Data System (ADS)

    Adeyemo, Aderonke Ajibola; Adeoye, Idowu Olatunbosun; Bello, Olugbenga Solomon

    2015-09-01

    Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.

  14. Activated carbon derived from carbon residue from biomass gasification and its application for dye adsorption: Kinetics, isotherms and thermodynamic studies.

    PubMed

    Maneerung, Thawatchai; Liew, Johan; Dai, Yanjun; Kawi, Sibudjing; Chong, Clive; Wang, Chi-Hwa

    2016-01-01

    In this work, activated carbon (AC) as an effective and low-cost adsorbent was successfully prepared from carbon residue (or char, one of the by-products from woody biomass gasification) via physical activation. The surface area of char was significantly increased from 172.24 to 776.46m(2)/g after steam activation at 900°C. The obtained activated carbons were then employed for the adsorption of dye (Rhodamine B) and it was found that activated carbon obtained from steam activation exhibited the highest adsorption capability, which is mainly attributed to the higher surface area and the abundance of hydroxyl (-OH) and carboxyl (-COOH) groups on the activated carbon surface. Moreover, it was also found that the adsorption capability significantly increased under the basic condition, which can be attributed to the increased electrostatic interaction between the deprotonated (negatively charged) activated carbon and dye molecules. Furthermore, the equilibrium data were fitted into different adsorption isotherms and found to fit well with Langmuir model (indicating that dye molecules form monolayer coverage on activated carbon) with a maximum monolayer adsorption capability of 189.83mg/g, whereas the adsorption kinetics followed the pseudo-second-order kinetics. PMID:26512858

  15. Hair dye poisoning

    MedlinePlus

    Hair tint poisoning ... Different types of hair dye contain different harmful ingredients. The harmful ingredients in permanent dyes are: Naphthylamine Other aromatic amino compounds Phenylenediamines Toluene ...

  16. Adsorption studies of cationic, anionic and azo-dyes via monodispersed Fe3O4 nanoparticles.

    PubMed

    Chaudhary, Ganga Ram; Saharan, Priya; Kumar, Arun; Mehta, S K; Mor, Suman; Umar, Ahmad

    2013-05-01

    The present paper reports the applicability of magnetite (Fe3O4) nanoparticles as an adsorbent for the removal of three dyes viz. Acridine orange (cationic dye), Comassie Brilliant Blue R-250 (anionic dye) and Congo red (azo dye) from their aqueous solution. The Fe3O4 nanoparticles were synthesized via simple chemical precipitation method using CTAB, as surfactant. The as-prepared nanoparticles were characterized in terms of their morphological, structural and optical properties by using transmission electron microscopy X-ray diffraction and UV-visible spectroscopic measurements. The dye removal efficiency of Fe3O4 NPs have been determined by investigating several factors such as effect of pH, amount of adsorbent dose and effect of contact time on different dye concentrations. Langmuir and Freundlich adsorption isotherms have also been studied to explain the interaction of dyes. The experimental data indicate that the adsorption rate follows pseudo- second-order kinetics for the removal of all the three dyes. Moreover, the nanoparticles and the adsorbed dyes were desorbed. The identities of recovered nanoparticles as well as the three dyes have been found, as same and were reused. PMID:23858837

  17. Just Dyeing to Find Out.

    ERIC Educational Resources Information Center

    Monhardt, Becky Meyer

    1996-01-01

    Presents a multidisciplinary unit on natural dyes designed to take advantage of the natural curiosity of middle school students. Discusses history of dyes, natural dyes, preparation of dyes, and the dyeing process. (JRH)

  18. Improving the dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Willig, Frank

    2007-09-01

    Two dye sensitized solar cells (DSC) can be joined to form a tandem cell with two separate absorption ranges for the two different absorber materials. This can enhance the solar conversion efficiency and in particular the photovoltage of the DSC. Water splitting appears as a realistic long term target. The DSC tandem can be realized as n-n junction employing known dye molecules with optimal absorption spectra. Dye molecules with elongated shapes can be realized by covalently attaching a conducting bridge group terminated by an anchor group to a desired chromophore. Due to the long conducting bridge group separating the hole state of the dye from the surface of the semiconductor recombination is slowed down. The ordered molecular structure can be self-assembled on the recently introduced rod or cylinder shaped oxide electrodes but will not slow down recombination in the nm-cavities of the conventional TiO II Graetzel electrode.

  19. Detecting the mass and position of an adsorbate on a drum resonator

    PubMed Central

    Zhang, Y.; Zhao, Y. P.

    2014-01-01

    The resonant frequency shifts of a circular membrane caused by an adsorbate are the sensing mechanism for a drum resonator. The adsorbate mass and position are the two major (unknown) parameters determining the resonant frequency shifts. There are infinite combinations of mass and position which can cause the same shift of one resonant frequency. Finding the mass and position of an adsorbate from the experimentally measured resonant frequencies forms an inverse problem. This study presents a straightforward method to determine the adsorbate mass and position by using the changes of two resonant frequencies. Because detecting the position of an adsorbate can be extremely difficult, especially when the adsorbate is as small as an atom or a molecule, this new inverse problem-solving method should be of some help to the mass resonator sensor application of detecting a single adsorbate. How to apply this method to the case of multiple adsorbates is also discussed. PMID:25294971

  20. Orbital tomography for highly symmetric adsorbate systems

    NASA Astrophysics Data System (ADS)

    Stadtmüller, B.; Willenbockel, M.; Reinisch, E. M.; Ules, T.; Bocquet, F. C.; Soubatch, S.; Puschnig, P.; Koller, G.; Ramsey, M. G.; Tautz, F. S.; Kumpf, C.

    2012-10-01

    Orbital tomography is a new and very powerful tool to analyze the angular distribution of a photoemission spectroscopy experiment. It was successfully used for organic adsorbate systems to identify (and consequently deconvolute) the contributions of specific molecular orbitals to the photoemission data. The technique was so far limited to surfaces with low symmetry like fcc(110) oriented surfaces, owing to the small number of rotational domains that occur on such surfaces. In this letter we overcome this limitation and present an orbital tomography study of a 3,4,9,10-perylene-tetra-carboxylic-dianhydride (PTCDA) monolayer film adsorbed on Ag(111). Although this system exhibits twelve differently oriented molecules, the angular resolved photoemission data still allow a meaningful analysis of the different local density of states and reveal different electronic structures for symmetrically inequivalent molecules. We also discuss the precision of the orbital tomography technique in terms of counting statistics and linear regression fitting algorithm. Our results demonstrate that orbital tomography is not limited to low-symmetry surfaces, a finding which makes a broad field of complex adsorbate systems accessible to this powerful technique.

  1. Utilization of carbon nanotubes for the removal of rhodamine B dye from aqueous solutions.

    PubMed

    Kumar, Sandeep; Bhanjana, Gaurav; Jangra, Kavita; Dilbaghi, Neeraj; Umar, Ahmad

    2014-06-01

    Carbon nanotubes (CNTs) are attracting increasing research interest as promising adsorbents for harmful cations, anions, and other organic and inorganic impurities present in natural sources of water. This study examined the feasibility of removing Rhodamine B dye from aqueous solutions using multi walled carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition (CVD) method. The effects of dye concentration, pH and contact time on adsorption of direct dye by CNTs were also evaluated. The study used the Langmuir and Temkin isotherms to describe equilibrium adsorption. Additionally, pseudo second-order model was adopted to evaluate experimental data and thereby elucidate the kinetic adsorption process. The adsorption percentage of dye increased as contact time increased. Conversely, the adsorption percentage of dye decreased as dye concentration increased. The pseudo second-order model best represented adsorption kinetics. The capacity of CNTs to adsorb Rhodamine B was 65-90% at different pH values. PMID:24738392

  2. Surface-enhanced fluorescence and surface-enhanced Raman scattering of push-pull molecules: sulfur-functionalized 4-amino-7-nitrobenzofurazan adsorbed on Ag and Au nanostructured substrates.

    PubMed

    Muniz-Miranda, Maurizio; Del Rosso, Tommaso; Giorgetti, Emilia; Margheri, Giancarlo; Ghini, Giacomo; Cicchi, Stefano

    2011-04-01

    We investigated the chemisorption of self-assembled monolayers of sulfur-functionalized 4-amino-7-nitrobenzofurazan on gold and silver nanoisland films (NIFs) by means of surface-enhanced fluorescence (SEF) and surface-enhanced Raman scattering (SERS). The ligand is a push-pull molecule, where an intramolecular charge transfer occurs between an electron-donor and an electron-acceptor group, thus exhibiting nonlinear optical properties that are related to both SERS and SEF effects. The presence of different heteroatoms in the molecule ensures the possibility of chemical interaction with both silver and gold substrates. The SERS spectra suggest that furazan is bound to silver via lone pairs of the nitrogen atoms, whereas the ligand is linked to gold via a sulfur atom. Silver NIFs provide more efficient enhancement of both fluorescence and Raman scattering in comparison with gold NIFs. The present SEF and SERS investigation could provide useful information for foreseeing changes in the nonlinear responses of this push-pull molecule. PMID:21331491

  3. Equilibrium molecular theory of two-dimensional adsorbate drops on surfaces of heterogeneous adsorbents

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2016-08-01

    A molecular statistical theory for calculating the linear tension of small multicomponent droplets in two-dimensional adsorption systems is developed. The theory describes discrete distributions of molecules in space (on a scale comparable to molecular size) and continuous distributions of molecules (at short distances inside cells) in their translational and vibrational motions. Pair intermolecular interaction potentials (the Mie type potential) in several coordination spheres are considered. For simplicity, it is assumed that distinctions in the sizes of mixture components are slight and comparable to the sizes of adsorbent adsorption centers. Expressions for the pressure tensor components inside small droplets on the heterogeneous surface of an adsorbent are obtained, allowing calculations of the thermodynamic characteristics of a vapor-fluid interface, including linear tension. Problems in refining the molecular theory are discussed: describing the properties of small droplets using a coordination model of their structure, considering the effect an adsorbate has on the state of a near-surface adsorbent region, and the surface heterogeneity factor in the conditions for the formation of droplets.

  4. Uniform silica nanoparticles encapsulating two-photon absorbing fluorescent dye

    SciTech Connect

    Wu Weibing; Liu Chang; Wang Mingliang; Huang Wei; Zhou Shengrui; Jiang Wei; Sun Yueming; Cui Yiping; Xu Chunxinag

    2009-04-15

    We have prepared uniform silica nanoparticles (NPs) doped with a two-photon absorbing zwitterionic hemicyanine dye by reverse microemulsion method. Obvious solvatochromism on the absorption spectra of dye-doped NPs indicates that solvents can partly penetrate into the silica matrix and then affect the ground and excited state of dye molecules. For dye-doped NP suspensions, both one-photon and two-photon excited fluorescence are much stronger and recorded at shorter wavelength compared to those of free dye solutions with comparative overall dye concentration. This behavior is possibly attributed to the restricted twisted intramolecular charge transfer (TICT), which reduces fluorescence quenching when dye molecules are trapped in the silica matrix. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells with low cytotoxicity. - Graphical abstract: Water-soluble silica NPs doped with a two-photon absorbing zwitterionic hemicyanine dye were prepared. They were found of enhanced one-photon and two-photon excited fluorescence compared to free dye solutions. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells.

  5. Chirality transfer from gold nanocluster to adsorbate evidenced by vibrational circular dichroism

    PubMed Central

    Dolamic, Igor; Varnholt, Birte; Bürgi, Thomas

    2015-01-01

    The transfer of chirality from one set of molecules to another is fundamental for applications in chiral technology and has likely played a crucial role for establishing homochirality on earth. Here we show that an intrinsically chiral gold cluster can transfer its handedness to an achiral molecule adsorbed on its surface. Solutions of chiral Au38(2-PET)24 (2-PET=2-phenylethylthiolate) cluster enantiomers show strong vibrational circular dichroism (VCD) signals in vibrations of the achiral adsorbate. Density functional theory (DFT) calculations reveal that 2-PET molecules adopt a chiral conformation. Chirality transfer from the cluster to the achiral adsorbate is responsible for the preference of one of the two mirror images. Intermolecular interactions between the adsorbed molecules on the crowded cluster surface seem to play a dominant role for the phenomena. Such chirality transfer from metals to adsorbates likely plays an important role in heterogeneous enantioselective catalysis. PMID:25960309

  6. Fluorescence quenching and photocatalytic degradation of textile dyeing waste water by silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Kavitha, S. R.; Umadevi, M.; Janani, S. R.; Balakrishnan, T.; Ramanibai, R.

    2014-06-01

    Silver nanoparticles (Ag NPs) of different sizes have been prepared by chemical reduction method and characterized using UV-vis spectroscopy and transmission electron microscopy (HRTEM). Fluorescence spectral analysis showed that the quenching of fluorescence of textile dyeing waste water (TDW) has been found to decrease with decrease in the size of the Ag NPs. Experimental results show that the silver nanoparticles can quench the fluorescence emission of adsorbed TDW effectively. The fluorescence interaction between Ag NPs (acceptor) and TDW (donor) confirms the Förster Resonance Energy Transfer (FRET) mechanism. Long range dipole-dipole interaction between the excited donor and ground state acceptor molecules is the dominant mechanism responsible for the energy transfer. Furthermore, photocatalytic degradation of TDW was measured spectrophotometrically by using silver as nanocatalyst under UV light illumination. The kinetic study revealed that synthesized Ag NPs was found to be effective in degrading TDW.

  7. Laser-induced desorption of organic molecules from front- and back-irradiated metal foils

    SciTech Connect

    Zinovev, Alexander V.; Veryovkin, Igor V.; Pellin, Michael J.

    2009-03-17

    Laser-Induced Acoustic Desorption (LIAD) from thin metal foils is a promising technique for gentle and efficient volatilization of intact organic molecules from surfaces of solid substrates. Using the Single Photon Ionization (SPI) method combined with time-of-flight mass-spectrometry (TOF MS), desorbed flux in LIAD was examined and compared to that from direct laser desorption (LD). Molecules of various organic dyes were used in experiments. Translational velocities of the desorbed intact molecules did not depend on the desorbing laser intensity, which implies the presence of more sophisticated mechanism of energy transfer than the direct mechanical or thermal coupling between the laser pulse and the adsorbed molecules. The results of our experiments indicate that the LIAD phenomenon cannot be described in terms of a simple mechanical shake-off nor the direct laser desorption. Rather, they suggest that multi-step energy transfer processes are involved. Possible qualitative mechanism of LIAD that are based on formation of non-equilibrium energy states in the adsorbate-substrate system are proposed and discussed.

  8. Laser-induced desorption of organic molecules from front- and back-irradiated metal foils.

    SciTech Connect

    Zinovev, A. V.; Veryovkin, I. V.; Pellin, M. J.; Materials Science Division

    2009-01-01

    Laser-Induced Acoustic Desorption (LIAD) from thin metal foils is a promising technique for gentle and efficient volatilization of intact organic molecules from surfaces of solid substrates. Using the Single Photon Ionization (SPI) method combined with time-of-flight mass-spectrometry (TOF MS), desorbed flux in LIAD was examined and compared to that from direct laser desorption (LD). Molecules of various organic dyes were used in experiments. Translational velocities of the desorbed intact molecules did not depend on the desorbing laser intensity, which implies the presence of more sophisticated mechanism of energy transfer than the direct mechanical or thermal coupling between the laser pulse and the adsorbed molecules. The results of our experiments indicate that the LIAD phenomenon cannot be described in terms of a simple mechanical shake-off nor the direct laser desorption. Rather, they suggest that multi-step energy transfer processes are involved. Possible qualitative mechanism of LIAD that are based on formation of non-equilibrium energy states in the adsorbate-substrate system are proposed and discussed.

  9. Oxidative degradation of azo dyes using tourmaline.

    PubMed

    Wang, Cuiping; Zhang, Yanwei; Yu, Li; Zhang, Zhiyuan; Sun, Hongwen

    2013-09-15

    This study aimed to investigate the catalyzed degradation ability of tourmaline on the dyes methylene blue (MB), rhodamine B (RhB), and congo red (CR) at different pH values. Interestingly, tourmaline strongly adsorbed anionic dyes, but it did not adsorb cationic dyes. When H₂O₂ was introduced into the tourmaline-dye systems, the degradation percentage for CR catalysis by tourmaline was lower than the percentage of adsorption, whereas the opposite was true for MB and RhB systems. Notably, the catalyzed degradation decreased from 100% to 45% for MB, 100% to 15% for RhB and 100% to 25% for CR as the pH increased from 3.0 to 10.0, respectively, which was much greater than the degradation obtained for previously reported materials at pH values ranging from 4.0 to 10.0. Tourmaline catalytically degraded the dyes over a broad range of pH values, which was attributed to tourmaline automatically adjusting the pH of the dye solutions to approximately 5.5 from an initial range of 4.2-10.0. An electron paramagnetic resonance spin trapping technique observed peroxyl (ROO·) and alkoxy (RO·) or alkyl (R·) radicals originated from the attack of ·OH radicals and O₂(·-) radicals, indicating that these radicals were involved in the catalyzed degradation of MB. Importantly, four intermediate products of MB at m/z 383, 316, 203 and 181 were observed by LC/MS. PMID:23876254

  10. Biodegradable hollow zein nanoparticles for removal of reactive dyes from wastewater.

    PubMed

    Xu, Helan; Zhang, Yue; Jiang, Qiuran; Reddy, Narendra; Yang, Yiqi

    2013-08-15

    In this study, biodegradable hollow zein nanoparticles with diameters less than 100 nm were developed to remove reactive dyes from simulated post-dyeing wastewater with remarkably high efficiency. Reactive dyes are widely used to color cellulosic materials, such as cotton and rayon. Wastewater from reactive dyeing process contains up to 50% dye and electrolytes with concentrations up to 100 g L(-1). Current methods to remove reactive dyes from wastewater are suffering from low adsorption capacities or low biodegradability of the sorbents. In this research, biodegradable zein nanoparticles showed high adsorption capacities for dyes. Hollow zein nanoparticles showed higher adsorption for Reactive Blue 19 than solid structures, and the adsorption amount increased as temperature decreased, pH decreased or initial dye concentration increased. At pH 6.5 and pH 9.0, increasing electrolyte concentration could improve dye adsorption significantly. Under simulated post-dyeing condition with 50.0 g L(-1) salt and pH 9.0, maximum adsorption of 1016.0 mg dye per gram zein nanoparticles could be obtained. The adsorption capacity was much higher than that of various biodegradable adsorbents developed to remove reactive dye. It is suggested that the hollow zein nanoparticles are good candidates to remove reactive dye immediately after dyeing process. PMID:23643969

  11. Metachromasy as an indicator of photostabilization of methylene blue adsorbed to clays and minerals.

    PubMed

    Samuels, Maya; Mor, Omer; Rytwo, Giora

    2013-04-01

    The influence of methylene blue adsorption to different clays on its photodegradation was studied. Methylene blue in solution was decomposed by sunlight in a zero-order process. Adsorption to some clay minerals (sepiolite and vermiculite) and a zeolite (clinoptilolite) accelerated the degradation process, and converted it to a first-order reaction. On the other hand, adsorption to other clay minerals (palygorskite and montmorillonite) stabilized the dye and prevented its degradation. Interestingly, in the clay-dye complexes that exhibited stability, clear metachromasy of the adsorbed methylene blue occurred, whereas the effect was not observed in the clay-dye complexes that underwent photodegradation. PMID:23474529

  12. Adsorption of methylene blue dye from aqueous solutions using Eichhornia crassipes.

    PubMed

    Wanyonyi, Wycliffe Chisutia; Onyari, John Mmari; Shiundu, Paul Mwanza

    2013-09-01

    Adsorption of methylene blue (MB) from aqueous solution using dried roots, stems, and leaves of Eichhornia crassipes biomass obtained from Lake Victoria was studied. Batch experimental results revealed that the adsorption process was highly dependent on adsorbent dosage, initial MB concentration, E. crassipes particle size and aqueous solution temperature. The isotherm data fitted Freundlich mathematical models with maximum dye adsorption of 35.37 mg g(-1). Roots adsorbed over 99 % of the MB in <5 min. Sorption kinetics followed a pseudo-second-order model. Results provide evidence that E. crassipes is an effective and inexpensive biomaterial for dye removal from aqueous dye solutions and industrial effluents. PMID:23839152

  13. Modeling of the dye loading time influence on the electrical impedance of a dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Pugliese, D.; Shahzad, N.; Sacco, A.; Tresso, E.; Alexe-Ionescu, A. L.

    2013-09-01

    A hemisquaraine dye molecule (CT1) was used as TiO2 sensitizer. The influence of the dye-adsorption time on the electrical impedance of a CT1-based dye-sensitized solar cell (DSC) was analyzed. Differently from what we observed with commercial Ru dye-based DSC, a non-monotonic effect of the impregnation time on the impedance has been found and the dye loading time is much reduced, a desirable outcome in economic grounds. This feature is analyzed in terms of the dye molecules tendency to aggregate close to the TiO2/electrolyte interface. A physical model that fits well the experimental data is proposed, which also takes into account a correction related to the difference between the illuminated area of the cell and the total area available in the electrical measurements.

  14. Molecular aggregation of rhodamine dyes in dispersions of layered silicates: influence of dye molecular structure and silicate properties.

    PubMed

    Bujdák, Juraj; Iyi, Nobuo

    2006-02-01

    The molecular aggregation of six rhodamine dyes (rhodamine 560, B, 3B, 19, 6G, 123) in layered silicate (saponite and fluorohectorite) dispersions was investigated by using visible (vis) spectroscopy. The dye molecular aggregation was influenced by the properties of both the silicates and the dyes themselves. The layer charge of the silicates enhanced the molecular aggregation of the hydrophilic, cationic dyes. The presence of a carboxyl acid group in the dye molecules inhibited adsorption of the dyes on the surface of fluorohectorite, a silicate with a high charge density. A lower or no adsorption could be observed by vis spectroscopy. Strong association of the dyes to the silicate surface led to remarkable changes in the dye spectra, mainly due to the molecular aggregation. Dye assemblies initially formed after mixing the dye solutions with silicate dispersions were unstable. Decomposition of the dye molecular assemblies, and the formation of new species or molecular aggregate rearrangements, were studied on the bases of time-difference spectra. The reaction pathways were specific, not only for the dyes, depending upon their molecular structure and properties, but also on the silicate substrates. PMID:16471802

  15. Preparation and characterization of a novel adsorbent from Moringa oleifera leaf

    NASA Astrophysics Data System (ADS)

    Bello, Olugbenga Solomon; Adegoke, Kayode Adesina; Akinyunni, Opeyemi Omowumi

    2015-10-01

    A new and novel adsorbent was obtained by impregnation of Moringa oleifera leaf in H2SO4 and NaOH, respectively. Prepared adsorbents were characterized using elemental analysis, FT-IR, SEM, TGA and EDX analyses, respectively. The effects of operational parameters, such as pH, moisture content, ash content, porosity and iodine number on these adsorbents were investigated and compared with those of commercial activated carbon (CAC). EDX results of acid activated M. oleifera leaf have the highest percentage of carbon by weight (69.40 %) and (76.11 %) by atom, respectively. Proximate analysis showed that the fixed carbon content of acid activated M. oleifera leaf (69.14 ± 0.01) was the highest of all adsorbents studied. Conclusively, the present investigation shows that acid activated M. oleifera leaf is a good alternative adsorbent that could be used in lieu of CAC for recovery of dyes and heavy metal from aqueous solutions and other separation techniques.

  16. Adsorption kinetics of diatomic molecules.

    PubMed

    Burde, Jared T; Calbi, M Mercedes

    2014-05-01

    The adsorption dynamics of diatomic molecules on solid surfaces is examined by using a Kinetic Monte Carlo algorithm. Equilibration times at increasing loadings are obtained, and explained based on the elementary processes that lead to the formation of the adsorbed film. The ability of the molecules to change their orientation accelerates the overall uptake and leads to competitive kinetic behaviour between the different orientations. The dependence of the equilibration time on coverage follows the same decreasing trend obtained experimentally for ethane adsorption on closed-end carbon nanotube bundles. The exploration of molecule-molecule interaction effects on this trend provides relevant insights to understand the kinetic behaviour of other species, from simpler molecules to larger polyatomic molecules, adsorbing on surfaces with different binding strength. PMID:24654004

  17. A fragment method for systematic improvement of anharmonic adsorbate vibrational frequencies: Acetylene on Cu(001)

    SciTech Connect

    Chulkov, Sergey K. Benoit, David M.

    2013-12-07

    We suggest a novel method for systematic improvement of anharmonic adsorbate frequencies based on a fragment approach. The calculations are carried out by considering the adsorbed molecule separately and computing an energy correction using high-level ab initio method in addition to a standard calculation of the whole adsorbed system using quantum mechanical techniques with periodic boundary conditions. We demonstrate its reliability for a C{sub 2}H{sub 2} molecule chemisorbed on a Cu(001) surface. We also show that the accuracy of the presented approach with a suitable description of the periodic surface depends mainly on the accuracy of the high-level ab initio method used to describe the adsorbate molecule. Moreover, our technique potentially allows to predict adsorbate vibrational spectra with spectroscopic accuracy.

  18. Investigation on removal of malachite green using EM based compost as adsorbent.

    PubMed

    Bhagavathi Pushpa, T; Vijayaraghavan, J; Sardhar Basha, S J; Sekaran, V; Vijayaraghavan, K; Jegan, J

    2015-08-01

    The discarded materials from different sources can be utilized as effective materials in wastewater remediation. This proposed study was aimed mainly to investigate the possibility of Effective Microorganisms based compost (EMKC), which is derived from the kitchen solid waste, as a non-conventional low cost adsorbent for the removal of malachite green from aqueous solution. Batch experiments were carried out to evaluate the optimum operating parameters like pH (2-9), initial dye concentration (50-1000mg/L), adsorbent particle size (0.6-2.36mm) and adsorbent dosage (2-12g/L). EMKC recorded maximum uptake of 136.6mg/g of MG at pH 8, initial dye concentration 1000mg/L, adsorbent particle size 1.18mm and adsorbent dosage 4g/L. Two and three parameter adsorption models were employed to describe experimental biosorption isotherm data. The results revealed that the Sips model resulted in better fit than other models. The pseudo-first and -second order models were applied to describe kinetic data, of which the pseudo-second order described experimental data better with high correlation coefficient. This investigation suggested that EMKC could be an effective and low cost material for the removal of malachite green dye from aqueous solution. PMID:25938698

  19. Single stage batch adsorber design for efficient Eosin yellow removal by polyaniline coated ligno-cellulose.

    PubMed

    Debnath, Sushanta; Ballav, Niladri; Maity, Arjun; Pillay, Kriveshini

    2015-01-01

    Polyaniline-coated lignin-based adsorbent (PLC) was synthesized and used for uptake of reactive dye eosin yellow (EY) from aqueous solution. The adsorption capability of the adsorbent was found to be more effective than the unmodified adsorbent (LC). In particular, the adsorption capability of the PLC was effective over a wider pH range. This could be owing to its higher point of zero charge, which is more favorable for the uptake of the anionic dye. Adsorption isotherm models suggested a monolayer adsorption was predominant. The mean free energy of adsorption (E(DR)) was found to have values between 8 and 16 kJ mol(-1) which suggests that an electrostatic mechanism of adsorption predominated over other underlying mechanisms. The adsorption process was also found to be spontaneous, with increasing negative free energy values observed at higher temperatures. Chemisorption process was supported by the changes in enthalpy above 40 kJ mol(-1) and by the results of desorption studies. This new adsorbent was also reusable and regenerable over four successive adsorption-desorption cycles. The single stage adsorber design revealed that PLC can be applicable as an effective biosorbent for the treatment of industrial effluents containing EY dye. PMID:25256550

  20. Halide anion effect on surface enhanced Raman scattering of 2-amino,5-nitropyridine adsorbed on silver sols

    NASA Astrophysics Data System (ADS)

    Muniz-Miranda, Maurizio; Neto, Natale; Sbrana, Giuseppe

    1995-03-01

    2-Amino,5-nitropiridine (ANP) can be adsorbed on silver sols as neutral molecule or ANP- anion, as detected by SERS. The adsorption of the ANP- is related to the presence of hydroxide ions on the metal surface. Strongly adsorbed halide anions are able to remove hydroxide ions from the silver surface, inducing the adsorption of ANP as neutral molecule.

  1. Selective adsorption and separation of organic dyes from aqueous solution on polydopamine microspheres.

    PubMed

    Fu, Jianwei; Xin, Qianqian; Wu, Xuechen; Chen, Zhonghui; Yan, Ya; Liu, Shujun; Wang, Minghuan; Xu, Qun

    2016-01-01

    Polydopamine (PDA) microspheres, synthesized by a facile oxidation polymerization route, were evaluated as a potential adsorbent for selective adsorption and separation of organic dyes. The adsorption processes towards nine water-soluble dyes (anionic dyes: methyl orange (MO), eosin-Y (EY), eosin-B (EB), acid chrome blue K (ACBK), neutral dye: neutral red (NR), and cationic dyes: rhodamine B (RhB), malachite green (MG), methylene blue (MB), safranine T (ST)) were thoroughly investigated. The adsorption selectivity of organic dyes onto PDA microspheres was successfully applied for the separation of dyes mixtures. Various influential factors such as solution pH, temperature, and contact time were employed to ascertain the optimal condition for adsorption of representative organic dyes including MB, MG and NR. The pseudo-first-order and pseudo-second-order kinetics models were used to fit the adsorption kinetics process. Five isothermal adsorption models (Langmuir, Dubnin-Radushkevich, Temkin, Freundlich and Harkins-Jura) were used to investigate the adsorption thermodynamics properties. The results showed that the PDA microspheres owned good selective adsorption ability towards cationic dyes. The adsorption kinetics process conformed to the pseudo-second-order kinetics model and the Langmuir isotherm model was more appropriate for tracing the adsorption behavior than other isotherm models. Thus, we can conclude PDA microspheres may be a high-efficiency selective adsorbent towards some cationic dyes. PMID:26407057

  2. ANALYSIS OF ANIONIC METALLIZED AZO AND FORMAZAN DYES BY CAPILLARY ELECTROPHORESIS/MASS SPECTROMETRY

    EPA Science Inventory

    Capillary electrophoresis-mass spectrometry was applied to the separation of several anionic dyes containing copper(II), chromium(III), or cobalt(III) as part of the dye molecule. The dyes were separated using a 110 cmX50 mu m uncoated fused-silica capillary and a 5 mM ammonium a...

  3. Dyes extracted from Trigonella seeds as photosensitizers for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Batniji, Amal; Abdel-Latif, Monzir S.; El-Agez, Taher M.; Taya, Sofyan A.; Ghamri, Hatem

    2016-06-01

    In this paper, the extract of Trigonella seeds was used as sensitizer for dye-sensitized solar cells (DSSCs). The natural dye was extracted from the seeds using water and alcohol as solvents for the raw material. The UV-Vis absorption spectra of Trigonella extract solution and dye adsorbed on TiO2 film were measured. DSSCs sensitized by Trigonella extracted using water as a solvent exhibited better performance with efficiency of 0.215 %. The performance of the fabricated DSSCs was attempted to enhance by acid treatment of the FTO substrates with HNO3, H3PO4, and H2SO4. Electrochemical impedance spectroscopy of the fabricated cells was also carried out.

  4. Magnetic nanopowder as effective adsorbent for the removal of Congo Red from aqueous solution.

    PubMed

    Paşka, O; Ianoş, R; Păcurariu, C; Brădeanu, A

    2014-01-01

    A magnetic iron oxide nanopowder (MnP), prepared by a simple and efficient combustion synthesis technique, was tested for the removal of the anionic dye Congo Red (CR) from aqueous solution. The influence of solution pH, adsorbent dose, temperature, contact time and initial dye concentration on the adsorption of CR onto MnP were investigated. It was shown that the CR adsorption was pH dependent and the adsorption mechanism was governed by electrostatic forces. The adsorption kinetic was best described by the pseudo-second-order model and the equilibrium data were well fitted to the Langmuir isotherm, yielding maximum adsorption capacity of 54.46 mg g(-1). The undeniable advantages of the MnP adsorbent such as inexpensive preparation method, good adsorption capacity and easy separation using an external magnetic field, recommend it as a promising candidate for the removal of anionic dyes from polluted water. PMID:24647189

  5. Removal of basic dye (Astrazon Blue FGRL) using macroalga Caulerpa lentillifera.

    PubMed

    Marungrueng, Khanidtha; Pavasant, Prasert

    2006-02-01

    The macroalga Caulerpa lentillifera was found to have adsorption capacity for a basic dye, Astrazon Blue FGRL. For the whole range of concentrations employed in this work (20-1280 mgl(-1)), the adsorption reached equilibrium within the first hour. The kinetic data corresponded well with the pseudo second-order kinetic model where the rate constants decreased as initial dye concentrations increased. At low dye concentrations (20-80 mgl(-1)), an increase in the adsorbent dosage resulted in a higher removal percentage of the dye, but a lower amount of dye adsorbed per unit mass (q). The adsorption isotherm followed both the Langmuir and Freundlich models within the temperature range employed in this work (18-70 degrees C). The highest maximum adsorption capacity (q(m)) was obtained at 50 degrees C. The enthalpy of adsorption was estimated at 14.87 kJmol(-1) suggesting a chemical adsorption mechanism. PMID:16112338

  6. Photobleaching effect in azo-dye containing epoxy resin films: the potentiality of carbon nanotubes as azo-dye dispensers

    NASA Astrophysics Data System (ADS)

    Díaz Costanzo, Guadalupe; Goyanes, Silvia; Ledesma, Silvia

    2015-04-01

    Azo-dye molecules may suffer from bleaching under certain illumination conditions. When this photoinduced process occurs, it generates an irreversible effect that is characterized by the loss of absorption of the dye molecule. Moreover, the well-known isomerization of azodye molecules does not occur anymore. In this work it is shown how the addition of a small amount of multi-walled carbon nanotubes (MWCNTs) helps to decrease the bleaching effect in a photosensitive guest-host azo-polymer film. Two different systems were fabricated using an epoxy resin as polymer matrix. An azo-dye, Disperse Orange 3, was used as photosensitive material in both systems and MWCNTs were added into one of them. The optical response of the polymeric systems was studied considering the degree of photoinduced birefringence. Photobleaching of the azo-dye was observed in all cases however, the effect is lower for the composite material containing 0.2 wt % MWCNTs. The weak interaction between MWCNTs and dye molecules is less favorable when the material is heated. The optical behavior of the heated composite material suggests that carbon nanotubes can be potentially used as azo dye dispensers. The results are interpreted in terms of the non-covalent interaction between azo-dye molecules and MWCNTs.

  7. Extension lifetime for dye-sensitized solar cells through multiple dye adsorption/desorption process

    NASA Astrophysics Data System (ADS)

    Chiang, Yi-Fang; Chen, Ruei-Tang; Shen, Po-Shen; Chen, Peter; Guo, Tzung-Fang

    2013-03-01

    In this study, we propose a novel concept of extending the lifetime of dye-sensitized solar cells (DSCs) and reducing the costs of re-conditioning DSCs by recycling the FTO/TiO2 substrates. The photovoltaic performances of DSCs using substrates with various cycles of dye uptake and rinse off history are tested. The results show that dye adsorption and Voc are significantly increased under multiple dye adsorption/desorption process and resulted in the improvement of power conversion efficiency. Moreover, the dyeing kinetics is faster after multiple recycling processes, which is favorable for the industrial application. With surface analysis and charge transport characteristics, we also demonstrate the optimal functionality of TiO2/dye interface for the improved Voc and efficiency. The results confirm that the improved performances are due to increased dye loading and dense packing of dye molecules. Our results are beneficial for the understanding on the extension of DSCs lifetime after long-term operation in the application of DSC modules. This approach may also be applied in the replacement of newly synthesized photosensitizes to the active cells.

  8. Process for separating and recovering an anionic dye from an aqueous solution

    DOEpatents

    Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

    1998-01-01

    A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

  9. Process for separating and recovering an anionic dye from an aqueous solution

    DOEpatents

    Rogers, R.; Horwitz, E.P.; Bond, A.H.

    1998-01-13

    A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution. 7 figs.

  10. Stimulated Raman scattering of laser dye mixtures dissolved in multiple scattering media

    SciTech Connect

    Yashchuk, V P; Komyshan, A O; Tikhonov, E A; Olkhovyk, L A

    2014-10-31

    Stimulated Raman scattering (SRS) of a mixture of rhodamine 6G and pyrromethene 605 laser dyes in vesicular films is studied. It is shown that a peculiar interaction of dyes occurs under conditions of multiple scattering of light from vesicles. This interaction manifests itself as SRS excitation of one of the dyes by random lasing of the other dye, provided that the random lasing spectrum overlaps the Stokes lines of the first dye. In addition, there is energy transfer between molecules of these dyes if their luminescence and absorption spectra overlap. The results obtained confirm that the mechanism of SRS from laser dyes in multiple scattering media is similar to that in coherent-active Raman spectroscopy. These results extend the possibility of determining the vibrational spectrum of dye molecules from their secondary radiation in these media. (nonlinear optical phenomena)

  11. Adsorption kinetics and isotherm of anionic dyes onto organo-bentonite from single and multisolute systems.

    PubMed

    Shen, Dazhong; Fan, Jianxin; Zhou, Weizhi; Gao, Baoyu; Yue, Qinyan; Kang, Qi

    2009-12-15

    The performances of polydiallydimethylammonium modified bentonite (PDADMA-bentonite) as an adsorbent to remove anionic dyes, namely Acid Scarlet GR (AS-GR), Acid Turquoise Blue 2G (ATB-2G) and Indigo Carmine (IC), were investigated in single, binary and ternary dye systems. In adsorption from single dye solutions with initial concentration of 100 micromol/L, the dosage of PDADMA-bentonite needed to remove 95% dye was 0.42, 0.68 and 0.75 g/L for AS-GR, ATB-2G and IC, respectively. The adsorption isotherms of the three dyes obeyed the Langmuir isotherm model with the equilibrium constants of 0.372, 0.629 and 4.31 L/micromol, the saturation adsorption amount of 176.3, 149.2 and 228.7 micromol/g for ATB-2G, IC and AS-GR, respectively. In adsorption from mixed dye solutions, the isotherm of each individual dye followed an expanded Langmuir isotherm model and the relationship between the total amount of dyes adsorbed and the total equilibrium dye concentration was interpreted well by Langmuir isotherm model. In the region of insufficient dosage of PDADMA-bentonite, the dye with a larger affinity was preferentially removed by adsorption. Desorption was observed in the kinetic curve of the dye with lower affinity on PDADMA-bentonite surface by the competitive adsorption. The kinetics in single dye solution and the total adsorption of dyes in binary and ternary dye systems nicely followed pseudo-second-order kinetic model. PMID:19631461

  12. Adsorption of organic molecules on silica surface.

    PubMed

    Parida, Sudam K; Dash, Sukalyan; Patel, Sabita; Mishra, B K

    2006-09-13

    The adsorption behaviour of various organic adsorbates on silica surface is reviewed. Most of the structural information on silica is obtained from IR spectral data and from the characteristics of water present at the silica surface. Silica surface is generally embedded with hydroxy groups and ethereal linkages, and hence considered to have a negative charged surface prone to adsorption of electron deficient species. Adsorption isotherms of the adsorbates delineate the nature of binding of the adsorbate with silica. Aromatic compounds are found to involve the pi-cloud in hydrogen bonding with silanol OH group during adsorption. Cationic and nonionic surfactants adsorb on silica surface involving hydrogen bonding. Sometimes, a polar part of the surfactants also contributes to the adsorption process. Styryl pyridinium dyes are found to anchor on silica surface in flat-on position. On modification of the silica by treating with alkali, the adsorption behaviour of cationic surfactant or polyethylene glycol changes due to change in the characteristics of silica or modified silica surface. In case of PEG-modified silica, adsolubilization of the adsorbate is observed. By using a modified adsorption equation, hemimicellization is proposed for these dyes. Adsorptions of some natural macromolecules like proteins and nucleic acids are investigated to study the hydrophobic and hydrophilic binding sites of silica. Artificial macromolecules like synthetic polymers are found to be adsorbed on silica surface due to the interaction of the multifunctional groups of the polymers with silanols. Preferential adsorption of polar adsorbates is observed in case of adsorbate mixtures. When surfactant mixtures are considered to study competitive adsorption on silica surface, critical micelle concentration of individual surfactant also contributes to the adsorption isotherm. The structural study of adsorbed surface and the thermodynamics of adsorption are given some importance in this review

  13. Adsorption and surface-enhanced Raman of dyes on silver and gold sols

    SciTech Connect

    Lee, P.C.; Meisel, D.

    1982-08-19

    Several negatively charged dyes were investigated for their possible adsorption on the surface of silver and gold colloidal particles. Those dyes that were found to adsorb on the particles were then checked for surface enhancement of Raman scattering. Highly efficient surface-enhanced Raman scattering (SERS) was observed from a carbocyanine dye in both sols. Excitation-dependence studies as well as adsorption studies confirm the SERS nature of the Raman spectra obtained. The dye is probably aggregated on adsorption and is probably attached through the naphthalene side moiety to the surface. Less efficient SERS was also observed for copper phthalocyanine.

  14. Diffusion of dye solution in the intermolecular nanostructure of polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Nishimura, Tatsuya; Sakiyama, Kohei; Nakagawa, Michinori

    2012-09-01

    Polydimethylsiloxane (PDMS) contains a large, flexible free space between weakly-bonded molecules, which allows notable molecular diffusion. A toluene solution of diarylethene (photochromic dye) was mixed with a PDMS oil, and then the mixture was cured in a glass vessel by adding a curing agent. Violet laser (405 nm wavelength) irradiation induced an absorption band at around 530 nm, and consequently, the irradiated portion exhibited a red color. The colored portion gradually expanded to the entire sample because of diffusion of the dye molecules. This diffusion characteristic was used for improving an organic dye durability against a photo-induced degradation.

  15. Sorption of methylene blue on treated agricultural adsorbents: equilibrium and kinetic studies

    NASA Astrophysics Data System (ADS)

    Tiwari, D. P.; Singh, S. K.; Sharma, Neetu

    2015-03-01

    Agricultural adsorbents are reported to have a remarkable performance for adsorption of dyes. In the present study, formaldehyde and sulphuric acid treated two agricultural adsorbents; potato peel and neem bark are used to adsorb methylene blue. On the whole, the acid-treated adsorbents are investigated to have high sorption efficiency compared to HCHO treated adsorbents. The percentage removal efficiency of H2SO4 treated potato peel (APP) increases considerably high from 75 to 100 % with increase in adsorbent dose, whereas the removal efficiency of H2SO4 treated neem bark (ANB) is found to be 98 % after adding the first dose only. The monolayer sorption behaviour of HCHO treated potato peel (PP) and APP is well defined by Langmuir, whereas the chemisorptions behaviour of HCHO treated neem bark (NB) and ANB is suggested by Temkin's isotherm model. The maximum adsorption capacity measured is highest in ANB followed by NB, PP and APP with the values of 1000, 90, 47.62 and 40.0 mg/g, respectively. The pseudo-second-order kinetic model fitted well with the observed data of all the four adsorbents. The results obtained reveal that NB and ANB both are good adsorbents compared to PP and APP.

  16. Experimental and Computational Studies on the Design of Dyes for Water-splitting Dye-sensitized Photoelectrochemical Tandem Cells

    NASA Astrophysics Data System (ADS)

    Mendez-Hernandez, Dalvin D.

    Solar energy is a promising alternative for addressing the world's current and future energy requirements in a sustainable way. Because solar irradiation is intermittent, it is necessary to store this energy in the form of a fuel so it can be used when required. The light-driven splitting of water into oxygen and hydrogen (a useful chemical fuel) is a fascinating theoretical and experimental challenge that is worth pursuing because the advance of the knowledge that it implies and the availability of water and sunlight. Inspired by natural photosynthesis and building on previous work from our laboratory, this dissertation focuses on the development of water-splitting dye-sensitized photoelectrochemical tandem cells (WSDSPETCs). The design, synthesis, and characterization of high-potential porphyrins and metal-free phthalocyanines with phosphonic anchoring groups are reported. Photocurrents measured for WSDSPETCs made with some of these dyes co-adsorbed with molecular or colloidal catalysts on TiO2 electrodes are reported as well. To guide in the design of new molecules we have used computational quantum chemistry extensively. Linear correlations between calculated frontier molecular orbital energies and redox potentials were built and tested at multiple levels of theory (from semi-empirical methods to density functional theory). Strong correlations (with r2 values > 0.99) with very good predictive abilities (rmsd < 50 mV) were found when using density functional theory (DFT) combined with a continuum solvent model. DFT was also used to aid in the elucidation of the mechanism of the thermal relaxation observed for the charge-separated state of a molecular triad that mimics the photo-induced proton coupled electron transfer of the tyrosine-histidine redox relay in the reaction center of Photosystem II. It was found that the inclusion of explicit solvent molecules, hydrogen bonded to specific sites within the molecular triad, was essential to explain the observed

  17. Removal of Direct Red 12B by garlic peel as a cheap adsorbent: Kinetics, thermodynamic and equilibrium isotherms study of removal

    NASA Astrophysics Data System (ADS)

    Asfaram, A.; Fathi, M. R.; Khodadoust, S.; Naraki, M.

    2014-06-01

    The removal of dyes from industrial waste is very important from health and hygiene point of view and for environmental protection. In this work, efficiency and performance of garlic peel (GP) adsorbent for the removal of Direct Red 12B (DR12B) from wastewater was investigated. The influence of variables including pH, concentration of the dye and amount of adsorbent, particle size, contact time and temperature on the dye removal has been investigated. It was observed that the pseudo-second-order kinetic model fits better with good correlation coefficient and the equilibrium data fitted well with the Langmuir model. More than 99% removal efficiency was obtained within 25 min at adsorbent dose of 0.2 g per 50 ml for initial dye concentration of 50 mg L-1. Calculation of various thermodynamic parameters such as, Gibb's free energy, entropy and enthalpy of the on-going adsorption process indicate feasibility and endothermic nature of DR12B adsorption.

  18. Adsorption of phenol and reactive dye from aqueous solution on activated carbons derived from solid wastes.

    PubMed

    Nakagawa, Kyuya; Namba, Akio; Mukai, Shin R; Tamon, Hajime; Ariyadejwanich, Pisit; Tanthapanichakoon, Wiwut

    2004-04-01

    Activated carbons were produced from several solid wastes, namely, waste PET, waste tires, refuse derived fuel and wastes generated during lactic acid fermentation from garbage. Activated carbons having various pore size distributions were obtained by the conventional steam-activation method and via the pre-treatment method (i.e., mixture of raw materials with a metal salt, carbonization and acid treatment prior to steam-activation) that was proposed by the authors. The liquid-phase adsorption characteristics of organic compounds from aqueous solution on the activated carbons were determined to confirm the applicability of these carbons, where phenol and a reactive dye, Black5, were employed as representative adsorbates. The hydrophobic surface of the carbons prepared was also confirmed by water vapor adsorption. The characteristics of a typical commercial activated carbon were also measured and compared. It was found that the activated carbons with plentiful mesopores prepared from PET and waste tires had quite high adsorption capacity for large molecules. Therefore they are useful for wastewater treatment, especially, for removal of bulky adsorbates. PMID:15026233

  19. Structural systematic features of photoelectric effect in aromatic polymers with polymethine dyes

    SciTech Connect

    Aleksandrova, E. L.

    2007-12-15

    The structural systematic features of quantum-yield variation in charge-carrier photogeneration are investigated for polymer systems with molecules into which polymethine dyes of various structures had been introduced. The correlations between the quantum yields and the second-harmonic-generation efficiency in the media containing such dyes are revealed, and relations of the quantum yields to such dye-molecule structural parameters as the ionization potential of its donor fragment, the electron affinity of its acceptor fragment, and the electron-transfer distance between donor and acceptor fragments of the dye molecule are established.

  20. Laser dye stability

    NASA Astrophysics Data System (ADS)

    Fletcher, N.

    1980-06-01

    Lasing characteristics and bleaching of four Eastman Kodak ir dyes have been examined in dimethyl sulfoxide. These ir dyes are shown to improve in performance in the absence of oxygen. Their photochemical stability was found to be comparable to the quinolone laser dyes when exposed to flashlamp excitation. Photodecomposition of the ir dyes under lasing conditions was found to vary between 1.6 and 6×10-10 moles of dye for each joule (electrical) of input energy; in comparison, the photodecomposition values for the better coumarin dyes was 0.2 to 1.0×10-10 moles/J at a concentration of 1.0×10-4 M in ethanol. It was also found that increasing the concentration of these tricarbocyanine dyes gives a marked improvement in the useful lifetime of these solutions as lasing media in the absence of oxygen.

  1. Optical Properties of Rhodamine 6G Laser Dye and Ag-Nanoparticle Aggregates

    NASA Astrophysics Data System (ADS)

    Noginov, M. A.; Drachev, V. P.

    2005-03-01

    Optical absorption and luminescence spectra of Rhodamine 6G (Rh6G) laser dye of different concentration with a solution of aggregated silver nanoparticles are studied. New emission band located near 610 nm is found at very high concentration of Rh6G and/or in a solution of Rh6G and Ag nanoparticles. Electron energy structure and optical functions of single Rh6G molecules, molecular complexes, and Rh6G molecules adsorbed on Ag(111) surface are studied by generalized gradient approximation method within density functional theory using ab initio pseudopotentials. Equilibrium geometries of the systems studied are obtained from both molecular dynamics simulations and X-ray diffraction measurements. Electronic structure of J-type molecular complexes (when two molecules aligned along their dipole moment axes) substantially differs from that of H-type aggregates (with parallel and anti-parallel molecular dipole moments). It is demonstrated that new luminescence line is associated with J-type molecular complexes. Observed modifications of optical properties of Rh6G and Rh6G+Ag complexes are explained in terms of both the changes of electronic structure of the systems and due to the electromagnetic interactions of dipole-dipole and dipole-surface types.

  2. Ultrasonic dyeing of cellulose nanofibers.

    PubMed

    Khatri, Muzamil; Ahmed, Farooq; Jatoi, Abdul Wahab; Mahar, Rasool Bux; Khatri, Zeeshan; Kim, Ick Soo

    2016-07-01

    Textile dyeing assisted by ultrasonic energy has attained a greater interest in recent years. We report ultrasonic dyeing of nanofibers for the very first time. We chose cellulose nanofibers and dyed with two reactive dyes, CI reactive black 5 and CI reactive red 195. The cellulose nanofibers were prepared by electrospinning of cellulose acetate (CA) followed by deacetylation. The FTIR results confirmed complete conversion of CA into cellulose nanofibers. Dyeing parameters optimized were dyeing temperature, dyeing time and dye concentrations for each class of the dye used. Results revealed that the ultrasonic dyeing produced higher color yield (K/S values) than the conventional dyeing. The color fastness test results depicted good dye fixation. SEM analysis evidenced that ultrasonic energy during dyeing do not affect surface morphology of nanofibers. The results conclude successful dyeing of cellulose nanofibers using ultrasonic energy with better color yield and color fastness results than conventional dyeing. PMID:26964959

  3. Abatement of Azo Dye from Wastewater Using Bimetal-Chitosan

    PubMed Central

    Asgari, Ghorban; Farjadfard, Sima

    2013-01-01

    We introduce a new adsorbent, bimetallic chitosan particle (BCP) that is successfully synthesized and applied to remove the orange II dye from wastewater. The effects of pH, BCP quantity, and contact time are initially verified on the basis of the percentage of orange II removed from the wastewater. Experimental data reveal that the Cu/Mg bimetal and chitosan have a synergistic effect on the adsorption process of the adsorbate, where the dye adsorption by Cu/Mg bimetal, chitosan alone, and bimetal-chitosan is 10, 49, and 99.5%, respectively. The time required for the complete decolorization of orange II by 1 mg/L of BCP is 10 min. The Langmuir model is the best fit for the experimental data, which attains a maximum adsorption capacity of 384.6 mg/g. The consideration of the kinetic behavior indicates that the adsorption of orange II onto the BCP fits best with the pseudo-second-order and Elovich models. Further, the simulated azo dye wastewater can be effectively treated using a relatively low quantity of the adsorbent, 1 mg/L, within a short reaction time of 20 min. Overall, the use of BCP can be considered a promising method for eliminating the azo dye from wastewater effectively. PMID:24348163

  4. Adsorbed water and CO on Pt electrode modified with Ru

    NASA Astrophysics Data System (ADS)

    Futamata, Masayuki; Luo, Liqiang

    Highly sensitive ATR-SEIRA spectroscopy was exploited to elucidate water, CO and electrolyte anions adsorbed on the Ru modified Pt film electrode. CO on Ru domains was oxidized below ca. +0.3 V, followed by pronounced water adsorption. Since the oxidation potential of CO on Pt domain was significantly reduced compared to bare Pt, these water molecules on Ru obviously prompt CO oxidation on adjacent Pt surface as consistent with the bifunctional mechanism. Diffusion of adsorbate from Ru to Pt surfaces was indicated in dilute CH 3OH solution by spectral changes with potential.

  5. Ruthenium phthalocyanine-bipyridyl dyads as sensitizers for dye-sensitized solar cells: dye coverage versus molecular efficiency.

    PubMed

    Rawling, Tristan; Austin, Christine; Buchholz, Florian; Colbran, Stephen B; McDonagh, Andrew M

    2009-04-01

    The application of ruthenium phthalocyanine complexes as sensitizing dyes in dye-sensitized solar cells (DSCs) is explored. Four monomeric complexes are reported which vary in peripheral substitution and axial ligand anchoring groups. Sensitizing dyes containing two ruthenium centers are also presented. These dyads, which contain ruthenium phthalocyanine and bipyridyl chromophores, were prepared using a protection/deprotection strategy that allows for convenient purification. DSCs fabricated using the phthalocyanine complexes and dyads were less efficient than those incorporating a standard DSC dye. However, on the basis of the number of molecules bound to the TiO(2) electrode surfaces, several of the new complexes were more efficient at photocurrent generation. The results highlight the importance of molecular size, and thus the dye coverage of the electrode surface in the design of new sensitizing dyes. PMID:19278209

  6. Isolation of colour components from native dye-bearing plants in northeastern India.

    PubMed

    Bhuyan, Ranjana; Saikia, C N

    2005-02-01

    Recently dyes derived from natural sources have emerged as important alternatives to synthetic dyes. A study was initiated in the year 2000 at the RRL (CSIR), Jorhat to extract dyes from parts of five different plant species indigenous to northeastern India. The colour components responsible for dyeing were isolated and their chemical constituents were established based on chemical and spectroscopic investigations. The principal colour components from the species Morinda angustifolia Roxb., Rubia cordifolia Linn. and Tectona grandis Linn. were found to contain mainly anthraquinone moieties in their molecules. Those from the species Mimusops elengi Linn. and Terminalia arjuna (Roxb.) Wight & Arn. contained flavonoid moieties in their molecules. The absorption of dye (%) on fibres increased with increasing concentrations of dye in the dye-bath. Maximum absorption of dyes on fibres was obtained at 3% concentration of dyes obtained from R. cordfolia (35.350%), M. angustifolia (31.580%) and T. grandis (25.888%) and at 4% concentration of the dyes from M. elengi (31.917%) and T. arjuna (12.246%). The K/S values were found to increase with the increase in concentration of mordants. The colour co-ordinates of dyed samples were found to lie in the yellow-red quadrant of the colour space diagram. The dyes obtained from the native plants may be alternative sources to synthetic dyes for the dyeing of natural silk and cotton. PMID:15474939

  7. Microwave assisted thermal treatment of defective coffee beans press cake for the production of adsorbents.

    PubMed

    Franca, Adriana S; Oliveira, Leandro S; Nunes, Anne A; Alves, Cibele C O

    2010-02-01

    Defective coffee press cake, a residue from coffee oil biodiesel production, was evaluated as an adsorbent for removal of basic dyes (methylene blue--MB) from aqueous solutions. The adsorbent was prepared by microwave treatment, providing a significant reduction in processing time coupled to an increase in adsorption capacity in comparison to conventional carbonization in a muffle furnace. Batch adsorption tests were performed at 25 degrees C and the effects of particle size, contact time, adsorbent dosage and initial solution pH were investigated. Adsorption kinetics was better described by a second-order model. The experimental adsorption equilibrium data were fitted to Langmuir, Freundlich and Tempkin adsorption models, with Langmuir providing the best fit. The results presented in this study show that microwave activation presents great potential as an alternative method in the production of adsorbents. PMID:19767204

  8. Microcolumn studies of dye adsorption onto manganese oxides modified diatomite.

    PubMed

    Al-Ghouti, M A; Khraisheh, M A M; Ahmad, M N; Allen, S J

    2007-07-19

    The method described here cannot fully replace the analysis of large columns by small test columns (microcolumns). The procedure, however, is suitable for speeding up the determination of adsorption parameters of dye onto the adsorbent and for speeding up the initial screening of a large adsorbent collection that can be tedious if a several adsorbents and adsorption conditions must be tested. The performance of methylene blue (MB), a basic dye, Cibacron reactive black (RB) and Cibacron reactive yellow (RY) was predicted in this way and the influence of initial dye concentration and other adsorption conditions on the adsorption behaviour were demonstrated. On the basis of the experimental results, it can be concluded that the adsorption of RY onto manganese oxides modified diatomite (MOMD) exhibited a characteristic "S" shape and can be simulated effectively by the Thomas model. It is shown that the adsorption capacity increased as the initial dye concentration increased. The increase in the dye uptake capacity with the increase of the adsorbent mass in the column was due to the increase in the surface area of adsorbent, which provided more binding sites for the adsorption. It is shown that the use of high flow rates reduced the time that RY in the solution is in contact with the MOMD, thus allowing less time for adsorption to occur, leading to an early breakthrough of RY. A rapid decrease in the column adsorption capacity with an increase in particle size with an average 56% reduction in capacity resulting from an increase in the particle size from 106-250 microm to 250-500 microm. The experimental data correlated well with calculated data using the Thomas equation and the bed depth-service time (BDST) equation. Therefore, it might be concluded that the Thomas equation and the BDST equations can produce accurate predication for variation of dye concentration, mass of the adsorbent, flow rate and particle size. In general, the values of adsorption isotherm capacity

  9. Chemisorption on surfaces — an historical look at a representative adsorbate: carbon monoxide

    NASA Astrophysics Data System (ADS)

    Yates, John T.

    1994-01-01

    The study of the interaction of molecules with clean surfaces extends back to the work of Irving Langmuir. In this historical account, the development of selected experimental methods for the study of molecular adsorption will be discussed. This will be done by historically reviewing research on one of the most well-studied adsorbate molecules, carbon monoxide. Many of the modern surface science techniques have first been used to study chemisorbed carbon monoxide, and the CO molecule is employed even today as a test molecule for currently developing surface measurement instruments such as the low temperature STM. In addition to being a good test molecule for new surface measurement techniques, adsorbed carbon monoxide is one of the centrally important molecules in the field of heterogeneous catalysis where the production of synthetic fuels and useful organic molecules often depends on the catalytic behavior of the adsorbed CO molecule. Interestingly, the carbon monoxide molecule also serves as a bridge between surface chemistry on the transition metals and the field of organometallic chemistry. Concepts about the chemical bonding and the reactive behavior of CO chemisorbed on transition metal surfaces and CO bound in transition metal carbonyls link these two fields together in a significant manner. The carbon monoxide molecule has been the historical focal point of many endeavors in surface chemistry and surface physics, and research on adsorbed carbon monoxide well represents many of the key advances which characterize the first thirty years of the development of surface science.

  10. Polymer composites containing photochromic dye solution

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Sakiyama, Kohei; Mochizuki, Ryosuke; Ohashi, Kenji

    2010-05-01

    Photochromic polymer composites were fabricated by encapsulating dye solution in a polycarbonate membrane. The membrane contained through holes of 50 nm diameter. These nanoholes provided a sufficient free volume for the dye molecules to change their structure in the photochromic isomerization process. A polymer composite containing a toluene solution of diarylethene exhibited red color when it was irradiated with violet laser, and returned to the transparent state by green laser irradiation. Another polymer composite containing spiropyran turned to blue by ultraviolet lamp irradiation and returned to the transparent state by green laser irradiation. A nonlinear input-output characteristic and a rewritable-grating function were demonstrated by using these photochromic polymers.

  11. Bioaccumulation of Cu-complex reactive dye by growing pellets of Penicillium oxalicum and its mechanism.

    PubMed

    Xin, Baoping; Chen, Gang; Zheng, Wenchai

    2010-06-01

    In this paper bioaccumulation of Cu-complex reactive dye by growing pellets of Penicillium oxalicum and its mechanism was investigated. Shaking flasks experiment showed that 99.7% of dye removal at 400 mg/l was attained after 48 h contact. Column reactor experiment showed that air lift ferment tower was a suitable reactor for both pellets formation and dye bioaccumulation. Repeated inoculation of the dye-loaded pellets accelerated dye bioaccumulation, leading to complete dye removal within 12 h. Dye initially was adsorbed on surface of cell, followed by penetration into cytoplasm. During bioaccumulation, mycelium expanded unevenly and thickened locally in diameter, generating a chain of spindles along the mycelium. In addition, the cell walls grew loose and thickened remarkably, being 4-5 folds as thick as the control one. The loose cell wall may offer both dye accumulation space and route way for dye to enter cytoplasm. There were certain unknown active matters in cytoplasm, which played an important role in dye accumulation. Desorption experiments suggested that electrostatic attraction was mainly attributed to the dye bioaccumulation. PMID:20421123

  12. A slowing down of proton motion from HPTS to water adsorbed on the MCM-41 surface.

    PubMed

    Alarcos, Noemí; Cohen, Boiko; Douhal, Abderrazzak

    2016-01-28

    We report on the steady-state and femtosecond-nanosecond (fs-ns) behaviour of 8-hydroxypyrene-1,3,6-trisulfonate (pyranine, HPTS) and its interaction with mesoporous silica based materials (MCM-41) in both solid-state and dichloromethane (DCM) suspensions in the absence and presence of water. In the absence of water, HPTS forms aggregates which are characterized by a broad emission spectrum and multiexponential behavior (τsolid-state/DCM = 120 ps, 600 ps, 2.2 ns). Upon interaction with MCM41, the aggregate population is found to be lower, leading to the formation of adsorbed monomers. In the presence of water (1%), HPTS with and without MCM41 materials in DCM suspensions undergoes an excited-state intermolecular proton-transfer (ESPT) reaction in the protonated form (ROH*) producing a deprotonated species (RO(-)*). The long-time emission decays of the ROH* in different systems in the presence of water are multiexponential, and are analysed using the diffusion-assisted geminate recombination model. The obtained proton-transfer and recombination rate constants for HPTS and HPTS/MCM41 complexes in DCM suspensions in the presence of water are kPT = 13 ns(-1), krec = 7.5 Å ns(-1), and kPT = 5.4 ns(-1), krec = 2.2 Å ns(-1), respectively, The slowing down of both processes in the latter case is explained in terms of specific interactions of the dye and of the water molecules with the silica surface. The ultrafast dynamics (fs-regime) of the HPTS/MCM41 complexes in DCM suspensions, without and with water, shows two components which are assigned to intramolecular vibrational-energy relaxation (IVR) (∼120 fs vs. ∼0.8 ps), and vibrational relaxation/cooling (VC), and charge transfer (CT) processes (∼2 ps without water and ∼5 ps with water) of the adsorbed ROH*. Our results provide new knowledge on the interactions and the proton-transfer reaction dynamics of HPTS adsorbed on mesoporous materials. PMID:26705542

  13. Experimental data for synthesis of bi-metalized chitosan particle for attenuating of an azo dye from wastewater

    PubMed Central

    Hajivandi, Abdollah; Farjadfard, Sima; Ramavandi, Bahman; Akbarzadeh, Samad

    2016-01-01

    In this data article, we introduce data acquired from new adsorbent, bi-metalized chitosan particle that is successfully synthesized and applied to remove the orange II dye, an azo dye, from textile wastewater. The adsorbent was meso- and macro-porous material with BET surface area of 12.69 m2/g and pHzpc 6.6. The simulated textile-wastewater can be significantly treated using a relatively low quantity of the adsorbent. Overall, the use of bi-metalized chitosan particle can be considered a promising method for eliminating the azo dye from wastewater effectively. Accordingly, these data will be useful for decolorizing of azo dyes from textile wastewater. PMID:26955651

  14. Quince seed mucilage magnetic nanocomposites as novel bioadsorbents for efficient removal of cationic dyes from aqueous solutions.

    PubMed

    Hosseinzadeh, Hossein; Mohammadi, Sina

    2015-12-10

    This study investigated the potential use of quince seed mucilage (QSM) as alternative bioadsorbents for methylene blue (MB) dye from aqueous solutions. This novel magnetic nanocomposite adsorbent (MNCA) based on QSM was synthesized by in situ formation of magnetic iron oxide nanoparticles into QSM solution. The MNCAs were characterized using FTIR, SEM, TEM, XRD, and VSM. Removal of MB was investigated by batch adsorption technique. The thermodynamic parameters suggest that the dye adsorption process is spontaneous and exothermic in nature. Moreover, the adsorbents showed high selectivity for the adsorption of cationic dyes with regenerated properties. The pseudo-second-order kinetics and Langmuir adsorption isotherm models also provide the best correlation of the experimental data for MB adsorption. The results indicate that the MNCAs can be employed as efficient low cost adsorbents with excellent dye adsorption performance in wastewater treatment process. PMID:26428118

  15. Experimental data for synthesis of bi-metalized chitosan particle for attenuating of an azo dye from wastewater.

    PubMed

    Hajivandi, Abdollah; Farjadfard, Sima; Ramavandi, Bahman; Akbarzadeh, Samad

    2016-06-01

    In this data article, we introduce data acquired from new adsorbent, bi-metalized chitosan particle that is successfully synthesized and applied to remove the orange II dye, an azo dye, from textile wastewater. The adsorbent was meso- and macro-porous material with BET surface area of 12.69 m(2)/g and pHzpc 6.6. The simulated textile-wastewater can be significantly treated using a relatively low quantity of the adsorbent. Overall, the use of bi-metalized chitosan particle can be considered a promising method for eliminating the azo dye from wastewater effectively. Accordingly, these data will be useful for decolorizing of azo dyes from textile wastewater. PMID:26955651

  16. Rapid dye adsorption via surface modification of TiO2 photoanodes for dye-sensitized solar cells.

    PubMed

    Kim, Boeun; Park, Se Woong; Kim, Jae-Yup; Yoo, Kicheon; Lee, Jin Ah; Lee, Min-Woo; Lee, Doh-Kwon; Kim, Jin Young; Kim, BongSoo; Kim, Honggon; Han, Sunghwan; Son, Hae Jung; Ko, Min Jae

    2013-06-12

    A facile method for increasing the reaction rate of dye adsorption, which is the most time-consuming step in the production of dye-sensitized solar cells (DSSCs), was developed. Treatment of a TiO2 photoanode with aqueous nitric acid solution (pH 1) remarkably reduced the reaction time required to anchor a carboxylate anion of the dye onto the TiO2 nanoparticle surface. After optimization of the reaction conditions, the dye adsorption process became 18 times faster than that of the conventional adsorption method. We studied the influence of the nitric acid treatment on the properties of TiO2 nanostructures, binding modes of the dye, and adsorption kinetics, and found that the reaction rate improved via the synergistic effects of the following: (1) electrostatic attraction between the positively charged TiO2 surface and ruthenium anion increases the collision frequency between the adsorbent and the anchoring group of the dye; (2) the weak anchoring affinity of NO3(-) in nitric acid with metal oxides enables the rapid coordination of an anionic dye with the metal oxide; and (3) sufficient acidity of the nitric acid solution effectively increases the positive charge density on the TiO2 surface without degrading or transforming the TiO2 nanostructure. These results demonstrate the developed method is effective for reducing the overall fabrication time without sacrificing the performance and long-term stability of DSSCs. PMID:23679678

  17. Adsorption and kinetic studies of seven different organic dyes onto magnetite nanoparticles loaded tea waste and removal of them from wastewater samples.

    PubMed

    Madrakian, Tayyebeh; Afkhami, Abbas; Ahmadi, Mazaher

    2012-12-01

    Adsorption of seven different organic dyes from aqueous solutions onto magnetite nanoparticles loaded tea waste (MNLTW) was studied. MNLTW was prepared via a simple method and was fully characterized. The properties of this magnetic adsorbent were characterized by scanning electron microscopy and X-ray diffraction. Adsorption characteristics of the MNLTW adsorbent was examined using Janus green, methylene blue, thionine, crystal violet, Congo red, neutral red and reactive blue 19 as adsorbates. Dyes adsorption process was thoroughly studied from both kinetic and equilibrium points of view for all adsorbents. The experimental isotherm data were analyzed using Langmuir, Freundlich, Sips, Redlich-Peterson, Brouers-Sotolongo and Temkin isotherms. The results from Langmuir isotherm indicated that the capacity of MNLTW for the adsorption of cationic dyes was higher than that for anionic dyes. The adsorption kinetics was tested for the pseudo-first order and pseudo-second order kinetic models at different experimental conditions. PMID:23058993

  18. Adsorption and kinetic studies of seven different organic dyes onto magnetite nanoparticles loaded tea waste and removal of them from wastewater samples

    NASA Astrophysics Data System (ADS)

    Madrakian, Tayyebeh; Afkhami, Abbas; Ahmadi, Mazaher

    2012-12-01

    Adsorption of seven different organic dyes from aqueous solutions onto magnetite nanoparticles loaded tea waste (MNLTW) was studied. MNLTW was prepared via a simple method and was fully characterized. The properties of this magnetic adsorbent were characterized by scanning electron microscopy and X-ray diffraction. Adsorption characteristics of the MNLTW adsorbent was examined using Janus green, methylene blue, thionine, crystal violet, Congo red, neutral red and reactive blue 19 as adsorbates. Dyes adsorption process was thoroughly studied from both kinetic and equilibrium points of view for all adsorbents. The experimental isotherm data were analyzed using Langmuir, Freundlich, Sips, Redlich-Peterson, Brouers-Sotolongo and Temkin isotherms. The results from Langmuir isotherm indicated that the capacity of MNLTW for the adsorption of cationic dyes was higher than that for anionic dyes. The adsorption kinetics was tested for the pseudo-first order and pseudo-second order kinetic models at different experimental conditions.

  19. Chitosan, nanoclay and chitosan-nanoclay composite as adsorbents for Rhodamine-6G and the resulting optical properties.

    PubMed

    Vanamudan, Ageetha; Pamidimukkala, Padmaja

    2015-03-01

    The objective of this study was to investigate the use of chitosan-clay nanocomposite (CC) as an adsorbent for Rhodamine 6G (Rh-6G). The effects of adsorbent dose, contact time, and concentration on the adsorption process were systematically studied. Isotherm models were applied to the experimental equilibrium data obtained from spectrophotometric measurements of dye adsorption. Various Kinetic models were used to describe the kinetic data and evaluate of rate constants. Rh-6G loaded adsorbents were investigated for their optical and photophysical properties. PMID:25526692

  20. Comparison of color removal from reactive dye contaminated water by systems containing fungal biosorbent, active carbon and their mixture.

    PubMed

    Gül, Ulküye Dudu; Silah, Hülya

    2014-01-01

    The adsorption of Everzol Black (EB) from synthetic aqueous solution onto active carbon (AC) and dried fungal biosorbent (Rhizopus arrhizus) was studied under the same experimental conditions. The effects of initial dye concentration, adsorbent dosage and contact time were examined at a batch-scale level. As an alternative to AC, fungus was investigated as a low-cost adsorbent for dye removal. The amount of EB adsorbed onto AC was lower compared with fungal biosorbent; dye adsorption capacity of AC and fungal biosorbent were 94.48 and 106.61 mg/g, respectively. The adsorbent dosage experiments showed that 4 g/L biosorbent removed 100% of EB (Co: 114.39 mg/L) after 2 hours. The results obtained from this study showed that biosorbent effectively removed reactive dye from dye-containing water in a short time period. Langmuir and Freundlich adsorption isotherm models were used for mathematical description of the biosorption equilibrium data; the Freundlich model was found to exhibit good fits to the experimental data. According to the Freundlich isotherm, the maximum dye adsorption capacities of AC and biosorbent were calculated as 344.82 and 357.14 mg/g, respectively. The Fourier transform infrared spectroscopy spectral analysis showed the involvement of functional groups for dye bindings. PMID:25325540

  1. Photodecomposition of chloromethanes adsorbed on silica surfaces

    NASA Technical Reports Server (NTRS)

    Ausloos, P.; Rebbert, R. E.; Glasgow, L.

    1977-01-01

    Irradiation of CCl4, CFCl3, and CF2Cl2 in the presence of C2H6 in vessels containing silica sand or fused quartz tubing results in the formation of chlorine-containing products. The formation of these compounds occurs at wavelengths extending up to approximately 400 nm, that is, at wavelengths well beyond the absorption threshold of the chloromethanes in the gas phase. It is suggested that CCl4 adsorbed on silica surfaces photodissociates to yield CCl3 and CCl2 species. The poor material balance obtained in these experiments indicates that several of the chlorine-containing fragments are strongly adsorbed on the surface. At a CCl4 pressure of 13 Pa (0.1 torr), photolysis with 366 nm light in the presence of sand results in the decomposition of one molecule for every 10,000 photons striking the surface. Under otherwise identical conditions, the photon-induced breadkdown of CFCl3 and CF2Cl2 is respectively only 10% or 3% as efficient.

  2. Adsorption of reactive dyes from aqueous solutions by fly ash: kinetic and equilibrium studies.

    PubMed

    Dizge, N; Aydiner, C; Demirbas, E; Kobya, M; Kara, S

    2008-02-11

    Adsorption kinetic and equilibrium studies of three reactive dyes namely, Remazol Brillant Blue (RB), Remazol Red 133 (RR) and Rifacion Yellow HED (RY) from aqueous solutions at various initial dye concentration (100-500 mg/l), pH (2-8), particle size (45-112.5 microm) and temperature (293-323 K) on fly ash (FA) were studied in a batch mode operation. The adsorbent was characterized with using several methods such as SEM, XRD and FTIR. Adsorption of RB reactive dye was found to be pH dependent but both RR and RY reactive dyes were not. The result showed that the amount adsorbed of the reactive dyes increased with increasing initial dye concentration and contact time. Batch kinetic data from experimental investigations on the removal of reactive dyes from aqueous solutions using FA have been well described by external mass transfer and intraparticle diffusion models. It was found that external mass transfer and intraparticle diffusion had rate limiting affects on the removal process. This was attributed to the relatively simple macropore structure of FA particles. The adsorption data fitted well with Langmuir and Freundlich isotherm models. The optimum conditions for removal of the reactive dyes were 100mg/l initial dye concentration, 0.6g/100ml adsorbent dose, temperature of 293 K, 45 microm particle size, pH 6 and agitation speed of 250 rpm, respectively. The values of Langmuir and Freundlich constants were found to increase with increasing temperature in the range 135-180 and 15-34 mg/g for RB, 47-86 and 1.9-3.7 mg/g for RR and 37-61 and 3.0-3.6 mg/g for RY reactive dyes, respectively. Different thermodynamic parameters viz., changes in standard free energy, enthalpy and entropy were evaluated and it was found that the reaction was spontaneous and endothermic in nature. PMID:17574338

  3. High capacity cryogel-type adsorbents for protein purification.

    PubMed

    Singh, Naveen Kumar; Dsouza, Roy N; Grasselli, Mariano; Fernández-Lahore, Marcelo

    2014-08-15

    Cryogel bodies were modified to obtain epoxy groups by graft-copolymerization using both chemical and gamma irradiation initiation techniques. The free epoxy adsorbents were reacted further to introduce diethylaminoethanol (DEAE) functionalities. The resulting weak anion-exchange cryogel adsorbents showed dynamic binding capacities of ca. 27±3mg/mL, which was significantly higher than previously reported for this type of adsorbent material. Gamma irradiated grafting initiation showed a 4-fold higher capacity for proteins than chemical grafting initiation procedures. The phosphate capacity for these DEAE cryogels was 119mmol/L and also showed similar column efficiency as compared to commercial adsorbents. The large pores in the cryogel structure ensure convective transport of the molecules to active binding sites located on the polymer-grafted surface of cryogels. However, as cryogels have relatively large pores (10-100μm), the BET area available for surface activation is low, and consequently, the capacity of the cryogels is relatively low for biomolecules, especially when compared to commercial beaded adsorbents. Nevertheless, we have shown that gamma ray mediated surface grafting of cryogel matrices greatly enhance their functional and adsorptive properties. PMID:24980092

  4. FRET Sensor for Erythrosine Dye Based on Organic Nanoparticles: Application to Analysis of Food Stuff.

    PubMed

    Mahajan, Prasad G; Bhopate, Dhanaji P; Kolekar, Govind B; Patil, Shivajirao R

    2016-07-01

    An aqueous suspension of fluorescent nanoparticles (PHNNPs) of naphthol based fluorescent organic compound 1-[(Z)-(2-phenylhydrazinylidene) methyl] naphthalene -2-ol (PHN) were prepared using reprecipitation method shows bathochromically shifted aggregation induced enhanced emission (AIEE) in the spectral region where erythrosine (ETS) food dye absorbs strongly. The average size of 72.6 nm of aqueous suspension of PHNNPs obtained by Dynamic light scattering results shows a narrow particle size distribution. The negative zeta potential of nano probe (-22.6 mV) responsible to adsorb oppositely charged analyte on its surface and further permit to bind nano probe and analyte within the close distance proximity required for efficient fluorescence resonance energy transfer (FRET) to take place from donor (PHNNPs) to acceptor (ETS). Systematic FRET experiments performed by measuring fluorescence quenching of PHNNPs with successive addition of ETS solution exploited the use of the PHNNPs as a novel nano probe for the detection of ETS in aqueous solution with extremely lower limit of detection equal to 3.6 nM (3.1 ng/mL). The estimation of photo kinetic and thermodynamic parameters such as quenching rate constant, enthalpy change (∆H), Gibbs free energy change (∆G) and entropy change (∆S) was obtained by the quenching results obtained at different constant temperatures which were found to fit the well-known Stern-Volmer relation. The mechanism of binding and fluorescence quenching of PHNNPs by ETS food dye is proposed on the basis of results obtained in photophysical studies, thermodynamic parameter, energy transfer efficiency, critical energy transfer distance (R0) and distance of approach between donor-acceptor molecules (r). The proposed FRET method based on fluorescence quenching of PHNNPs was successfully applied to develop an analytical method for estimation of ETS from food stuffs without interference of other complex ingredients. Graphical Abstract A

  5. First principles study of thieno[2,3-b]indole-based organic dyes for dye-sensitized solar cells: Screen novel π-linkers and explore the interface between photosensitizers and TiO2

    NASA Astrophysics Data System (ADS)

    Wen, Yaping; Wu, Wenpeng; Li, Yuanyuan; Zhang, Weiyi; Zeng, Zhaoyang; Wang, Li; Zhang, Jinglai

    2016-09-01

    Four organic compounds with different π-linkers are theoretically explored as potential photosensitizers for application in dye-sensitized solar cells (DSSCs). Besides the isolated dyes, the interfacial properties of dyes adsorbed on TiO2 anatase (101) surface are theoretically investigated. The overall conversion efficiency (η) of DSSCs is evaluated by the following items on the basis of the isolated dyes, including structures, absorption spectrum, energy gap, open-circuit voltage (Voc), short-circuit current density (Jsc), and reorganization energies (λtotal). After adsorbed on the TiO2 surface, the electron would be efficiently injected from dye into the TiO2 surface because of the increased of the lowest unoccupied molecular orbital (LUMO) energy level of the dyes, the decreased of the conduction band of TiO2 surface, and the narrowed band gaps for both dye and TiO2. Moreover, the injection times are in a reasonable range indicating that they are ideal dyes. Combination of all items, the performance of THI-2T-C (See Scheme 1, the sketch structures of all the investigated isolated dyes) stands out from the rest investigated dyes from the theoretical viewpoint. Only enlargement of the π-linker extent is not a smart choice, since the nature of π-linker plays a more important role in affecting the performance of DSSCs.

  6. The density and refractive index of adsorbing protein layers.

    PubMed

    Vörös, Janos

    2004-07-01

    The structure of the adsorbing layers of native and denatured proteins (fibrinogen, gamma-immunoglobulin, albumin, and lysozyme) was studied on hydrophilic TiO(2) and hydrophobic Teflon-AF surfaces using the quartz crystal microbalance with dissipation and optical waveguide lightmode spectroscopy techniques. The density and the refractive index of the adsorbing protein layers could be determined from the complementary information provided by the two in situ instruments. The observed density and refractive index changes during the protein-adsorption process indicated the presence of conformational changes (e.g., partial unfolding) in general, especially upon contact with the hydrophobic surface. The structure of the formed layers was found to depend on the size of the proteins and on the experimental conditions. On the TiO(2) surface smaller proteins formed a denser layer than larger ones and the layer of unfolded proteins was less dense than that adsorbed from the native conformation. The hydrophobic surface induced denaturation and resulted in the formation of thin compact protein films of albumin and lysozyme. A linear correlation was found between the quartz crystal microbalance measured dissipation factor and the total water content of the layer, suggesting the existence of a dissipative process that is related to the solvent molecules present inside the adsorbed protein layer. Our measurements indicated that water and solvent molecules not only influence the 3D structure of proteins in solution but also play a crucial role in their adsorption onto surfaces. PMID:15240488

  7. A multifunctional azobenzene-based polymeric adsorbent for effective water remediation

    NASA Astrophysics Data System (ADS)

    Wan, Decheng; Chen, Feng; Geng, Qingrui; Lu, Hang; Willcock, Helen; Liu, Qiuming; Wang, Fangyingkai; Zou, Kaidian; Jin, Ming; Pu, Hongting; Du, Jianzhong

    2014-12-01

    The efficient removal of trace carcinogenic organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and ionic dyes, from water is an important technical challenge. We report a highly effective recyclable multifunctional azobenzene (AZ)-based silica-supported polymeric adsorbent which can simultaneously remove both PAHs and anionic dyes from water to below parts per billion (ppb) level based on multiple interactions such as the hydrophobic effect, π-π stacking and electrostatic interactions, thus providing a new strategy for designer water remediation materials.

  8. A multifunctional azobenzene-based polymeric adsorbent for effective water remediation

    PubMed Central

    Wan, Decheng; Chen, Feng; Geng, Qingrui; Lu, Hang; Willcock, Helen; Liu, Qiuming; Wang, Fangyingkai; Zou, Kaidian; Jin, Ming; Pu, Hongting; Du, Jianzhong

    2014-01-01

    The efficient removal of trace carcinogenic organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and ionic dyes, from water is an important technical challenge. We report a highly effective recyclable multifunctional azobenzene (AZ)-based silica-supported polymeric adsorbent which can simultaneously remove both PAHs and anionic dyes from water to below parts per billion (ppb) level based on multiple interactions such as the hydrophobic effect, π–π stacking and electrostatic interactions, thus providing a new strategy for designer water remediation materials. PMID:25465671

  9. Conformational changes of adsorbed proteins

    NASA Astrophysics Data System (ADS)

    Allen, Scott

    2005-03-01

    The adsorption of bovine serum albumin (BSA) and pepsin to gold surfaces has been studied using surface plasmon resonance (SPR). Proteins are adsorbed from solution onto a gold surface and changes in the conformation of the adsorbed proteins are induced by changing the buffer solution. We selected pH and ionic strength values for the buffer solutions that are known from our circular dichroism measurements to cause conformational changes of the proteins in bulk solution. We find that for both BSA and pepsin the changes in conformation are impeded by the interaction of the protein with the gold surface.

  10. Solid-state fermentation: tool for bioremediation of adsorbed textile dyestuff on distillery industry waste-yeast biomass using isolated Bacillus cereus strain EBT1.

    PubMed

    Kadam, Avinash A; Kamatkar, Jeevan D; Khandare, Rahul V; Jadhav, Jyoti P; Govindwar, Sanjay P

    2013-02-01

    Bioremediation of textile dyestuffs under solid-state fermentation (SSF) using industrial wastes as substrate pose an economically feasible, promising, and eco-friendly alternative. The purpose of this study was to adsorb Red M5B dye, a sample of dyes mixture and a real textile effluent on distillery industry waste-yeast biomass (DIW-YB) and its further bioremediation using Bacillus cereus EBT1 under SSF. Textile dyestuffs were allowed to adsorb on DIW-YB. DIW-YB adsorbed dyestuffs were decolorized under SSF by using B. cereus. Enzyme analysis was carried out to ensure decolorization of Red M5B. Metabolites after dye degradation were analyzed using UV-Vis spectroscopy, FTIR, HPLC, and GC-MS. DIW-YB showed adsorption of Red M5B, dyes mixture and a textile wastewater sample up to 87, 70, and 81 %, respectively. DIW-YB adsorbed Red M5B was decolorized up to 98 % by B. cereus in 36 h. Whereas B. cereus could effectively reduce American Dye Manufacture Institute value from DIW-YB adsorbed mixture of textile dyes and textile wastewater up to 70 and 100 %, respectively. Induction of extracellular enzymes such as laccase and azoreductase suggests their involvement in dye degradation. Repeated utilization of DIW-YB showed consistent adsorption and ADMI removal from textile wastewater up to seven cycles. HPLC and FTIR analysis confirms the biodegradation of Red M5B. GC-MS analysis revealed the formation of new metabolites. B. cereus has potential to bioremediate adsorbed textile dyestuffs on DIW-YB. B. cereus along with DIW-YB showed enhanced decolorization performance in tray bioreactor which suggests its potential for large-scale treatment procedures. PMID:22562346

  11. Use of jute processing wastes for treatment of wastewater contaminated with dye and other organics.

    PubMed

    Banerjee, Souvik; Dastidar, M G

    2005-11-01

    A study was conducted to examine the potential of jute processing waste (JPW) for the treatment of wastewater contaminated with dye and other organics generated from various activities associated with jute cultivation and fibre production. Adsorption studies in batch mode have been conducted using dye solution as an adsorbate and JPW as an adsorbent. A comparative adsorption study was made with standard adsorbents such as powdered and granular activated carbon (PAC and GAC, respectively). A maximum removal of 81.7% was obtained with methylene blue dye using JPW as compared to 61% using PAC and 40% using GAC under similar conditions. The adsorption potential of JPW was observed to be dependent on various parameters such as type of dye, initial dye concentration, pH and dosage of adsorbent. The batch sorption data conformed well to the Langmuir and Freundlich isotherms. However, lower BOD (33.3%) and COD (13.8%) removal from retting effluent was observed using JPW as compared to 75.6% BOD removal and 71.1% COD removal obtained with GAC. PMID:16084372

  12. Studies in treatment of disperse dye waste: Membrane-wet oxidation process

    SciTech Connect

    Dhale, A.D.; Mahajani, V.V.

    2000-07-01

    An integrated process, membrane-wet oxidation (MEMWO) has been demonstrated to treat the disperse dye bath waste. The dye bath waste stream containing azo class disperse dye CL 79, was studied to demonstrate the process. A nanofiltration membrane (MPT 30) showed > 99% color and 97% chemical oxygen demand (COD) rejection of dye compound. The concentrate was then treated by wet oxidation (WO) process. WO of dye was studied in the range of 160--225 C and oxygen partial pressure 0.69--1.38 MPa. A homogeneous copper sulfate was found to be a suitable catalyst to effectively destroy the dye as well as the real waste. While non catalytic WO of dye achieved 75% reduction in COD during 120 min with 99% color destruction, the catalytic WO showed about 90% reduction in COD. The performance of WO of actual waste stream was comparable with that of pure dye molecule.

  13. Influence of the layer charge and clay particle size on the interactions between the cationic dye methylene blue and clays in an aqueous suspension.

    PubMed

    Neumann, Miguel G; Gessner, Fergus; Schmitt, Carla C; Sartori, Rogerio

    2002-11-15

    The spectroscopic behavior of the dye MB in suspensions of different clays have been used for evaluating layer charge density influence on the adsorption properties of the particles. The clays with higher charge density, like SAz-1 and SCa-3, promote a higher aggregation and do not show deaggregation at longer times, so that practically only the aggregate peak at approximately 570 nm is observed, without any change with time. This is due to, on one side, the larger particle size that decreases the surface area available for adsorption. Additionally, the clay layers will be held together more tightly, avoiding the migration of the dye to the interlamellar region. On the other hand, SWy-1, having a lower charge density, shows a completely different behavior. The dye molecules, initially adsorbed as aggregates on the outer surface of the clay, deaggregate to form monomers that migrate to the interlamellar spaces, giving rise to absorption bands at 670 and 760 nm. Experiments using Ca-exchanged SWy-1, variation of the ionic strength by addition of salt, and the use of different size fractions of the clays confirm the finding that the main factor ruling the adsorption behavior of the probe is the size of the clay particles. PMID:12505071

  14. Efficient dye regeneration at low driving force achieved in triphenylamine dye LEG4 and TEMPO redox mediator based dye-sensitized solar cells.

    PubMed

    Yang, Wenxing; Vlachopoulos, Nick; Hao, Yan; Hagfeldt, Anders; Boschloo, Gerrit

    2015-06-28

    Minimizing the driving force required for the regeneration of oxidized dyes using redox mediators in an electrolyte is essential to further improve the open-circuit voltage and efficiency of dye-sensitized solar cells (DSSCs). Appropriate combinations of redox mediators and dye molecules should be explored to achieve this goal. Herein, we present a triphenylamine dye, LEG4, in combination with a TEMPO-based electrolyte in acetonitrile (E(0) = 0.89 V vs. NHE), reaching an efficiency of up to 5.4% under one sun illumination and 40% performance improvement compared to the previously and widely used indoline dye D149. The origin of this improvement was found to be the increased dye regeneration efficiency of LEG4 using the TEMPO redox mediator, which regenerated more than 80% of the oxidized dye with a driving force of only ∼0.2 eV. Detailed mechanistic studies further revealed that in addition to electron recombination to oxidized dyes, recombination of electrons from the conducting substrate and the mesoporous TiO2 film to the TEMPO(+) redox species in the electrolyte accounts for the reduced short circuit current, compared to the state-of-the-art cobalt tris(bipyridine) electrolyte system. The diffusion length of the TEMPO-electrolyte based DSSCs was determined to be ∼0.5 μm, which is smaller than the ∼2.8 μm found for cobalt-electrolyte based DSSCs. These results show the advantages of using LEG4 as a sensitizer, compared to previously record indoline dyes, in combination with a TEMPO-based electrolyte. The low driving force for efficient dye regeneration presented by these results shows the potential to further improve the power conversion efficiency (PCE) of DSSCs by utilizing redox couples and dyes with a minimal need of driving force for high regeneration yields. PMID:26016854

  15. Tailoring the Interface to Improve Voc in Dye-Sensitized Solar Cells

    SciTech Connect

    Neale, N. R.; Kopidakis, N.; van de Lagemaat, J.; Frank, A. J.

    2005-01-01

    Adding certain adsorbents in conjunction with the sensitizing dye employed in high-efficiency TiO2 nanoparticle solar cells has been shown to increase the photovoltage. It is has been speculated that the increased photovoltage is due to these hydrophobic adsorbents passivating surface states that mitigate the recombination of photoinjected electrons with redox species in the electrolyte. In collaboration with the DOE Office of Science Program, we are conducting transient-photovoltage measurements to determine the mechanism for the improved photovoltage.

  16. Radiolysis of alanine adsorbed in a clay mineral

    NASA Astrophysics Data System (ADS)

    Aguilar-Ovando, Ellen Y.; Negrón-Mendoza, Alicia

    2013-07-01

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  17. Radiolysis of alanine adsorbed in a clay mineral

    SciTech Connect

    Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

    2013-07-03

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  18. Dyes and Redox Couples with Matched Energy Levels: Elimination of the Dye-Regeneration Energy Loss in Dye-Sensitized Solar Cells.

    PubMed

    Jiang, Dianlu; Darabedian, Narek; Ghazarian, Sevak; Hao, Yuanqiang; Zhgamadze, Maxim; Majaryan, Natalie; Shen, Rujuan; Zhou, Feimeng

    2015-11-16

    In dye-sensitized solar cells (DSSCs), a significant dye-regeneration force (ΔG(reg)(0)≥0.5 eV) is usually required for effective dye regeneration, which results in a major energy loss and limits the energy-conversion efficiency of state-of-art DSSCs. We demonstrate that when dye molecules and redox couples that possess similar conjugated ligands are used, efficient dye regeneration occurs with zero or close-to-zero driving force. By using Ru(dcbpy)(bpy)2(2+) as the dye and Ru(bpy)2(MeIm)2(3+//2+) as the redox couple, a short-circuit current (J(sc)) of 4 mA cm(-2) and an open-circuit voltage (V(oc)) of 0.9 V were obtained with a ΔG(reg)(0) of 0.07 eV. The same was observed for the N3 dye and Ru(bpy)2(SCN)2(1+/0) (ΔG(reg)(0)=0.0 eV), which produced an J(sc) of 2.5 mA cm(-2) and V(oc) of 0.6 V. Charge recombination occurs at pinholes, limiting the performance of the cells. This proof-of-concept study demonstrates that high V(oc) values can be attained by significantly curtailing the dye-regeneration force. PMID:26314383

  19. Novel energy relay dyes for high efficiency dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Mahbubur; Ko, Min Jae; Lee, Jae-Joon

    2015-02-01

    4',6-Diamidino-2-phenylindole (DAPI) and Hoechst 33342 (H33342) were used as novel energy relay dyes (ERDs) for an efficient energy transfer to the N719 dye in I-/I3- based liquid-junction dye-sensitized solar cells (DSSCs). The introduction of the ERDs, either as an additive in the electrolyte or as a co-adsorbent, greatly enhanced the power conversion efficiencies (PCEs), mainly because of an increase in short-circuit current density (Jsc). This was attributed to the effects of non-radiative Förster-type excitation energy transfer as well as the radiative (emission)-type fluorescent energy transfer to the sensitizers. The net PCEs for the N719-sensitized DSSCs with DAPI and H33342 were 10.65% and 10.57%, and showed an improvement of 12.2% and 11.4% over control devices, respectively.4',6-Diamidino-2-phenylindole (DAPI) and Hoechst 33342 (H33342) were used as novel energy relay dyes (ERDs) for an efficient energy transfer to the N719 dye in I-/I3- based liquid-junction dye-sensitized solar cells (DSSCs). The introduction of the ERDs, either as an additive in the electrolyte or as a co-adsorbent, greatly enhanced the power conversion efficiencies (PCEs), mainly because of an increase in short-circuit current density (Jsc). This was attributed to the effects of non-radiative Förster-type excitation energy transfer as well as the radiative (emission)-type fluorescent energy transfer to the sensitizers. The net PCEs for the N719-sensitized DSSCs with DAPI and H33342 were 10.65% and 10.57%, and showed an improvement of 12.2% and 11.4% over control devices, respectively. Electronic supplementary information (ESI) available: Details of the materials and instrumentation, device fabrication, measurement and calculations of the quantum yield (Qd), calculations of the Förster radius (R0), optimization of the ERDs mixed with electrolyte according to Type-A strategy; normalized absorption profiles of the N3, Ru505, and Z907 dyes and the emission profiles of DAPI and H33342

  20. Hair dye poisoning

    MedlinePlus

    ... temporary dyes are: Arsenic Bismuth Denatured alcohol Lead ( lead poisoning ) Mercury Pyrogallol Silver Hair dyes may contain other ... infection. Continued exposure to lead or mercury can lead to permanent brain and nervous system damage. Alternative ... References Lee DC. Hydrocarbons. In: Marx JA, Hockberger ...

  1. Oxazine laser dyes

    DOEpatents

    Hammond, Peter R.; Field, George F.

    1992-01-01

    New oxazine compounds useful as dye laser media in solution, are superiior to prior art materials. The oxazine dyes useful when pumped by the 578.2 nm copper line to operate in the 700-800 nm range are described by formula I ##STR1##

  2. Mesoporous multi-shelled ZnO microspheres for the scattering layer of dye sensitized solar cell with a high efficiency

    NASA Astrophysics Data System (ADS)

    Xia, Weiwei; Mei, Chao; Zeng, Xianghua; Chang, Shuai; Wu, Guoqing; Shen, Xiaoshuang

    2016-03-01

    Both light scattering and dye adsorbing are important for the power conversion efficiency PCE performance of dye sensitized solar cell (DSSC). Nanostructured scattering layers with a large specific surface area are regarded as an efficient way to improve the PCE by increasing dye adsorbing, but excess adsorbed dye will hinder light scattering and light penetration. Thus, how to balance the dye adsorbing and light penetration is a key problem to improve the PCE performance. Here, multiple-shelled ZnO microspheres with a mesoporous surface are fabricated by a hydrothermal method and are used as scattering layers on the TiO2 photoanode of the DSSC in the presence of N719 dye and iodine-based electrolyte, and the results reveal that the DSSCs based on triple shelled ZnO microsphere with a mesoporous surface exhibit an enhanced PCE of 7.66%, which is 13.0% higher than those without the scattering layers (6.78%), indicating that multiple-shelled microspheres with a mesoporous surface can ensure enough light scattering between the shells, and a favorable concentration of the adsorbed dye can improve the light penetration. These results may provide a promising pathway to obtain the high efficient DSSCs.

  3. Catalyzed degradation of azo dyes under ambient conditions.

    PubMed

    Wu, Jin-Ming; Wen, Wei

    2010-12-01

    Phase-pure layered perovskite La(4)Ni(3)O(10) powders were synthesized by a solution combustion approach. It is found that, in the presence of the La(4)Ni(3)O(10) powders, aqueous azo dyes can be degraded catalytically and efficiently under ambient conditions. Neither light nor additional reagents are needed in the catalytic reaction. The dye degradation procedure can be accelerated markedly by magnetic stirring. A systemic series of chemical and electrochemical experiments suggested that the dye degradation proceeds through electron transfers from the dye molecules to the catalyst and then to electron acceptors such as dissolved oxygen. The present catalytic degradation requires no additional reagents or external energy input, which hence provides a potentially low-cost alternative for the remediation of azo-dye effluents. PMID:21049925

  4. Polyphosphazenes with Immobilized Dyes as Potential Color Filter Materials.

    PubMed

    Li, Zhongjing; Allcock, Harry R

    2015-06-24

    Red, green, and blue dye molecules were linked covalently to polyphosphazenes to generate soluble, film-forming materials appropriate for the formation of patterned tricolor filters for possible use in liquid crystalline and other display devices or in camera sensors. The monofunctional dyes (a red 1-[(E)-(4-nitrophenyl)diazenyl]-2-naphthol, a green tetraphenylporphyrin [5-(4-hydroxyphenyl)-10,15,20-tetraphenylporphyrin], and a toluidine blue dye) were employed as representative chromophores. The cosubstituents employed included 2,2,2-trifluoroethoxy with and without aryloxy groups or cyclopentanoxy groups. The optical densities were varied by adopting several dye-to-cosubstituent side group ratios. These dyes are models for a wide range of different chromophores that can be linked to polyphosphazene chains. PMID:26018938

  5. Adsorption properties of crosslinking carboxymethyl cellulose grafting dimethyldiallylammonium chloride for cationic and anionic dyes.

    PubMed

    Lin, Qingwen; Gao, Mengfan; Chang, Jiali; Ma, Hongzhu

    2016-10-20

    Novel and efficient microspheres adsorbent (MCA-E0.7/CMC-g- PDMDAAC), based on monochloroacetic acid (MCA) modified epichlorohydrin (ECH) cross-linked carboxymethyl cellulose (CMC), then grafting by dimethyldiallylammonium chloride (DMDAAC), was synthesized and its adsorption properties on cationic and anionic dyes were investigated. The results demonstrated that such MCA-E0.7/CMC-g-PDMDAAC microspheres showed pH-sensitive and could effectively adsorb cationic dye methylene blue (MB) or anionic dye orange II (OR II), at near neutral (pH>4) or acidic (pH<3) condition, respectively. Moreover, it could selectively adsorb the cationic dye MB from the cationic/anionic dye mixture at neutral pH condition. The desorption experiments were mainly performed under acidic (pH 3) or basic (pH 11) condition, over 98.54% of MB and 83.07% of OR II can be desorbed within 20min, respectively. The pseudo-second-order kinetic model and Langmuir isotherm provide better correlation with the experimental data for the adsorption of dyes onto MCA-E0.7/CMC-g-PDMDAAC microspheres. PMID:27474569

  6. Monolithic dye laser amplifier

    DOEpatents

    Kuklo, Thomas C.

    1993-01-01

    A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

  7. Monolithic dye laser amplifier

    DOEpatents

    Kuklo, T.C.

    1993-03-30

    A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

  8. Preparation and spectral characterization of polymeric nanocapsules containing DR1 organic dye

    NASA Astrophysics Data System (ADS)

    Sharifimehr, Mohammad Reza; Ghanbari, Khadijeh; Ayoubi, Kazem; Mohajerani, Ezedin

    2015-07-01

    In order to provide necessary degree of freedom for organic dye molecules in optical applications and also for safety improvement, water insoluble Disperse Red 1 (DR1) dye molecules were placed inside the polymeric nanocapsules along with suitable surfactants and using controlled phase-separation method. TEM images were used to investigate the morphology of prepared nanocapsules. Total dye concentration for a solution consist of obtained polymeric nanocapsules was determined using decomposition of nanocapsules and a reference absorption spectrum. Absorption spectrum of a solution containing DR1 and dichloromethane was also compared with prepared nanocapsules at the same dye concentration, thereby a red-shift in absorption spectrum was detected.

  9. Removal of Acid Orange 7 from aqueous solution using magnetic graphene/chitosan: a promising nano-adsorbent.

    PubMed

    Sheshmani, Shabnam; Ashori, Alireza; Hasanzadeh, Saeed

    2014-07-01

    Magnetic graphene/chitosan (MGCh) nanocomposite was fabricated through a facile chemical route and its application as a new adsorbent for Acid Orange 7 (AO7) removal was also investigated. After synthesis, the full characterization with various techniques (FTIR, XRD, VSM, and SEM) was achieved revealing many possible interactions/forces of dye-composite system. The results showed that, benefiting from the surface property of graphene oxide, the abundant amino and hydroxyl functional groups of chitosan, and from the magnetic property of Fe3O4, the adsorbent possesses quite a good and versatile adsorption capacity to the dye under investigation, and can be easily and rapidly extracted from water by magnetic attraction. The maximum absorption capacity was reached at initial pH 3 and 120min contact time. The batch adsorption experiments showed that the adsorption of the AO7 is considerably dependent on pH of milieu, amount of adsorbent, and contact time. The adsorption kinetics and isotherms were investigated to indicate that the kinetic and equilibrium adsorption were well-described by pseudo-first order kinetic and Langmuir isotherm model, respectively. The adsorption behavior suggested that the adsorbent surface was homogeneous in nature. The study suggests that the MGCh is a promising nano adsorbent for removal of anionic azo dyes from aqueous solution. PMID:24813679

  10. Triphenylamine based organic dyes for dye sensitized solar cells: A theoretical approach

    NASA Astrophysics Data System (ADS)

    Mohankumar, V.; Pandian, Muthu Senthil; Ramasamy, P.

    2016-05-01

    The geometry, electronic structure and absorption spectra for newly designed triphenylamine based organic dyes were investigated by density functional theory (DFT) and time dependent density functional theory (TD-DFT) with the Becke 3-Parameter-Lee-Yang-parr(B3LYP) functional, where the 6-31G(d,p) basis set was employed. All calculations were performed using the Gaussian 09 software package. The calculated HOMO and LUMO energies show that charge transfer occurs in the molecule. Ultraviolet-visible (UV-vis) spectrum was simulated by TD-DFT in gas phase. The calculation shows that all of the dyes can potentially be good sensitizers for DSSC. The LUMOs are just above the conduction band of TiO2 and their HOMOs are under the reduction potential energy of the electrolytes (I-/I3-) which can facilitate electron transfer from the excited dye to TiO2 and charge regeneration process after photo oxidation respectively. The simulated absorption spectrum of dyes match with solar spectrum. Frontier molecular orbital results show that among all the three dyes, the "dye 3" can be used as potential sensitizer for DSSC.

  11. Chitosan and chemically modified chitosan beads for acid dyes sorption.

    PubMed

    Azlan, Kamari; Wan Saime, Wan Ngah; Lai Ken, Liew

    2009-01-01

    The capabilities of chitosan and chitosan-EGDE (ethylene glycol diglycidyl ether) beads for removing Acid Red 37 (AR 37) and Acid Blue 25 (AB 25) from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function of pH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan for both acid dyes were comparatively higher than those of chitosan-EGDE. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3+ on chitosan. Langmuir isotherm model showed the best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment. PMID:19634439

  12. Do Methanethiol Adsorbates on the Au(111) Surface Dissociate?

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Ge; Hagelberg, Frank

    2006-07-01

    The interaction of methanethiol molecules CH3SH with the Au(111) surface is investigated, and it is found for the first time that the S-H bond remains intact when the methanethiol molecules are adsorbed on the regular Au(111) surface. However, it breaks if defects are present in the Au(111) surface. At low coverage, the fcc region is favored for S atom adsorption, but at saturated coverage the adsorption energies at various sites are almost isoenergetic. The presented calculations show that a methanethiol layer on the regular Au(111) surface does not dimerize.

  13. Molecular switches from benzene derivatives adsorbed on metal surfaces

    PubMed Central

    Liu, Wei; Filimonov, Sergey N.; Carrasco, Javier; Tkatchenko, Alexandre

    2013-01-01

    Transient precursor states are often experimentally observed for molecules adsorbing on surfaces. However, such precursor states are typically rather short-lived, quickly yielding to more stable adsorption configurations. Here we employ first-principles calculations to systematically explore the interaction mechanism for benzene derivatives on metal surfaces, enabling us to selectively tune the stability and the barrier between two metastable adsorption states. In particular, in the case of the tetrachloropyrazine molecule, two equally stable adsorption states are identified with a moderate and conceivably reversible barrier between them. We address the feasibility of experimentally detecting the predicted bistable behaviour and discuss its potential usefulness in a molecular switch. PMID:24157660

  14. Temperature programmed desorption of weakly bound adsorbates on Au(111)

    NASA Astrophysics Data System (ADS)

    Engelhart, Daniel P.; Wagner, Roman J. V.; Meling, Artur; Wodtke, Alec M.; Schäfer, Tim

    2016-08-01

    We have performed temperature programmed desorption (TPD) experiments to analyze the desorption kinetics of Ar, Kr, Xe, C2H2, SF6, N2, NO and CO on Au(111). We report desorption activation energies (Edes), which are an excellent proxy for the binding energies. The derived binding energies scale with the polarizability of the molecules, consistent with the conclusion that the surface-adsorbate bonds arise due to dispersion forces. The reported results serve as a benchmark for theories of dispersion force interactions of molecules at metal surfaces.

  15. Irradiation treatment of azo dye containing wastewater: An overview

    NASA Astrophysics Data System (ADS)

    Wojnárovits, László; Takács, Erzsébet

    2008-03-01

    The radiation-induced decolouration and degradation of aqueous solutions of azo dyes and their model compounds (anilines, phenols, triazines) are reviewed together with practical applications and the experimental methods (pulse radiolysis, steady-state gamma radiolysis, as well as end-product analysis) used for studying the reactions. The proposed mechanisms and the rate coefficients for the reactions of rad OH, e aq- and rad H water radiolysis intermediates with the dye molecules and with model compounds are summarized.

  16. TEXTILE DYES AND DYEING EQUIPMENT: CLASSIFICATION, PROPERTIES, AND ENVIRONMENTAL ASPECTS

    EPA Science Inventory

    The report gives results of a study of available information on textile dyeing equipment, dyeing procedures, and dye chemistry, to serve as background data for estimating the properties and evaluating the associated risks of new commercial dyestuffs. It reports properties of dyes...

  17. Structure and spectral properties of truxene dye S5

    NASA Astrophysics Data System (ADS)

    Baryshnikov, G. V.; Minaev, B. F.; Minaeva, V. A.; Ning, Z.; Zhang, Q.

    2012-02-01

    On the ground of functional theory with the B3LYP and BMK functionals, we have studied the structure and optical properties of a truxene dye sensitizer S5 for photoelectric transducers. Based on the calculations of the vertical excitations energy of the dye molecule and accounting the influence of the solvent, we have revealed a positive solvatochromic effect that is weak compared to results obtained in the vacuum approximation. We have studied new features describing stabilization of the planar structure of the cyanothiophene-acrylic fragment of the S5 dye.

  18. In-Situ Spectroscopic Analyses of the Dye Uptake on ZnO and TiO2 Photoanodes for Dye-Sensitized Solar Cells.

    PubMed

    Shahzad, Nadia; Pugliese, Diego; Shahzad, Muhammad Imran; Tresso, Elena

    2015-08-01

    UV-Vis spectroscopic measurements have been performed on Dye-Sensitized Solar Cell (DSSC) photoanodes at different dye impregnation times ranging from few minutes to 24 hours. In addition to the traditional absorbance experiments, based on diffuse and specular reflectance of dye impregnated thin films and on the desorption of dye molecules from the photoanodes by means of a basic solution, an alternative in-situ solution depletion measurement, which enables fast and continuous evaluation of dye uptake, has been employed. Two different nanostructured semiconducting oxide films (mesoporous TiO2 and sponge-like ZnO) and two different dyes, the traditional Ruthenizer 535-bisTBA (N719) and a newly introduced metal-free organic dye based on a hemi-squaraine molecule (CT1), have been analyzed. DSSCs have been fabricated with the dye-impregnated photoanodes using a customized microfluidic architecture. The dye adsorption results are discussed and correlated to the obtained DSSC electrical performances such as photovoltaic conversion efficiencies and Incident Photon-to-electron Conversion Efficiency (IPCE) spectra. It is shown that simple UV-Vis measurements can give useful insights on the dye adsorption mechanisms and on the evaluation of the optimal impregnation times. PMID:26369186

  19. Dye system for dye laser applications

    DOEpatents

    Hammond, Peter R.

    1991-01-01

    A dye of the DCM family, [2-methyl-6-[2-(1,2,3,4-tetrahydro-1-methyl-6-quinolinyl)ethenyl]-4H-pyran -4-ylidene]-propanedinitrile, dissolved in 2-phenoxyethanol, is non-mutagenic, stable and efficient, particularly in a pumped continuous wave laser system.

  20. Mesoporous carbon nanomaterials as environmental adsorbents.

    PubMed

    Tripathi, Pranav K; Gan, Lihua; Liu, Mingxian; Rao, Nageswara N

    2014-02-01

    The transportation and diffusion of the guest objects or molecules in the porous carbon nanomaterials can be facilitated by reducing the pathway and resistance. The reduced pathway depends on the porous nature of carbon nanomaterials. Classification of porous carbon materials by the International Union of Pure and Applied Chemistry (IUPAC) has given a new opportunity to design the pores as per their applicability and to understand the mobility of ions, atoms, and molecules in the porous network of carbon materials and also advanced their countless applicability. However, synthesis of carbon nanomaterials with a desired porous network is still a great challenge. Although, remarkable developments have taken place in the recent years, control over the pores size and/or hierarchical porous architectures, especially in the synthesis of carbon nanospheres (CNSs) and ordered mesoporous carbon (OMCs) is still intriguing. The micro and mesoporous CNSs and OMCs have been prepared by a variety of procedures and over a wide range of compositions using various different surfactant templates and carbon precursors etc. The mechanisms of formation of micromesopore in the CNSs and OMCs are still evolving. On the other hand, the urge for adsorbents with very high adsorption capacities for removing contaminants from water is growing steadily. In this review, we address the state-of-the-art synthesis of micro and mesoporous CNSs and OMCs, giving examples of their applications for adsorptive removals of contaminants including our own research studies. PMID:24749459

  1. Adsorption studies of methylene blue dye on tunisian activated lignin

    NASA Astrophysics Data System (ADS)

    Kriaa, A.; Hamdi, N.; Srasra, E.

    2011-02-01

    Activated carbon prepared from natural lignin, providing from a geological deposit, was used as the adsorbent for the removal of methylene blue (MB) dye from aqueous solutions. Batch adsorption studies were conducted to evaluate various experimental parameters like pH and contact time for the removal of this dye. Effective pH for MB removal was 11. Kinetic study showed that the adsorption of dye was gradual process. Quasi equilibrium reached in 4 h. Pseudo-first-order, pseudo-second-order were used to fit the experimental data. Pseudo-second-order rate equation was able to provide realistic description of adsorption kinetics. The experimental isotherms data were also modelled by the Langmuir and Freundlich equation of adsorption. Equilibrium data fitted well with the Langmuir model with maximum monolayer adsorption capacity of 147 mg/g. Activated lignin was shown to be a promising material for adsorption of MB from aqueous solutions.

  2. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    SciTech Connect

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-19

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  3. Metal-organic gel templated synthesis of magnetic porous carbon for highly efficient removal of organic dyes.

    PubMed

    Wang, Luhuan; Ke, Fei; Zhu, Junfa

    2016-03-21

    Magnetic porous carbon composites are promising materials in various applications, such as adsorbents, supercapacitors and catalyst supports, due to their high surface area, thermal and chemical stability, and easy separation. However, despite the increasing number of reports of magnetic porous carbon composites, the preparation of these materials with environmentally friendly procedures still remains a great challenge. Herein, we report a facile method to prepare a magnetic porous carbon composite with high surface area from a Fe-based metal-organic gel (MOG) template, an extended structure of a metal-organic framework (MOF). The obtained magnetic porous carbon composite was applied to remove organic dyes from an aqueous solution by selecting methyl orange (MO) as a model molecule. It exhibits excellent adsorption capacity (182.82 mg g(-1)), fast adsorption kinetics (8.13 × 10(-3) g mg(-1) min(-1)), and a perfect magnetic separation performance for the MO removal. This study demonstrates a new way to achieve clean synthesis of magnetic porous carbon materials, and opens a new door for the application of MOGs in organic dye removal. PMID:26842305

  4. TiO2 nanocrystals coated rutile nanorod microspheres as the scattering layers for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Mengyu; Wang, Hongzhi; Li, Yaogang; Zhang, Qinghong

    2013-12-01

    Anatase TiO2 nanocrystals were deposited on the rutile TiO2 nanorod microspheres (NCRNMs) via the controlled hydrolysis and condensation of titanium (IV) bis(ammonium lactato) dihydroxide (TALH) in the presence of polyethyleneimine (PEI). The anatase TiO2 nanocrystals prevented the growth of rutile TiO2 nanorod microspheres from sintering process. By coating of anatase nanocrystals, the decreasing of specific surface area of rutile TiO2 nanorod microspheres (RNMs) were efficiently inhibited. The specific surface area of NCRNM was 47.0 m2/g after sintering at 500 °C,which was 50% increment compared to RNM. The dye sensitized solar cells (DSSCs) were assembled using the semitransparent underlayers and NCRNM scattering layers as the photoanodes. The incident photon to current conversion efficiency (IPCE) analysis showed the DSSCs in the presence of NCRNMs adsorbed more dye molecules while kept a high light-harvesting efficiency. The cell covered with the NCRNM scattering layer had the efficiency of 7.33%, which was 20% increment compared to that of the absence one.

  5. Chemical and structural evaluation of activated carbon prepared from jute sticks for Brilliant Green dye removal from aqueous solution.

    PubMed

    Asadullah, Mohammad; Asaduzzaman, Mohammad; Kabir, Mohammad Shajahan; Mostofa, Mohammad Golam; Miyazawa, Tomohisa

    2010-02-15

    Activated carbons have been prepared from jute sticks by chemical activation using ZnCl(2) and physical activation using steam for the removal of Brilliant Green dye from aqueous solution. The activated carbons and charcoal prepared from jute sticks were characterized by evaluating the surface chemistry, structural features and surface morphology. The maximum BET surface area was obtained to be 2304 m(2)/g for chemical activated carbon (ACC) while it is 730 and 80 m(2)/g for steam activated carbon (ACS) and charcoal, respectively. The FT-IR spectra exhibited that the pyrolysis and steam activation of jute sticks resulted in the release of aliphatic and O-containing functional groups by thermal effect. However, the release of functional groups is the effect of chemical reaction in the ZnCl(2) activation process. A honeycomb-type carbon structure in ACC was formed as observed on SEM images. Although charcoal and ACC were prepared at 500 degrees C the ACC exhibited much lower Raman sensitivity due to the formation of condensed aromatic ring systems. Due to high surface area and high porous structure with abundance of functional groups, the ACC adsorbed dye molecules with much higher efficiency than those of ACS and charcoal. PMID:19815339

  6. Performance of Kerria japonica and Rosa chinensis flower dyes as sensitizers for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hemalatha, K. V.; Karthick, S. N.; Justin Raj, C.; Hong, N.-Y.; Kim, S.-K.; Kim, H.-J.

    2012-10-01

    The natural dyes carotenoid and anthocyanin were extracted from Kerria japonica and Rosa chinensis, respectively, using a simple extraction technique without any further purification. They were then used as sensitizers in dye-sensitized solar cells (DSSCs), and their characteristics were studied. The ranges of short-circuit current (JSC) from 0.559 to 0.801 (mA/cm2), open-circuit voltage (VOC) from 0.537 to 0.584 V, and fill factor from 0.676 to 0.705 were obtained for the DSSCs made using the extracted dyes. Sugar molecules were added externally to the dye for stabilization and to increase the conversion efficiency. The efficiencies of the K. japonica and R. chinensis dyes were 0.22% and 0.29%, respectively; after the addition of sugar, the efficiency increased to 0.29% for K. japonica and decreased to 0.27% for R. chinensis. Thus, the addition of sugar molecules increased the conversion efficiency slightly with the carotenoid dye of K. japonica, while there was no considerable change with the anthocyanin of R. chinensis. This paper briefly discusses the simple extraction technique of these natural dyes and their performance in DSSCs.

  7. Performance of Kerria japonica and Rosa chinensis flower dyes as sensitizers for dye-sensitized solar cells.

    PubMed

    Hemalatha, K V; Karthick, S N; Justin Raj, C; Hong, N-Y; Kim, S-K; Kim, H-J

    2012-10-01

    The natural dyes carotenoid and anthocyanin were extracted from Kerria japonica and Rosa chinensis, respectively, using a simple extraction technique without any further purification. They were then used as sensitizers in dye-sensitized solar cells (DSSCs), and their characteristics were studied. The ranges of short-circuit current (J(SC)) from 0.559 to 0.801(mA/cm(2)), open-circuit voltage (V(OC)) from 0.537 to 0.584 V, and fill factor from 0.676 to 0.705 were obtained for the DSSCs made using the extracted dyes. Sugar molecules were added externally to the dye for stabilization and to increase the conversion efficiency. The efficiencies of the K. japonica and R. chinensis dyes were 0.22% and 0.29%, respectively; after the addition of sugar, the efficiency increased to 0.29% for K. japonica and decreased to 0.27% for R. chinensis. Thus, the addition of sugar molecules increased the conversion efficiency slightly with the carotenoid dye of K. japonica, while there was no considerable change with the anthocyanin of R. chinensis. This paper briefly discusses the simple extraction technique of these natural dyes and their performance in DSSCs. PMID:22698848

  8. Dyeing of Polyester with Disperse Dyes: Part 2. Synthesis and Dyeing Characteristics of Some Azo Disperse Dyes for Polyester Fabrics.

    PubMed

    Al-Etaibi, Alya M; Alnassar, Huda S; El-Apasery, Morsy Ahmed

    2016-01-01

    The goal of this study was to utilize carrier for accelerating the rate of dyeing not only to enhance dyeing of polyester fabrics dyed with disperse dyes 3a,b, but also to save energy. Both the color strength expressed as dye uptake and the fastness properties of the dyed fabrics were evaluated. PMID:27367659

  9. Resonance energy transfer in DNA duplexes labeled with localized dyes.

    PubMed

    Cunningham, Paul D; Khachatrian, Ani; Buckhout-White, Susan; Deschamps, Jeffrey R; Goldman, Ellen R; Medintz, Igor L; Melinger, Joseph S

    2014-12-18

    The growing maturity of DNA-based architectures has raised considerable interest in applying them to create photoactive light harvesting and sensing devices. Toward optimizing efficiency in such structures, resonant energy transfer was systematically examined in a series of dye-labeled DNA duplexes where donor-acceptor separation was incrementally changed from 0 to 16 base pairs. Cyanine dyes were localized on the DNA using double phosphoramidite attachment chemistry. Steady state spectroscopy, single-pair fluorescence, time-resolved fluorescence, and ultrafast two-color pump-probe methods were utilized to examine the energy transfer processes. Energy transfer rates were found to be more sensitive to the distance between the Cy3 donor and Cy5 acceptor dye molecules than efficiency measurements. Picosecond energy transfer and near-unity efficiencies were observed for the closest separations. Comparison between our measurements and the predictions of Förster theory based on structural modeling of the dye-labeled DNA duplex suggest that the double phosphoramidite linkage leads to a distribution of intercalated and nonintercalated dye orientations. Deviations from the predictions of Förster theory point to a failure of the point dipole approximation for separations of less than 10 base pairs. Interactions between the dyes that alter their optical properties and violate the weak-coupling assumption of Förster theory were observed for separations of less than four base pairs, suggesting the removal of nucleobases causes DNA deformation and leads to enhanced dye-dye interaction. PMID:25397906

  10. Chemical stabilization of laser dyes

    NASA Astrophysics Data System (ADS)

    Koch, Tad H.

    1987-05-01

    Coumarin laser dyes upon excitation degrade to produce products which absorb at the lasing wavelength. This results in attenuation of dye laser output through interference of stimulated emission. The roles of singlet oxygen and excitation intensity on dye degradation were explored. Singlet oxygen is formed but its reactions with the dye do not appear to be a major cause of dye laser output deterioration. High light intensity results in dye sensitized, solvent oligomerization to yield materials which interfere with dye stimulated emission. 1, 4-Diazabicyclo2,2,2octane (DABCO)inhibits this oligomerization.

  11. Extra adsorption and adsorbate superlattice formation in metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Sung Cho, Hae; Deng, Hexiang; Miyasaka, Keiichi; Dong, Zhiyue; Cho, Minhyung; Neimark, Alexander V.; Ku Kang, Jeung; Yaghi, Omar M.; Terasaki, Osamu

    2015-11-01

    Metal-organic frameworks (MOFs) have a high internal surface area and widely tunable composition, which make them useful for applications involving adsorption, such as hydrogen, methane or carbon dioxide storage. The selectivity and uptake capacity of the adsorption process are determined by interactions involving the adsorbates and their porous host materials. But, although the interactions of adsorbate molecules with the internal MOF surface and also amongst themselves within individual pores have been extensively studied, adsorbate-adsorbate interactions across pore walls have not been explored. Here we show that local strain in the MOF, induced by pore filling, can give rise to collective and long-range adsorbate-adsorbate interactions and the formation of adsorbate superlattices that extend beyond an original MOF unit cell. Specifically, we use in situ small-angle X-ray scattering to track and map the distribution and ordering of adsorbate molecules in five members of the mesoporous MOF-74 series along entire adsorption-desorption isotherms. We find in all cases that the capillary condensation that fills the pores gives rise to the formation of ‘extra adsorption domains’—that is, domains spanning several neighbouring pores, which have a higher adsorbate density than non-domain pores. In the case of one MOF, IRMOF-74-V-hex, these domains form a superlattice structure that is difficult to reconcile with the prevailing view of pore-filling as a stochastic process. The visualization of the adsorption process provided by our data, with clear evidence for initial adsorbate aggregation in distinct domains and ordering before an even distribution is finally reached, should help to improve our understanding of this process and may thereby improve our ability to exploit it practically.

  12. Supercritical fluid regeneration of adsorbents

    NASA Astrophysics Data System (ADS)

    Defilippi, R. P.; Robey, R. J.

    1983-05-01

    The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

  13. Adsorption of reactive blue BF-5G dye by soybean hulls: kinetics, equilibrium and influencing factors.

    PubMed

    Honorio, Jacqueline Ferandin; Veit, Márcia Teresinha; Gonçalves, Gilberto da Cunha; de Campos, Élvio Antonio; Fagundes-Klen, Márcia Regina

    2016-01-01

    The textile industry is known for the high use of chemicals, such as dyes, and large volumes of effluent that contaminate waters, a fact that has encouraged research and improved treatment techniques. In this study, we used unprocessed soybean hulls for the removal of reactive blue BF-5G dye. The point of zero charge of soybean hulls was 6.76. Regarding the speed of agitation in the adsorption process, the resistance to mass transfer that occurs in the boundary layer was eliminated at 100 rpm. Kinetics showed an experimental amount of dye adsorbed at equilibrium of 57.473 mg g(-1) obtained under the following conditions: dye initial concentration = 400 mg L(-1); diameter of particle = 0.725 mm; dosage = 6 g L(-1); pH 2; 100 rpm; temperature = 30 °C; and duration of 24 hours. The pseudo-second order best showed the dye removal kinetics. The adsorption isotherms performed at different temperatures (20, 30, 40 and 50 °C) showed little variation in the concentration range assessed, being properly adjusted by the Langmuir isotherm model. The maximum capacity of dye adsorption was 72.427 mg g(-1) at 30 °C. Since soybean hull is a low-cost industrial byproduct, it proved to be a potential adsorbent for the removal of the textile dye assessed. PMID:26942540

  14. Magnetic Pycnoporus sanguineus-loaded alginate composite beads for removing dye from aqueous solutions.

    PubMed

    Yang, Chih-Hui; Shih, Ming-Cheng; Chiu, Han-Chen; Huang, Keng-Shiang

    2014-01-01

    Dye pollution in wastewater is a severe environmental problem because treating water containing dyes using conventional physical, chemical, and biological treatments is difficult. A conventional process is used to adsorb dyes and filter wastewater. Magnetic filtration is an emerging technology. In this study, magnetic Pycnoporus sanguineus-loaded alginate composite beads were employed to remove a dye solution. A white rot fungus, P. sanguineus, immobilized in alginate beads were used as a biosorbent to remove the dye solution. An alginate polymer could protect P. sanguineus in acidic environments. Superparamagnetic nanomaterials, iron oxide nanoparticles, were combined with alginate gels to form magnetic alginate composites. The magnetic guidability of alginate composites and biocompatibility of iron oxide nanoparticles facilitated the magnetic filtration and separation processes. The fungus cells were immobilized in loaded alginate composites to study the influence of the initial dye concentration and pH on the biosorption capacity. The composite beads could be removed easily post-adsorption by using a magnetic filtration process. When the amount of composite beads was varied, the results of kinetic studies of malachite green adsorption by immobilized cells of P. sanguineus fitted well with the pseudo-second-order model. The results indicated that the magnetic composite beads effectively adsorbed the dye solution from wastewater and were environmentally friendly. PMID:24945580

  15. Insight into removal kinetic and mechanisms of anionic dye by calcined clay materials and lime.

    PubMed

    Vimonses, Vipasiri; Jin, Bo; Chow, Christopher W K

    2010-05-15

    Our recent work reported that a mixed adsorbent with natural clay materials and lime demonstrated an enhanced capacity and efficiency to remove anionic Congo Red dye from wastewater. This study aims to investigate the removal kinetic and mechanisms of the mixed materials involved in the decolourisation of the dye to maximise their prospective applications for industrial wastewater treatment. The experimental results showed that dye removal was governed by combined physiochemical reactions of adsorption, ion-exchange, and precipitation. Ca-dye precipitation contributed over 70% total dye removal, followed by adsorption and ion-exchange. The dye removal kinetic followed the pseudo-second-order expression and was well described by the Freundlich isotherm model. This study indicated pH was a key parameter to govern the removal mechanisms, i.e. adsorption/coagulation at acidic pH and precipitation at basic condition. Yet, the overall removal efficiency was found to be independent to the operation conditions, resulting in more than 94% dye removal. This work revealed that the mixed clays and lime can be applied as alternative low-cost adsorbents for industrial wastewater treatment. PMID:20079967

  16. Probes labelled with energy transfer coupled dyes

    DOEpatents

    Mathies, R.A.; Glazer, A.; Ju, J.

    1997-11-18

    Compositions are provided comprising sets of fluorescent labels carrying pairs of donor and acceptor dye molecules, designed for efficient excitation of the donors at a single wavelength and emission from the acceptor in each of the pairs at different wavelengths. The different molecules having different donor-acceptor pairs can be modified to have substantially the same mobility under separation conditions, by varying the distance between the donor and acceptor in a given pair. Particularly, the fluorescent compositions find use as labels in sequencing nucleic acids. 7 figs.

  17. Probes labelled with energy transfer coupled dyes

    DOEpatents

    Mathies, Richard A.; Glazer, Alexander; Ju, Jingyue

    1997-01-01

    Compositions are provided comprising sets of fluorescent labels carrying pairs of donor and acceptor dye molecules, designed for efficient excitation of the donors at a single wavelength and emission from the acceptor in each of the pairs at different wavelengths. The different molecules having different donor-acceptor pairs can be modified to have substantially the same mobility under separation conditions, by varying the distance between the donor and acceptor in a given pair. Particularly, the fluorescent compositions find use as labels in sequencing nucleic acids.

  18. Fluorescent aggregates Cyan 40 and Thiazole Orange dyes in solution

    NASA Astrophysics Data System (ADS)

    Nizomov, Negmat; Kurtaliev, Eldar N.; Rahimov, Sherzod I.

    2012-12-01

    Absorption and fluorescence electronic spectra of cyanine dyes Cyan 40 and Thiazole Orange (TO) in water and in binary mixtures: water + ethanol, water + DMF, water + dioxane and chloroform + hexane were studied. It was revealed, that increase of concentration of Cyan 40 and TO dyes in water and chloroform + hexane binary mixture promotes the formation of fluorescent H-aggregates. Meanwhile, in contrary to the well-known fluorescent aggregates, electronic absorption band of aggregated molecules is shifted to the shorter wavelengths and fluorescence band is shifted to the longer wavelengths relative to the bands of the monomer molecules. Observed spectral changes are explained on the basis of Davidov's theory of molecular excitons as splitting of the electron-excited states due to the aggregation of dye molecules.

  19. Footprint organization of chiral molecules on metallic surfaces

    NASA Astrophysics Data System (ADS)

    Uñac, R. O.; Rabaza, A. V. Gil; Vidales, A. M.; Zgrablich, G.

    2007-10-01

    We study the behavior of chiral molecules adsorbed on clean metallic surfaces using a lattice-gas model and Monte Carlo simulation. The aim is to model and simulate the structure (footprints and organization) formed by molecules on the surface as they adsorb. The model, which is applicable to chiral species like S- and R-alanine, or similar, discloses the conditions to generate different ordered phases that have been observed in experiments by other authors. In our model, each enantiomer may adsorb in two different configurations (species) and several effects are taken into account: inhibition, blockage of neighboring adsorptive sites (steric effects) and promotion of sites representing, in some sense, modifications in the surface properties due to molecule-surface interactions. These adsorption rules are inspired by the enantiomeric character of adsorbed species. We perform a systematic study of the different phases formed in order to qualitatively understand the mechanism for the formation of adsorbate structures experimentally found by other authors.

  20. Selective adsorption of cationic dyes by UiO-66-NH2

    NASA Astrophysics Data System (ADS)

    Chen, Qi; He, Qinqin; Lv, Mengmeng; Xu, Yanli; Yang, Hanbiao; Liu, Xueting; Wei, Fengyu

    2015-02-01

    Herein, two zirconium(IV)-based MOFs UiO-66 and UiO-66-NH2 had been successfully prepared by a facile solvothermal method and were characterized by X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS), and zeta potential. They exhibit small size, large surface area, and can remove cationic dyes from aqueous solution more effectively than anionic dyes. This adsorption selectivity is due to the favorable electrostatic interactions between the adsorbents and cationic dyes. Furthermore, owing to the individual micropore structure of UiO-66-NH2 and its more negative zeta potential resulted from the charge balance for the protonation of -NH2, UiO-66-NH2 displays much higher adsorption capacity for cationic dyes and lower adsorption capacity for anionic dyes than UiO-66.

  1. Removal of Congo red dye from aqueous solutions using a halloysite-magnetite-based composite.

    PubMed

    Ferrarini, F; Bonetto, L R; Crespo, Janaina S; Giovanela, M

    2016-01-01

    Adsorption has been considered as one of the most effective methods to remove dyes from aqueous solutions due to its ease of operation, high efficiency and wide adaptability. In view of all these aspects, this study aimed to evaluate the adsorption capacity of a halloysite-magnetite-based composite in the removal of Congo red dye from aqueous solutions. The effects of stirring rate, pH, initial dye concentration and contact time were investigated. The results revealed that the adsorption kinetics followed the pseudo-second-order model, and equilibrium was well represented by the Brunauer-Emmett-Teller isotherm. The thermodynamic data showed that dye adsorption onto the composite was spontaneous and endothermic and occurred by physisorption. Finally, the composite could also be regenerated at least four times by calcination and was shown to be a promising adsorbent for the removal of this dye. PMID:27148714

  2. Co-sensitized natural dyes potentially used to enhance light harvesting capability

    NASA Astrophysics Data System (ADS)

    Amelia, R.; Sawitri, D.; Risanti, D. D.

    2015-01-01

    We present the photoelectrochemical properties of dye-sensitized solar cells using natural pigments containing anthocyanins, betalains, and caroteins. The dyes were adsorbed by a photoanode that was fabricated from nanocrystalline TiO2 on transparent conductive glass. TiO2 comprises of 100% anatase and 90:10 anatase:rutile fraction. The dyes extracted from mangosteen pericarp, Musa aromatica pericarp, Celosia cristata flower and red beet root were characterized through UV-vis and IPCE. The effectiveness of the dyes was explained through photocurrent as a function of incident light power. It was found that the cocktail and multilayered dyes comprised of anthocyanins and caroteins is beneficial to obtain high photocurrent, whereas betalains is not recommended to be applied on untreated TiO2. Due to the bandgap properties of rutile and anatase, the presence of 10% rutile in TiO2 is favourable to further enhance the electron transport.

  3. Selective Gas Capture Ability of Gas-Adsorbent-Incorporated Cellulose Nanofiber Films.

    PubMed

    Shah, Kinjal J; Imae, Toyoko

    2016-05-01

    The 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized cellulose nanofibers (TOCNF) were hybridized with cation and anion-exchange organoclays, where poly(amido amine) dendrimers were loaded to enhance the functionality of gas adsorption, since dendrimers have the high adsorbability and the enough selectivity on the gas adsorption. The thin films were prepared from the organoclay-TOCNF hybrids and supplied to the gas adsorption. The adsorption of CO2 and NH3 gases increased with an increasing amount of organoclays in TOCNF films, but the behavior of the increase depended on gases, clays, and dendrimers. The hydrotalcite organoclay-TOCNF films displayed the highest adsorption of both gases, but the desorption of CO2 gas from hydrotalcite organoclay-TOCNF films was drastically high in comparison with the other systems. While the CO2 gas is adsorbed and remained on cationic dendrimer sites in cation-exchange organoclay-TOCNF films, the CO2 gas is adsorbed on cationic clay sites in anion exchange organoclay-TOCNF films, and it is easily desorbed from the films. The NH3 adsorption is inversive to the CO2 adsorption. Then the CO2 molecules adsorbed on the cationic dendrimers and the NH3 molecules adsorbed on the anionic dendrimers are preferably captured in these adsorbents. The present research incorporated dendrimers will be contributing to the development of gas-specialized adsorbents, which are selectively storable only in particular gases. PMID:27035217

  4. Plasma surface functionalization and dyeing kinetics of Pan-Pmma copolymers

    NASA Astrophysics Data System (ADS)

    Labay, C.; Canal, C.; Rodríguez, C.; Caballero, G.; Canal, J. M.

    2013-10-01

    Fiber surface modification with air corona plasma has been studied through dyeing kinetics under isothermal conditions at 30 °C on an acrylic-fiber fabric with a cationic dye (CI Basic Blue 3) analyzing the absorption, desorption and fixing on the surface of molecules having defined cationic character. The initial dyeing rate in the first 60 s indicates an increase of 58.3% in the dyeing rate due to the effect of corona plasma on the acrylic fiber surface. At the end of the dyeing process, the plasma-treated fabrics absorb 24.7% more dye, and the K/S value of the acrylic fabric increases by 8.8%. With selected dyestuff molecules, new techniques can be designed to amplify the knowledge about plasma-treated surface modifications of macromolecules.

  5. Smart Adsorbents with Photoregulated Molecular Gates for Both Selective Adsorption and Efficient Regeneration.

    PubMed

    Cheng, Lei; Jiang, Yao; Yan, Ni; Shan, Shu-Feng; Liu, Xiao-Qin; Sun, Lin-Bing

    2016-09-01

    Selective adsorption and efficient regeneration are two crucial issues for adsorption processes; unfortunately, only one of them instead of both is favored by traditional adsorbents with fixed pore orifices. Herein, we fabricated a new generation of smart adsorbents through grafting photoresponsive molecules, namely, 4-(3-triethoxysilylpropyl-ureido)azobenzene (AB-TPI), onto pore orifices of the support mesoporous silica. The azobenzene (AB) derivatives serve as the molecular gates of mesopores and are reversibly opened and closed upon light irradiation. Irradiation with visible light (450 nm) causes AB molecules to isomerize from cis to trans configuration, and the molecular gates are closed. It is easy for smaller adsorbates to enter while difficult for the larger ones, and the selective adsorption is consequently facilitated. Upon irradiation with UV light (365 nm), the AB molecules are transformed from trans to cis isomers, promoting the desorption of adsorbates due to the opened molecular gates. The present smart adsorbents can consequently benefit not only selective adsorption but also efficient desorption, which are exceedingly desirable for adsorptive separation but impossible for traditional adsorbents with fixed pore orifices. PMID:27559985

  6. Competition between Displacement and Dissociation of a Strong Acid Compared to a Weak Acid Adsorbed on Silica Particle Surfaces: The Role of Adsorbed Water.

    PubMed

    Fang, Yuan; Tang, Mingjin; Grassian, Vicki H

    2016-06-16

    The adsorption of nitric (HNO3) and formic (HCOOH) acids on silica particle surfaces and the effect of adsorbed water have been investigated at 296 K using transmission FTIR spectroscopy. Under dry conditions, both nitric and formic acids adsorb reversibly on silica. Additionally, the FTIR spectra show that both of these molecules remain in the protonated form. At elevated relative humidities (RH), adsorbed water competes both for surface adsorption sites with these acids as well as promotes their dissociation to hydronium ions and the corresponding anions. Compared to HNO3, the extent of dissociation is much smaller for HCOOH, very likely because it is a weaker acid. This study provides valuable insights into the interaction of HNO3 and HCOOH with silica surface on the molecular level and further reveals the complex roles of surface-adsorbed water in atmospheric heterogeneous chemistry of mineral dust particles-many of these containing silica. PMID:27220375

  7. Method And Apparatus For Regenerating Nox Adsorbers

    DOEpatents

    Driscoll, J. Joshua; Endicott, Dennis L.; Faulkner, Stephen A.; Verkiel, Maarten

    2006-03-28

    Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.

  8. Photochronocoulometric measurement of the coverage of surface-bound dyes on titanium dioxide crystal surfaces.

    PubMed

    Lu, Yunfeng; Spitler, Mark T; Parkinson, B A

    2006-12-21

    Atomically flat terraced single-crystal anatase and rutile surfaces can be prepared allowing for the reproducible adsorption of covalently attached sensitizing dyes. Once reproducible surfaces and dye coverages are achieved, a photochronocoulometric technique is developed to measure the surface coverage of the dyes, an important parameter in determining the efficiency of sensitization. The surface-bound dyes are irreversibly oxidized by exposure to a light pulse with the n-type oxide semiconductor electrode held in depletion. A double-exponential decay of the subsequent photocurrent is then measured, where the integration of the faster decay is associated with the adsorbed dye coverage and the second much slower decay is attributed to trace regenerators, including water, in the nonaqueous electrolyte. The ruthenium-based N3 dye shows the expected linear dependence of the rate constant on light intensity whereas a dicarboxylated thiacyanine dye shows a square root dependence of its photooxidation rate on light intensity. The sublinear response of the thiacyanine dye is discussed in terms of the more complex surface chemistry that is known for this family of sensitizing dyes. PMID:17165972

  9. Photoconductivity of organic polymer films doped with porous silicon nanoparticles and ionic polymethine dyes

    SciTech Connect

    Davidenko, N. A. Skrichevsky, V. A.; Ishchenko, A. A.; Karlash, A. Yu.; Mokrinskaya, E. V.

    2009-05-15

    Features of electrical conductivity and photoconductivity of polyvinylbutyral films containing porous silicon nanoparticles and similar films doped with cationic and anionic polymethine dyes are studied. Sensitization of the photoelectric effect by dyes with different ionicities in films is explained by the possible photogeneration of holes and electrons from dye molecules and the intrinsic bipolar conductivity of porous silicon nanoparticles. It is assumed that the electronic conductivity in porous silicon nanoparticles is higher in comparison with p-type conductivity.

  10. Light harvesting over a wide range of wavelength using natural dyes of gardenia and cochineal for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Park, Kyung-Hee; Kim, Tae-Young; Han, Shin; Ko, Hyun-Seok; Lee, Suk-Ho; Song, Yong-Min; Kim, Jung-Hun; Lee, Jae-Wook

    2014-07-01

    Two natural dyes extracted from gardenia yellow (Gardenia jasminoides) and cochineal (Dactylopius coccus) were used as sensitizers in the assembly of dye-sensitized solar cells (DSSCs) to harvest light over a wide range of wavelengths. The adsorption characteristics, electrochemical properties and photovoltaic efficiencies of the natural DSSCs were investigated. The adsorption kinetics data of the dyes were obtained in a small adsorption chamber and fitted with a pseudo-second-order model. The photovoltaic performance of a photo-electrode adsorbed with single-dye (gardenia or cochineal) or the mixture or successive adsorption of the two dyes, was evaluated from current-voltage measurements. The energy conversion efficiency of the TiO2 electrode with the successive adsorption of cochineal and gardenia dyes was 0.48%, which was enhanced compared to single-dye adsorption. Overall, a double layer of the two natural dyes as sensitizers was successfully formulated on the nanoporous TiO2 surface based on the differences in their adsorption affinities of gardenia and cochineal.

  11. Nanometer Resolution Imaging by SIngle Molecule Switching

    SciTech Connect

    Hu, Dehong; Orr, Galya

    2010-04-02

    The fluorescence intensity of single molecules can change dramatically even under constant laser excitation. The phenomenon is frequently called "blinking" and involves molecules switching between high and low intensity states.[1-3] In additional to spontaneous blinking, the fluorescence of some special fluorophores, such as cyanine dyes and photoactivatable fluorescent proteins, can be switched on and off by choice using a second laser. Recent single-molecule spectroscopy investigations have shed light on mechanisms of single molecule blinking and photoswitching. This ability to controllably switch single molecules led to the invention of a novel fluorescence microscopy with nanometer spatial resolution well beyond the diffraction limit.

  12. Distribution of metal and adsorbed guest species in zeolites

    SciTech Connect

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  13. Preparation of surface modified zinc oxide nanoparticle with high capacity dye removal ability

    SciTech Connect

    Mahmoodi, Niyaz Mohammad; Najafi, Farhood

    2012-07-15

    Highlights: ► Amine-functionalized zinc oxide nanoparticle (AFZON) was synthesized. ► Isotherm and kinetics data followed Langmuir isotherm and pseudo-second order kinetic model, respectively. ► Q{sub 0} of ZON for AB25, DR23 and DR31 was 20, 12 and 15 mg/g, respectively. ► Q{sub 0} of AFZON for AB25, DR23 and DR31 was 1250, 1000 and 1429 mg/g, respectively. ► AFZON was regenerated at pH 12. -- Abstract: In this paper, the surface modification of zinc oxide nanoparticle (ZON) by amine functionalization was studied to prepare high capacity adsorbent. Dye removal ability of amine-functionalized zinc oxide nanoparticle (AFZON) and zinc oxide nanoparticle (ZON) was also investigated. The physical characteristics of AFZON were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Acid Blue 25 (AB25), Direct Red 23 (DR23) and Direct Red 31 (DR31) were used as model compounds. The effect of operational parameters such as dye concentration, adsorbent dosage, pH and salt on dye removal was evaluated. The isotherm and kinetic of dye adsorption were studied. The maximum dye adsorption capacity (Q{sub 0}) was 20 mg/g AB25, 12 mg/g DR23 and 15 mg/g DR31 for ZON and 1250 mg/g AB25, 1000 mg/g DR23 and 1429 mg/g DR31 for AFZON. It was found that dye adsorption followed Langmuir isotherm. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. Dye desorption tests (adsorbent regeneration) showed that the maximum dye release of 90% AB25, 86% for DR23 and 90% for DR31 were achieved in aqueous solution at pH 12. Based on the data of the present investigation, it can be concluded that the AFZON being an adsorbent with high dye adsorption capacity might be a suitable alternative to remove dyes from colored aqueous solutions.

  14. Direct Measurement of Adsorbed Gas Redistribution in Metal–Organic Frameworks

    SciTech Connect

    Chen, Ying-Pin; Liu, Yangyang; Liu, Dahuan; Bosch, Mathieu; Zhou, Hong-Cai

    2015-03-04

    Knowledge about the interactions between gas molecules and adsorption sites is essential to customize metal-organic frameworks (MOFs) as adsorbents. The dynamic interactions occurring during adsorption/desorption working cycles with several states are especially complicated. Even so, the gas dynamics based upon experimental observations and the distribution of guest molecules under various conditions in MOFs have not been extensively studied yet. In this work, a direct time-resolved diffraction structure envelope (TRDSE) method using sequential measurements by in situ synchrotron powder X-ray diffraction has been developed to monitor several gas dynamic processes taking place in MOFs: infusion, desorption, and gas redistribution upon temperature change. The electron density maps indicate that gas molecules prefer to redistribute over heterogeneous types of sites rather than to exclusively occupy the primary binding sites. We found that the gas molecules are entropically driven from open metal sites to larger neighboring spaces during the gas infusion period, matching the localized-to-mobile mechanism. In addition, the partitioning ratio of molecules adsorbed at each site varies with different temperatures, as opposed to an invariant distribution mode. Equally important, the gas adsorption in MOFs is intensely influenced by the gas–gas interactions, which might induce more molecules to be accommodated in an orderly compact arrangement. This sequential TRDSE method is generally applicable to most crystalline adsorbents, yielding information on distribution ratios of adsorbates at each type of site.

  15. Laser-driven acoustic desorption of organic molecules from back-irradiated solid foils.

    SciTech Connect

    Zinovev, A. V.; Veryovkin, I. V.; Moore, J. F.; Pellin, M. J.; Materials Science Division; Mass Think

    2007-11-01

    Laser-induced acoustic desorption (LIAD) from thin metal foils is a promising technique for gentle and efficient volatilization of intact organic molecules from surfaces of solid substrates. Using the single-photon ionization method combined with time-of-flight mass spectrometry, we have examined the neutral component of the desorbed flux in LIAD and compared it to that from direct laser desorption. These basic studies of LIAD, conducted for molecules of various organic dyes (rhodamine B, fluorescein, anthracene, coumarin, BBQ), have demonstrated detection of intact parent molecules of the analyte even at its surface concentrations corresponding to a submonolayer coating. In some cases (rhodamine B, fluorescein, BBQ), the parent molecular ion peak was accompanied by a few fragmentation peaks of comparable intensity, whereas for others, only peaks corresponding to intact parent molecules were detected. At all measured desorbing laser intensities (from 100 to 500 MW/cm{sup 2}), the total amount of desorbed parent molecules depended exponentially on the laser intensity. Translational velocities of the desorbed intact molecules, determined for the first time in this work, were of the order of hundreds of meters per second, less than what has been observed in our experiments for direct laser desorption, but substantially greater than the possible perpendicular velocity of the substrate foil surface due to laser-generated acoustic waves. Moreover, these velocities did not depend on the desorbing laser intensity, which implies the presence of a more sophisticated mechanism of energy transfer than direct mechanical or thermal coupling between the laser pulse and the adsorbed molecules. Also, the total flux of desorbed intact molecules as a function of the total number of desorbing laser pulses, striking the same point on the target, decayed following a power law rather than an exponential function, as would have been predicted by the shake-off model. To summarize, the

  16. Phytoremediation of dye contaminated soil by Leucaena leucocephala (subabul) seed and growth assessment of Vigna radiata in the remediated soil

    PubMed Central

    Jayanthy, V.; Geetha, R.; Rajendran, R.; Prabhavathi, P.; Karthik Sundaram, S.; Dinesh Kumar, S.; Santhanam, P.

    2013-01-01

    The present study was investigated for soil bioremediation through sababul plant biomass (Leucaena leucocephala). The soil contaminated with textile effluent was collected from Erode (chithode) area. Various physico-chemical characterizations like N, P, and K and electrical conductivity were assessed on both control and dye contaminated soils before and after remediation. Sababul (L. leucocephala) powder used as plant biomass for remediation was a tool for textile dye removal using basic synthetic dyes by column packing and eluting. The concentration of the dye eluted was compared with its original concentration of dye and were analyzed by using UV–vis spectrophotometer. Sababul plant biomass was analyzed for its physico-chemical properties and active compounds were detected by GC–MS, HPTLC and FTIR. Plant growth was assessed with green gram on the textile contaminated soil and sababul had the potential of adsorbing the dye as the contaminated soil and also check the growth of green gram. PMID:25183943

  17. Preparation and characterization of ammonium-functionalized silica nanoparticle as a new adsorbent to remove methyl orange from aqueous solution

    NASA Astrophysics Data System (ADS)

    Liu, Jinshui; Ma, Shi; Zang, Lingjie

    2013-01-01

    Quaternary ammonium polyethylenimine (PEI) was successfully modified to silica nanoparticle (QPEI/SiO2) as a new adsorbent to remove methyl orange from aqueous solution. The isotherm and kinetics of dye adsorption were studied, which showed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity of QPEI/SiO2 for methyl orange is 105.4 mg/g. The equilibrium time for methyl orange adsorption onto QPEI/SiO2 was as short as 10 min, indicating that the adsorbent has a strong affinity for methyl orange. The adsorption capacities of the methyl orange are slightly influenced by the pH in the range of 3.2-9.6. The QPEI/SiO2 adsorbent can be used in the wide pH range, which is different from other adsorbent. This may attribute to the quaternary ammonium carrying positive charges in acidic and basic solution.

  18. Efficiency Enhancement of Cocktail Dye of Ixora coccinea and Tradescantia spathacea in DSSC

    PubMed Central

    Zolkepli, Zularif; Lim, Andery; Ekanayake, Piyasiri; Tennakoon, Kushan

    2015-01-01

    The use of anthocyanin dyes extracted from epidermal leaves of Tradescantia spathacea (Trant) and petals of Ixora coccinea (IX) was evaluated in the application of dye-sensitized solar cells (DSSCs). Subsequently, cocktail anthocyanin dyes from these dyes were prepared and how they enhanced the cell's overall performance was assessed using five different volume-to-volume ratios. Cocktail dyes absorbed a wider range of light in the visible region, thus increasing the cell efficiencies of the cocktail dyes when compared to the DSSC sensitized by individual dyes. The surface charge (zeta-potential), average size of aggregated anthocyanin molecules (zetasizer), and anthocyanin stability in different storage temperatures were analyzed and recorded. Lower size of aggregated dye molecules as revealed from the cocktail dyes ensured better adsorption onto the TiO2 film. Tradescantia/Ixora pigments mixed in 1 : 4 ratio showed the highest cell efficiency of η = 0.80%, under the irradiance of 100 mW cm−2, with a short-circuit current density 4.185 mA/cm2, open-circuit voltage of 0.346 V, and fill factor of 0.499. It was found that the desired storage temperature for these cocktail dyes to be stable over time was −20°C, in which the anthocyanin half-life was about approximately 1727 days. PMID:26793239

  19. Supramolecular guest-host systems: combining high dye doping level with low aggregation tendency

    NASA Astrophysics Data System (ADS)

    Priimagi, Arri; Cattaneo, Stefano; Ras, Robin H. A.; Valkama, Sami; Ikkala, Olli; Kauranen, Martti

    2006-08-01

    We demonstrate that the aggregation tendency of dye molecules in a host polymer can be significantly reduced by exploiting non-covalent interactions between the host polymer and guest dye molecules. Such interactions occur spontaneously with no need for chemical synthesis, and could thus be utilized to combine the ease of processing of traditional guest-host systems with the high dye concentrations achievable in covalently linked systems. We studied the aggregation properties of the common azo-dye Disperse Red 1 in polymers with different functional groups. Compared to a nonpolar polymer (polystyrene), dye aggregation tendency is substantially reduced in polar polymer matrices containing hydrogen-bond donating [poly(vinylphenol)] or hydrogen-bond accepting [poly(4-vinylpyridine)] functional sites. Furthermore, by forming a polyelectrolyte-dye complex [Disperse Red 1/poly(styrenesulfonic acid)], a dye monomer can be attached to approximately each polymer unit, resulting in dye concentration of 63 wt. %. Complexation through proton transfer was further studied by using a fluorescent dye 5-phenyl-2-(4-pyridyl)oxazole. Our results indicate that polymer-dye complexes could provide a facile route for new type of optical materials, with potential applications in various fields of optics and photonics.

  20. Efficiency Enhancement of Cocktail Dye of Ixora coccinea and Tradescantia spathacea in DSSC.

    PubMed

    Zolkepli, Zularif; Lim, Andery; Ekanayake, Piyasiri; Tennakoon, Kushan

    2015-01-01

    The use of anthocyanin dyes extracted from epidermal leaves of Tradescantia spathacea (Trant) and petals of Ixora coccinea (IX) was evaluated in the application of dye-sensitized solar cells (DSSCs). Subsequently, cocktail anthocyanin dyes from these dyes were prepared and how they enhanced the cell's overall performance was assessed using five different volume-to-volume ratios. Cocktail dyes absorbed a wider range of light in the visible region, thus increasing the cell efficiencies of the cocktail dyes when compared to the DSSC sensitized by individual dyes. The surface charge (zeta-potential), average size of aggregated anthocyanin molecules (zetasizer), and anthocyanin stability in different storage temperatures were analyzed and recorded. Lower size of aggregated dye molecules as revealed from the cocktail dyes ensured better adsorption onto the TiO2 film. Tradescantia/Ixora pigments mixed in 1 : 4 ratio showed the highest cell efficiency of η = 0.80%, under the irradiance of 100 mW cm(-2), with a short-circuit current density 4.185 mA/cm(2), open-circuit voltage of 0.346 V, and fill factor of 0.499. It was found that the desired storage temperature for these cocktail dyes to be stable over time was -20°C, in which the anthocyanin half-life was about approximately 1727 days. PMID:26793239

  1. Degradation of various dyes using Laccase enzyme.

    PubMed

    Dhaarani, S; Priya, A K; Rajan, T Vel; Kartic, D Navamani

    2012-10-01

    Disposal of untreated dyeing effluent in water bodies, from textile industries, cause serious environmental and health hazards. The chemical structures of dye molecules are designed to resist fading on exposure to light or chemical attack, and they prove to be quite resistant towards microbial degradation. Therefore, current conventional biological processes may not be able to meet wastewater discharge criteria and reuse. An enzymatic treatment undergoes oxidative cleavage avoiding formation of toxic amines. Laccase is a multi-copper containing protein that catalyzes the oxidation of a wide range of aromatic substrates concomitantly with the reduction of molecular oxygen to water. UV visible spectral analysis of various synthetic dyes was performed in the study and wavelengths of maximum absorbance determined. Laccase enzyme was obtained from the fungi Pleorotus ostreatus. The enzyme showed high efficiency against Malachite Green, Basic Red and Acid Majanta with decolorization capacities of 97%, 94% and 94% respectively. Further, these dyes can be used for optimization of degradation parameters and analysis of degradation products. PMID:25151712

  2. Tunable optofluidic distributed feedback dye lasers

    NASA Astrophysics Data System (ADS)

    Li, Zhenyu; Zhang, Zhaoyu; Emery, Teresa; Scherer, Axel; Psaltis, Demetri

    2006-08-01

    We demonstrated a continuously tunable optofluidic distributed feedback (DFB) dye laser on a monolithic poly(dimethylsiloxane) (PDMS) elastomer chip. The optical feedback was provided by a phase-shifted higher order Bragg grating embedded in the liquid core of a single mode buried channel waveguide. We achieved nearly 60nm continuously tunable output by mechanically varying the grating period with two dye molecules Rhodamine 6G (Rh6G) and Rhodamine 101 (Rh101). Single-mode operation was obtained with <0.1nm linewidth. Because of the higher order grating, a single laser, when operated with different dye solutions, can provide tunable output covering from near UV to near IR spectral region. The low pump threshold (< 1uJ) makes it possible to use a single high energy pulsed laser to pump hundreds of such lasers on a chip. An integrated array of five DFB dye lasers with different lasing wavelengths was also demonstrated. Such laser arrays make it possible to build highly parallel optical sensors on a chip. The laser chip is fully compatible with PDMS based soft microfluidics.

  3. Effect of hydrophobicity of cationic carbocyanine dyes DiOC n on their binding to anionic surfactant micelles

    NASA Astrophysics Data System (ADS)

    Lebed, A. S.; Yefimova, S. L.; Guralchuk, G. Ya.; Sorokin, A. V.; Borovoy, I. A.; Malyukin, Yu. V.

    2010-05-01

    The interaction of a series of cationic dialkyloxacarbocyanine perchlorate (DiOC n ) dyes of different degrees of hydrophobicity with micelles of an anionic surfactant, sodium dodecylsulfate (SDS), has been studied spectrophotometrically in aqueous solutions. The Benesi-Hildebrand equation was used to calculate binding constants ( K b ) of the dyes to surfactant micelles, the fraction of dye bound to the micelles ( f mic ), and the standard free-energy change (Δ G 0) for the transfer of dye from the aqueous to micellar phase. It has been shown that the interaction of oppositely charged dye molecules and surfactant micelles is controlled by both electrostatic and hydrophobic interactions. A small increase in dye hydrophobicity due to lengthening of the hydrocarbon radical has been shown to cause an abrupt nonlinear increase of the fmic value. This points to a key role of hydrophobic interactions in the binding of dye molecules with the micelles.

  4. Adsorbate-induced curvature and stiffening of graphene.

    PubMed

    Svatek, Simon A; Scott, Oliver R; Rivett, Jasmine P H; Wright, Katherine; Baldoni, Matteo; Bichoutskaia, Elena; Taniguchi, Takashi; Watanabe, Kenji; Marsden, Alexander J; Wilson, Neil R; Beton, Peter H

    2015-01-14

    The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology. PMID:25469625

  5. Monte Carlo lattice models for adsorbed polymer conformation

    NASA Technical Reports Server (NTRS)

    Good, B. S.

    1985-01-01

    The adhesion between a polymer film and a metal surface is of great technological interest. However, the prediction of adhesion and wear properties of polymer coated metals is quite difficult because a fundamental understanding of the polymer surface interaction does not yet exist. A computer model for the conformation of a polymer molecule adsorbed on a surface is discussed. The chain conformation is assumed to be described by a partially directed random walk on a three dimensional simple cubic lattice. An attractive surface potential is incorporated into the model through the use of a random walk step probability distribution that is anisotropic in the direction normal to the attractive surface. The effects of variations in potential characteristics are qualitatively included by varying both the degree of anisotropy of the step distribution and the range of the anisotropy. Polymer conformation is characterized by the average end to end distance, average radius of gyration, and average number of chain segments adsorbed on the surface.

  6. Surface Adsorbate Fluctuations and Noise in Nanoelectromechanical Systems

    PubMed Central

    Yang, Y. T.; Callegari, C.; Feng, X. L.; Roukes, M. L.

    2013-01-01

    Physisorption on solid surfaces is important in both fundamental studies and technology. Adsorbates can also be critical for the performance of miniature electromechanical resonators and sensors. Advances in resonant nanoelectromechanical systems (NEMS), particularly mass sensitivity attaining the single-molecule level, make it possible to probe surface physics in a new regime, where a small number of adatoms cause a detectable frequency shift in a high quality factor (Q) NEMS resonator, and adsorbate fluctuations result in resonance frequency noise. Here we report measurements and analysis of the kinetics and fluctuations of physisorbed xenon (Xe) atoms on a high-Q NEMS resonator vibrating at 190.5 MHz. The measured adsorption spectrum and frequency noise, combined with analytic modeling of surface diffusion and adsorption–desorption processes, suggest that diffusion dominates the observed excess noise. This study also reveals new power laws of frequency noise induced by diffusion, which could be important in other low-dimensional nanoscale systems. PMID:21388120

  7. Allantoin as a solid phase adsorbent for removing endotoxins.

    PubMed

    Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Gagnon, Pete

    2013-10-01

    In this study we present a simple and robust method for removing endotoxins from protein solutions by using crystals of the small-molecule compound 2,5-dioxo-4-imidazolidinyl urea (allantoin) as a solid phase adsorbent. Allantoin crystalline powder is added to a protein solution at supersaturated concentrations, endotoxins bind and undissolved allantoin crystals with bound endotoxins are removed by filtration or centrifugation. This method removes an average of 99.98% endotoxin for 20 test proteins. The average protein recovery is ∼80%. Endotoxin binding is largely independent of pH, conductivity, reducing agent and various organic solvents. This is consistent with a hydrogen-bond based binding mechanism. Allantoin does not affect protein activity and stability, and the use of allantoin as a solid phase adsorbent provides better endotoxin removal than anion exchange, polymixin affinity and biological affinity methods for endotoxin clearance. PMID:24001944

  8. Uptake of dyes by a promising locally available agricultural solid waste: coir pith.

    PubMed

    Namasivayam, C; Radhika, R; Suba, S

    2001-01-01

    The adsorption of rhodamine-B and acid violet by coir pith carbon was carried out by varying the parameters such as agitation time, dye concentration, adsorbent dose and pH. The adsorption followed both Langmuir and Freundlich isotherms. The adsorption capacity was found to be 2.56 mg and 8.06 mg dye per g of the adsorbent for rhodamine-B and acid violet, respectively. Adsorption of dyes followed first order rate kinetics. Acidic pH was favorable for the adsorption of acid violet and alkaline pH was favorable to rhodamine-B. Desorption studies showed that alkaline pH was favorable for the desorption of acid violet and acidic pH was favorable for the desorption of rhodamine-B. PMID:11300538

  9. Graphene-enhanced Raman spectroscopy of thymine adsorbed on single-layer graphene

    NASA Astrophysics Data System (ADS)

    Fesenko, Olena; Dovbeshko, Galyna; Dementjev, Andrej; Karpicz, Renata; Kaplas, Tommi; Svirko, Yuri

    2015-04-01

    Graphene-enhanced Raman scattering (GERS) spectra and coherent anti-Stokes Raman scattering (CARS) of thymine molecules adsorbed on a single-layer graphene were studied. The enhancement factor was shown to depend on the molecular groups of thymine. In the GERS spectra of thymine, the main bands are shifted with respect to those for molecules adsorbed on a glass surface, indicating charge transfer for thymine on graphene. The probable mechanism of the GERS enhancement is discussed. CARS spectra are in accord with the GERS results, which indicates similar benefit from the chemical enhancement.

  10. A DNA Crystal Designed to Contain Two Molecules per Asymmetric Unit

    SciTech Connect

    T Wang; R Sha; J Birktoft; J Zheng; C Mao; N Seeman

    2011-12-31

    We describe the self-assembly of a DNA crystal that contains two tensegrity triangle molecules per asymmetric unit. We have used X-ray crystallography to determine its crystal structure. In addition, we have demonstrated control over the colors of the crystals by attaching either Cy3 dye (pink) or Cy5 dye (blue-green) to the components of the crystal, yielding crystals of corresponding colors. Attaching the pair of dyes to the pair of molecules yields a purple crystal.

  11. Molecule nanoweaver

    DOEpatents

    Gerald, II; Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  12. Influence of dye content on the conduction band edge of titania in the steam-treated dye-dispersing titania electrodes.

    PubMed

    Setiawan, Rudi Agus; Nishikiori, Hiromasa; Tanaka, Nobuaki; Fujii, Tsuneo

    2014-01-01

    The titania and dye-dispersing titania electrodes were prepared by a nitric acid-catalyzed sol-gel process. The dye-dispersing titania contains the dye molecules dispersed on the surface of the individual nanosized titania particles. The photo-cyclic voltammetry (Photo-CV) and photoelectric measurements of the dye-dispersing titania electrodes were conducted to clarify the factors changing the conduction band edge of the titania and the open-circuit voltage (Voc ) of the electrodes. The remaining nitrate ions caused a negative shift of conduction band edge of the titania of the dye-dispersing titania. The conduction band edge of the titania was shifted in a negative direction in the electrode containing a greater amount of the dye. These results are due to the adsorption of nitrate ions and the dye-titania complex formation on the titania particle surface. The effect of the dye-titania complex formation on the shift in the titania conduction band edge was greater than that of the adsorption of nitrate ions due to strong interaction between the dye and titania through the carboxylate and quinone-like groups of the dye. The shift in the titania conduction band edge corresponded to the change in the Voc value. PMID:24893823

  13. Kinetic modeling of liquid-phase adsorption of Congo red dye using guava leaf-based activated carbon

    NASA Astrophysics Data System (ADS)

    Ojedokun, Adedamola Titi; Bello, Olugbenga Solomon

    2016-02-01

    Guava leaf, a waste material, was treated and activated to prepare adsorbent. The adsorbent was characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR) and Energy-Dispersive X-ray (EDX) techniques. The carbonaceous adsorbent prepared from guava leaf had appreciable carbon content (86.84 %). The adsorption of Congo red dye onto guava leaf-based activated carbon (GLAC) was studied in this research. Experimental data were analyzed by four different model equations: Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms and it was found to fit Freundlich equation most. Adsorption rate constants were determined using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion model equations. The results clearly showed that the adsorption of CR dye onto GLAC followed pseudo-second-order kinetic model. Intraparticle diffusion was involved in the adsorption process. The mean energy of adsorption calculated from D-R isotherm confirmed the involvement of physical adsorption. Thermodynamic parameters were obtained and it was found that the adsorption of CR dye onto GLAC was an exothermic and spontaneous process at the temperatures under investigation. The maximum adsorption of CR dye by GLAC was found to be 47.62 mg/g. The study shows that GLAC is an effective adsorbent for the adsorption of CR dye from aqueous solution.

  14. Surface modified magnetic nanoparticles as efficient and green sorbents: Synthesis, characterization, and application for the removal of anionic dye

    NASA Astrophysics Data System (ADS)

    Rajabi, Hamid Reza; Arjmand, Hooman; Hoseini, S. Jafar; Nasrabadi, Hasan

    2015-11-01

    The object of this study was to evaluate the removal efficiency of sunset yellow (SY) anionic dye from aqueous solutions by using new surface modified iron oxide magnetic nanoparticles (MNPs). Pure Fe3O4 MNPs were synthesized and then functionalized by aminopropyltriethoxysilane (APTES), through a chemical precipitation method. Characterization of the prepared MNP adsorbents was performed by furrier transform infrared (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM). According to XRD and TEM results, average size of the magnetic Fe3O4/APTES NPs was estimated to be around 12 nm. The prepared magnetic adsorbent can be well dispersed in the water and easily separated magnetically from the medium after loaded with adsorbate. In the adsorption process, the effect of main experimental parameters such as pH of dye solution, initial concentration of SY dye, reaction time, and amount of MNP adsorbent on the removal of SY were studied and optimized. The small amount of this adsorbent (10 mg) is applicable for the removal of high concentrations of SY dye in reasonable time (17 min), at pH 3.1. Additionally, the adsorption studies show that the Langmuir model is a suitable model to explain the experimental data with high correlation coefficient.

  15. ESTIMATION OF IONIZATION CONSTANTS OF AZO DYES AND RELATED AROMATIC AMINES: ENVIRONMENTAL IMPLICATIONS

    EPA Science Inventory

    Ionization constants for 214 dye molecules were calculated from molecular structures using the chemical reactivity models developed in SPARC (SPARC Performs Automated Reasoning in Chemistry). hese models used fundamental chemical structure theory to predict chemical reactivities ...

  16. Synthesis of Charge Transfer Dyes for Use as Molecular Sensors in Biological Systems

    NASA Technical Reports Server (NTRS)

    Christie, Joseph J.

    2003-01-01

    This is a continuation of last year's project to synthesize tetraaryl substituted benzodifurans for use as molecular probes in biological systems. The project will involve the synthesis and chemical characterization of dyes and precursor molecules.

  17. Coherence-Modulated Third Harmonic Generation for Second Hyper-Raman Spectroscopy of Molecules at an Interface

    NASA Astrophysics Data System (ADS)

    Dillman, Kevin; Wilson, Jesse; Bartels, Randy; Levinger, Nancy

    2012-02-01

    We have developed a method of probing the low-frequency (sub-1000 cm-1) vibrational modes of molecules at interfaces using third-harmonic generation (THG). The THG process is enhanced at an interface due to the differences in the third-order nonlinear susceptibilities of the materials. We have used this method to collect low-frequency second hyper-Raman spectra from BGO, BaF2 and CdWO4 crystals. In addition, we have observed coherent second hyper-Raman scattering arising from CCl4 molecules at the liquid-glass interface. We are presently extending these techniques to observe resonant second hyper-Raman scattering from dye molecules adsorbed on gold nanoparticles in order to gain surface enhancement effects. We aim to use this method to characterize the environment at interfaces of reverse micelle systems. The development of this method is significant because we can sensitively probe the low-frequency vibrational modes of only those molecules at an interface.

  18. Electrochemical removal of synthetic textile dyes from aqueous solutions using Ti/Pt anode: role of dye structure.

    PubMed

    Araújo, Cynthia K C; Oliveira, Gustavo R; Fernandes, Nedja S; Zanta, Carmem L P S; Castro, Suely Souza Leal; da Silva, Djalma R; Martínez-Huitle, Carlos A

    2014-01-01

    In this work, the efficiency of electrochemical oxidation (EO) was investigated for removing a dye mixture containing Novacron Yellow (NY) and Remazol Red (RR) in aqueous solutions using platinum supported on titanium (Ti/Pt) as anode. Different current densities (20, 40 and 60 mA cm(-2)) and temperatures (25, 40 and 60 °C) were studied during electrochemical treatment. After that, the EO of each of these dyes was separately investigated. The EO of each of these dyes was performed, varying only the current density and keeping the same temperature (25 °C). The elimination of colour was monitored by UV-visible spectroscopy, and the degradation of organic compounds was analysed by means of chemical oxygen demand (COD). Data obtained from the analysis of the dye mixture showed that the EO process was effective in colour removal, in which more than 90% was removed. In the case of COD removal, the application of a current density greater than 40 mA cm(-2) favoured the oxygen evolution reaction, and no complete oxidation was achieved. Regarding the analysis of individual anodic oxidation dyes, it was appreciated that the data for the NY were very close to the results obtained for the oxidation of the dye mixture while the RR dye achieved higher colour removal but lower COD elimination. These results suggest that the oxidation efficiency is dependent on the nature of the organic molecule, and it was confirmed by the intermediates identified. PMID:24801286

  19. Water soluble laser dyes

    DOEpatents

    Hammond, Peter R.; Feeman, James F.; Field, George F.

    1998-01-01

    Novel water soluble dyes of the formula I are provided ##STR1## wherein R.sup.1 and R.sup.4 are alkyl of 1 to 4 carbon atoms or hydrogen; or R.sup.1 -R.sup.2 or R.sup.2 -R.sup.4 form part of aliphatic heterocyclic rings; R.sup.2 is hydrogen or joined with R.sup.1 or R.sup.4 as described above; R.sup.3 is --(CH.sub.2).sub.m --SO.sub.3.sup.-, where m is 1 to 6; X is N, CH or ##STR2## where Y is 2 --SO.sub.3.sup.- ; Z is 3, 4, 5 or 6 --SO.sub.3.sup.-. The novel dyes are particularly useful as the active media in water solution dye lasers.

  20. Water soluble laser dyes

    DOEpatents

    Hammond, P.R.; Feeman, J.F.; Field, G.F.

    1998-08-11

    Novel water soluble dyes of the formula 1 are provided by the formula described in the paper wherein R{sup 1} and R{sup 4} are alkyl of 1 to 4 carbon atoms or hydrogen; or R{sup 1}--R{sup 2} or R{sup 2}--R{sup 4} form part of aliphatic heterocyclic rings; R{sup 2} is hydrogen or joined with R{sup 1} or R{sup 4} as described above; R{sup 3} is --(CH{sub 2}){sub m}--SO{sub 3}{sup {minus}}, where m is 1 to 6; X is N, CH or formula 2 given in paper where Y is 2 --SO{sub 3}{sup {minus}} ; Z is 3, 4, 5 or 6 --SO{sub 3}{sup {minus}}. The novel dyes are particularly useful as the active media in water solution dye lasers.

  1. Laser dye technology

    SciTech Connect

    Hammond, P R

    1999-09-01

    The author has worked with laser dyes for a number of years. A first interest was in the Navy blue-green program where a flashlamp pumped dye laser was used as an underwater communication and detection device. It made use of the optical window of sea-water--blue for deep ocean, green for coastal water. A major activity however has been with the Atomic Vapor Laser Isotope Separation Program (AVLIS) at the Lawrence Livermore National Laboratory. The aim here has been enriching isotopes for the nuclear fuel cycle. The tunability of the dye laser is utilized to selectively excite one isotope in uranium vapor, and this isotope is collected electrostatically as shown in Figure 1. The interests in the AVLIS program have been in the near ultra-violet, violet, red and deep-red.

  2. Adsorption of methylene blue on low-cost adsorbents: a review.

    PubMed

    Rafatullah, Mohd; Sulaiman, Othman; Hashim, Rokiah; Ahmad, Anees

    2010-05-15

    In this article, the use of low-cost adsorbents for the removal of methylene blue (MB) from solution has been reviewed. Adsorption techniques are widely used to remove certain classes of pollutants from waters, especially those which are not easily biodegradable. The removal of MB, as a pollutant, from waste waters of textile, paper, printing and other industries has been addressed by the researchers. Currently, a combination of biological treatment and adsorption on activated carbon is becoming more common for removal of dyes from wastewater. Although commercial activated carbon is a preferred adsorbent for color removal, its widespread use is restricted due to its relatively high cost which led to the researches on alternative non-conventional and low-cost adsorbents. The purpose of this review article is to organize the scattered available information on various aspects on a wide range of potentially low-cost adsorbents for MB removal. These include agricultural wastes, industrial solid wastes, biomass, clays minerals and zeolites. Agricultural waste materials being highly efficient, low cost and renewable source of biomass can be exploited for MB remediation. It is evident from a literature survey of about 185 recently published papers that low-cost adsorbents have demonstrated outstanding removal capabilities for MB. PMID:20044207

  3. Preparation and Characterization of Chitosan/Feldspar Biohybrid as an Adsorbent: Optimization of Adsorption Process via Response Surface Modeling

    PubMed Central

    Yazdani, Maryam; Bahrami, Hajir; Arami, Mokhtar

    2014-01-01

    Chitosan/feldspar biobased beads were synthesized, characterized, and tested for the removal of Acid Black 1 dye from aquatic phases. A four-factor central composite design (CCD) accompanied by response surface modeling (RSM) and optimization was used to optimize the dye adsorption by the adsorbent (chitosan/feldspar composite) in 31 different batch experiments. Independent variables of temperature, pH, initial dye concentration, and adsorbent dose were used to change to coded values. To anticipate the responses, a quadratic model was applied. Analysis of variance (ANOVA) tested the significance of the process factors and their interactions. The adequacy of the model was investigated by the correlation between experimental and predicted data of the adsorption and the calculation of prediction errors. The results showed that the predicted maximum adsorption amount of 21.63 mg/g under the optimum conditions (pH 3, temperature 15°C, initial dye concentration 125 mg/L, and dose 0.2 g/50 mL) was close to the experimental value of 19.85 mg/g. In addition, the results of adsorption behaviors of the dye illustrated that the adsorption process followed the Langmuir isotherm model and the pseudo-second-order kinetic model. Langmuir sorption capacity was found to be 17.86 mg/g. Besides, thermodynamic parameters were evaluated and revealed that the adsorption process was exothermic and favourable. PMID:24587722

  4. Hair Dye and Hair Relaxers

    MedlinePlus

    ... For Consumers Consumer Information by Audience For Women Hair Dye and Hair Relaxers Share Tweet Linkedin Pin it More sharing ... products. If you have a bad reaction to hair dyes and relaxers, you should: Stop using the ...

  5. Chemisorption of a thiol-functionalized ruthenium dye on zinc oxide nanoparticles: Implications for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Singh, Jagdeep; Im, Jisun; Whitten, James E.; Soares, Jason W.; Steeves, Diane M.

    2010-09-01

    ZnO is an alternative to TiO 2-based dye-sensitized solar cells (DSSCs). Adsorption of cis-ruthenium-bis[2,2'-bipyridine]-bis[4-thiopyridine] onto ZnO nanorods has been studied using X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS). XPS indicates chemisorption with a surface density of ca. 1 × 10 15 molecules/cm 2, confirming the possibility of using thiol-terminated dyes for ZnO-based DSSC devices. The energy level diagram, based on UPS and absorbance spectroscopy, indicates that the LUMO of this dye is lower in energy than the ZnO conduction band edge, providing minimal enthalpic driving force for photovoltaic electron injection. However, optimization of thiol-functionalized Ru dyes could result in competitive ZnO-based DSSCs.

  6. Excitation energy migration in yellow fluorescent protein (citrine) layers adsorbed on modified gold surfaces

    NASA Astrophysics Data System (ADS)

    Yusoff, Hanis Mohd; Rzeźnicka, Izabela I.; Hoshi, Hirotaka; Kajimoto, Shinji; Horimoto, Noriko Nishizawa; Sogawa, Kazuhiro; Fukumura, Hiroshi

    2013-09-01

    The nature of functional proteins adsorbed on solid surfaces is interesting from the perspective of developing of bioelectronics and biomaterials. Here we present evidence that citrine (one of yellow fluorescent protein variants) adsorbed on modified gold surfaces would not undergo denaturation and energy transfer among the adsorbed citrine molecules would occur. Gold substrates were chemically modified with 3-mercaptopropionic acid and tert-butyl mercaptan for the preparation of hydrophilic and hydrophobic surfaces, respectively. A pure solution of citrine was dropped and dried on the modified gold substrates and their surface morphology was studied with scanning tunnelling microscopy (STM). The obtained STM images showed multilayers of citrine adsorbed on the modified surfaces. On hydrophobic surfaces, citrine was adsorbed more randomly, formed various non-uniform aggregates, while on hydrophilic surfaces, citrine appeared more aligned and isolated uniform protein clusters were observed. Fluorescence lifetime and anisotropy decay of these dried citrine layers were also measured using the time correlated single photon counting method. Fluorescence anisotropy of citrine on the hydrophobic surface decayed faster than citrine on the hydrophilic surface. From these results we concluded that fluorescence energy migration occurred faster among citrine molecules which were randomly adsorbed on the hydrophobic surface to compare with the hydrophilic surface.

  7. Photoexcitation of adsorbates on metal surfaces: One-step or three-step

    SciTech Connect

    Petek, Hrvoje

    2012-09-07

    In this essay we discuss the light-matter interactions at molecule-covered metal surfaces that initiate surface photochemistry. The hot-electron mechanism for surface photochemistry, whereby the absorption of light by a metal surface creates an electron-hole pair, and the hot electron scatters through an unoccupied resonance of adsorbate to initiate nuclear dynamics leading to photochemistry, has become widely accepted. Yet, ultrafast spectroscopic measurements of molecule-surface electronic structure and photoexcitation dynamics provide scant support for the hot electron mechanism. Instead, in most cases the adsorbate resonances are excited through photoinduced substrate-to-adsorbate charge transfer. Based on recent studies of the role of coherence in adsorbate photoexcitation, as measured by the optical phase and momentum resolved two-photon photoemission measurements, we examine critically the hot electron mechanism, and propose an alternative description based on direct charge transfer of electrons from the substrate to adsorbate. The advantage of this more quantum mechanically rigorous description is that it informs how material properties of the substrate and adsorbate, as well as their interaction, influence the frequency dependent probability of photoexcitation and ultimately how light can be used to probe and control surface femtochemistry.

  8. Mobility of adsorbed proteins: a Brownian dynamics study.

    PubMed

    Ravichandran, S; Talbot, J

    2000-01-01

    We simulate the adsorption of lysozyme on a solid surface, using Brownian dynamics simulations. A protein molecule is represented as a uniformly charged sphere and interacts with other molecules through screened Coulombic and double-layer forces. The simulation starts from an empty surface and attempts are made to introduce additional proteins at a fixed time interval that is inversely proportional to the bulk protein concentration. We examine the effect of ionic strength and bulk protein concentration on the adsorption kinetics over a range of surface coverages. The structure of the adsorbed layer is examined through snapshots of the configurations and quantitatively with the radial distribution function. We extract the surface diffusion coefficient from the mean square displacement. At high ionic strengths the Coulombic interaction is effectively shielded, leading to increased surface coverage. This effect is quantified with an effective particle radius. Clustering of the adsorbed molecules is promoted by high ionic strength and low bulk concentrations. We find that lateral protein mobility decreases with increasing surface coverage. The observed trends are consistent with previous theoretical and experimental studies. PMID:10620278

  9. A novel fiber-based adsorbent technology

    SciTech Connect

    Reynolds, T.A.

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  10. Aggregation and adsorption of reactive dyes in the presence of an anionic surfactant on mesoporous aminopropyl silica.

    PubMed

    Cestari, Antonio R; Vieira, Eunice F S; Vieira, Gláucia S; Almeida, Luis E

    2007-05-15

    A surface tension technique was used to determine the critical aggregation concentration (cac) of a yellow and a red dye in relation to the presence of the anionic surfactant sodium dodecylbenzene sulfonate (DBS) and to temperature changes in buffered aqueous solutions. The cac values of the yellow dye increase from 25 to 45 degrees C (from 41.37 to 50.32 mg L-1) and decrease from 45 to 55 degrees C (from 50.32 to 38.72 mg L-1). The cac values for the red dye/DBS aggregates decrease (from 124.52 to 88.50 mg L-1) from 25 to 55 degrees C. Adsorption of the two dyes onto a mesoporous aminopropyl silica (Sil-NH2) was also studied. The adsorption of the yellow dye increases with an increase in temperature from 25 to 55 degrees C. In the presence of DBS the adsorption on Sil-NH2 for the yellow dye decreases, and for the red dye increases from 25 to 55 degrees C. Adsorptions occurred below and above the cac of the anionic dyes/DBS aggregates. Adsorption of the dyes onto Sil-NH2 fitted well to the Langmuir, Freundlich, and Redlich-Peterson adsorption models. However, in the presence of DBS, only the Freundlich model fit the experimental adsorption data at low dye concentrations (less than 400 mg L-1). In this case, the Redlich-Peterson model was only fitted to the red dye adsorption data. The magnitude of the Dubinin-Radushkevich energetic parameters (E, from 7.00 to 15.00 kJ mol-1) indicates that the adsorption of the dyes onto Sil-NH2, in the absence and in the presence of DBS, is controlled by water adsorbed/dye in solution ion-exchange interactions. It is observed that the values of DeltaadsH are positive for both dyes and the values are quite similar to each other. The exception is the adsorption of the yellow dye in the presence of DBS, which is slightly exothermic. The DeltaadsG values are all negative. However, the interactions of the dyes with Sil-NH2 silica are more spontaneous in the presence of the surfactant. The positive adsorption entropy values (Deltaads

  11. Hair care and dyeing.

    PubMed

    Draelos, Zoe Diana

    2015-01-01

    Alopecia can be effectively camouflaged or worsened through the use of hair care techniques and dyeing. Proper hair care, involving hair styling and the use of mild shampoos and body-building conditioners, can amplify thinning scalp hair; however, chemical processing, including hair dyeing, permanent waving, and hair straightening, can encourage further hair loss through breakage. Many patients suffering from alopecia attempt to improve their hair through extensive manipulation, which only increases problems. Frequent haircuts to minimize split ends, accompanied by gentle handling of the fragile fibers, is best. This chapter offers the dermatologist insight into hair care recommendations for the alopecia patient. PMID:26370650

  12. Dye filled security seal

    DOEpatents

    Wilson, Dennis C. W.

    1982-04-27

    A security seal for providing an indication of unauthorized access to a sealed object includes an elongate member to be entwined in the object such that access is denied unless the member is removed. The elongate member has a hollow, pressurizable chamber extending throughout its length that is filled with a permanent dye under greater than atmospheric pressure. Attempts to cut the member and weld it together are revealed when dye flows through a rupture in the chamber wall and stains the outside surface of the member.

  13. Cu(II)-selective bispidine-dye conjugates.

    PubMed

    Brox, Dominik; Comba, Peter; Herten, Dirk-Peter; Kimmle, Esther; Morgen, Michael; Rühl, Carmen L; Rybina, Arina; Stephan, Holger; Storch, Golo; Wadepohl, Hubert

    2015-07-01

    The substitution of tetradentate bispidine ligands with rhodamine and cyanine dye molecules, coupled to an amine donor, forming an amide as potential fifth donor, is described. Bispidines are known to lead to very stable Cu(II) complexes, and the coordination to Cu(II) was expected to efficiently quench the fluorescence of dye molecules. However, at physiological pH the amide is not coordinated, as shown by titration experiments and crystallographic structural data of three possible isomers of these complexes. This may be due to the specific cavity shape of bispidines and the Jahn-Teller lability of the Cu(II) center. While Cu(II) coordination in aqueous solution leads to efficient fluorescence quenching, experiments show that the complex stabilities are not large enough for Cu(II) sensing in biological media, and possibilities are discussed, how this may be achieved by optimized bispidine-dye conjugates. PMID:26048430

  14. Plasmonic nanoparticles enhanced dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Liu, Fang; Meng, Weisi; Huang, Yidong

    2013-12-01

    Here we present investigations on utilizing two kinds of plasmonic nanoparticles (NPs) to enhance the efficiency of dye sensitized solar cells (DSCs). The Au@PVP NPs is proposed and present the specialty of adhesiveness to dye molecules, which could help to localize additional dye molecules near the plasmonic NPs, hence increasing the optical absorption consequently the power conversion efficiency (PCE) of the DSCs by 30% from 3.3% to 4.3%. Meanwhile, an irregular Au-Ag alloy popcorn-shaped NPs (popcorn NPs) with plenty of fine structures is also proposed and realized to enhance the light absorption of DSC. A pronounced absorption enhancement in a broadband wavelength range is observed due to the excitation of localized surface plasmon at different wavelengths. The PCE is enhanced by 32% from 5.94% to 7.85%.

  15. Spectroscopic Studies of Abiotic and Biological Nanomaterials: Silver Nanoparticles, Rhodamine 6G Adsorbed on Graphene, and c-Type Cytochromes and Type IV Pili in Geobacter sulfurreducens

    NASA Astrophysics Data System (ADS)

    Thrall, Elizabeth S.

    This thesis describes spectroscopic studies of three different systems: silver nanoparticles, the dye molecule rhodamine 6G adsorbed on graphene, and the type IV pili and c-type cytochromes produced by the dissimilatory metal-reducing bacterium Geobacter sulfurreducens. Although these systems are quite different in some ways, they can all be considered examples of nanomaterials. A nanomaterial is generally defined as having at least one dimension below 100 nm in size. Silver nanoparticles, with sub-100 nm size in all dimensions, are examples of zero-dimensional nanomaterials. Graphene, a single atomic layer of carbon atoms, is the paradigmatic two-dimensional nanomaterial. And although bacterial cells are on the order of 1 μm in size, the type IV pili and multiheme c-type cytochromes produced by G. sulfurreducens can be considered to be one- and zero-dimensional nanomaterials respectively. A further connection between these systems is their strong interaction with visible light, allowing us to study them using similar spectroscopic tools. The first chapter of this thesis describes research on the plasmon-mediated photochemistry of silver nanoparticles. Silver nanoparticles support coherent electron oscillations, known as localized surface plasmons, at resonance frequencies that depend on the particle size and shape and the local dielectric environment. Nanoparticle absorption and scattering cross-sections are maximized at surface plasmon resonance frequencies, and the electromagnetic field is amplified near the particle surface. Plasmonic effects can enhance the photochemistry of silver particles alone or in conjunction with semiconductors according to several mechanisms. We study the photooxidation of citrate by silver nanoparticles in a photoelectrochemical cell, focusing on the wavelength-dependence of the reaction rate and the role of the semiconductor substrate. We find that the citrate

  16. The aqueous-polyelectrolyte dye solution as an active laser medium

    SciTech Connect

    Akimov, A I; Saletskii, A M

    2000-11-30

    The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes - polyacrylic and polymethacrylic acids - are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions. (lasers, active media)

  17. Highly effective adsorption of cationic and anionic dyes on magnetic Fe/Ni nanoparticles doped bimodal mesoporous carbon.

    PubMed

    Liu, Yuanyuan; Zeng, Guangming; Tang, Lin; Cai, Ye; Pang, Ya; Zhang, Yi; Yang, Guide; Zhou, Yaoyu; He, Xiaoxiao; He, Yan

    2015-06-15

    Magnetic Fe/Ni nanoparticles doped bimodal mesoporous carbon (MBMC) was prepared for highly effective adsorption of cationic dye methylene blue (MB) and anionic dye methyl orange (MO). Structure characterization demonstrated that Fe/Ni nanoparticles were embedded into the interior of the mesoprous carbon, and MBMC maintained ordered and bimodal mesopores. The effects of several parameters such as contact time, pH, temperature, ionic strength and dye molecular structure on the adsorption were investigated. Alkaline pH was better for MB adsorption, while acidic pH was more favorable for MO uptake. The adsorption capacity was slightly enhanced when existing ion concentrations increased. Adsorption on MBMC was affected by the molecular structures of different dyes, and both primary and secondary pores of MBMC were involved in dye adsorption. The adsorption kinetics fitted well with pseudo-second-order model and exhibited 3-stage intraparticle diffusion mode. Equilibrium data were best described by Langmuir model, and the estimated maximum adsorption capacity for MB and MO was 959.5mg/g and 849.3mg/g, respectively. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. Moreover, the adsorbent could be regenerated using ethanol, and the regenerated adsorbent after seven cycles could retain over 80% of the adsorption capacity for the fresh adsorbent. The results suggested that MBMC could be considered as very effective and promising materials for both anionic and cationic dyes removal from wastewater. PMID:25765736

  18. Selective removal of toxic anionic dyes using a novel nanocomposite derived from cationically modified guar gum and silica nanoparticles.

    PubMed

    Patra, Abhay Shankar; Ghorai, Soumitra; Ghosh, Shankhamala; Mandal, Barun; Pal, Sagar

    2016-01-15

    A novel nanocomposite derived from cationically modified guar gum and in-situ incorporated SiO2 NP (cat-GG/SiO2) has been developed. The cat-GG has been synthesised by grafting poly(2-(diethylamino)ethyl methacrylate) on GG backbone. Various analyses endorse the suitability of cat-GG as well-organized template for the development of homogeneous SiO2 NPs. Dye adsorption studies predict that cat-GG/SiO2 efficiently and selectively adsorb anionic dyes (reactive blue-RB and Congo red-CR) from mixture of dye solutions. This is because of high surface area, multifunctional chelating H-bonding interactions and electrostatic interactions of cationic adsorbent with anionic dyes. Dyes adsorbed on the composite surface are desorbed reversibly using pH 10 stripping solution. Besides, cat-GG/SiO2 has been recycled efficiently with no prominent loss of dye uptake capacity, even after 4 adsorption-desorption cycles. PMID:26348145

  19. Design and characterisation of bodipy sensitizers for dye-sensitized NiO solar cells.

    PubMed

    Summers, Gareth H; Lefebvre, Jean-François; Black, Fiona A; Davies, E Stephen; Gibson, Elizabeth A; Pullerits, Tönu; Wood, Christopher J; Zidek, Karel

    2016-01-14

    A series of photosensitizers for NiO-based dye-sensitized solar cells is presented. Three model compounds containing a triphenylamine donor appended to a boron dipyrromethene (bodipy) chromophore have been successfully prepared and characterised using emission spectroscopy, electrochemistry and spectroelectrochemistry, to ultimately direct the design of dyes with more complex structures. Carboxylic acid anchoring groups and thiophene spacers were appended to the model compounds to provide five dyes which were adsorbed onto NiO and integrated into dye-sensitized solar cells. Solar cells incorporating the simple Bodipy-CO₂H dye were surprisingly promising relative to the more complex dye 4. Cell performances were improved with dyes which had increased electronic communication between the donor and acceptor, achieved by incorporating a less hindered bodipy moiety. Further increases in performances were obtained from dyes which contained a thiophene spacer. Thus, the best performance was obtained for 7 which generated a very promising photocurrent density of 5.87 mA cm(-2) and an IPCE of 53%. Spectroelectrochemistry combined with time-resolved transient absorption spectroscopy were used to determine the identity and lifetime of excited state species. Short-lived (ps) transients were recorded for 4, 5 and 7 which are consistent with previous studies. Despite a longer lived (25 ns) charge-separated state for 6/NiO, there was no increase in the photocurrent generated by the corresponding solar cell. PMID:26660278

  20. Evaluation on over photocurrents measured from unmasked dye-sensitized solar cells

    SciTech Connect

    Lee, Gi-Won; Kim, Donghwan; Ko, Min Jae; Kim, Kyungkon; Park, Nam-Gyu

    2010-03-15

    We have investigated the change in photocurrent density (J{sub SC}) of dye-sensitized solar cell (DSSC) before and after covering an aperture mask on the cell, especially its dependence on solar absorption range in dye. Four different dyes having absorption threshold at 460 nm (P5), 520 nm (TA-St-CA), 680 nm (N719) and 820 nm (N749) are tested. J{sub SC} of the DSSC without mask decreases after mask, where the decreasing rate (triangle J{sub SC} = J{sub SC} (no mask) -J{sub SC} (with mask)/J{sub SC} (no mask)) becomes larger when dye absorption threshold decreases. triangle J{sub SC} at the given TiO{sub 2} film thickness of 10 {mu}m is determined to be about 20%, 15% and 13% for P5, TA-St-CA and N719-N749, respectively, which is reduced to 14% (TA-St-CA), 11.3% (N719) and 10.5% (N749) after increasing the thickness to 20 {mu}m, except for P5 dye remaining unchanged. According to the analysis based on IPCE and photon flux data, the over photocurrents observed for the unmasked dye-sensitized solar cells and their dependence on dye absorption range are found to be attributed to diffuse light leaving the dye-adsorbed TiO{sub 2} active area. (author)