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Sample records for capacity mercury adsorption

  1. The adsorptive capacity of vapor-phase mercury chloride onto powdered activated carbon derived from waste tires.

    PubMed

    Lin, Hsun-Yu; Yuan, Chung-Shin; Wu, Chun-Hsin; Hung, Chung-Hsuang

    2006-11-01

    Injection of powdered activated carbon (PAC) upstream of particulate removal devices (such as electrostatic precipitator and baghouses) has been used effectively to remove hazardous air pollutants, particularly mercury-containing pollutants, emitted from combustors and incinerators. Compared with commercial PACs (CPACs), an alternative PAC derived from waste tires (WPAC) was prepared for this study. The equilibrium adsorptive capacity of mercury chloride (HgCl2) vapor onto the WPAC was further evaluated with a self-designed bench-scale adsorption column system. The adsorption temperatures investigated in the adsorption column were controlled at 25 and 150 degrees C. The superficial velocity and residence time of the flow were 0.01 m/sec and 4 sec, respectively. The adsorption column tests were run under nitrogen gas flow. Experimental results showed that WPAC with higher Brunauer-Emmett-Teller (BET) surface area could adsorb more HgCl2 at room temperature. The equilibrium adsorptive capacity of HgCl2 for WPAC measured in this study was 1.49 x 10(-1) mg HgCl2/g PAC at 25 degrees C with an initial HgCI2 concentration of 25 microg/m3. With the increase of adsorption temperature < or = 150 degrees C, the equilibrium adsorptive capacity of HgCl2 for WPAC was decreased to 1.34 x 10(-1) mg HgCl2/g PAC. Furthermore, WPAC with higher sulfur contents could adsorb even more HgCl2 because of the reactions between sulfur and Hg2+ at 150 degrees C. It was demonstrated that the mechanisms for adsorbing HgCl2 onto WPAC were physical adsorption and chemisorption at 25 and 150 degrees C, respectively. Experimental results also indicated that the apparent overall driving force model appeared to have the good correlation with correlation coefficients (r) > 0.998 for HgCl2 adsorption at 25 and 150 degrees C. Moreover, the equilibrium adsorptive capacity of HgCl2 for virgin WPAC was similar to that for CPAC at 25 degrees C, whereas it was slightly higher for sulfurized WPAC than for

  2. Removal of mercury by adsorption: a review.

    PubMed

    Yu, Jin-Gang; Yue, Bao-Yu; Wu, Xiong-Wei; Liu, Qi; Jiao, Fei-Peng; Jiang, Xin-Yu; Chen, Xiao-Qing

    2016-03-01

    Due to natural and production activities, mercury contamination has become one of the major environmental problems over the world. Mercury contamination is a serious threat to human health. Among the existing technologies available for mercury pollution control, the adsorption process can get excellent separation effects and has been further studied. This review is attempted to cover a wide range of adsorbents that were developed for the removal of mercury from the year 2011. Various adsorbents, including the latest adsorbents, are presented along with highlighting and discussing the key advancements on their preparation, modification technologies, and strategies. By comparing their adsorption capacities, it is evident from the literature survey that some adsorbents have shown excellent potential for the removal of mercury. However, there is still a need to develop novel, efficient adsorbents with low cost, high stability, and easy production and manufacture for practical utility.

  3. Mercury adsorption-desorption and transport in soils.

    PubMed

    Liao, Lixia; Selim, H M; Delaune, R D

    2009-01-01

    Kinetic sorption and column miscible displacement transport experiments were performed to quantify the extent of retention/release and the mobility of mercury in different soils. Results indicated that adsorption of mercury was rapid and highly nonlinear with sorption capacities having the following sequence: Sharkey clay > Olivier loam > Windsor sand. Mercury adsorption by all soils was strongly irreversible where the amounts released or desorbed were often less than 1% of that applied. Moreover, the removal of soil organic matter resulted in a decrease of mercury adsorption in all soils. Adsorption was described with limited success using a nonlinear (Freundlich) model. Results from the transport experiments indicated that the mobility of mercury was highly retarded, with extremely low concentrations of mercury in column effluents. Furthermore, mercury breakthrough curves exhibited erratic patterns with ill-distinguished peaks. Therefore, mercury is best regarded as strongly retained and highly "immobile" in the soils investigated. This is most likely due to highly stable complex formation (irreversible forms) and strong binding to high-affinity sites. In a column packed with reference sand material, a symmetric breakthrough curve was obtained where the recovery of mercury in the leachate was only 17.3% of that applied. Mercury retention by the reference sand was likely due to adsorption by quartz and metal-oxides.

  4. Effects of sulfur impregnation temperature on the properties and mercury adsorption capacities of activated carbon fibers (ACFs)

    USGS Publications Warehouse

    Hsi, H.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2001-01-01

    Laboratory studies were conducted to determine the role of sulfur functional groups and micropore surface area of carbon-based adsorbents on the adsorption of Hg0 from simulated coal combustion flue gases. In this study, raw activated carbon fibers that are microporous (ACF-20) were impregnated with elemental sulfur between 250 and 650 ??C. The resulting samples were saturated with respect to sulfur content. Total sulfur content of the sulfur impregnated ACF samples decreased with increasing impregnation temperatures from 250 and 500 ??C and then remained constant to 650 ??C. Results from sulfur K-edge X-ray absorption near-edge structure (S-XANES) spectroscopy showed that sulfur impregnated on the ACF samples was in both elemental and organic forms. As sulfur impregnation temperature increased, however, the relative amounts of elemental sulfur decreased with a concomitant increase in the amount of organic sulfur. Thermal analyses and mass spectrometry revealed that sulfur functional groups formed at higher impregnation temperatures were more thermally stable. In general, sulfur impregnation decreased surface area and increased equilibrium Hg0 adsorption capacity when compared to the raw ACF sample. The ACF sample treated with sulfur at 400 ??C had a surface area of only 94 m2/g compared to the raw ACF sample's surface area of 1971 m2/g, but at least 86% of this sample's surface area existed as micropores and it had the largest equilibrium Hg0adsorption capacities (2211-11343 ??g/g). Such a result indicates that 400 ??C is potentially an optimal sulfur impregnation temperature for this ACF. Sulfur impregnated on the ACF that was treated at 400 ??C was in both elemental and organic forms. Thermal analyses and CS2extraction tests suggested that elemental sulfur was the main form of sulfur affecting the Hg0 adsorption capacity. These findings indicate that both the presence of elemental sulfur on the adsorbent and a microporous structure are important properties for

  5. Preparation of hybrid organic-inorganic mesoporous silicas applied to mercury removal from aqueous media: Influence of the synthesis route on adsorption capacity and efficiency.

    PubMed

    Pérez-Quintanilla, Damián; Sánchez, Alfredo; Sierra, Isabel

    2016-06-15

    New hybrid organic-inorganic mesoporous silicas were prepared by employing three different synthesis routes and mercury adsorption studies were done in aqueous media using the batch technique. The organic ligands employed for the functionalization were derivatives of 2-mercaptopyrimidine or 2-mercaptothiazoline, and the synthesis pathways used were post-synthesis, post-synthesis with surface ion-imprinting and co-condensation with ion-imprinting. The incorporation of functional groups and the presence of ordered mesopores in the organosilicas was confirmed by XRD, TEM and SEM, nitrogen adsorption-desorption isotherms, (13)C MAS-NMR, (29)Si MAS-NMR, elemental and thermogravimetric analysis. The highest adsorption capacity and selectivity observed was for the material functionalized with 2-mercaptothiazoline ligand by means the co-condensation with ion-imprinting route (1.03 mmol g(-1) at pH 6). The prepared material could be potential sorbent for the extraction of this heavy metal from environmental and drinking waters.

  6. Mercury adsorption properties of sulfur-impregnated adsorbents

    USGS Publications Warehouse

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  7. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies.

  8. Roles of metal/activated carbon hybridization on elemental mercury adsorption.

    PubMed

    Bae, Kyong-Min; Kim, Byung-Joo; Rhee, Kyong Yop; Park, Soo-Jin

    2014-08-01

    In this study, the elemental mercury removal behavior of metal (copper or nickel)/activated carbon hybrid materials were investigated. The pore structures and total pore volumes of the hybrid materials were analyzed using the N2/77 K adsorption isotherms. The microstructure and surface morphologies of the hybrid materials were characterized by X-ray diffraction and scanning electron microscopy, respectively. In the experimental results, the elemental mercury adsorption capacities of all copper/activated carbon hybrid materials were higher than that of the as-received material despite the decrease in specific surface areas and total pore volumes after the metal loading. All the samples containing the metal particles showed excellent elemental mercury adsorption. The Ni/ACs exhibited superior elemental mercury adsorption to those of Cu/ACs. This suggests that Ni/ACs have better elemental mercury adsorption due to the higher activity of nickel.

  9. Adsorption potential of mercury(II) from aqueous solutions onto Romanian peat moss.

    PubMed

    Bulgariu, Laura; Ratoi, Mioara; Bulgariu, Dumitru; Macoveanu, Matei

    2009-06-01

    This study was undertaken to evaluate the adsorption potential of Romanian peat moss for the removal of mercury(II) from aqueous solutions. The batch system experiments carried out showed that this natural material was effective in removing mercury(II). The analysis of FT-IR spectra indicated that the mechanism involved in the adsorption can be mainly attributed to the binding of mercury(II) with the carboxylic groups of Romanian peat moss. Adsorption equilibrium approached within 60 min. The adsorption data fitted well the Langmuir isotherm model. The maximum adsorption capacity (qmax) was 98.94 mg g(-1). Pseudo-second-order kinetic model was applicable to the adsorption data. The thermodynamic parameters indicate that the adsorption process was spontaneous as the Gibbs free energy values were found to be negative (between -17.58 and -27.25 kJ mol(-1)) at the temperature range of 6-54 degrees C.

  10. Adsorption properties and gaseous mercury transformation rate of natural biofilm.

    PubMed

    Cheng, Jinping; Zhao, Wenchang; Liu, Yuanyuan; Wu, Cheng; Liu, Caie; Wang, Wenhua

    2008-11-01

    Biofilms were developed on glass microscope slides in a natural aquatic environment and their mercury adsorption properties were evaluated. Results demonstrated that the biofilms contained a large number of bacterial cells and associated extracellular polymers. Mercury forms detected in the biofilms were mainly bound to residual matter and organic acids. The adsorption processes could be described by a Langmuir isotherm. The optimum conditions for adsorption of mercury to natural biofilm were an ionic strength of 0.1 mol/L, pH 6 and an optimum adsorption time of 40 min. The transformation rate was 0.79 microg gaseous mercury per gram of biofilm.

  11. Enhancement of elemental mercury adsorption by silver supported material.

    PubMed

    Khunphonoi, Rattabal; Khamdahsag, Pummarin; Chiarakorn, Siriluk; Grisdanurak, Nurak; Paerungruang, Adjana; Predapitakkun, Somrudee

    2015-06-01

    Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations, which are stringent in order to avoid releasing to the environment. Herein, vapor mercury adsorption was therefore investigated using two kinds of supports, granular activated carbon (GAC) and titanium dioxide (TiO2). Both supports were impregnated by silver (5 and 15 wt.%), before testing against a commercial adsorbent (sulfur-impregnated activated carbon, SAC). The adsorption isotherm, kinetics, and its thermodynamics of mercury adsorption were reported. The results revealed that Langmuir isotherm provided a better fit to the experimental data. Pseudo second-order was applicable to describe adsorption kinetics. The higher uniform Ag dispersion was a key factor for the higher mercury uptake. TiO2 supported silver adsorbent showed higher mercury adsorption than the commercial one by approximately 2 times. Chemisorption of mercury onto silver active sites was confirmed by an amalgam formation found in the spent adsorbents.

  12. Mercury adsorption of modified mulberry twig chars in a simulated flue gas.

    PubMed

    Shu, Tong; Lu, Ping; He, Nan

    2013-05-01

    Mulberry twig chars were prepared by pyrolysis, steam activation and impregnation with H2O2, ZnCl2 and NaCl. Textural characteristics and surface functional groups were performed using nitrogen adsorption and FTIR, respectively. Mercury adsorption of different modified MT chars was investigated in a quartz fixed-bed absorber. The results indicated that steam activation and H2O2-impregnation can improve pore structure significantly and H2O2-impregnation and chloride-impregnation promote surface functional groups. However, chloride-impregnation has adverse effect on pore structure. Mercury adsorption capacities of impregnated MT chars with 10% or 30% H2O2 are 2.02 and 1.77 times of steam activated MT char, respectively. Mercury adsorption capacity of ZnCl2-impregnated MT char increase with increasing ZnCl2 content and is better than that of NaCl-impregnated MT char at the same chloride content. The modified MT char (MT873-A-Z5) prepared by steam activation following impregnation with 5% ZnCl2 exhibits a higher mercury adsorption capacity (29.55 μg g(-1)) than any other MT chars.

  13. Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces.

    PubMed

    Liu, Jing; Cheney, Marcos A; Wu, Fan; Li, Meng

    2011-02-15

    A systematic theoretical study using density functional theory is performed to provide molecular-level understanding of the effects of chemical functional groups on mercury adsorption on carbonaceous surfaces. The zigzag and armchair edges were used in modeling the carbonaceous surfaces to simulate different adsorption sites. The edge atoms on the upper side of the models are unsaturated to simulate active sites. All calculations (optimizations, energies, and frequencies) were made at B3PW91 density functional theory level, using RCEP60VDZ basis set for mercury and 6-31G(d) pople basis set for other atoms. The results indicate that the embedding of halogen atom can increase the activity of its neighboring site which in turn increases the adsorption capacity of the carbonaceous surface for Hg(0). The adsorption belongs to chemisorptions, which is in good agreement with the experimental results. For the effects of oxygen functional groups, lactone, carbonyl and semiquinone favor Hg(0) adsorption because they increase the neighboring site's activity for mercury adsorption. On the contrary, phenol and carboxyl functional groups show a physisorption of Hg(0), and reduce Hg capture. This result can explain the seemingly conflicting experimental results reported in the literature concerning the influence of oxygen functional groups on mercury adsorption on carbonaceous surface.

  14. ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON

    EPA Science Inventory

    Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

  15. ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

    EPA Science Inventory

    The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

  16. Use of adsorption process to remove organic mercury thimerosal from industrial process wastewater.

    PubMed

    Velicu, Magdalena; Fu, Hongxiang; Suri, Rominder P S; Woods, Kevin

    2007-09-30

    Carbon adsorption process is tested for removal of high concentration of organic mercury (thimerosal) from industrial process wastewater, in batch and continuously flow through column systems. The organic mercury concentration in the process wastewater is about 1123 mg/L due to the thimerosal compound. Four commercially available adsorbents are tested for mercury removal and they are: Calgon F-400 granular activated carbon (GAC), CB II GAC, Mersorb GAC and an ion-exchange resin Amberlite GT73. The adsorption capacity of each adsorbent is described by the Freundlich isotherm model at pH 3.0, 9.5 and 11.0 in batch isotherm experiments. Acidic pH was favorable for thimerosal adsorption onto the GACs. Columns-in-series experiments are conducted with 30-180 min empty bed contact times (EBCTs). Mercury breakthrough of 30 mg/L occurred after about 47 h (96 Bed Volume Fed (BVF)) of operation, and 97 h (197 BVF) with 120 min EBCT and 180 min EBCT, respectively. Most of the mercury removal is attributed to the 1st adsorbent column. Increase in contact time by additional adsorbent columns did not lower the effluent mercury concentration below 30 mg/L. However, at a lower influent wastewater pH 3, the mercury effluent concentration decreased to less than 7 mg/L for up to 90 h of column operation (183 BVF).

  17. Kinetic studies of elemental mercury adsorption in activated carbon fixed bed reactor.

    PubMed

    Skodras, G; Diamantopoulou, Ir; Pantoleontos, G; Sakellaropoulos, G P

    2008-10-01

    Activated carbons are suitable materials for Hg(0) adsorption in fixed bed operation or in injection process. The fixed bed tests provide good indication of activated carbons effectiveness and service lives, which depend on the rates of Hg(0) adsorption. In order to correlate fixed bed properties and operation conditions, with their adsorptive capacity and saturation time, Hg(0) adsorption tests were realized in a bench-scale unit, consisted of F400 activated carbon fixed bed reactor. Hg(0) adsorption tests were conducted at 50 degrees C, under 0.1 and 0.35 ng/cm(3) Hg(0) initial concentrations and with carbon particle sizes ranging between 75-106 and 150-250 microm. Based on the experimental breakthrough data, kinetic studies were performed to investigate the mechanism of adsorption and the rate controlling steps. Kinetic models evaluated include the Fick's intraparticle diffusion equation, the pseudo-first order model, the pseudo-second order model and Elovich kinetic equation. The obtained experimental results revealed that the increase in particle size resulted in significant decrease of breakthrough time and mercury adsorptive capacity, due to the enhanced internal diffusion limitations and smaller external mass transfer coefficients. Additionally, higher initial mercury concentrations resulted in increased breakthrough time and mercury uptake. From the kinetic studies results it was observed that all the examined models describes efficiently Hg(0) breakthrough curves, from breakpoint up to equilibrium time. The most accurate prediction of the experimental data was achieved by second order model, indicating that the chemisorption rate seems to be the controlling step in the procedure. However, the successful attempt to describe mercury uptake with Fick's diffusion model and the first order kinetic model, reveals that the adsorption mechanism studied was complex and followed both surface adsorption and particle diffusion.

  18. Adsorption enhancement of elemental mercury onto sulphur-functionalized silica gel adsorbents.

    PubMed

    Johari, Khairiraihanna; Saman, Norasikin; Mat, Hanapi

    2014-01-01

    In this study, elemental mercury (EM) adsorbents were synthesized using tetraethyl orthosilicate (TEOS) and 3-mercaptopropyl trimethoxysilane as silica precursors. The synthesized silica gel (SG)-TEOS was further functionalized through impregnation with elemental sulphur and carbon disulphide (CS2). The SG adsorbents were then characterized by using scanning electron microscope, Fourier transform infra-red spectrophotometer, nitrogen adsorption/desorption, and energy-dispersive X-ray diffractometer. The EM adsorption of the SG adsorbents was determined using fabricated fixed-bed adsorber. The EM adsorption results showed that the sulphur-functionalized SG adsorbents had a greater Hgo breakthrough adsorption capacity, confirming that the presence of sulphur in silica matrices can improve Hgo adsorption performance due to their high affinity towards mercury. The highest Hgo adsorption capacity was observed for SG-TEOS(CS2) (82.62 microg/g), which was approximately 2.9 times higher than SG-TEOS (28.47 microg/g). The rate of Hgo adsorption was observed higher for sulphur-impregnated adsorbents, and decreased with the increase in the bed temperatures.

  19. Mechanisms of CPB Modified Zeolite on Mercury Adsorption in Simulated Wastewater.

    PubMed

    Liu, Jiang; Huang, Hui; Huang, Rong; Zhang, Jinzhong; Hao, Shuoshuo; Shen, Yuanyuan; Chen, Hong

    2016-06-01

    A systematic study was carried out to analyze the effects of mercury(II) adsorption by surface modified zeolite (SMZ) and adsorption mechanism. Cetylpyridinium bromide (CPB) was used to prepare SMZ. The characterization methods by means of powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM) showed that both the surface and internal zeolite were covered with CPB molecules, but the main binding sites were surface. Results showed that the organic carbon and cation exchange capacity of the SMZ were 7.76 times and 4.22 times higher than those of natural zeolite (NZ), respectively. Zeta potentials before and after modification were measured at -7.80 mV and -30.27 mV, respectively. Moreover, the saturation adsorptive capacity of SMZ was 16.35 times higher than NZ in mercury-containing wastewater. The possible mechanisms of mercury elimination were surface adsorption, hydrophobic interaction, ion exchange, electricity neutralization. The adsorption process was affected little by competitive ions.

  20. Gas adsorption capacity of wood pellets

    DOE PAGES

    Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; ...

    2016-02-03

    In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO2) uptake compared to the regular and torrefied pellets. The high CO2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pellets was challengingmore » due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

  1. Gas adsorption capacity of wood pellets

    SciTech Connect

    Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; Lau, A.; Bi, X. T.

    2016-02-03

    In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO2) uptake compared to the regular and torrefied pellets. The high CO2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pellets was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.

  2. Adsorption of mercury from water by modified multi-walled carbon nanotubes: adsorption behaviour and interference resistance by coexisting anions.

    PubMed

    Chen, Paris Honglay; Hsu, Cheng-Feng; Tsai, David Dah-wei; Lu, Yen-Ming; Huang, Winn-Jung

    2014-08-01

    This investigation reports the use of modified multi-walled carbon nanotubes (MWCNTs) with various functional groups for adsorbing inorganic divalent mercury (Hg(II)) from water samples. To elucidate the behaviours and mechanisms of Hg(II) adsorption by modified MWCNTs, their adsorption capacity was studied by considering adsorption isotherms and kinetics. Particular attention was paid to interference of coexisting inorganic ions with Hg(II) adsorption. The results reveal that functionalization with oxygen-containing groups improved the Hg(II) adsorption capacity of the MWCNTs. Kinetic analysis demonstrated that the adsorption of Hg(II) by MWCNTs was closely described by the pseudo-second-order and Elovich models, suggesting that the adsorption of Hg(II) by MWCNTs was significantly affected by chemical adsorption. The kinetic results were also analysed using the intraparticle diffusion model, which revealed that intraparticle diffusion was not the only rate-controlling mechanism. The adsorption of Hg(II) on MWCNTs fell drastically as the ionic strength increased from 0 to 1.0mol/L chloride ions, and declined significantly as the pH increased from 2.2 to 10.5. The elemental maps obtained by energy-dispersive spectrometer (EDS) revealed the formation of surface complexes of chloride ions with functional groups on MWCNTs, which reduced the number of available sites for the adsorption of Hg(II) and strengthened the repulsive forces between Hg(II) and MWCNTs. The EDS results suggest that chloride ions are important in controlling Hg(II) speciation and adsorption on the surfaces of MWCNTs.

  3. Mercury adsorption to gold nanoparticle and thin film surfaces

    NASA Astrophysics Data System (ADS)

    Morris, Todd Ashley

    Mercury adsorption to gold nanoparticle and thin film surfaces was monitored by spectroscopic techniques. Adsorption of elemental mercury to colloidal gold nanoparticles causes a color change from wine-red to orange that was quantified by UV-Vis absorption spectroscopy. The wavelength of the surface plasmon mode of 5, 12, and 31 nm gold particles blue-shifts 17, 14, and 7.5 nm, respectively, after a saturation exposure of mercury vapor. Colorimetric detection of inorganic mercury was demonstrated by employing 2.5 nm gold nanoparticles. The addition of low microgram quantities of Hg 2+ to these nanoparticles induces a color change from yellow to peach or blue. It is postulated that Hg2+ is reduced to elemental mercury by SCN- before and/or during adsorption to the nanoparticle surface. It has been demonstrated that surface plasmon resonance spectroscopy (SPRS) is sensitive to mercury adsorption to gold and silver surfaces. By monitoring the maximum change in reflectivity as a function of amount of mercury adsorbed to the surface, 50 nm Ag films were shown to be 2--3 times more sensitive than 50 nm Au films and bimetallic 15 nm Au/35 nm Ag films. In addition, a surface coverage of ˜40 ng Hg/cm2 on the gold surface results in a 0.03° decrease in the SPR angle of minimum reflectivity. SPRS was employed to follow Hg exposure to self-assembled monolayers (SAMs) on Au. The data indicate that the hydrophilic or hydrophobic character of the SAM has a significant effect on the efficiency of Hg penetration. Water adsorbed to carboxylic acid end group of the hydrophilic SAMs is believed to slow the penetration of Hg compared to methyl terminated SAMs. Finally, two protocols were followed to remove mercury from gold films: immersion in concentrated nitric acid and thermal annealing up to 200°C. The latter protocol is preferred because it removes all of the adsorbed mercury from the gold surface and does not affect the morphology of the gold surface.

  4. Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell.

    PubMed

    Khaloo, Shokooh Sadat; Matin, Amir Hossein; Sharifi, Sahar; Fadaeinia, Masoumeh; Kazempour, Narges; Mirzadeh, Shaghayegh

    2012-01-01

    The application of almond shell as a low cost natural adsorbent to remove Hg(2+) from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg(2+) uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG(0), ΔH(0) and ΔS(0), indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg(2+) removal from a synthetic effluent.

  5. Adsorption of mercury in coal-fired power plants gypsum slurry on TiO2/chitosan composite material

    NASA Astrophysics Data System (ADS)

    Gao, P.; Gao, B. B.; Gao, J. Q.; Zhang, K.; Chen, Y. J.; Yang, Y. P.; Chen, H. W.

    2016-07-01

    In this study, a simple method was used to prepare a chitosan adsorbent to mix with KI and TiO2. Gravimetric analysis (TG), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the samples before and after adsorption of Hg2+. A mercury adsorption experiment was also conducted in the gypsum slurry. The results show that using hydrobromic acid as a solvent of adsorbent resulted in a better adsorption effect than using acetic acid alone. Also, the sample (CS-KI/TiO2-HBr) had a maximum mercury adsorption capacity when the pH=5 and the t=50°C. The characterization experiments showed that the thermal stability of composite materials declined and the TiO2 uniformly dispersed in the surface of the samples with a lamellar structure, generating a lot of cracks and recesses that increased the reactive sites. Furthermore, when the TiO2 reacted with CS, it resulted in Ti-C, Ti-O and Ti-N bonds. The Br- can prevent the growth of TiO2 crystal grains and strengthen the ability of I- to remove mercury. The adsorption isotherm and kinetic results indicated that the adsorption behaviour of CS-KI/TiO2-HBr as it removes Hg2+ is an inhomogeneous multilayer adsorption process. The surface adsorption and intraparticle diffusion effects are both important in the Hg2+ adsorption process.

  6. Development of coconut pith chars towards high elemental mercury adsorption performance - Effect of pyrolysis temperatures.

    PubMed

    Johari, Khairiraihanna; Saman, Norasikin; Song, Shiow Tien; Cheu, Siew Chin; Kong, Helen; Mat, Hanapi

    2016-08-01

    In this study, chars from coconut pith (CP) were prepared aiming for superior adsorption towards elemental mercury (Hg(o)). The yield, proximate analysis, textural characteristics, surface functional groups and elemental composition analyses of the chars produced at pyrolysis temperature of 300 °C, 500 °C, 700 °C and 900 °C were compared. The surface area, pore volume, ash and carbon content of chars increased, while the yield and moisture content decreased with increasing pyrolysis temperatures. The changing of physical and chemical properties of the chars produced at variety pyrolysis temperature was much effect on the Hg(o) adsorption performance and definitely provides important information on the Hg(o) adsorption mechanism. The highest Hg(o) adsorption capacity was observed for CP900 (6067.49 μg/g), followed by CP700 (2395.98 μg/g), CP500 (289.76 μg/g), CP300 (1.68 μg/g), and CP (0.73 μg/g). The equilibrium data were well described by the Freundlich adsorption isotherm model. The pseudo-second order best described the kinetic data of the Hg(o) adsorption onto CP and CP300. For chars produced at higher pyrolysis temperature, however, the pseudo-zero order and pseudo-second order fitted well for the adsorption and breakthrough regions, respectively. The Hg(o) adsorption capacity of chars obtained from high pyrolysis temperature of CP significantly outperformed the commercial activated carbon (Darco KB-B) as well as superior to chars reported in the literature indicating the CP can be used as a precursor for preparation of chars as elemental mercury adsorbents.

  7. Enhanced and selective adsorption of mercury ions on chitosan beads grafted with polyacrylamide via surface-initiated atom transfer radical polymerization.

    PubMed

    Li, Nan; Bai, Renbi; Liu, Changkun

    2005-12-06

    Enhanced and selective removal of mercury ions was achieved with chitosan beads grafted with polyacrylamide (chitosan-g-polyacrylamide) via surface-initiated atom transfer radical polymerization (ATRP). The chitosan-g-polyacrylamide beads were found to have significantly greater adsorption capacities and faster adsorption kinetics for mercury ions than the chitosan beads. At pH 4 and with initial mercury concentrations of 10-200 mg/L, the chitosan-g-polyacrylamide beads can achieve a maximum adsorption capacity of up to 322.6 mg/g (in comparison with 181.8 mg/g for the chitosan beads) and displayed a short adsorption equilibrium time of less than 60 min (compared to more than 15 h for the chitosan beads). Coadsorption experiments with both mercury and lead ions showed that the chitosan-g-polyacrylamide beads had excellent selectivity in the adsorption of mercury ions over lead ions at pH < 6, in contrast to the chitosan beads, which did not show clear selectivity for either of the two metal species. Mechanism study suggested that the enhanced mercury adsorption was due to the many amide groups grafted onto the surfaces of the beads, and the selectivity in mercury adsorption can be attributed to the ability of mercury ions to form covalent bonds with the amide. It was found that adsorbed mercury ions on the chitosan-g-polyacrylamide beads can be effectively desorbed in a perchloric acid solution, and the regenerated beads can be reused almost without any loss of adsorption capacity.

  8. Influence of the pore structure and surface chemical properties of activated carbon on the adsorption of mercury from aqueous solutions.

    PubMed

    Lu, Xincheng; Jiang, Jianchun; Sun, Kang; Wang, Jinbiao; Zhang, Yanping

    2014-01-15

    Reactivation and chemical modification were used to obtain modified activated carbons with different pore structure and surface chemical properties. The samples were characterized by nitrogen absorption-desorption, Fourier transform infrared spectroscopy and the Bothem method. Using mercury chloride as the target pollutant, the Hg(2+) adsorption ability of samples was investigated. The results show that the Hg(2+) adsorption capacity of samples increased significantly with increases in micropores and acidic functional groups and that the adsorption process was exothermic. Different models and thermodynamic parameters were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through a monolayer mechanism by a two-speed process involving both rapid adsorption and slow adsorption. The adsorption rate was determined by chemical reaction.

  9. Adsorption energies of mercury-containing species on CaO and temperature effects on equilibrium constants predicted by density functional theory calculations.

    PubMed

    Kim, Bo Gyeong; Li, Xinxin; Blowers, Paul

    2009-03-03

    The adsorption of Hg, HgCl, and HgCl2 on the CaO surface was investigated theoretically so the fundamental interactions between Hg species and this potential sorbent can be explored. Surface models of a 4 x 4 x 2 cluster, a 5 x 5 x 2 cluster, and a periodic structure using density functional theory calculations with LDA/PWC and GGA/BLYP functionals, as employed in the present work, offer a useful description for the thermodynamic properties of adsorption on metal oxides. The effect of temperature on the equilibrium constant for the adsorption of mercury-containing species on the CaO (0 0 1) surface was investigated with GGA/BLYP calculations in the temperature range of 250-600 K. Results show that, at low coverage of elemental mercury, adsorption on the surface is physisorption while the two forms of oxidized mercury adsorption undergo stronger adsorption. The adsorption energies decrease with increasing coverage for elemental mercury on the surfaces. The chlorine atom enhances the adsorption capacity and adsorbs mercury to the CaO surface more strongly. The adsorption energy is changed as the oxidation state varies, and the equilibrium constant decreases as the temperature increases, in good agreement with data for exothermic adsorption systems.

  10. Thorough removal of inorganic and organic mercury from aqueous solutions by adsorption on Lemna minor powder.

    PubMed

    Li, Shun-Xing; Zheng, Feng-Ying; Yang, Huang; Ni, Jian-Cong

    2011-02-15

    The adsorption ability of duckweed (Lemna minor) powders for removing inorganic and organic mercury (methyl and ethyl mercury) has been studied using cold vapour atomic absorption spectrometry. The optimal adsorption conditions were: (a) the pH value of the solution 7.0 for inorganic and ethyl mercury, 9.0 for methyl mercury, and (b) equilibrium adsorption time 10, 20, and 40 min for inorganic mercury, methyl mercury, and ethyl mercury, respectively. After adsorption by L. minor powder for 40 min, when the initial concentrations of inorganic and organic mercury were under 12.0 μg L(-1) and 50.0 μg L(-1), respectively, the residual concentrations of mercury could meet the criterion of drinking water (1.0 μg L(-1)) and the permitted discharge limit of wastewater (10.0 μg L(-1)) set by China and USEPA, respectively. Thorough removal of both inorganic and organic mercury from aqueous solutions was reported for the first time. The significant adsorption sites were C-O-P and phosphate groups by the surface electrostatic interactions with aqueous inorganic and organic mercury cations, and then the selective adsorption was resulted from the strong chelating interaction between amine groups and mercury on the surface of L. minor cells.

  11. Adsorption of mercury on laterite from Guizhou Province, China.

    PubMed

    Yu, Xiaohong; Zhu, Lijun; Guo, Baiwei; He, Shouyang

    2008-01-01

    The adsorption behaviors of Hg(II) on laterite from Guizhou Province, China, were studied and the adsorption mechanism was discussed. The results showed that different mineral compositons in the laterite will cause differences in the adsorption capacity of laterite to Hg(II). Illite and non-crystalloids are the main contributors to enhancing the adsorption capacity of laterite to Hg(II). The pH of the solution is an important factor affecting the adsorption of Hg(II) on laterite. The alkalescent environment (pH 7-9) is favorable to the adsorption of Hg(II). The amount of adsorbed Hg(II) increases with increasing pH. When the pH reaches a certain value, the amount of the adsorbed Hg(II) will reach the maximum level. The amount of adsorbed Hg(II) decreases with increasing pH. The optimal pHs of laterite and kaolinite are 9 and 8, respectively. The optimal initial concentrations of Hg(II) on laterite and kaolinite are 250 and 200 microg/ml, respectively. The adsorption isotherms were described by the Langmuir model. The adsorption of Hg(II) on laterite is a quick process while that of Hg(II) on kaolinite is a slow reaction. Laterite from Guizhou Province is a promising environmental material which can be used in the removal of Hg(II) from wastewater.

  12. Mercury adsorption on granular activated carbon in aqueous solutions containing nitrates and chlorides.

    PubMed

    Di Natale, F; Erto, A; Lancia, A; Musmarra, D

    2011-09-15

    Adsorption is an effective process to remove mercury from polluted waters. In spite of the great number of experiments on this subject, the assessment of the optimal working conditions for industrial processes is suffering the lack of reliable models to describe the main adsorption mechanisms. This paper presents a critical analysis of mercury adsorption on an activated carbon, based on the use of chemical speciation analysis to find out correlations between mercury adsorption and concentration of dissolved species. To support this analysis, a comprehensive experimental study on mercury adsorption at different mercury concentrations, temperatures and pH was carried out in model aqueous solutions. This study pointed out that mercury capture occurs mainly through adsorption of cationic species, the adsorption of anions being significant only for basic pH. Furthermore, it was shown that HgOH(+) and Hg(2+) are captured to a higher extent than HgCl(+), but their adsorption is more sensitive to solution pH. Tests on the effect of temperature in a range from 10 to 55 °C showed a peculiar non-monotonic trend for mercury solution containing chlorides. The chemical speciation and the assumption of adsorption exothermicity allow describing this experimental finding without considering the occurrence of different adsorption mechanisms at different temperature.

  13. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  14. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash.

    PubMed

    Liu, Minmin; Hou, Li-An; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-15

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and (29)Si and (27)Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  15. Synthesis and characterization of gum acacia inspired silica hybrid xerogels for mercury(II) adsorption.

    PubMed

    Singh, Vandana; Singh, Somit Kumar

    2011-04-01

    In a sol-gel process, gum acacia inspired silica xerogels have been synthesized from tetraethylorthosilicate. Besides showing photoluminescence under ultraviolet excitation, the hybrid xerogels were very efficient in capturing mercury(II) from synthetic solution. To synthesize the optimum sample (in terms of Hg(II) uptake), different ratios of H(2)O:TEOS:EtOH were taken at fixed GA and catalyst concentrations where 4:1:1 ratio was found to be most favorable. Calcination in air further enhanced the mercury binding capacity of this sample. Optimum sample (H4) was obtained on calcination of the gel at 600°C. The hybrids have been structurally characterized using Infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermo gravimetric analysis, photoluminescence spectroscopy and Brunauer-Emmett-Teller analysis. In a preliminary batch adsorption experiment, H4 was evaluated to be highly efficient in the removal Hg(II) from synthetic aqueous solution.

  16. Characteristics and Stability of Mercury Vapor Adsorption over Two Kinds of Modified Semicoke

    PubMed Central

    Huawei, Zhang; Xiuli, Liu; Li, Wang; Peng, Liang

    2014-01-01

    In an attempt to produce effective and lower price gaseous Hg0 adsorbents, two methods of HCl and KMnO4/heat treatment were used respectively for the surface modification of liginite semicoke from inner Mongolia. The different effects of modification process on the surface physical and chemical properties were analyzed. The characteristics and stability of mercury vapor adsorption over two kinds of modified semicoke were investigated. The results indicated that modification process caused lower micropore quantity and volume capacity of semicoke; the C-Cl functional groups, C=O bond and delocalized electron π on the surface of Cl-SC, the amorphous higher valency Mnx+, and O=C–OH functional groups on the surface of Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg0. Modification process led to higher mercury removal efficiency of semicoke at 140°C and reduced the stability of adsorbed mercury of semicoke in simulated water circumstance simultaneously. PMID:25309948

  17. Characteristics and stability of mercury vapor adsorption over two kinds of modified semicoke.

    PubMed

    Huawei, Zhang; Xiuli, Liu; Li, Wang; Peng, Liang

    2014-01-01

    In an attempt to produce effective and lower price gaseous Hg(0) adsorbents, two methods of HCl and KMnO4/heat treatment were used respectively for the surface modification of liginite semicoke from inner Mongolia. The different effects of modification process on the surface physical and chemical properties were analyzed. The characteristics and stability of mercury vapor adsorption over two kinds of modified semicoke were investigated. The results indicated that modification process caused lower micropore quantity and volume capacity of semicoke; the C-Cl functional groups, C=O bond and delocalized electron π on the surface of Cl-SC, the amorphous higher valency Mn (x+) , and O=C-OH functional groups on the surface of Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg(0). Modification process led to higher mercury removal efficiency of semicoke at 140°C and reduced the stability of adsorbed mercury of semicoke in simulated water circumstance simultaneously.

  18. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    PubMed Central

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-01-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics. PMID:23687400

  19. Predicting protein dynamic binding capacity from batch adsorption tests.

    PubMed

    Carta, Giorgio

    2012-10-01

    The dynamic binding capacity (DBC) and its dependence on residence time influence the design and productivity of adsorption columns used in protein capture applications. This paper offers a very simple approach to predict the DBC of an adsorption column based on a measurement of the equilibrium binding capacity (EBC) and of the time needed to achieve one-half of the EBC in a batch adsorption test. The approach is based on a mass transfer kinetics model that assumes pore diffusion with a rectangular isotherm; however, the same approach is also shown to work for other systems where solute transport inside the particle occurs through other transport mechanisms.

  20. Adsorption behavior of mercury on functionalized aspergillus versicolor mycelia: atomic force microscopic study.

    PubMed

    Das, Sujoy K; Das, Akhil R; Guha, Arun K

    2009-01-06

    The adsorption characteristics of mercury on Aspergillus versicolor mycelia have been studied under varied environments. The mycelia are functionalized by carbon disulfide (CS(2)) treatment under alkaline conditions to examine the enhance uptake capacity and explore its potentiality in pollution control management. The functionalized A. versicolor mycelia have been characterized by scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDXA), attenuated total reflection infrared (ATR-IR), and atomic force microscopy (AFM) probing. SEM and AFM images exhibit the formation of nanoparticles on the mycelial surface. ATR-IR profile confirms the functionalization of the mycelia following chemical treatment. ATR-IR and EDXA results demonstrate the binding of the sulfur groups of the functionalized mycelia to the mercury and consequent formation metal sulfide. AFM study reveals that the mycelial surface is covered by a layer of densely packed domain like structures. Sectional analysis yields significant increase in average roughness (R(rms)) value (20.5 +/- 1.82 nm) compared to that of the pristine mycelia (4.56 +/- 0.82 nm). Surface rigidity (0.88 +/- 0.06 N/m) and elasticity (92.6 +/- 10.2 MPa) obtained from a force distance curve using finite element modeling are found to increase significantly with respect to the corresponding values of (0.65 +/- 0.05 N/m and 32.8 +/- 4.5 MPa) of the nonfunctionalized mycelia. The maximum mercury adsorption capacity of the functionalized mycelia is observed to be 256.5 mg/g in comparison to 80.71 mg/g for the pristine mycelia.

  1. [Simulation study on the effect of salinity on the adsorption behavior of mercury in wastewater-irrigated area].

    PubMed

    Zheng, Shun-An; Li, Xiao-Hua; Xu, Zhi-Yu

    2014-05-01

    This study was designed to pinpoint the impact of salinity ( NaCl and Na2SO4, added at salinity levels of 0-5%, respectively) on the adsorption behavior of mercury in wastewater-irrigated areas of Tianjin City by batch and kinetic experiments. The results showed that, the Langmuir isotherm and the Elovich equation can well fitted batch and kinetic experimental data, respectively. As NaCI spiked in soil, Hg( II) adsorption capacity and strength had marked decreases, from 868.64 mgkg-1 and 1. 32 at control to 357.48 mgkg-1 and 0.63 at 5% salinity level of NaCI, respectively. As Na2SO4 spiked in soil, Hg(II) adsorption capacity (parameter qm in Langmuir isotherm) and strength (parameter k in Langmuir isotherm) changed slightly, from 868.64 mg kg-1 and 1.32 at control to 739.44 mg.kg-1 and 1. 18 at 5% salinity level of Na2 SO4, respectively. Kinetic data showed that, Hg( II) adsorption rate (parameter b in Elovich equation) in soil was not influenced by Na2SO, addition. However, the addition of NaC1 had a great effect on mercury adsorption rate. Hg(II ) adsorption capacity as a function of CI- or SO(2-)(4) content in soil could be simulated by the natural logarithm model, while Hg( II ) adsorption rate as a function of CI- content in soil could be simulated by the linear model. The study manifested that NaCI can significantly increase migration of Hg( II ) in the soil irrigated with wastewater, which may enhance Hg( II) bioavailability in the soil and cause a hazard to surface water. Especially, it will be harmful to human body through the food chain.

  2. Evaluating the Adsorptive Capacities of Chemsorb 1000 and Chemsorb 1425

    NASA Technical Reports Server (NTRS)

    Monje, Oscar Alberto Monje; Surma, Jan M.; Johnsey, Marissa N.; Melendez, Orlando

    2014-01-01

    The Air Revitalization Lab at KSC tested Chemsorb 1000 and 1425, two candidate sorbents for use in future air revitalization technologies being evaluated by the ARREM project. Chemsorb 1000 and 1425 are granular coconut-shell activated carbon sorbents produced by Molecular Products, Inc. that may be used in the TCCS. Chemsorb 1000 is a high grade activated carbon for organic vapor adsorption. In contrast, Chemsorb 1425 is a high-grade impregnated activated carbon for adsorption of airborne ammonia and amines. Chemsorb 1000 was challenged with simulated spacecraft gas streams in order to determine its adsorptive capacities for mixtures of volatile organics compounds. Chemsorb 1425 was challenged with various NH3 concentrations to determine its adsorptive capacity.

  3. Specific mercury(II) adsorption by thymine-based sorbent.

    PubMed

    Liu, Xiangjun; Qi, Cui; Bing, Tao; Cheng, Xiaohong; Shangguan, Dihua

    2009-04-15

    A new kind of polymer sorbent based on the specific interaction of Hg(II) with nucleic acid base, thymine, is described for the selective adsorption of Hg(II) from aqueous solution. Two types of sorbents immobilized with thymine were prepared by one-step swelling and polymerization and graft polymerization, respectively. The maximum static adsorption capacity of the new polymer sorbents for Hg(II) is proportional to the density of thymine on their surface, up to 200mg/g. Moreover, the new kind polymer sorbent shows excellent selectivity for Hg(II) over other interfering ions, such as Cu(II), Cd(II), Zn(II), Co(II), Ca(II) and Mg(II), exhibits very fast kinetics for Hg(II) adsorption from aqueous solution, and can be easily regenerated by 1.0M HCl. It also has been successfully used for the selective adsorption of spiked Hg(II) from real tap water samples. This new thymine polymer sorbent holds a great promise in laboratory and industrial applications such as separation, on-line enrichment, solid-phase extraction, and removal of Hg(II) from pharmaceutical, food and environmental samples.

  4. High capacity adsorption media and method of producing

    DOEpatents

    Tranter, Troy J.; Herbst, R. Scott; Mann, Nicholas R.; Todd, Terry A.

    2008-05-06

    A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

  5. High capacity adsorption media and method of producing

    DOEpatents

    Tranter, Troy J.; Mann, Nicholas R.; Todd, Terry A.; Herbst, Ronald S.

    2010-10-05

    A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving and/or suspending at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

  6. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-15

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  7. An In Situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode

    DTIC Science & Technology

    1988-07-15

    Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode by DJ. Blackwood and S. Pons Prepared for publication in J...Secunt ClaMwfkation) An in situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode D.lc...SUBJECT TERMS (Continue on roverse if necessary and identify by block ’e’ 9ELD I GROUP I SUB-GROUP infrared spectroelectrochemistry ,adsorption, mercury I

  8. CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION

    EPA Science Inventory

    The paper gives results of a characterization of the physical and chemical properties of the activated carbons used for elemental mercury (Hgo) adsorption, in order to understand the role of oxygen surface functional groups on the mechanism of Hgo adsorption by activated carbons....

  9. A study on the adsorption mechanism of mercury on Aspergillus versicolor biomass.

    PubMed

    Das, Sujoy K; Das, Akhil R; Guha, Arun K

    2007-12-15

    The adsorption behavior of mercury on Aspergillus versicolor biomass (AVB) has been investigated in aqueous solution to understand the physicochemical process involved and to explore the potentiality of AVB in pollution control management. This biomass has been successfully used for reducing the mercury concentration level in the effluent of chloralkali and battery industries to a permissible limit. The results establish that 75.6 mg of mercury is adsorbed per gram of biomass. The adsorption process is found to be a function of pH of the solution, with the optimum range being pH 5.0-6.0. The process obeys the Langmuir-Freundlich isotherm model. Scanning electron microscopic analysis demonstrates a conspicuous surface morphology change of the mercury-adsorbed biomass. A nearly uniform distribution of metal ions on the mycelial surface excepting a few aggregation points is revealed by X-ray elemental mapping profiles. The results of zeta potential measurement, Fourier transform infrared (FTIR) spectroscopy, and blocking of the functional groups by chemical modification reflect the binding of mercury on the biomass occurs through electrostatic and complexation reactions. The accumulation of mercury on the cell wall associated with negligible diffusion and or transportation into cytoplasm finds support from the results of adsorption kinetics and transmission electron micrographs. Mercury adsorption on biomass also leads to elongation of cells and cytoplasmic aggregation of spheroplast/protoplasts, indicating that the cell wall acts as a permeation barrier against this toxic metal.

  10. Evaluation of Fuller's earth for the adsorption of mercury from aqueous solutions: a comparative study with activated carbon.

    PubMed

    Oubagaranadin, John U Kennedy; Sathyamurthy, N; Murthy, Z V P

    2007-04-02

    Fuller's earth (FE) has been used as an adsorbent in this work to remove mercury from aqueous solutions. For the purpose of comparison, simultaneous experiments using activated carbon (AC) have also been done. The aim of the work is to test how best FE can be used as an adsorbent for mercury. Equilibrium isotherms, such as Freundlich, Langmuir, Dubinin-Redushkevich, Temkin, Harkins-Jura, Halsey and Henderson have been tested. Kinetic studies based on Lagergren first-order, pseudo-second-order rate expressions and intra-particle diffusion studies have been done. The batch experiments were conducted at room temperature (30 degrees C) and at the normal pH (6.7+/-0.2) of the solution. It has been observed that Hg(II) removal rate is better for FE than AC, due to large dosage requirement, whereas the adsorption capacity of AC is found to be much better than FE. Hence, although FE can be used as an adsorbent, a high dosage is required, when compared to AC. Hybrid fractional error function analysis shows that the best-fit for the adsorption equilibrium data is represented by Freundlich isotherm. Kinetic and film diffusion studies show that the adsorption of mercury on FE and AC is both intra-particle diffusion and film diffusion controlled.

  11. Surface functionalized nano-magnetic particles for wastewater treatment: adsorption and desorption of mercury.

    PubMed

    Tri, Pham Minh; Khim, Kwa Soo; Hidajat, K; Uddin, M S

    2009-02-01

    The present study deals with adsorption and desorption of mercury on surface functionalized nano-magnetic particles. The nano-magnetic particles (Fe3O4) were synthesized by chemical precipitation of Fe2+ and Fe3+ salts at 80 degrees C at alkaline condition and inert atmosphere. The particle surface was then functionalized in two different ways: surface charge controlled by solution pH and coating the surface with polymer (vinylpyrrolidone) with thiodiglycolic acid as the primary surfactant and 4-vinylaniline as the secondary surfactant. It was found that the adsorption of mercury was pH dependent and maximum adsorption occurred at pH of 7.5 with bare particles and at pH 10 for polymer grafted particles. Maximum adsorption of mercury was found to be 280 mg/g particle.

  12. Fabrication of a selective mercury sensor based on the adsorption of cold vapor of mercury on carbon nanotubes: determination of mercury in industrial wastewater.

    PubMed

    Safavi, Afsaneh; Maleki, Norouz; Doroodmand, Mohammad Mahdi

    2010-01-15

    A new sensor for the determination of mercury at microg ml(-1) levels is proposed based on the adsorption of mercury vapor on single-walled carbon nanotubes (SWCNTs). The changes in the impedance of SWCNTs were monitored upon adsorption of mercury vapor. The adsorption behaviour of mercury on SWCNTs was compared with that on multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs). Cold vapor of mercury was generated at 65 degrees C using Sn(II) solution as a reducing agent. The limit of detection was 0.64 microg ml(-1) for Hg(II) species. The calibration curve for Hg(II) was linear from 1.0 to 30.0 microg ml(-1). The relative standard deviation (RSD) of eight replicate analyses of 15 microg ml(-1) of Hg(II) was 2.7%. The results showed no interfering effects from many foreign species and hydride forming elements. The system was successfully applied to the determination of the mercury content of different types of wastewater samples.

  13. Enhancing the adsorption of vapor-phase mercury chloride with an innovative composite sulfur-impregnated activated carbon.

    PubMed

    Ie, Iau-Ren; Chen, Wei-Chin; Yuan, Chung-Shin; Hung, Chung-Hsuang; Lin, Yuan-Chung; Tsai, Hsieh-Hung; Jen, Yi-Shiu

    2012-05-30

    Mercury chloride (HgCl(2)) is the major mercury derivate emitted from municipal solid waste incinerators, which has high risk to the environment and human health. This study investigated the adsorption of vapor-phase HgCl(2) with an innovative composite sulfurized activated carbon (AC), which was derived from the pyrolysis, activation, and sulfurization of waste tires. The composite sulfur-impregnation process impregnated activated carbon with aqueous-phase sodium sulfide (Na(2)S) and followed with vapor-phase elemental sulfur (S(0)). Thermogravimetric analysis (TGA) was applied to investigate the adsorptive capacity of vapor-phase HgCl(2) using the composite sulfurized AC. The operating parameters included the types of composite sulfurized AC, the adsorption temperature, and the influent HgCl(2) concentration. Experimental results indicated that the sulfur-impregnation process could increase the sulfur content of the sulfurized AC, but decreased its specific surface area. This study further revealed that the composite sulfurized AC impregnated with aqueous-phase Na(2)S and followed with vapor-phase S(0) (Na(2)S+S(0) AC) had much higher saturated adsorptive capacity of HgCl(2) than AC impregnated in the reverse sequence (S(0)+Na(2)S AC). A maximum saturated adsorptive capacity of HgCl(2) up to 5236 μg-HgCl(2)/g-C was observed for the composite Na(2)S+S(0) AC, which was approximately 2.00 and 3.17 times higher than those for the single Na(2)S and S(0) ACs, respectively.

  14. Mechanistic studies of mercury adsorption and oxidation by oxygen over spinel-type MnFe2O4.

    PubMed

    Yang, Yingju; Liu, Jing; Zhang, Bingkai; Liu, Feng

    2017-01-05

    MnFe2O4 has been regarded as a very promising sorbent for mercury emission control in coal-fired power plants because of its high adsorption capacity, magnetic, recyclable and regenerable properties. First-principle calculations based on density functional theory (DFT) were used to elucidate the mercury adsorption and oxidation mechanisms on MnFe2O4 surface. DFT calculations show that Mn-terminated MnFe2O4 (1 0 0) surface is much more stable than Fe-terminated surface. Hg(0) is physically adsorbed on Fe-terminated MnFe2O4 (1 0 0) surface. Hg(0) adsorption on Mn-terminated MnFe2O4 (1 0 0) surface is a chemisorption process. The partial density of states (PDOS) analysis indicates that Hg atom interacts strongly with surface Mn atoms through the orbital hybridization. HgO is adsorbed on the MnFe2O4 surface in a chemical adsorption manner. The small HOMO-LUMO energy gap implies that HgO molecular shows high chemical reactivity for HgO adsorption on MnFe2O4 surface. The energy barriers of Hg(0) oxidation by oxygen on Fe- and Mn-terminated MnFe2O4 surfaces are 206.37 and 76.07kJ/mol, respectively. Mn-terminated surface is much more favorable for Hg(0) oxidation than Fe-terminated surface. In the whole Hg(0) oxidation process, the reaction between adsorbed mercury and surface oxygen is the rate-determining step.

  15. Characteristic and mercury adsorption of activated carbon produced by CO2 of chicken waste.

    PubMed

    Huang, Yaji; Jin, Baosheng; Zhong, Zhaoping; Zhong, Wenqi; Xiao, Rui

    2008-01-01

    Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process (drying at 200 degrees C, pyrolysis in N2 atmosphere, followed by CO2 activation) was used for the production of activated samples. The effects of carbonization temperature (400-600 degrees C), activation temperature (700-900 degrees C), and activation time (1-2.5 h) on the physicochemical properties (weight-loss and BET surface) of the prepared carbon were investigated. Adsorptive removal of mercury from real flue gas onto activated carbon has been studied. The activated carbon from chicken waste has the same mercury capacity as commercial activated carbon (Darco LH) (Hg(v): 38.7% vs. 53.5%, Hg(0): 50.5% vs. 68.8%), although its surface area is around 10 times smaller, 89.5 m2/g vs. 862 m2/g. The low cost activated carbon can be produced from chicken waste, and the procedure is suitable.

  16. Mercury oxidation and adsorption characteristics of potassium permanganate modified lignite semi-coke.

    PubMed

    Zhang, Huawei; Chen, Jitao; Liang, Peng; Wang, Li

    2012-01-01

    The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke (SC) for gaseous Hg0 were investigated in an attempt to produce more effective and lower price adsorbents for the control of elemental mercury emission. Brunauer-Emmett-Teller (BET) measurements, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to analyze the surface physical and chemical properties of SC, Mn-SC and Mn-H-SC before and after mercury adsorption. The results indicated that potassium permanganate modification had significant influence on the properties of semi-coke, such as the specific surface area, pore structure and surface chemical functional groups. The mercury adsorption efficiency of modified semi-coke was lower than that of SC at low temperature, but much higher at high temperature. Amorphous Mn7+, Mn6+ and Mn4+ on the surface of Mn-SC and Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg0, which oxidized the elemental mercury into Hg2+ and captured it. Thermal treatment reduced the average oxidation degree of Mn(x+) on the surface of Mn-SC from 3.80 to 3.46. However, due to the formation of amorphous MnOx, the surface oxidation active sites for gaseous Hg0 increased, which gave Mn-H-SC higher mercury adsorption efficiency than that of Mn-SC at high temperature.

  17. Evaluation of the adsorption capacity of alkali-treated waste materials for the adsorption of sulphamethoxazole.

    PubMed

    Kurup, Lisha

    2012-01-01

    The present work is to develop potential adsorbents from waste material and employ them for the removal of a hazardous antibacterial, sulphamethoxazole, from the wastewater by the Adsorption technique. The Adsorption technique was used to impound the dangerous antibiotics from wastewater using Deoiled Soya (DOS), an agricultural waste, and Water Hyacinth (WH), a prolific colonizer. The adsorption capacity of these adsorbents was further enhanced by treating them with sodium hydroxide solution and it was seen that the adsorption capacity increases by 10 to 25%. Hence a comparative account of the adsorption studies of all the four adsorbents, i.e. DOS, Alkali-treated DOS, WH and Alkali-treated Water Hyacinth has been discussed in this paper. Different isotherms like Freundlich, Langmuir and Dubinin-Radushkevich were also deduced from the adsorption data. Isotherm studies were in turn used in estimating the thermodynamic parameters. DOS showed sorption capacity of 0.0007 mol g(-1) while Alkali-treated Deoiled Soya exhibited 0.0011 mol g(-1) of sorption capacity, which reveals that the adsorption is higher in case of alkali-treated adsorbent. The mean sorption energy (E) was obtained between 9 and 12 kJ mol, which shows that the reaction proceeds by ion exchange reaction. Kinetic study reveals that the reaction follows pseudo-second-order rate equation. Moreover, mass transfer studies performed for the ongoing processes show that the mass transfer coefficient obtained for alkali-treated moieties was higher than the parent moieties. The breakthrough curves plotted from the column studies show percentage saturation of 90-98%. About 87-97% of sulphamethoxazole was recovered from column by desorption.

  18. Multifractal analysis of soil porosity based on mercury porosimetry and nitrogen adsorption

    NASA Astrophysics Data System (ADS)

    Paz-Ferreiro, J.; Vidal Vázquez, E.; Miranda, J. G. V.

    2009-04-01

    The soil pore space is composed of a continuum of pores extremely variable in size which include structures smaller than nanometres and as large as macropores > 20 mm in diameter, i.e. with an upper size limit of the order of centimetres. Thus, a ratio of at least 106 is displayed in soil pore sizes. Soil pore size distribution directly influences many soil physical, chemical and biological properties. Characterization of soil structure may be achieved by pore size distribution analysis. There is not a unique method for determining soil pore size distributions all over the size scale. Mercury injection porosimetry and N2 adsorption isotherms are techniques commonly used for assessing equivalent pore size diameters in selected ranges. The Hg injection technique provides pore size distributions in the range from about 50 nm to 100 m, whereas N2 adsorption isotherms may be used for finer pores ranging in size from about 2 to 500 nm. In this work, multifractal formalism has been used to describe Hg injection porosimetry and N2 adsorption isotherms measured in a Mollisol and in a Vertisol with four different soil use intensities, ranging from native, never cultivated, land to continuous cropping. Three samples per treatment were analyzed resulting in a total of twelve samples per soil. All the Hg injection curves and N2 adsorption isotherms exhibited multifractal behaviour as shown by singularity spectra and Rényi dimension spectra. The capacity dimension, D0, for both Hg injection and N2 adsorption data sets was not significantly different from 1.00. However, significantly different values of entropy dimension, D1, and correlation dimension, D2, were obtained for mercury injection and nitrogen adsorption experimental data. For instance, entropy dimension, D1, values extracted from multifractal spectra of Hg intrusion porosimetry were on average 0.913 and varied from 0.889 to 0.939. However, the corresponding figures for N2 adsorption isotherms were on average 0

  19. Adsorption of toxic mercury(II) by an extracellular biopolymer poly(gamma-glutamic acid).

    PubMed

    Inbaraj, B Stephen; Wang, J S; Lu, J F; Siao, F Y; Chen, B H

    2009-01-01

    Adsorption of mercury(II) by an extracellular biopolymer, poly(gamma-glutamic acid) (gamma-PGA), was studied as a function of pH, temperature, agitation time, ionic strength, light and heavy metal ions. An appreciable adsorption occurred at pH>3 and reached a maximum at pH 6. Isotherms were well predicted by Redlich-Peterson model with a dominating Freundlich behavior, implying the heterogeneous nature of mercury(II) adsorption. The adsorption followed an exothermic and spontaneous process with increased orderliness at solid/solution interface. The adsorption was rapid with 90% being attained within 5 min for a 80 mg/L mercury(II) solution, and the kinetic data were precisely described by pseudo second order model. Ionic strength due to added sodium salts reduced the mercury(II) binding with the coordinating ligands following the order: Cl(-) >SO(4)(2-) >NO(3)(-). Both light and heavy metal ions decreased mercury(II) binding by gamma-PGA, with calcium(II) ions showing a more pronounced effect than monovalent sodium and potassium ions, while the interfering heavy metal ions followed the order: Cu(2+) > Cd(2+) > Zn(2+). Distilled water adjusted to pH 2 using hydrochloric acid recovered 98.8% of mercury(II), and gamma-PGA reuse for five cycles of operation showed a loss of only 6.5%. IR spectra of gamma-PGA and Hg(II)-gamma-PGA revealed binding of mercury(II) with carboxylate and amide groups on gamma-PGA.

  20. Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor.

    PubMed

    Zhang, Yongsheng; Zhao, Lilin; Guo, Ruitao; Song, Na; Wang, Jiawei; Cao, Yan; Orndorff, William; Pan, Wei-ping

    2015-07-01

    In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl2, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr2 and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr2 and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.

  1. Removal of trace level aqueous mercury by adsorption and photocatalysis on silica-titania composites.

    PubMed

    Byrne, Heather E; Mazyck, David W

    2009-10-30

    Silica-titania composites (STCs) were applied to trace level mercury solutions (100 microg/L Hg) to determine the degree of mercury removal that could be accomplished via adsorption and photocatalysis. STCs are a porous, high surface area silica substrate (> 200 m(2)/g), manufactured using sol-gel methodology, impregnated with TiO2 nanoparticles. The performance of this material along with its precursors, silica and Degussa P25 TiO2 were compared. Under adsorption alone (no UV illumination), STCs were able to achieve approximately 90% removal of mercury, which is comparable to that of Degussa P25. Silica without TiO2 performed poorly in comparison and was minimally affected by UV illumination. Contrary to expectations, the performance of Degussa P25 was not largely changed by UV irradiation and the STC was detrimentally affected under the same conditions. It was concluded that elemental mercury was formed under UV irradiation with or without the presence of TiO2 due to photochemical reactions, decreasing the mercury removal by STC. Additionally, the primary particle size of the STC was reduced to increase mass transfer. The result was improved Hg removal under adsorption and photocatalysis conditions. Improved adsorption kinetics were also achieved by altering the STC pore size and TiO2 loading.

  2. Silver impregnated carbon for adsorption and desorption of elemental mercury vapors.

    PubMed

    Karatza, Despina; Prisciandaro, Marina; Lancia, Amedeo; Musmarra, Dino

    2011-01-01

    The Hg(0) vapor adsorption experimental results on a novel sorbent obtained by impregnating a commercially available activated carbon (Darco G60 from BDH) with silver nitrate were reported. The study was performed by using a fundamental approach, in an apparatus at laboratory scale in which a synthetic flue gas, formed by Hg(0) vapors in a nitrogen gas stream, at a given temperature and mercury concentration, was flowed through a fixed bed of adsorbent material. Breakthrough curves and adsorption isotherms were obtained for bed temperatures of 90, 120 and 150 degrees C and for Hg(0) concentrations in the gas varying in the range of 0.8-5.0 mg/m3. The experimental gas-solid equilibrium data were used to evaluate the Langmuir parameters and the heat of adsorption. The experimental results showed that silver impregnated carbon was very effective to capture elemental mercury and the amount of mercury adsorbed by the carbon decreased as the bed temperature increased. In addition, to evaluate the possibility of adsorbent recovery, desorption was also studied. Desorption runs showed that both the adsorbing material and the mercury could be easily recovered, since at the end of desorption the residue on solid was almost negligible. The material balance on mercury and the constitutive equations of the adsorption phenomenon were integrated, leading to the evaluation of only one kinetic parameter which fits well both the experimentally determined breakthrough and desorption curves.

  3. Multiscale characterization of pore size distributions using mercury porosimetry and nitrogen adsorption

    NASA Astrophysics Data System (ADS)

    Paz-Ferreiro, J.; Tarquis, A. M.; Miranda, J. G. V.; Vidal Vázquez, E.

    2009-04-01

    The soil pore space is a continuum extremely variable in size, including structures smaller than nanometres and as large as macropores or cracks with millimetres or even centimetres size. Pore size distributions (PSDs) affects important soil functions, such as those related with transmission and storage of water, and root growth. Direct and indirect measurements of PSDs are becoming increasingly used to characterize soil structure. Mercury injection porosimetry and nitrogen adsorption isotherms are techniques commonly employed for assessing equivalent pore size diameters in the range from about 50 nm to 100 m and 2 to 500 nm, respectively. The multifractal formalism was used to describe Hg injection curves and N2 adsorption isotherms from two series of a Mollisol cultivated under no tillage and minimum tillage. Soil samples were taken from 0-10, 10-20 and 20-30 cm depths in two experimental fields located in the north of Buenos Aires and South of Santa Fe provinces, Argentina. All the data sets analyzed from the two studied soil attributes showed remarkably good scaling trends as assessed by singularity spectrum and generalized dimension spectrum. Both, experimental Hg injection curves and N2 adsorption isotherms could be fitted reasonably well with multifractal models. A wide variety of singularity and generalized dimension spectra was found for the variables. The capacity dimensions, D0, for both Hg injection and N2 adsorption data were not significantly different from the Euclidean dimension. However, the entropy dimension, D1, and correlation dimension, D2, obtained from mercury injection and nitrogen adsorption data showed significant differences. So, D1 values were on average 0.868 and varied from 0.787 to 0.925 for Hg intrusion curves. Entropy dimension, D1, values for N2 adsorption isotherms were on average 0.582 significantly lower than those obtained when using the former technique. Twenty-three out of twenty-four N2 isotherms had D1 values in a

  4. Adsorption of pyrantel pamoate on mercury from aqueous solutions: studies by stripping voltammetry.

    PubMed

    Gupta, Vinod K; Jain, Rajeev; Jadon, N; Radhapyari, K

    2010-10-01

    Adsorption and electrochemical reduction of pyrantel pamoate are studied in Britton Robinson buffer medium at hanging mercury drop electrode (HMDE) by Adsorptive Stripping Voltammetric technique. The peak current shows a linear dependence with the drug concentration over the range 250 ng mL(-1) to 64 microg mL(-1). Applicability to assay the drug in urine samples is illustrated in the concentration range 5-20 microg mL(-1).

  5. Effect of calcium on adsorption capacity of powdered activated carbon.

    PubMed

    Li, Gang; Shang, Junteng; Wang, Ying; Li, Yansheng; Gao, Hong

    2013-12-01

    We investigated the effect of calcium ion on the adsorption of humic acid (HA) (as a target pollutant) by powered activated carbon. The HA adsorption isotherms at different pH and kinetics of two different solutions including HA alone and HA doped Ca(2+), were performed. It was showed that the adsorption capacity of powdered activated carbon (PAC) for HA was markedly enhanced when Ca(2+) was doped into HA. Also, HA and Ca(2+) taken as nitrate were tested on the uptake of each other respectively and it was showed that the adsorbed amounts of both of them were significantly promoted when HA and calcium co-existed. Furthermore, the adsorbed amount of HA slightly decreased with the increasing of Ca(2+) concentration, whereas the amount of calcium increased with the increasing of HA concentration, but all above the amounts without addition. Finally, the change of pH before and after adsorption process is studied. In the two different solutions including HA alone and HA doped Ca(2+), pH had a small rise, but the extent of pH of later solution was bigger.

  6. EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

    EPA Science Inventory

    The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

  7. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  8. ROLE OF HCL IN ADSORPTION OF ELEMENTAL MERCURY VAPOR BY CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of a study to identify active sites and surface functional groups that may contribute to the adsorption of elemental mercury (Hg?) by relatively inexpensive calcium (Ca)-based sorbents. (NOTE: Hg? capture has been mostly investigated using high-surface-ar...

  9. THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

    EPA Science Inventory

    Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

  10. Proteomic analysis of protein adsorption capacity of different haemodialysis membranes.

    PubMed

    Urbani, Andrea; Lupisella, Santina; Sirolli, Vittorio; Bucci, Sonia; Amoroso, Luigi; Pavone, Barbara; Pieroni, Luisa; Sacchetta, Paolo; Bonomini, Mario

    2012-04-01

    Protein-adsorptive properties are a key feature of membranes used for haemodialysis treatment. Protein adsorption is vital to the biocompatibility of a membrane material and influences membrane's performance. The object of the present study is to investigate membrane biocompatibility by correlating the adsorbed proteome repertoire with chemical feature of the membrane surfaces. Dialyzers composed of either cellulose triacetate (Sureflux 50 L, effective surface area 0.5 m(2); Nipro Corporation, Japan) or the polysulfone-based helixone (FX40, effective surface area 0.4 m(2); Fresenius Medical Care AG, Germany) materials were employed to develop an ex vivo apparatus to study protein adsorption. Adsorbed proteins were eluted by a strong chaotropic buffer condition and investigated by a proteomic approach. The profiling strategy was based on 2D-electrophoresis separation of desorbed protein coupled to MALDI-TOF/TOF analysis. The total protein adsorption was not significantly different between the two materials. An average of 179 protein spots was visualised for helixone membranes while a map of retained proteins of cellulose triacetate membranes was made up of 239 protein spots. The cellulose triacetate material showed a higher binding capacity for albumin and apolipoprotein. In fact, a number of different protein spots belonging to the gene transcript of albumin were visible in the cellulose triacetate map. In contrast, helixone bound only a small proportion of albumin, while proved to be particularly active in retaining protein associated with the coagulation cascade, such as the fibrinogen isoforms. Our data indicate that proteomic techniques are a useful approach for the investigation of proteins surface-adsorbed onto haemodialysis membranes, and may provide a molecular base for the interpretation of the efficacy and safety of anticoagulation treatment during renal replacement therapy.

  11. Chemical modification of oxalate decarboxylase to improve adsorption capacity.

    PubMed

    Lin, Rihui; He, Junbin; Wu, Jia; Cai, Xinghua; Long, Han; Chen, Shengfeng; Liu, Haiqian

    2017-02-03

    In order to enhance the adsorption capacity of oxalate decarboxylase (Oxdc) on calcium oxalate monohydrate crystals and improve the application performance of Oxdc, chemical modification of Oxdc with ethylenediaminetetraacetic dianhydride (EDTAD) was investigated in this work. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography tandem mass spectrometry (LC/MS) analysis results demonstrated that Oxdc and EDTAD have been covalently bound, and suggested that the chemical modification occurred at the free amino of the side chain and the α-amine of the N-terminus of Oxdc. Fluorescene and circular dichroic measurement showed that the structure and conformation of Oxdc were tinily altered after modification by EDTAD. The optimum pH of EDTAD-modified Oxdc was shifted to the alkaline side about 1.5 unit and it has a higher thermostability. The analysis of kinetic parameters indicated that the EDTAD-modified Oxdc showed a higher affinity towards the substrate. Through modification the adsorption capacity of Oxdc onto CaOx monohydrate crystals was increased by 42.42%.

  12. Enhanced adsorption of mercury ions on thiol derivatized single wall carbon nanotubes.

    PubMed

    Bandaru, Narasimha Murthy; Reta, Nekane; Dalal, Habibullah; Ellis, Amanda V; Shapter, Joseph; Voelcker, Nicolas H

    2013-10-15

    Thiol-derivatized single walled carbon nanotube (SWCNT-SH) powders were synthesized by reacting acid-cut SWCNTs with cysteamine hydrochloride using carbodiimide coupling. Infrared (IR) spectroscopy, Raman spectroscopy and thermogravimetric analysis confirmed the successful functionalization of the SWCNTs. SWCNT-SH powders exhibited a threefold higher adsorption capacity for Hg(II) ions compared to pristine SWCNTs, and a fourfold higher adsorption capacity compared to activated carbon. The influence of adsorption time, pH, initial metal concentration and adsorbent dose on Hg(II) ion removal was investigated. The maximum adsorption capacity of the SWCNT-SH powders was estimated by using equilibrium isotherms, such as Freundlich and Langmuir, and the maximum adsorption capacity of the SWCNT-SH powder was found to be 131 mg/g. A first-order rate model was employed to describe the kinetic adsorption process of Hg(II) ions onto the SWCNT-SH powders. Desorption studies revealed that Hg(II) ions could be easily removed from the SWCNT-SH powders by altering the pH. Further, the adsorption efficiency of recovered SWCNT-SH powders was retained up to 91%, even after 5 adsorption/desorption cycles.

  13. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-01

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  14. Adsorption and Catalytic Oxidation of Gaseous Elemental Mercury in Flue Gas over MnOx/Alumina

    SciTech Connect

    Qiao, S.H.; Chen, J.; Li, J.F.; Qu, Z.; Liu, P.; Yan, N.Q.; Jia, J.Q.

    2009-04-15

    MnOx/Al{sub 2}O{sub 3} catalysts (i.e., impregnating manganese oxide on alumina) were employed to remove elemental mercury (Hg{sup 0}) from flue gas. MnOx/Al{sub 2}O{sub 3} was found to have significant adsorption performance on capturing Hg{sup 0} in the absence of hydrogen chloride (HCl), and its favorable adsorption temperature was about 600 K. However, the catalytic oxidation of Hg{sup 0} became dominant when HCl or chlorine (Cl{sub 2}) was present in flue gas, and the removal efficiency of Hg{sup 0} was up to 90% with 20 ppm of HCl or 2 ppm of Cl{sub 2}. In addition, the catalysts with adsorbed mercury could be chemically regenerated by rinsing with HCl gas to strip off the adsorbed mercury in the form of HgCl{sub 2}. Sulfur dioxide displayed inhibition to the adsorption of Hg{sup 0} on the catalysts, but the inhibition was less to the catalytic oxidation of Hg{sup 0}, especially in the presence of Cl{sub 2}. The analysis results of XPS and pyrolysis-AAS indicated that the adsorbed mercury was mainly in the forms of mercuric oxide (Hg{sup 0}) and the weakly bonded speciation, and the ratio of them varied with the adsorption amount and manganese content on catalysts. The multifunctional performances of MnOx/Al{sub 2}O{sub 3} on the removal of Hg{sup 0} appeared to the promising in the industrial applications.

  15. Adsorption of mercury on lignin: combined surface complexation modeling and X-ray absorption spectroscopy studies.

    PubMed

    Lv, Jitao; Luo, Lei; Zhang, Jing; Christie, Peter; Zhang, Shuzhen

    2012-03-01

    Adsorption of mercury (Hg) on lignin was studied at a range of pH values using a combination of batch adsorption experiments, a surface complexation model (SCM) and synchrotron X-ray absorption spectroscopy (XAS). Surface complexation modeling indicates that three types of acid sites on lignin surfaces, namely aliphatic carboxylic-, aromatic carboxylic- and phenolic-type surface groups, contributed to Hg(II) adsorption. The bond distance and coordination number of Hg(II) adsorption samples at pH 3.0, 4.0 and 5.5 were obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. The results of SCM and XAS combined reveal that the predominant adsorption species of Hg(II) on lignin changes from HgCl(2)(0) to monodentate complex -C-O-HgCl and then bidentate complex -C-O-Hg-O-C- with increasing pH value from 2.0 to 6.0. The good agreement between SCM and XAS results provides new insight into understanding the mechanisms of Hg(II) adsorption on lignin.

  16. Enhanced chromium adsorption capacity via plasma modification of natural zeolites

    NASA Astrophysics Data System (ADS)

    Cagomoc, Charisse Marie D.; Vasquez, Magdaleno R., Jr.

    2017-01-01

    Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.

  17. High-capacity adsorption of aniline using surface modification of lignocellulose-biomass jute fibers.

    PubMed

    Gao, Da-Wen; Hu, Qi; Pan, Hongyu; Jiang, Jiping; Wang, Peng

    2015-10-01

    Pyromellitic dianhydride (PMDA) modified jute fiber (MJF) were prepared with microwave treatment to generate a biosorbent for aniline removal. The characterization of the biosorbent was investigated by SEM, BET and FT-IR analysis to discuss the adsorption mechanism. The studies of various factors influencing the adsorption behavior indicated that the optimum dosage for aniline adsorption was 3g/L, the maximum adsorption capacity was observed at pH 7.0 and the adsorption process is spontaneous and endothermic. The aniline adsorption follows the pseudo second order kinetic model and Langmuir isotherm model. Moreover, the biosorbent could be regenerated through the desorption of aniline by using 0.5M HCl solution, and the adsorption capacity after regeneration is even higher than that of virgin MJF. All these results prove MJF is a promising adsorbent for aniline removal in wastewater.

  18. Removal of mercury(II) ions in aqueous solution using the peel biomass of Pachira aquatica Aubl: kinetics and adsorption equilibrium studies.

    PubMed

    Santana, Andrea J; dos Santos, Walter N L; Silva, Laiana O B; das Virgens, Cesário F

    2016-05-01

    Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.

  19. Assessment of pumped mercury vapour adsorption tubes as passive samplers using a micro-exposure chamber.

    PubMed

    Brown, Richard J C; Burdon, Melia K; Brown, Andrew S; Kim, Ki-Hyun

    2012-09-01

    Mercury vapour adsorption tubes manufactured for pumped sampling and analysis have been evaluated for their performance as passive samplers. This has been done by exposing these tubes in a novel micro-exposure chamber. The uptake rates of these tubes have been found to be low (approximately 0.215 ml min(-1)) as compared to bespoke passive samplers for mercury vapour (typically in excess of 50 ml min(-1)). The measured uptake rates were shown to vary significantly between tubes and this was attributed to the variability in the air-sorbent interface and the proportion of the cross sectional area removed by the crimp in the quartz tubes used to secure the sorbent material. As a result of this variability the uptake rate of each tube must be determined using the micro-exposure chamber prior to deployment. Results have shown that the uptake rate determined in the micro-exposure chamber is invariant of concentration, and therefore these uptakes rates may be determined at a high mercury vapour concentration for many tubes at once in less than one hour. The uptake rate of the adsorption tubes under these conditions may be determined with a precision of 5%. Measurements made on a limited field trial in indoor and outdoor ambient air have shown that these tubes give results in acceptable agreement with more traditional pumped sampling methods, although longer sampling periods are required in order to reduce the uncertainty of the measurement, which is currently approximately 30%.

  20. Mercury

    MedlinePlus

    ... the lungs Medicine to remove mercury and heavy metals from the body INORGANIC MERCURY For inorganic mercury ... Baum CR. Mercury: Heavy metals and inorganic agents. In: Shannon MW, ... and Winchester's Clinical Management of Poisoning and Drug ...

  1. Capability of defective graphene-supported Pd13 and Ag13 particles for mercury adsorption

    NASA Astrophysics Data System (ADS)

    Meeprasert, Jittima; Junkaew, Anchalee; Rungnim, Chompoonut; Kunaseth, Manaschai; Kungwan, Nawee; Promarak, Vinich; Namuangruk, Supawadee

    2016-02-01

    Reactivity of single-vacancy defective graphene (DG) and DG-supported Pdn and Agn (n = 1, 13) for mercury (Hg0) adsorption has been studied using density functional theory calculation. The results show that Pdn binds defective site of DG much stronger than the Agn, while metal nanocluster binds DG stronger than single metal atom. Metal clustering affects the adsorption ability of Pd composite while that of Ag is comparatively less. The binding strength of -8.49 eV was found for Pd13 binding on DG surface, indicating its high stability. Analyses of structure, energy, partial density of states, and d-band center (ɛd) revealed that the adsorbed metal atom or cluster enhances the reactivity of DG toward Hg adsorption. In addition, the Hg adsorption ability of Mn-DG composite is found to be related to the ɛd of the deposited Mn, in which the closer ɛd of Mn to the Fermi level correspond to the higher adsorption strength of Hg on Mn-DG composite. The order of Hg adsorption strength on Mn-DG composite are as follows: Pd13 (-1.68 eV) >> Ag13 (-0.67 eV) ∼ Ag1 (-0.69 eV) > Pd1 (-0.62 eV). Pd13-DG composite is therefore more efficient sorbent for Hg0 removal in terms of high stability and high adsorption reactivity compared to the Ag13. Further design of highly efficient carbon based sorbents should be focused on tailoring the ɛd of deposited metals.

  2. Modeling high adsorption capacity and kinetics of organic macromolecules on super-powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Ando, Naoya; Yoshida, Tomoaki; Kurotobi, Ryuji; Matsushita, Taku; Ohno, Koichi

    2011-02-01

    The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on small particle-size activated carbon (super-powdered activated carbon, SPAC) is higher than that on larger particle-size activated carbon (powdered-activated carbon, PAC). Increased adsorption capacity is likely attributable to the larger external surface area because the NOM and PSS molecules do not completely penetrate the adsorbent particle; they preferentially adsorb near the outer surface of the particle. In this study, we propose a new isotherm equation, the Shell Adsorption Model (SAM), to explain the higher adsorption capacity on smaller adsorbent particles and to describe quantitatively adsorption isotherms of activated carbons of different particle sizes: PAC and SPAC. The SAM was verified with the experimental data of PSS adsorption kinetics as well as equilibrium. SAM successfully characterized PSS adsorption isotherm data for SPACs and PAC simultaneously with the same model parameters. When SAM was incorporated into an adsorption kinetic model, kinetic decay curves for PSSs adsorbing onto activated carbons of different particle sizes could be simultaneously described with a single kinetics parameter value. On the other hand, when SAM was not incorporated into such an adsorption kinetic model and instead isotherms were described by the Freundlich model, the kinetic decay curves were not well described. The success of the SAM further supports the adsorption mechanism of PSSs preferentially adsorbing near the outer surface of activated carbon particles.

  3. High-capacity hydrogen and nitric oxide adsorption and storage in a metal-organic framework.

    PubMed

    Xiao, Bo; Wheatley, Paul S; Zhao, Xuebo; Fletcher, Ashleigh J; Fox, Sarah; Rossi, Adriano G; Megson, Ian L; Bordiga, S; Regli, L; Thomas, K Mark; Morris, Russell E

    2007-02-07

    Gas adsorption experiments have been carried out on a copper benzene tricarboxylate metal-organic framework material, HKUST-1. Hydrogen adsorption at 1 and 10 bar (both 77 K) gives an adsorption capacity of 11.16 mmol H2 per g of HKUST-1 (22.7 mg g(-)1, 2.27 wt %) at 1 bar and 18 mmol per g (36.28 mg g(-)1, 3.6 wt %) at 10 bar. Adsorption of D2 at 1 bar (77 K) is between 1.09 (at 1 bar) and 1.20(at <100 mbar) times the H2 values depending on the pressure, agreeing with the theoretical expectations. Gravimetric adsorption measurements of NO on HKUST-1 at 196 K (1 bar) gives a large adsorption capacity of approximately 9 mmol g(-1), which is significantly greater than any other adsorption capacity reported on a porous solid. At 298 K the adsorption capacity at 1 bar is just over 3 mmol g(-1). Infra red experiments show that the NO binds to the empty copper metal sites in HKUST-1. Chemiluminescence and platelet aggregometry experiments indicate that the amount of NO recovered on exposure of the resulting complex to water is enough to be biologically active, completely inhibiting platelet aggregation in platelet rich plasma.

  4. Adsorption-desorption characteristics of mercury in paddy soils of China.

    PubMed

    Jing, Y D; He, Z L; Yang, X E

    2008-01-01

    Mercury (Hg) has received considerable attention because of its association with various human health problems. Adsorption-desorption behavior of Hg at contaminated levels in two paddy soils was investigated. The two representative soils for rice production in China, locally referred to as a yellowish red soil (YRS) and silty loam soil (SLS) and classified as Gleyi-Stagnic Anthrosols in FAO/UNESCO nomenclature, were respectively collected from Jiaxin County and Xiasha District of Hangzhou City, Zhejiang Province. The YRS adsorbed more Hg(2+) than the SLS. The characteristics of Hg adsorption could be described by the simple Langmuir adsorption equation (r2 = 0.999 and 0.999, P < 0.01, respectively, for the SLS and YRS). The maximum adsorption values (Xm) that were obtained from the simple Langmuir model were 111 and 213 mg Hg(2+) kg(-1) soil, respectively, for the SLS and YRS. Adsorption of Hg(2+) decreased soil pH by 0.75 unit for the SLS soil and 0.91 unit for the YRS soil at the highest loading. The distribution coefficient (kd) of Hg in the soil decreased exponentially with increasing Hg(2+) loading. After five successive desorptions with 0.01 mol L(-1) KCl solution (pH 5.4), 0 to 24.4% of the total adsorbed Hg(2+) in the SLS soil was desorbed and the corresponding value of the YRS soil was 0 to 14.4%, indicating that the SLS soil had a lower affinity for Hg(2+) than the YRS soil at the same Hg(2+) loading. Different mechanisms are likely involved in Hg(2+) adsorption-desorption at different levels of Hg(2+) loading and between the two soils.

  5. [Effects of particle-sizes, pH and organic matter on adsorption and desorption of mercury to sediments in the Songhua River].

    PubMed

    Zhu, Hui; Yan, Bai-Xing; Zhang, Feng-Song; Lu, Yong-Zheng; Wang, Li-Xia

    2010-10-01

    The present study aims to further reveal the environmental behavior of mercury on sediments surface. Effects of particle-sizes, pH and concentrations of dissolved organic matter (DOM) on mercury adsorption and desorption to the surface of sediments in the Songhua River were investigated by simulation experiments. A distinct variety of absorption ability among sediments with different particle-sizes was observed. Under this experimental condition, the absorption ability increased inversely with particle-size of sediments. In all absorption systems, mercury adsorption was enhanced when pH increased from 3.5 to 4.5, while mercury adsorption was inhibited significantly with the increasing of pH when pH values were above 4.5. With the increasing of pH values, the desorption of mercury presented a decreasing-increasing trend, the minimum desorption occurred at pH 5. Citric acid inhibited the mercury adsorption, and the intensity was correlated with mercury concentrations. Effects of citric acid on desorption of mercury were also apparently. With the increasing of citric acid concentrations, its effect on desorption presented a trend as enhanced-inhibited-steadied. Therefore, the above factors affected the mercury adsorption and desorption obviously, and it was necessary to take these factors into consideration in conducting the rivers' mercury control and dealing with a sudden pollution incident.

  6. Methane Adsorption on Aggregates of Fullerenes: Site-Selective Storage Capacities and Adsorption Energies

    PubMed Central

    Kaiser, Alexander; Zöttl, Samuel; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2013-01-01

    Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118–281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane–methane and fullerene–methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes. PMID:23744834

  7. Methane adsorption on aggregates of fullerenes: site-selective storage capacities and adsorption energies.

    PubMed

    Kaiser, Alexander; Zöttl, Samuel; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2013-07-01

    Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118-281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane-methane and fullerene-methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes.

  8. Preparation of amine group-containing chelating fiber for thorough removal of mercury ions.

    PubMed

    Ma, Nianfang; Yang, Ying; Chen, Shuixia; Zhang, Qikun

    2009-11-15

    An aminated chelating fiber (AF) with high adsorption capacity for mercury ions was prepared by grafting copolymerization of acrylonitrile onto polypropylene fiber, followed by aminating with chelating molecule diethylenetriamine. Effects of reaction conditions such as temperature, reaction time, bath ratio and dosage of catalyst on the grafting yield were studied. Chemical structure, tensile strength and thermal stability of AF were characterized. The adsorption performances for mercury were evaluated by batch adsorption experiments and kinetic experiments. The results show that AF is effective for the removal of mercury over a wide range of pH. The chelating fiber also shows much higher adsorption capacities for mercury, the equilibrium adsorption amount could be as high as 657.9 mg/g for mercury. The high adsorption capacity of Hg(2+) on AF is resulted from the strong chelating interaction between amine groups and mercury ions. Two amine groups coordinate with one mercury ion could be speculated from the adsorption capacity and amine group content on AF. The kinetic adsorption results indicate that the adsorption rates of AF for mercury are very rapid. Furthermore, the residual concentration was less than 1 microg/L with feed concentration of mercury below 1mg/L, which can meet the criterion of drinking water, which indicates that the chelating fiber prepared in this study could be applied to low-level Hg contaminated drinking water purification.

  9. Efficient removal and highly selective adsorption of Hg2+ by polydopamine nanospheres with total recycle capacity

    NASA Astrophysics Data System (ADS)

    Zhang, Xiulan; Jia, Xin; Zhang, Guoxiang; Hu, Jiamei; Sheng, Wenbo; Ma, Zhiyuan; Lu, Jianjiang; Liu, Zhiyong

    2014-09-01

    This study reported a new method for efficient removal of Hg2+ from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150-200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg2+ were studied. Adsorption of Hg2+ was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg2+ and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg2+ adsorption. Considering their efficient and highly Hg2+ selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications.

  10. Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

    NASA Astrophysics Data System (ADS)

    Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon

    2014-05-01

    A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution ( i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested (-2°C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

  11. Modeling the adsorption of mercury(II) on (hydr)oxides. 2: {alpha}-FeOOH (goethite) and amorphous silica

    SciTech Connect

    Bonnissel-Gissinger, P.; Alnot, M.; Ehrhardt, J.J.; Lickes, J.P.; Behra, P.

    1999-07-15

    The surface complexation model is used to describe sorption experiments of inorganic mercury(II) in the presence of an amorphous silica, Aerosil 200, or an iron (hydr)oxide, the goethite {alpha}-FeOOH (Bayferrox 910). In the simulations, one assumes the formation of a monodentate surface complex {triple_bond}S{single_bond}OHgOH and {triple_bond}S{single_bond}OHgCl, when chlorides are present in solution. Participation of the complex {triple_bond}S{single_bond}OHgCl has been especially evidenced. Comparisons with other data from the literature have been made to investigate the influence of the nature of the oxide on the mechanism of mercury(II) adsorption. X-ray photoelectron spectroscopy was used to characterize the surface of the (hydr)oxides prior to adsorption and to observe when possible the mercury surface compounds.

  12. Reduction of adsorption capacity of coconut shell activated carbon for organic vapors due to moisture contents.

    PubMed

    Abiko, Hironobu; Furuse, Mitsuya; Takano, Tsuguo

    2010-01-01

    In occupational hygiene, activated carbon produced from coconut shell is a common adsorbent material for harmful substances including organic vapors due to its outstanding adsorption capacity and cost advantage. However, moisture adsorption of the carbon generally decreases the adsorption capacity for organic vapors. In a previous report, we prepared several coconut shell activated carbons which had been preconditioned by equilibration with moisture at different relative humidities and measured the breakthrough times for 6 kinds of organic vapor, in order to clarify the effect of preliminary moisture content in activated carbon on the adsorption capacity in detail. We found that the relative percent weight increase due to moisture adsorption of the carbon specimen had a quantitative effect, reducing the breakthrough time. In this report, we carried out further measurements of the effect of moisture content on the adsorption of 13 kinds of organic vapor, and investigated the relationship between moisture adsorption and the reduction of the breakthrough time of activated carbon specimens. We also applied the data to the Wood's breakthrough time estimation model which is an extension of the Wheeler-Jonas equation.

  13. Solid phase extraction and spectrophotometric determination of mercury by adsorption of its diphenylthiocarbazone complex on an alumina column.

    PubMed

    Rajesh, N; Gurulakshmanan, G

    2008-02-01

    A simple method has been developed for the preconcentration of mercury based on the adsorption of its diphenylthiocarbazone complex on a neutral alumina column. The influence of acidity, eluting agents, stability of the column, sample volume and interfering ions has been investigated in detail. The adsorbed complex could be eluted using environmentally benign polyethylene glycol (PEG 400) and the concentration of mercury was determined by visible spectrophotometry at a wavelength maximum of 520nm. A detection limit of 4microgL(-1) could be achieved and the developed procedure was successfully applied for the determination of mercury in spiked water samples and city waste incineration ash (CRM176). The preconcentration factor attainable for quantitative recovery (>95%) of mercury(II) was 100 for a 1000mL sample volume.

  14. Mercury

    MedlinePlus

    Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If ... with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used ...

  15. Better adsorption capacity of SnO2 nanoparticles with different graphene addition

    NASA Astrophysics Data System (ADS)

    Paramarta, V.; Taufik, A.; Saleh, R.

    2016-11-01

    The adsorption capacity of SnO2 nanoparticle has been studied by graphene and nanographene platelets (NGP) additions using co-precipitation method. The crystalline phase, composition, and morphology of the samples are analyzed using X-Ray Diffraction (XRD), Energy Dispersive X-Ray (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), and Transmission Electron Microscope (TEM). Tetragonal structure of SnO2 is shown for the nanoparticle and its composites. The presence of graphene and NGP is also confirmed. The adsorption capacity of the nanoparticle and its composites are analyzed by observing the degradation of methylene blue (MB) as the organic dye model using UV-Vis Spectroscopy. The result shows that SnO2 composite with graphene achieves higher adsorption capacity of about 20% than the composite with NGP. The fitting of equilibrium adsorption capacity result indicates that the adsorption mechanism of SnO2 composite with graphene tends to follow the Langmuir adsorption-isotherm model.

  16. Innate stimulatory capacity of high molecular weight transition metals Au (gold) and Hg (mercury).

    PubMed

    Rachmawati, Dessy; Alsalem, Inás W A; Bontkes, Hetty J; Verstege, Marleen I; Gibbs, Sue; von Blomberg, B M E; Scheper, Rik J; van Hoogstraten, Ingrid M W

    2015-03-01

    Nickel, cobalt and palladium ions can induce an innate immune response by triggering Toll-like receptor (TLR)-4 which is present on dendritic cells (DC). Here we studied mechanisms of action for DC immunotoxicity to gold and mercury. Next to gold (Na3Au (S2O3)2⋅2H2O) and mercury (HgCl2), nickel (NiCl2) was included as a positive control. MoDC activation was assessed by release of the pro-inflammatory mediator IL-8. Also PBMC were studied, and THP-1 cells were used as a substitution for DC for evaluation of cytokines and chemokines, as well as phenotypic, alterations in response to gold and mercury. Our results showed that both Na3Au (S2O3)2⋅2H2O and HgCl2 induce substantial release of IL-8, but not IL-6, CCL2 or IL-10, from MoDc, PBMC, or THP-1 cells. Also gold and, to a lesser extent mercury, caused modest dendritic cell maturation as detected by increased membrane expression of CD40 and CD80. Both metals thus show innate immune response capacities, although to a lower extent than reported earlier for NiCl2, CoCl2 and Na2 [PdCl4]. Importantly, the gold-induced response could be ascribed to TLR3 rather than TLR4 triggering, whereas the nature of the innate mercury response remains to be clarified. In conclusion both gold and mercury can induce innate immune responses, which for gold could be ascribed to TLR3 dependent signalling. These responses are likely to contribute to adaptive immune responses to these metals, as reflected by skin and mucosal allergies.

  17. Enhancement of the anionic dye adsorption capacity of clinoptilolite by Fe(3+)-grafting.

    PubMed

    Akgül, Murat

    2014-02-28

    In this paper, a batch system was applied to study the adsorption behavior of congo red (CR) on raw and modified clinoptilolites. Raw clinoptilolite (Raw-CL) was treated with Fe(NO3)3 in ethanol to obtain its iron-grafted form (Fe-CL). Adsorbents were characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), energy dispersive X-ray spectroscopy (EDX), thermogravimetric/differential thermal analysis (TG/DTA), zeta-potential measurement and N2 gas adsorption-desorption techniques. Effects of the experimental parameters (initial pH, dye concentration, temperature and adsorption time) were investigated to find optimum conditions that result in highest adsorption capacity for CR removal. The obtained results suggest that the solution pH appears to be a key factor of the CR adsorption process. The maximum dye adsorption was achieved with Fe-CL adsorbent at pH ∼6.3 and the corresponding adsorption capacity was found to be 36.7mg/g, which is higher than that of its raw counterpart (16.9mg/g). A significant decrease in CR removal was given by Fe-CL between pH 7 and 11 opposite to Raw-CL which has nearly constant qe in the same pH range. The Fe(3+)-grafting increased the zeta potential of raw clinoptilolite, leading to a higher adsorption capacity compared to that of unfunctionalized adsorbent. Also, temperature change was found to have a significant effect on the adsorption process.

  18. Correlation and prediction of adsorption capacity and affinity of aromatic compounds on carbon nanotubes.

    PubMed

    Wu, Wenhao; Yang, Kun; Chen, Wei; Wang, Wendi; Zhang, Jie; Lin, Daohui; Xing, Baoshan

    2016-01-01

    Adsorption of 22 nonpolar and polar aromatic compounds on 10 carbon nanotubes (CNTs) with various diameters, lengths and surface oxygen-containing group contents was investigated to develop predictive correlations for adsorption, using the isotherm fitting of Polanyi theory-based Dubinin-Ashtakhov (DA) model. Adsorption capacity of aromatic compounds on CNTs is negatively correlated with melting points of aromatic compounds, and surface oxygen-containing group contents and surface area ratios of mesopores to total pores of CNTs, but positively correlated with total surface area of CNTs. Adsorption affinity is positively correlated with solvatochromic parameters of aromatic compounds, independent of tube lengths and surface oxygen-containing group contents of CNTs, but negatively correlated with surface area ratios of mesopores to total pores of CNTs. The correlations of adsorption capacity and adsorption affinity with properties of both aromatic compounds and CNTs clearly have physical significance, can be used successfully with DA model to predict adsorption of aromatic compounds on CNTs from the well-known physiochemical properties of aromatic compounds (i.e., solvatochromic parameters, melting points) and CNTs (i.e., surface area and total acidic group contents), and thus can facilitate the environmental application of CNTs as sorbents and environmental risk assessment of both aromatic contaminants and CNTs.

  19. Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification.

    PubMed

    Yang, Hui Ying; Han, Zhao Jun; Yu, Siu Fung; Pey, Kin Leong; Ostrikov, Kostya; Karnik, Rohit

    2013-01-01

    Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.

  20. High-Capacity and Photoregenerable Composite Material for Efficient Adsorption and Degradation of Phenanthrene in Water.

    PubMed

    Liu, Wen; Cai, Zhengqing; Zhao, Xiao; Wang, Ting; Li, Fan; Zhao, Dongye

    2016-10-18

    We report a novel composite material, referred to as activated charcoal supported titanate nanotubes (TNTs@AC), for highly efficient adsorption and photodegradation of a representative polycyclic aromatic hydrocarbon (PAH), phenanthrene. TNTs@AC was prepared through a one-step hydrothermal method, and is composed of an activated charcoal core and a shell of carbon-coated titanate nanotubes. TNTs@AC offered a maximum Langmuir adsorption capacity of 12.1 mg/g for phenanthrene (a model PAH), which is ∼11 times higher than the parent activated charcoal. Phenanthrene was rapidly concentrated onto TNTs@AC, and subsequently completely photodegraded under UV light within 2 h. The photoregenerated TNTs@AC can then be reused for another adsorption-photodegradation cycle without significant capacity or activity loss. TNTs@AC performed well over a wide range of pH, ionic strength, and dissolved organic matter. Mechanistically, the enhanced adsorption capacity is attributed to the formation of carbon-coated ink-bottle pores of the titanate nanotubes, which are conducive to capillary condensation; in addition, the modified microcarbon facilitates transfer of excited electrons, thereby inhibiting recombination of the electron-hole pairs, resulting in high photocatalytic activity. The combined high adsorption capacity, photocatalytic activity, and regenerability/reusability merit TNTs@AC a very attractive material for concentrating and degrading a host of micropollutants in the environment.

  1. Mercury adsorption on a carbon sorbent derived from fruit shell of Terminalia catappa.

    PubMed

    Inbaraj, B Stephen; Sulochana, N

    2006-05-20

    A carbonaceous sorbent derived from the fruit shell of Indian almond (Terminalia catappa) by sulfuric acid treatment was used for the removal of mercury(II) from aqueous solution. Sorption of mercury depends on the pH of the aqueous solution with maximum uptake occurring in the pH range of 5-6. The kinetics of sorption conformed well to modified second order model among the other kinetic models (pseudo first order and pseudo second order) tested. The Langmuir and Redlich-Peterson isotherm models defined the equilibrium data precisely compared to Freundlich model and the monolayer sorption capacity obtained was 94.43 mg/g. Sorption capacity increased with increase in temperature and the thermodynamic parameters, DeltaH degrees , DeltaS degrees and DeltaG degrees , indicated the Hg(II) sorption to be endothermic and spontaneous with increased randomness at the solid-solution interface. An optimum carbon dose of 4 g/l was required for the maximum uptake of Hg(II) from 30 mg/l and the mathematical relationship developed showed a correlation of 0.94 between experimental and calculated percentage removals for any carbon dose studied. About 60% of Hg(II) adsorbed was recovered from the spent carbon at pH 1.0, while 94% of it was desorbed using 1.0% KI solution.

  2. Investigation of Morphology and Hydrogen Adsorption Capacity of Disordered Carbons

    NASA Astrophysics Data System (ADS)

    He, Lilin; Melnichenko, Yuri; Gallego, Nidia; Contescu, Cristian

    2014-03-01

    We have applied small angle neutron scattering (SANS) technique to study the morphologies and hydrogen adsorption capabilities of wood-based ultramicroporous carbon and poly(furfuryl alcohol) derived carbon. The Polydispersed Spherical model and chord length analysis of the scattering profiles were performed to obtain morphological parameters such as average pore size and pore size distribution of the dry carbons, which agreed reasonably well with the independent gas sorption measurements. The hydrogen physisorbed in these two carbons at room temperature and moderate pressures was investigated by In-situ SANS measurements. The experimental data analyzed using a modified Kalliat model for decoupling scattering contributions from pores with different sizes indicates that the molecular hydrogen condenses preferentially in narrow micropores at all measured pressures, which supports the theoretical prediction by quantum mechanical and thermodynamical models.

  3. Influence of clay mineral structure and surfactant nature on the adsorption capacity of surfactants by clays.

    PubMed

    Sánchez-Martín, M J; Dorado, M C; del Hoyo, C; Rodríguez-Cruz, M S

    2008-01-15

    Adsorption of three surfactants of different nature, Triton X-100 (TX100) (non-ionic), sodium dodecylsulphate (SDS) (anionic) and octadecyltrimethylammonium bromide (ODTMA) (cationic) by four layered (montmorillonite, illite, muscovite and kaolinite) and two non-layered (sepiolite and palygorskite) clay minerals was studied. The objective was to improve the understanding of surfactant behaviour in soils for the possible use of these compounds in remediation technologies of contaminated soils by toxic organic compounds. Adsorption isotherms were obtained using surfactant concentrations higher and lower than the critical micelle concentration (cmc). These isotherms showed different adsorption stages of the surfactants by the clay minerals, and were classified in different subgroups of the L-, S- or H-types. An increase in the adsorption of SDS and ODTMA by all clay minerals is observed up to the cmc of the surfactant in the equilibrium solution is reached. However, there was further TX100 adsorption when the equilibrium concentration was well above the cmc. Adsorption constants from Langmuir and Freundlich equations (TX100 and ODTMA) or Freundlich equation (SDS) were used to compare adsorption of different surfactants by clay minerals studied. These constants indicated the surfactant adsorption by clay minerals followed this order ODTMA>TX100>SDS. The adsorption of TX100 and ODTMA was higher by montmorillonite and illite, and the adsorption of SDS was found to be higher by kaolinite and sepiolite. Results obtained show the influence of clay mineral structure and surfactant nature on the adsorption capacity of surfactants by clays, and they indicate the interest to consider the soil mineralogical composition when one surfactant have to be selected in order to establish more efficient strategies for the remediation of soils and water contaminated by toxic organic pollutants.

  4. Memory effects on adsorption tubes for mercury vapor measurement in ambient air: elucidation, quantification, and strategies for mitigation of analytical bias.

    PubMed

    Brown, Richard J C; Kumar, Yarshini; Brown, Andrew S; Kim, Ki-Hyun

    2011-09-15

    The short- and long-term memory effects associated with measurements of mercury vapor in air using gold-coated silica adsorption tubes have been described. Data are presented to quantify these effects and to determine their dependence on certain relevant measurement parameters, such as number of heating cycles used for each analysis, age of adsorption tube, mass of mercury on adsorption tube, and the length of time between analyses. The results suggest that the long-term memory effect is due to absorption of mercury within the bulk gold in the adsorption tube, which may only be fully liberated by allowing enough time for this mercury to diffuse to the gold surface. The implications of these effects for air quality networks making these measurements routinely has been discussed, and recommendations have been made to ensure any measurement bias is minimized.

  5. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics

    SciTech Connect

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC) namely coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevant for drinking water treatment. Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns for the change in Freundlich KF and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated that film diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional mass transfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model. 32 refs., 3 figs., 2 tabs.

  6. Studies on adsorption of mercury from aqueous solution on activated carbons prepared from walnut shell.

    PubMed

    Zabihi, M; Haghighi Asl, A; Ahmadpour, A

    2010-02-15

    The adsorption ability of a powdered activated carbons (PAC) derived from walnut shell was investigated in an attempt to produce more economic and effective sorbents for the control of Hg(II) ion from industrial liquid streams. Carbonaceous sorbents derived from local walnut shell, were prepared by chemical activation methods using ZnCl(2) as activating reagents. Adsorption of Hg(II) from aqueous solutions was carried out under different experimental conditions by varying treatment time, metal ion concentration, pH and solution temperature. It was shown that Hg(II) uptake decreases with increasing pH of the solution. The proper choice of preparation conditions were resulted in microporous activated carbons with different BET surface areas of 780 (Carbon A, 1:0.5 ZnCl(2)) and 803 (Carbon B, 1:1 ZnCl(2))m(2)/g BET surface area. The monolayer adsorption capacity of these particular adsorbents were obtained as 151.5 and 100.9 mg/g for carbons A and B, respectively. It was determined that Hg(II) adsorption follows both Langmuir and Freundlich isotherms as well as pseudo-second-order kinetics.

  7. Non-contact analysis of the adsorptive ink capacity of nano silica pigments on a printing coating base.

    PubMed

    Jiang, Bo; Huang, Yu Dong

    2014-01-01

    Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled.

  8. [Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

    PubMed

    Zhang, Meng-Zhu; Li, Lin; Liu, Jun-Xin; Sun, Yong-Jun; Li, Guo-Bin

    2013-01-01

    Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

  9. Effect of purity on adsorption capacities of a Mars-like clay mineral at different pressures

    NASA Technical Reports Server (NTRS)

    Jenkins, Traci; Mcdoniel, Bridgett; Bustin, Roberta; Allton, Judith H.

    1992-01-01

    There has been considerable interest in adsorption of carbon dioxide on Marslike clay minerals. Some estimates of the carbon dioxide reservoir capacity of the martian regolith were calculated from the amount of carbon dioxide adsorbed on the ironrich smectite nontronite under martian conditions. The adsorption capacity of pure nontronite could place upper limits on the regolith carbon dioxide reservoir, both at present martian atmospheric pressure and at the postulated higher pressures required to permit liquid water on the surface. Adsorption of carbon dioxide on a Clay Mineral Society standard containing nontronite was studied over a wide range of pressures in the absence of water. Similar experiments were conducted on the pure nontronite extracted from the natural sample. Heating curves were obtained to help characterize and determine the purity of the clay sample.

  10. Assessment of CO₂ adsorption capacity on activated carbons by a combination of batch and dynamic tests.

    PubMed

    Balsamo, Marco; Silvestre-Albero, Ana; Silvestre-Albero, Joaquín; Erto, Alessandro; Rodríguez-Reinoso, Francisco; Lancia, Amedeo

    2014-05-27

    In this work, batch and dynamic adsorption tests are coupled for an accurate evaluation of CO2 adsorption performance of three different activated carbons (AC) obtained from olive stones by chemical activation followed by physical activation with CO2 at varying times (i.e., 20, 40, and 60 h). Kinetic and thermodynamic CO2 adsorption tests from simulated flue gas at different temperatures and CO2 pressures are carried out under both batch (a manometric equipment operating with pure CO2) and dynamic (a lab-scale fixed-bed column operating with a CO2/N2 mixture) conditions. The textural characterization of the AC samples shows a direct dependence of both micropore and ultramicropore volume on the activation time; hence, AC60 has the higher contribution. The adsorption tests conducted at 273 and 293 K showed that when CO2 pressure is lower than 0.3 bar, the lower the activation time, the higher CO2 adsorption capacity; a ranking of ω(eq)(AC20) > ω(eq)(AC40) > ω(eq)(AC60) can be exactly defined when T = 293 K. This result is likely ascribed to the narrower pore size distribution of the AC20 sample, whose smaller pores are more effective for CO2 capture at higher temperature and lower CO2 pressure, the latter representing operating conditions of major interest for decarbonation of flue gas effluent. Moreover, the experimental results obtained from dynamic tests confirm the results derived from the batch tests in terms of CO2 adsorption capacity. It is important to highlight the fact that the adsorption of N2 on the synthesized AC samples can be considered to be negligible. Finally, the importance of proper analysis for data characterization and adsorption experimental results is highlighted for the correct assessment of the CO2 removal performance of activated carbons at different CO2 pressures and operating temperatures.

  11. Fugitive gas adsorption capacity of biomass and animal-manure derived biochars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research characterized and investigated ammonia and hydrogen sulfide gas adsorption capacities of low- and high-temperature biochars made from wood shavings and chicken litter. The biochar samples were activated with steam or phosphoric acid. The specific surface areas and pore volumes of the a...

  12. Ammonia adsorption capacity of biomass and animal-manure derived biochars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to characterize and investigate ammonia and hydrogen sulfide gas adsorption capacities of low- and high-temperature biochars made from wood shavings and chicken litter. The biochar samples were activated with steam or phosphoric acid. The specific surface areas and...

  13. The effect of nitrogen doping on mercury oxidation/chemical adsorption on the CuCo2O4(110) surface: a molecular-level description.

    PubMed

    Mei, Zhijian; Fan, Maohong; Zhang, Ruiqing; Shen, Zhemin; Wang, Wenhua

    2014-07-14

    Based on density functional theory (DFT) calculations, the detailed mercury oxidation/chemical adsorption mechanisms on the N-doped CuCo2O4(110) surface are studied. The DFT calculations show that Ow (bonded with one Cu(2+) ion and one Co(3+) ion) is far more active than Os (bonded with three Co(3+) ions) and the mercury oxidation/chemical adsorption activation energy (Ea) on the virgin CuCo2O4(110) surface involving Ow is 0.85 eV. The physically adsorbed mercury overcomes the Ea and enters the energy well that plays an important role in mercury oxidation/chemical adsorption. Nitrogen doping can greatly increase the activity of Ow and decrease the activity of Os at the same time, which greatly affect the mercury oxidation/chemical adsorption abilities on the CuCo2O4(110) surface, and the Ea variation of mercury oxidation/chemical adsorption is as follows: 0.85 eV (virgin CuCo2O4(110)) → 0.76 eV (one N-doped CuCo2O4(110)) → 0.69 eV (two N-doped CuCo2O4(110)) → 0.48 eV (three N-doped CuCo2O4(110)). In addition, N-doping can decrease the adsorption energy of mercury and mercuric oxide. The effect of N-doping on the bonding mechanism of mercury adsorption on the CuCo2O4(110) surface is analyzed by the local density of state (LDOS) and the natural bonding orbital (NBO). The calculation results correspond well to the experimental data.

  14. Characteristics of fly ashes from full-scale coal-fired power plants and their relationship to mercury adsorption

    USGS Publications Warehouse

    Lu, Y.; Rostam-Abadi, M.; Chang, R.; Richardson, C.; Paradis, J.

    2007-01-01

    Nine fly ash samples were collected from the particulate collection devices (baghouse or electrostatic precipitator) of four full-scale pulverized coal (PC) utility boilers burning eastern bituminous coals (EB-PC ashes) and three cyclone utility boilers burning either Powder River Basin (PRB) coals or PRB blends,(PRB-CYC ashes). As-received fly ash samples were mechanically sieved to obtain six size fractions. Unburned carbon (UBC) content, mercury content, and Brunauer-Emmett-Teller (BET)-N2 surface areas of as-received fly ashes and their size fractions were measured. In addition, UBC particles were examined by scanning electron microscopy, high-resolution transmission microscopy, and thermogravimetry to obtain information on their surface morphology, structure, and oxidation reactivity. It was found that the UBC particles contained amorphous carbon, ribbon-shaped graphitic carbon, and highly ordered graphite structures. The mercury contents of the UBCs (Hg/UBC, in ppm) in raw ash samples were comparable to those of the UBC-enriched samples, indicating that mercury was mainly adsorbed on the UBC in fly ash. The UBC content decreased with a decreasing particle size range for all nine ashes. There was no correlation between the mercury and UBC contents of different size fractions of as-received ashes. The mercury content of the UBCs in each size fraction, however, generally increased with a decreasing particle size for the nine ashes. The mercury contents and surface areas of the UBCs in the PRB-CYC ashes were about 8 and 3 times higher than UBCs in the EB-PC ashes, respectively. It appeared that both the particle size and surface area of UBC could contribute to mercury capture. The particle size of the UBC in PRB-CYC ash and thus the external mass transfer was found to be the major factor impacting the mercury adsorption. Both the particle size and surface reactivity of the UBC in EB-PC ash, which generally had a lower carbon oxidation reactivity than the PRB

  15. Experimental and theoretical investigations of mercury adsorption on hematite (1-102) surfaces

    NASA Astrophysics Data System (ADS)

    Jung, J.; Wilcox, J.; Jew, A. D.; Rupp, E. C.; Brown, G. E.

    2013-12-01

    Fly ash is a primary byproduct of the coal combustion process. The release of fly ash into the environment and its use in consumer products are public health concerns because of the presence of toxic trace metals and metalloids, such as mercury (Hg), selenium (Se), and arsenic (As), which may exist as components of fly ash, partition onto fly ash as it cools, or is lost to the environment through smoke stacks in a vapor phase. Therefore, it is important to understand the components of fly ash and their interaction with trace metals. In this study, calculations using density functional theory (DFT) were carried out in conjunction with experimental studies to investigate the interaction between Hg and hematite, an important mineral component of fly ash. Our experimental study, designed to simulate Hg sorption in a coal-fired power plant exhaust system, involved exposure of the fine fraction of bituminous coal fly ash (≤ 0.1 μm) to methane combustion flue gas, supplemented with SO2, NOx, HCl, and Hg in a packed-bed reactor. Sorption reaction products were characterized by synchrotron-based x-ray fluorescence mapping (s-XRF), x-ray diffraction (XRD), and extended x-ray absorption fine structure (EXAFS) spectroscopy. Preliminary s-XRF results showed that Hg in the sample is correlated with Fe, S, Cl, Br, and to a lesser extent with Se and As. From the XRD analysis, the dominant mineral phases detected were quartz, iron oxide (hematite), and various sulfate-bearing cements. Based on the experimental results, DFT studies were carried out to investigate the adsorption of Hg on hematite (α-Fe2O3) (1-102) surfaces. The two α-Fe2O3 (1-102) surfaces modeled consisted of two different surface terminations: (1) M2-clean, which corresponds to the oxygen terminated r-cut surface with the first layer of cations removed and no hydroxyl group and (2) M2-OH2-OH which has bihydroxylated top oxygen atoms and a second layer of hydroxylated oxygen atoms. These surface terminations

  16. The effect of natural organic matter on the adsorption of mercury to bacterial cells

    NASA Astrophysics Data System (ADS)

    Dunham-Cheatham, Sarrah; Mishra, Bhoopesh; Myneni, Satish; Fein, Jeremy B.

    2015-02-01

    We investigated the ability of non-metabolizing Bacillus subtilis, Shewanella oneidensis MR-1, and Geobacter sulfurreducens bacterial species to adsorb mercury in the absence and presence of Suwanee River fulvic acid (FA). Bulk adsorption and X-ray absorption spectroscopy (XAS) experiments were conducted at three pH conditions, and the results indicate that the presence of FA decreases the extent of Hg adsorption to biomass under all of the pH conditions studied. Hg XAS results show that the presence of FA does not alter the binding environment of Hg adsorbed onto the biomass regardless of pH or FA concentration, indicating that ternary bacteria-Hg-FA complexes do not form to an appreciable extent under the experimental conditions, and that Hg binding on the bacteria is dominated by sulfhydryl binding. We used the experimental results to calculate apparent partition coefficients, Kd, for Hg under each experimental condition. The calculations yield similar coefficients for Hg onto each of the bacterial species studies, suggesting there is no significant difference in Hg partitioning between the three bacterial species. The calculations also indicate similar coefficients for Hg-bacteria and Hg-FA complexes. S XAS measurements confirm the presence of sulfhydryl sites on both the FA and bacterial cells, and demonstrate the presence of a wide range of S moieties on the FA in contrast to the bacterial biomass, whose S sites are dominated by thiols. Our results suggest that although FA can compete with bacterial binding sites for aqueous Hg, because of the relatively similar partition coefficients for the types of sorbents, the competition is not dominated by either bacteria or FA unless the concentration of one type of site greatly exceeds that of the other.

  17. Mercury reduction and cell-surface adsorption by Geobacter sulfurreducens PCA.

    PubMed

    Hu, Haiyan; Lin, Hui; Zheng, Wang; Rao, Balaji; Feng, Xinbin; Liang, Liyuan; Elias, Dwayne A; Gu, Baohua

    2013-10-01

    Both reduction and surface adsorption of mercuric mercury [Hg(II)] are found to occur simultaneously on G. sulfurreducens PCA cells under dark, anaerobic conditions. Reduction of Hg(II) to elemental Hg(0) initially follows a pseudo-first order kinetics with a half-life of <2 h in the presence of 50 nM Hg(II) and 10(11) cells L(-1) in a phosphate buffer (pH 7.4). Multiple gene deletions of the outer membrane cytochromes in this organism resulted in a decrease in reduction rate from ∼0.3 to 0.05 h(-1), and reduction was nearly absent with heat-killed cells or in the cell filtrate. Adsorption of Hg(II) by cells is found to compete with, and thus inhibit, Hg(II) reduction. Depending on the Hg to cell ratio, maximum Hg(II) reduction was observed at about 5 × 10(-19) mol Hg cell(-1), but reduction terminated at a low Hg to cell ratio (<10(-20) mol Hg cell(-1)). This inhibitory effect is attributed to bonding between Hg(II) and the thiol (-SH) functional groups on cells and validated by experiments in which the sorbed Hg(II) was readily exchanged by thiols (e.g., glutathione) but not by carboxylate compounds such as ethylenediamine-tetraacetate (EDTA). We suggest that coupled Hg(II)-cell interactions, i.e., reduction and surface binding, could be important in controlling Hg species transformation and bioavailability and should therefore be considered in microbial Hg(II) uptake and methylation studies.

  18. Adsorption and oxidation of elemental mercury over Ce-MnOx/Ti-PILCs.

    PubMed

    He, Chuan; Shen, Boxiong; Chen, Jianhong; Cai, Ji

    2014-07-15

    A series of innovative Ce-Mn/Ti-pillared-clay (Ce-Mn/Ti-PILC) catalysts combining the advantages of PILCs and Ce-Mn were investigated for elemental mercury (Hg0) capture at 100-350 °C in the absence of HCl in the flue gas. The fresh and used catalysts were characterized by scanning electron microscopy (SEM), nitrogen adsorption-desorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalyst characterization indicated that the 6%Ce-6%MnOx/Ti-PILC catalyst possessed a large specific surface area and high dispersion of Ce and Mn on the surface. The experimental results indicated that the 6%Ce-6%MnOx/Ti-PILC catalyst exhibited high Hg0 capture (>90%) at 100-350 °C. During the first stage of the reaction, the main Hg0 capture mechanism for the catalyst was adsorption. As the reaction proceeded, the Hg0 oxidation ability was substantially enhanced. Both the hydroxyl oxygen and the lattice oxygen on the surface of the catalysts participated in Hg0 oxidation. At a low temperature (150 °C), the hydroxyl oxygen and lattice oxygen from Ce4+→Ce3+ and Mn3+→Mn2+ on the surface contributed to Hg0 oxidation. However, at a high temperature (250 °C), the hydroxyl oxygen and lattice oxygen from Mn4+→Mn3+ contributed to Hg0 oxidation. Hg0 oxidation was preferred at a high temperature. The 6%Ce-6%MnOx/Ti-PILC catalyst was demonstrated to a good Hg0 adsorbent and catalytic oxidant in the absence of HCl in the flue gas.

  19. Mercury reduction and cell-surface adsorption by Geobacter sulfurreducens PCA

    SciTech Connect

    Hu, Haiyan; Lin, Hui; Zheng, Wang; Feng, Xinbin; Liang, Liyuan; Elias, Dwayne A; Gu, Baohua

    2013-01-01

    Both reduction and surface adsorption of mercuric mercury [Hg(II)] are found to occur simultaneously on G. sulfurreducens PCA cells under dark, anaerobic conditions. Reduction of Hg(II) to elemental Hg(0) initially follows a pseudo-first order kinetics with a half-life of < 2 h in the presence of 50 nM Hg(II) and 1011 cells L-1 in a phosphate buffer (pH 7.4). Multiple gene deletions of the outer membrane cytochromes in this organism resulted in decrease in reduction rate from ~ 0.3 to 0.05 h-1, and reduction was nearly absent with heat-killed cells or in the cell filtrate. Adsorption of Hg(II) by cells is found to compete with, and thus inhibit, Hg(II) reduction. Depending on the Hg to cell ratio, maximum Hg(II) reduction was observed at about 5 10-19 mol Hg cell-1, but reduction terminated at a low Hg to cell ratio (< 10-20 mol Hg cell-1). This inhibitory effect is attributed to strong binding between Hg(II) and the thiol ( SH) functional groups on cells and validated by experiments in which the sorbed Hg(II) was readily exchanged by thiols (e.g., glutathione) but not by carboxylic ligands such as ethylenediaminetetraacetate (EDTA). We suggest that coupled Hg(II)-cell interactions, i.e., reduction and surface binding, could be important in controlling Hg species transformation and bioavailability and should therefore be considered in microbial Hg(II) uptake and methylation studies.

  20. Influence of the inherent properties of drinking water treatment residuals on their phosphorus adsorption capacities.

    PubMed

    Bai, Leilei; Wang, Changhui; He, Liansheng; Pei, Yuansheng

    2014-12-01

    Batch experiments were conducted to investigate the phosphorus (P) adsorption and desorption on five drinking water treatment residuals (WTRs) collected from different regions in China. The physical and chemical characteristics of the five WTRs were determined. Combined with rotated principal component analysis, multiple regression analysis was used to analyze the relationship between the inherent properties of the WTRs and their P adsorption capacities. The results showed that the maximum P adsorption capacities of the five WTRs calculated using the Langmuir isotherm ranged from 4.17 to 8.20mg/g at a pH of 7 and further increased with a decrease in pH. The statistical analysis revealed that a factor related to Al and 200 mmol/L oxalate-extractable Al (Alox) accounted for 36.5% of the variations in the P adsorption. A similar portion (28.5%) was attributed to an integrated factor related to the pH, Fe, 200 mmol/L oxalate-extractable Fe (Feox), surface area and organic matter (OM) of the WTRs. However, factors related to other properties (Ca, P and 5 mmol/L oxalate-extractable Fe and Al) were rejected. In addition, the quantity of P desorption was limited and had a significant negative correlation with the (Feox+Alox) of the WTRs (p<0.05). Overall, WTRs with high contents of Alox, Feox and OM as well as large surface areas were proposed to be the best choice for P adsorption in practical applications.

  1. Effect of surface area and chemisorbed oxygen on the SO2 adsorption capacity of activated char

    USGS Publications Warehouse

    Lizzio, A.A.; DeBarr, J.A.

    1996-01-01

    The objective of this study was to determine whether activated char produced from Illinois coal could be used effectively to remove sulfur dioxide from coal combustion flue gas. Chars were prepared from a high-volatile Illinois bituminous coal under a wide range of pyrolysis and activation conditions. A novel char preparation technique was developed to prepare chars with SO2 adsorption capacities significantly greater than that of a commercial activated carbon. In general, there was no correlation between SO2 adsorption capacity and surface area. Temperature-programmed desorption (TPD) was used to determine the nature and extent of carbon-oxygen (C-O) complexes formed on the char surface. TPD data revealed that SO2 adsorption was inversely proportional to the amount of C-O complex. The formation of a stable C-O complex during char preparation may have served only to occupy carbon sites that were otherwise reactive towards SO2 adsorption. A fleeting C(O) complex formed during SO2 adsorption is postulated to be the reaction intermediate necessary for conversion of SO2 to H2SO4. Copyright ?? 1996 Elsevier Science Ltd.

  2. Impacts of amount of impregnated iron in granular activated carbon on arsenate adsorption capacities and kinetics.

    PubMed

    Chang, Qigang; Lin, Wei; Ying, Wei-Chi

    2012-06-01

    Iron-impregnated granular activated carbons (Fe-GAC) can remove arsenic effectively from water. In this study, Fe-GACs with iron content of 1.64 to 28.90% were synthesized using a new multi-step procedure for the investigation of effects of iron amount on arsenic adsorption capacities and kinetics. Langmuir model satisfactorily fit arsenic adsorption on Fe-GACs. The maximum arsenic adsorption capacity (q(m)) increased significantly with iron impregnation and reached 1,867 to 1,912 microg/g with iron content of 9.96 to 13.59%. Further increase of iron content (> 13.59%) caused gradual decrease of q(m). It was found that the amount of impregnated iron showed little impact on the affinity for arsenate. Kinetic study showed that the amount of impregnated iron affected the arsenic intraparticle diffusion rate greatly. The pseudo-second-order kinetic model fit arsenic adsorption kinetics on Fe-GACs better than the pseudo-first-order model. The arsenic adsorption rate increased with increasing of iron content from 1.64% to 13.59%, and then decreased with more impregnated iron (13.59 to 28.90%).

  3. Nanosheet-structured boron nitride spheres with a versatile adsorption capacity for water cleaning.

    PubMed

    Liu, Fei; Yu, Jie; Ji, Xixi; Qian, Muqi

    2015-01-28

    Here, we report the synthesis of nanosheet-structured boron nitride spheres (NSBNSs) by a catalyzing thermal evaporation method from solid B powders. The NSBNSs consist of radially oriented ultrathin nanosheets with the sheet edges oriented on the surface. Formation of this unique structure occurs only at a certain reaction temperature. The diameter from 4 μm to 700 nm and the nanosheet thickness from 9.1 to 3.1 nm of the NSBNSs can be well-controlled by appropriately changing the mass ratio of boron powders and catalyst. The NSBNSs possess versatile adsorption capacity, exhibiting excellent adsorption performance for oil, dyes, and heavy metal ions from water. The oil uptake reaches 7.8 times its own weight. The adsorption capacities for malachite green and methylene blue are 324 and 233 mg/g, while those for Cu(2+), Pb(2+), and Cd(2+) are 678.7, 536.7, and 107.0 mg/g, respectively. The adsorption capacities of the NSBNSs for Cu(2+) and Pb(2+) are higher or much higher than those of the adsorbents reported previously. These results demonstrate the great potential of NSBNSs for water treatment and cleaning.

  4. Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-05-03

    A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  5. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  6. MnOx/Graphene for the Catalytic Oxidation and Adsorption of Elemental Mercury.

    PubMed

    Xu, Haomiao; Qu, Zan; Zong, Chenxi; Huang, Wenjun; Quan, Fuquan; Yan, Naiqiang

    2015-06-02

    MnOx/graphene composites were prepared and employed to enhance the performance of manganese oxide (MnOx) for the capture of elemental mercury (Hg(0)) in flue gas. The composites were characterized using FT-IR, XPS, XRD, and TEM, and the results showed that the highly dispersed MnOx particles could be readily deposited on graphene nanosheets via hydrothermal process described here. Graphene appeared to be an ideal support for MnOx particles and electron transfer channels in the catalytic oxidation of Hg(0) at a high efficiency. Thus, MnOx/graphene-30% sorbents exhibited an Hg(0) removal efficiency of greater than 90% at 150 °C under 4% O2, compared with the 50% removal efficiency of pure MnOx. The mechanism of Hg(0) capture is discussed, and the main Hg(0) capture mechanisms of MnOx/graphene were catalytic oxidation and adsorption. Mn is the main active site for Hg(0) catalytic oxidation, during which high valence Mn (Mn(4+) or Mn(3+)) is converted to low valence Mn (Mn(3+) or Mn(2+)). Graphene enhanced the electrical conductivity of MnOx, which is beneficial for catalytic oxidation. Furthermore, MnOx/graphene exhibited an excellent regenerative ability, and is a promising sorbent for capturing Hg(0).

  7. Novel biosorbent with high adsorption capacity prepared by chemical modification of white pine (Pinus durangensis) sawdust. Adsorption of Pb(II) from aqueous solutions.

    PubMed

    Salazar-Rabago, J J; Leyva-Ramos, R

    2016-03-15

    The natural sawdust (NS) from white pine (Pinus durangensis) was chemically modified by a hydrothermal procedure using citric, malonic and tartaric acids. The adsorption capacity of modified sawdust (MS) towards Pb(II) was considerably enhanced due to the introduction of carboxylic groups on the surface of MS during the modification, and the adsorption capacity was almost linearly dependent on the concentration of carboxylic sites. The NS surface was acidic, and the MS surface became more acidic after the modification. At T = 25 °C and pH = 5, the maximum adsorption capacity of the optimal MS towards Pb(II) was 304 mg/g, which is exceptionally high compared to NS and other MS reported previously. The adsorption capacity of MS was considerably reduced from 304 to 154 mg/g by decreasing the solution pH from 5 to 3 due to electrostatic interactions. The adsorption of Pb(II) on MS was reversible at pH = 2, but not at pH = 5. The contribution percentage of ion exchange to the overall adsorption capacity ranged from 70 to 99% and 10-66% at the initial pH of 3 and 5, respectively. Hence, the adsorption of Pb(II) on MS was mainly due to ion exchange at pH = 3 and to both ion exchange and electrostatic attraction at pH = 5.

  8. Preparation and characterization of a hierarchical porous char from sewage sludge with superior adsorption capacity for toluene by a new two-step pore-fabricating process.

    PubMed

    Kong, Lingjun; Xiong, Ya; Tian, Shuanghong; Luo, Rongshu; He, Chun; Huang, Haibao

    2013-10-01

    A kind of hierarchical porous char (SCCA/Zn) was prepared from sewage sludge by a new two-step pore-fabricating process coupling citric acid (CA) with ZnCl2 in a pyrolysis process. The char was characterized by element analysis, N2-adsorption and mercury intrusion measurement etc. It is found that coupling CA and ZnCl2 can synergistically fabricate pores in the pyrolysis process, resulting in a hierarchical porous char, SCCA/Zn, with the largest SBET of 867.6 m(2) g(-1) due to the fact that the former contributes to the fabrication of macro-pores, which provides more space for fabricating meso- and micro-pores by ZnCl2 activation. Although the SBET of SCCA/Zn was 15% less than that of activated carbon fiber (ACF, SBET=999.5 m(2) g(-1)), SCCA/Zn had a higher toluene adsorption capacity (0.83 g g(-1)) than ACF. The inconsistence between their SBET and adsorption capacity can be ascribed to the strong hydrophobic property of SCCA/Zn.

  9. Modified inverse micelle synthesis for mesoporous alumina with a high D4 siloxane adsorption capacity

    SciTech Connect

    Zhong, Wei; Jiang, Ting; Jafari, Tahereh; Poyraz, Altug S.; Wu, Wei; Kriz, David A.; Du, Shoucheng; Biswas, Sourav; Thompson Pettes, Michael; Suib, Steven L.

    2016-10-18

    In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlled by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.

  10. Modified inverse micelle synthesis for mesoporous alumina with a high D4 siloxane adsorption capacity

    DOE PAGES

    Zhong, Wei; Jiang, Ting; Jafari, Tahereh; ...

    2016-10-18

    In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlledmore » by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.« less

  11. A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate

    NASA Astrophysics Data System (ADS)

    Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

    2016-02-01

    A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g‑1 at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na+, Mg2+, or Fe3+) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na+, Mg2+, and Fe3+ were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na+, Mg2+, and Fe3+. We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water.

  12. A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate

    PubMed Central

    Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

    2016-01-01

    A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g−1 at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na+, Mg2+, or Fe3+) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na+, Mg2+, and Fe3+ were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na+, Mg2+, and Fe3+. We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water. PMID:26843015

  13. Activated carbons prepared from wood particleboard wastes: characterisation and phenol adsorption capacities.

    PubMed

    Girods, P; Dufour, A; Fierro, V; Rogaume, Y; Rogaume, C; Zoulalian, A; Celzard, A

    2009-07-15

    The problems of valorisation of particleboard wastes on one hand, and contamination of aqueous effluents by phenolic compounds on the other hand, are simultaneously considered in this work. Preparation of activated carbons from a two steps thermo-chemical process, formerly designed for generating combustible gases, is suggested. The resultant carbonaceous residue is activated with steam at 800 degrees C. Depending on the preparation conditions, surface areas within the range 800-1300 m(2)/g are obtained, close to that of a commercial activated carbon (CAC) specially designed for water treatment and used as a reference material. The present work shows that particleboard waste-derived activated carbons (WAC) are efficient adsorbents for the removal of phenol from aqueous solutions, with maximum measured capacities close to 500 mg/g. However, most of times, the adsorption capacities are slightly lower than that of the commercial material in the same conditions, i.e., at equilibrium phenol concentrations below 300 ppm. Given the extremely low cost of activated carbons prepared from particleboard waste, it should not be a problem to use it in somewhat higher amounts than what is required with a more expensive commercial material. Phenol adsorption isotherms at 298 K were correctly fitted by various equations modelling type I and type II isotherms for CAC and WAC, respectively. Phenol adsorption isotherms of type II were justified by a 3-stages adsorption mechanism.

  14. CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

    NASA Astrophysics Data System (ADS)

    Yang, Ji-Chun; Yin, Xue-Bo

    2017-01-01

    In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L‑1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g‑1 for As(V) and 143.6 mg g‑1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy.

  15. CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

    PubMed Central

    Yang, Ji-Chun; Yin, Xue-Bo

    2017-01-01

    In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L−1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g−1 for As(V) and 143.6 mg g−1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy. PMID:28102334

  16. High adsorption capacity of V-doped TiO2 for decolorization of methylene blue

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh-Binh; Hwang, Moon-Jin; Ryu, Kwang-Sun

    2012-07-01

    In this study, pure TiO2 (V-TiO2-0) and V-doped TiO2 (V-TiO2-x, x = 1-10 mol%) were synthesized using a new sol-gel method. The adsorption capacity of the V-TiO2-x samples was evaluated by measuring the removal of methylene blue (MB) from aqueous solution via decolorization. Since the adsorption capacity was affected by the specific surface area, the interaction between adsorbate (MB) and adsorbent (V-TiO2-x), and the structure of the adsorbent, the physicochemical properties of the samples were investigated. Among the V-doped TiO2-x samples, the V-TiO2-10 sample showed the highest adsorption capacity, which was 11.36 times greater than that of pure TiO2, removing 85.2% of the MB after 2 h. Moreover, changing the molar ratio of the reactants in the V-TiO2-10 sample improved the performance of the material so that 91.6% of the MB was removed after 2 h.

  17. Adsorption of heavy metals on to sugar cane bagasse: improvement of adsorption capacities due to anaerobic degradation of the biosorbent.

    PubMed

    Joseph, Osnick; Rouez, Maxime; Métivier-Pignon, Hélène; Bayard, Rémy; Emmanuel, Evens; Gourdon, Rémy

    2009-12-01

    In this work, anaerobic degradation of sugar cane bagasse was studied with a dual objective: the production of biogas and the improvement of the material's characteristics for its implementation in adsorption processes. The biogas production was determined by means of biomethane potential tests carried out over two months of incubation at 35 degrees C. Biogas and methane cumulative productions were assumed to follow a first-order rate of decay. Theoretical cumulative methane and biogas productions were calculated using Buswell's equation. The anaerobic digestion resulted in a 92% decrease in the leachable organic fraction and a 40% mass loss of bagasse. The average productions of biogas and methane from the whole set of experiments were 293 +/- 6 and 122 +/- 4 mL g(-1) of volatile solids, respectively. The anaerobic incubation of the raw material led to an increase in adsorption capacities towards metal ions, which were multiplied by around 2.0 for Zn2+ and 2.3 for Cd2+.

  18. Complete Genome Sequence of a Marine Bacterium, Pseudomonas pseudoalcaligenes Strain S1, with High Mercury Resistance and Bioaccumulation Capacity

    PubMed Central

    Liu, Bing; Bian, Chao; Huang, Huiwei; Yin, Zhiwei

    2016-01-01

    Pseudomonas pseudoalcaligenes S1, a marine bacterium, exhibited strong resistance to a high concentration of Hg2+ and remarkable Hg2+ bioaccumulation capacity. Here, we report the 6.9-Mb genome sequence of P. pseudoalcaligenes S1, which may help clarify its phylogenetic status and provide further understanding of the mechanisms of mercury bioremediation in a marine environment. PMID:27198018

  19. The effects of mariculture activities on the adsorption/desorption and chemical fractionations of mercury on sediments.

    PubMed

    Liang, Peng; Wu, Sheng-Chun; Li, Yi-Chun; Li, Hong-Bo; Yu, Guang-bin; Yu, Shen; Wong, Ming H

    2012-04-01

    The aims of the present study were to investigate the effects of mariculture activities on inorganic mercury (Hg(2+)) adsorption/desorption on sediments and the distributions of newly adsorbed Hg(2+) on different chemical fractionations. The adsorption amount and binding energy of Hg(2+) on mariculture sediment (MS) were significantly higher (p<0.05) than reference sediment (RS). This may be explained by the strong complexation role that exists between Hg(2+) and organic matter (OM), which derived from unconsumed fish feed and fish metabolites. The reducible Hg(2+) in MS was significantly lower (p<0.01) than RS, which may have been caused by the decreasing amount of iron and manganese hydroxide in MS, lead to the decrease of Hg(2+) bound to them. On the contrary, the residual Hg(2+) was significantly higher (p<0.01) in MS than RS, which suggests that newly adsorbed Hg(2+) was more stable in MS than RS.

  20. High-capacity adsorption of dissolved hexavalent chromium using amine-functionalized magnetic corn stalk composites.

    PubMed

    Song, Wen; Gao, Baoyu; Zhang, Tengge; Xu, Xing; Huang, Xin; Yu, Huan; Yue, Qinyan

    2015-08-01

    Easily separable amine-functionalized magnetic corn stalk composites (AF-MCS) were employed for effective adsorption and reduction of toxic hexavalent chromium [Cr(VI)] to nontoxic Cr(III). The saturated magnetization of AF-MCS reached 6.2emu/g, and as a result, it could be separated from aqueous solution by a magnetic process for its superparamagnetism. The studies of various factors influencing the sorption behavior indicated that the optimum AF-MCS dosage for Cr(VI) adsorption was 1g/L, and the maximum adsorption capacity was observed at pH 3.0. The chromium adsorption perfectly fitted the Langmuir isotherm model and pseudo second order kinetic model. Furthermore, characterization of AF-MCS was investigated by means of XRD, SEM, TEM, FT-IR, BET, VSM and XPS analysis to discuss the uptake mechanism. Basically, these results demonstrated that AF-MCS prepared in this work has shown its merit in effective removal of Cr(VI) and rapid separation from effluents simultaneously.

  1. MERCURY(II) ADSORPTION FROM WASTEWATERS USING A THIOL FUNCTIONAL ADSORBENT

    EPA Science Inventory

    The removal of mercury(II) from wastewaters (coal-fired utility plant scrubber solutions) using a thiol functional organoceramic composite (SOL-AD-IV) is investigated. A simulant is employed as a surrogate to demonstrate the removal of mercury from real waste solutions. Equilibri...

  2. Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity

    NASA Astrophysics Data System (ADS)

    Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing

    2017-03-01

    Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.

  3. Unified method for the total pore volume and pore size distribution of hierarchical zeolites from argon adsorption and mercury intrusion.

    PubMed

    Kenvin, Jeffrey; Jagiello, Jacek; Mitchell, Sharon; Pérez-Ramírez, Javier

    2015-02-03

    A generalized approach to determine the complete distribution of macropores, mesopores, and micropores from argon adsorption and mercury porosimetry is developed and validated for advanced zeolite catalysts with hierarchically structured pore systems in powder and shaped forms. Rather than using a fragmented approach of simple overlays from individual techniques, a unified approach that utilizes a kernel constructed from model isotherms and model intrusion curves is used to calculate the complete pore size distribution and the total pore volume of the material. An added benefit of a single full-range pore size distribution is that the cumulative pore area and the area distribution are also obtained without the need for additional modeling. The resulting complete pore size distribution and the kernel accurately model both the adsorption isotherm and the mercury porosimetry. By bridging the data analysis of two primary characterization tools, this methodology fills an existing gap in the library of familiar methods for porosity assessment in the design of materials with multilevel porosity for novel technological applications.

  4. Intra- and inter-unit variation in fly ash petrography and mercury adsorption: Examples from a western Kentucky power station

    USGS Publications Warehouse

    Hower, J.C.; Finkelman, R.B.; Rathbone, R.F.; Goodman, J.

    2000-01-01

    Fly ash was collected from eight mechanical and 10 baghouse hoppers at each of the twin 150-MW wall-fired units in a western Kentucky power station. The fuel burned at that time was a blend of many low-sulfur, high-volatile bituminous Central Appalachian coals. The baghouse ash showed less variation between units than the mechanical hoppers. The mechanical fly ash, coarser than the baghouse ash, showed significant differences in the amount of total carbon and in the ratio of isotropic coke to both total carbon and total coke - the latter excluding inertinite and other unburned, uncoked coal. There was no significant variation in proportions of inorganic fly ash constituents. The inter-unit differences in the amount and forms of mechanical fly ash carbon appear to be related to differences in pulverizer efficiency, leading to greater amounts of coarse coal, therefore unburned carbon, in one of the units. Mercury capture is a function of both the total carbon content and the gas temperature at the point of fly ash separation, mercury content increasing with an increase in carbon for a specific collection system. Mercury adsorption on fly ash carbon increases at lower flue-gas temperatures. Baghouse fly ash, collected at a lower temperature than the higher-carbon mechanically separated fly ash, contains a significantly greater amount of Hg.

  5. A review on modification methods to cellulose-based adsorbents to improve adsorption capacity.

    PubMed

    Hokkanen, Sanna; Bhatnagar, Amit; Sillanpää, Mika

    2016-03-15

    In recent decades, increased domestic, agricultural and industrial activities worldwide have led to the release of various pollutants, such as toxic heavy metals, inorganic anions, organics, micropollutants and nutrients into the aquatic environment. The removal of these wide varieties of pollutants for better quality of water for various activities is an emerging issue and a robust and eco-friendly treatment technology is needed for the purpose. It is well known that cellulosic materials can be obtained from various natural sources and can be employed as cheap adsorbents. Their adsorption capacities for heavy metal ions and other aquatic pollutants can be significantly affected upon chemical treatment. In general, chemically modified cellulose exhibits higher adsorption capacities for various aquatic pollutants than their unmodified forms. Numerous chemicals have been used for cellulose modifications which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. This paper reviews the current state of research on the use of cellulose, a naturally occurring material, its modified forms and their efficacy as adsorbents for the removal of various pollutants from waste streams. In this review, an extensive list of various cellulose-based adsorbents from literature has been compiled and their adsorption capacities under various conditions for the removal of various pollutants, as available in the literature, are presented along with highlighting and discussing the key advancement on the preparation of cellulose-based adsorbents. It is evident from the literature survey presented herein that modified cellulose-based adsorbents exhibit good potential for the removal of various aquatic pollutants. However, still there is a need to find out the practical utility of these adsorbents on a commercial scale, leading to the improvement of pollution control.

  6. Trimodal nanoporous silica as a support for amine-based CO2 adsorbents: Improvement in adsorption capacity and kinetics

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Bhattacharjee, Samiran

    2017-02-01

    A trimodal nanoporous silica (TS) having unique trimodal pore structure viz., internal mesopores, textural mesopores and interconnected macropores, has been functionalized with amine using two different methods covalent grafting and wet impregnation. Both were studied as nanocomposite sorbents for CO2 capture. The effects of the amine loading, immobilization processes and the type of support were investigated. Commercially available silica gel (SG) with a purely mesoporous structure was studied as the support for the amine in order to compare differences in pore structure and amine loading with differences in CO2 adsorption capacity and kinetics. Amine-grafted TS exhibited much faster CO2 adsorption kinetics at 35 °C than amine-grafted SG. At the same amine loading, amine-impregnated TS showed higher CO2 adsorption capacity and faster CO2 adsorption kinetics than amine-impregnated SG. The CO2 adsorption capacity of amine-impregnated TS increased as the amine loading increased until 70%, with the highest value of 172 mg/g, while the amine-impregnated SG reached the highest CO2 adsorption capacity of only 78 mg/g at 40% amine loading. More importantly, amine-impregnated as-prepared TS exhibited even higher CO2 capture capacity than amine-impregnated TS when the amine loading was below 60%. Results suggest that amine-modified trimodal nanoporous silica sorbents meet the challenges of current CO2 capture technology.

  7. Quantitative analysis of the binding strength and adsorption capacity of zinc oxide nanoparticles onto unmodified and modified cotton fiber

    NASA Astrophysics Data System (ADS)

    Printz, Stephen Robert

    Risk of bacterial infection is always a concern in hospitals, so it is important to find ways to minimize this risk. One method for reducing the risk of infection is by using textiles with antimicrobial properties. Zinc oxide nanoparticles have antimicrobial properties, and can be adsorbed onto cotton fibers to pass these properties to the cloth. However, the binding of the zinc oxide nanoparticles to cotton is weak, so the particles desorb from the cloth after repeated washings. The goal of this project was to quantify the binding strength of zinc oxide nanoparticles onto different types of cotton fiber. The cotton was modified by grafting cyclodextrin onto it with citric acid as a crosslinking agent. Adsorption was tested with desized, unbleached cotton print cloth; desized, bleached cotton print cloth; and desized, bleached, mercerized cotton print cloth. As expected, adsorption to unmodified cloth was poor. Unbleached cloth had the highest adsorption capacity (Q 0 = 22 +/- 4 mg ZnO/g cloth), and bleached cloth had the lowest adsorption capacity (Q0 = 17 +/- 4 mg ZnO=g cloth). Mercerized cloth had the lowest strength (b = 0.010 +/- 0.003 ppm-1), and bleached cloth had the highest binding strength (b = 0.04 +/- 0.01 ppm-1). Modification with alpha-cyclodextrin increased adsorption capacity over unmodified cloth by 61, 80, and 70% for mercerized/bleached cloth, bleached cloth, and unbleached cloth, respectively, and increased b by 1601, 126, and 90% respectively. Modification with beta-cyclodextrin increased adsorption capacities by 80, 94, and 112%, respectively, and increased b by 2027, 427, and 46%. As a result, beta-CD modified unbleached cloth had the highest adsorption capacity and one of the lowest binding strengths. However, beta-cyclodextrin modified mercerized cloth has both a high adsorption capacity and a high binding strength, and would likely be the best candidate for use in antimicrobial textiles.

  8. Adsorption capacities of activated carbons for geosmin and 2-methylisoborneol vary with activated carbon particle size: Effects of adsorbent and adsorbate characteristics.

    PubMed

    Matsui, Yoshihiko; Nakao, Soichi; Sakamoto, Asuka; Taniguchi, Takuma; Pan, Long; Matsushita, Taku; Shirasaki, Nobutaka

    2015-11-15

    The adsorption capacities of nine activated carbons for geosmin and 2-methylisoborneol (MIB) were evaluated. For some carbons, adsorption capacity substantially increased when carbon particle diameter was decreased from a few tens of micrometers to a few micrometers, whereas for other carbons, the increase of adsorption capacity was small for MIB and moderate for geosmin. An increase of adsorption capacity was observed for other hydrophobic adsorbates besides geosmin and MIB, but not for hydrophilic adsorbates. The parameter values of a shell adsorption model describing the increase of adsorption capacity were negatively correlated with the oxygen content of the carbon among other characteristics. Low oxygen content indicated low hydrophilicity. The increase of adsorption capacity was related to the hydrophobic properties of both adsorbates and activated carbons. For adsorptive removal of hydrophobic micropollutants such as geosmin, it is therefore recommended that less-hydrophilic activated carbons, such as coconut-shell-based carbons, be microground to a particle diameter of a few micrometers to enhance their equilibrium adsorption capacity. In contrast, adsorption by hydrophilic carbons or adsorption of hydrophilic adsorbates occur in the inner pores, and therefore adsorption capacity is unchanged by particle size reduction.

  9. An adsorbent with a high adsorption capacity obtained from the cellulose sludge of industrial residues.

    PubMed

    Orlandi, Géssica; Cavasotto, Jéssica; Machado, Francisco R S; Colpani, Gustavo L; Magro, Jacir Dal; Dalcanton, Francieli; Mello, Josiane M M; Fiori, Márcio A

    2017-02-01

    One of the major problems in effluent treatment plants of the cellulose and paper industry is the large amount of residual sludge generated. Therefore, this industry is trying to develop new methods to treat such residues and to use them as new products, such as adsorbents. In this regard, the objective of this work was to develop an adsorbent using the raw activated sludge generated by the cellulose and paper industry. The activated cellulose sludge, after being dried, was chemically activated with 42.5% (v/v) phosphoric acid at 85 °C for 1 h and was charred at 500 °C, 600 °C and 700 °C for 2 h. The efficiency of the obtained adsorbent materials was evaluated using kinetic tests with methylene blue solutions. Using the adsorption kinetics, it was verified that the three adsorbents showed the capacity to adsorb dye, and the adsorbent obtained at a temperature of 600 °C showed the highest adsorption capacity of 107.1 mg g(-1). The kinetic model that best fit the experimental data was pseudo-second order. The Langmuir-Freudlich isotherm adequately described the experimental data. As a result, the cellulose sludge generated by the cellulose and paper industries could be used as an adsorbent.

  10. Amine-functionalized PVA-co-PE nanofibrous membrane as affinity membrane with high adsorption capacity for bilirubin.

    PubMed

    Wang, Wenwen; Zhang, Hao; Zhang, Zhifeng; Luo, Mengying; Wang, Yuedan; Liu, Qiongzhen; Chen, Yuanli; Li, Mufang; Wang, Dong

    2017-02-01

    In this study, poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane was activated by sodium hydroxide and cyanuric chloride, and then the activated membranes were functionalized by 1,3-propanediamine, hexamethylenediamine and diethylenetriamine to be affinity membranes for bilirubin removal, respectively. The chemical structures and morphologies of membranes were investigated by SEM, FTIR and XPS. And the adsorption ability of different amine-functionalized nanofibrous membranes for bilirubin was characterized. Furthermore, the effects of temperature, initial concentration of bilirubin, NaCl concentration and BSA concentration on the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane were studied. Results indicated that the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane could reach 85mg/g membrane when the initial bilirubin concentration was 200mg/L while the adsorption capacity could be increased to 110mg/g membrane if the initial bilirubin concentration was more than 400mg/L. The dynamic adsorption of diethylenetriamine-functionalized nanofibrous membrane showed that the ligands of amine groups on the membrane surface could be used as far as possible by recirculating the plasma with certain flow rates. Therefore, the diethylenetriamine-functionalized PVA-co-PE nanofibrous membrane possessed high adsorption capacity for bilirubin and it can be candidate as affinity membrane for bilirubin removal.

  11. Ultra-high adsorption capacity of zeolitic imidazole framework-67 (ZIF-67) for removal of malachite green from water.

    PubMed

    Lin, Kun-Yi Andrew; Chang, Hsuan-Ang

    2015-11-01

    Zeolitic imidazole frameworks (ZIFs), a new class of adsorbents, are proposed to adsorb Malachite Green (MG) in water. Particularly, ZIF-67 was selected owing to its stability in water and straightforward synthesis. The as-synthesized ZIF-67 was characterized and used to adsorb MG from water. Factors affecting the adsorption capacity were investigated including mixing time, temperature, the presence of salts and pH. The kinetics, adsorption isotherm and thermodynamics of the MG adsorption to ZIF-67 were also studied. The adsorption capacity of ZIF-67 for MG could be as high as 2430mgg(-1) at 20°C, which could be improved at the higher temperatures. Such an ultra-high adsorption capacity of ZIF-67 was almost 10-times of those of conventional adsorbents, including activated carbons and biopolymers. A mechanism for the high adsorption capacity was proposed and possibly attributed to the π-π stacking interaction between MG and ZIF-67. ZIF-67 also could be conveniently regenerated by washing with ethanol and the regeneration efficiency could remain 95% up to 4 cycles of the regeneration. ZIF-67 was also able to remove MG from the aquaculture wastewater, in which MG can be typically found. These features enable ZIF-67 to be one of the most effective and promising adsorbent to remove MG from water.

  12. Influence of Environmental Factors on the Adsorption Capacity and Thermal Conductivity of Silica Nano-Porous Materials.

    PubMed

    Zhang, Hu; Gu, Wei; Li, Ming-Jia; Fang, Wen-Zhen; Li, Zeng-Yao; Tao, Wen-Quan

    2015-04-01

    In this work, the influence of temperature and humidity environment on the water vapor adsorption capacity and effective thermal conductivity of silica nano-porous material is conducted within a relative humidity range from 15% to 90% at 25 °C, 40 °C and 55 °C, respectively. The experiment results show that both the temperature and relative humidity have significant influence on the adsorption capacity and effective thermal conductivity of silica nano-porous materials. The adsorption capacity and effective thermal conductivity increase with humidity because of the increases of water vapor concentration. The effective thermal conductivity increases linearly with adsorption saturation capacity at constant temperature. Because adsorption process is exothermic reaction, the increasing temperature is not conducive to the adsorption. But the effective thermal conductivity increases with the increment of temperature at the same water uptake because of the increment of water thermal conductivity with temperature Geometric models and unit cell structure are adopted to predict the effective thermal conductivity and comparisons with the experimental result are made, and for the case of moist silica nano-porous materials with high porosity no quantitative agreement is found. It is believed that the adsorbed water will fill in the nano-pores and gap and form lots of short cuts, leading to a significant reduction of the thermal resistance.

  13. Mercury

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Burns, J. A.; Cassen, P.; Strom, R. G.

    1977-01-01

    Prior to the flight of the Mariner 10 spacecraft, Mercury was the least investigated and most poorly known terrestrial planet (Kuiper 1970, Devine 1972). Observational difficulties caused by its proximity to the Sun as viewed from Earth caused the planet to remain a small, vague disk exhibiting little surface contrast or details, an object for which only three major facts were known: 1. its bulk density is similar to that of Venus and Earth, much greater than that of Mars and the Moon; 2. its surface reflects electromagnetic radiation at all wavelengths in the same manner as the Moon (taking into account differences in their solar distances); and 3. its rotation period is in 2/3 resonance with its orbital period. Images obtained during the flyby by Mariner 10 on 29 March 1974 (and the two subsequent flybys on 21 September 1974 and 16 March 1975) revealed Mercury's surface in detail equivalent to that available for the Moon during the early 1960's from Earth-based telescopic views. Additionally, however, information was obtained on the planet's mass and size, atmospheric composition and density, charged-particle environment, and infrared thermal radiation from the surface, and most significantly of all, the existence of a planetary magnetic field that is probably intrinsic to Mercury was established. In the following, this new information is summarized together with results from theoretical studies and ground-based observations. In the quantum jumps of knowledge that have been characteristic of "space-age" exploration, the previously obscure body of Mercury has suddenly come into sharp focus. It is very likely a differentiated body, probably contains a large Earth-like iron-rich core, and displays a surface remarkably similar to that of the Moon, which suggests a similar evolutionary history.

  14. Hydrophobic interaction chromatography of proteins. IV. Protein adsorption capacity and transport in preparative mode.

    PubMed

    To, Brian C S; Lenhoff, Abraham M

    2011-01-21

    The adsorption isotherms of four model proteins (lysozyme, α-lactalbumin, ovalbumin, and BSA) on eight commercial phenyl hydrophobic interaction chromatography media were measured. The isotherms were softer than those usually seen in ion-exchange chromatography of proteins, and the static capacities of the media were lower, ranging from 30 to 110 mg/mL, depending on the ammonium sulfate concentration and the protein and adsorbent types. The protein-accessible surface area appears to be the main factor determining the binding capacity, and little correlation was seen with the protein affinities of the adsorbents. Breakthrough experiments showed that the dynamic capacities of the adsorbents at 10% breakthrough were 20-80% of the static capacities, depending on adsorbent type. Protein diffusivities in the adsorbents were estimated from batch uptake experiments using the pore diffusion and homogeneous diffusion models. Protein transport was affected by the adsorbent pore structures. Apparent diffusivities were higher at lower salt concentrations and column loadings, suggesting that adsorbed proteins may retard intraparticle protein transport. The diffusivities estimated from the batch uptake experiments were used to predict column breakthrough behavior. Analytical solutions developed for ion-exchange systems were able to provide accurate predictions for lysozyme breakthrough but not for ovalbumin. Impurities in the ovalbumin solutions used for the breakthrough experiments may have affected the ovalbumin uptake and led to the discrepancies between the predictions and the experimental results.

  15. Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China).

    PubMed

    Zhang, Wei-Kang; Wang, Bing; Niu, Xiang

    2015-08-14

    Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm(-2), almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm(-2)). The adsorption capacities for PM10 of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM10 of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM10 in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas' frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily.

  16. Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China)

    PubMed Central

    Zhang, Wei-Kang; Wang, Bing; Niu, Xiang

    2015-01-01

    Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm−2, almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm−2). The adsorption capacities for PM10 of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM10 of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM10 in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas’ frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily. PMID:26287227

  17. Elemental mercury adsorption on sulfur-impregnated porous carbon - a review.

    PubMed

    Reddy, K Suresh Kumar; Shoaibi, Ahmed Al; Srinivasakannan, C

    2014-01-01

    The presence of elemental mercury in wellhead natural gas is an important industrial problem, since even low levels of mercury can damage cryogenic aluminium heat exchangers and other plant equipment. Mercury present in the natural gas stream will also dramatically shorten the useful life of precious metal catalysts. The present work reviews the overall process of elemental mercury removal in practice using non-regenerative adsorbents (e.g. sulfur-impregnated porous carbon), addressing the various influencing parameters such as the method of sulfur impregnation, the impregnation temperature, the sulfur to carbon ratio, the impregnation time, the impact of flue gas constituents, the effect of processing temperature, and the nature of any carbon-containing functional groups present. The distribution of elemental sulfur is found to be the key to developing an effective adsorbent, rather than quantity of sulfur impregnated. Modifying or developing an adsorbent for elemental mercury removal from natural gas needs a detail physical and chemical characteristics assessment of the adsorbent.

  18. Reservoir capacity estimates in shale plays based on experimental adsorption data

    NASA Astrophysics Data System (ADS)

    Ngo, Tan

    from different measurement techniques using representative fluids (such as CH4 and CO2) at elevated pressures, and the adsorbed density can range anywhere between the liquid and the solid state of the adsorbate. Whether these discrepancies are associated with the inherent heterogeneity of mudrocks and/or with poor data quality requires more experiments under well-controlled conditions. Nevertheless, it has been found in this study that methane GIP estimates can vary between 10-45% and 10-30%, respectively, depending on whether the free or the total amount of gas is considered. Accordingly, CO2 storage estimates range between 30-90% and 15-50%, due to the larger adsorption capacity and gas density at similar pressure and temperature conditions. A manometric system has been designed and built that allows measuring the adsorption of supercritical fluids in microporous materials. Preliminary adsorption tests have been performed using a microporous 13X zeolite and CO 2 as an adsorbing gas at a temperature of 25oC and 35oC and at pressures up to 500 psi. Under these conditions, adsorption is quantified with a precision of +/- 3%. However, relative differences up to 15-20% have been observed with respect to data published in the literature on the same adsorbent and at similar experimental conditions. While it cannot be fully explained with uncertainty analysis, this discrepancy can be reduced by improving experiment practice, thus including the application of a higher adsorbent's regeneration temperature, of longer equilibrium times and of a careful flushing of the system between the various experimental steps. Based on the results on 13X zeolite, virtual tests have been conducted to predict the performance of the manometric system to measure adsorption on less adsorbing materials, such as mudrocks. The results show that uncertainties in the estimated adsorbed amount are much more significant in shale material and they increase with increasing pressure. In fact, relative

  19. Adsorption capacities of poly-γ-glutamic acid and its sodium salt for cesium removal from radioactive wastewaters.

    PubMed

    Sakamoto, Shigeki; Kawase, Yoshinori

    2016-12-01

    Cesium removal from radioactive wastewaters was examined using water-insoluble poly-γ-glutamic acid (γ-PGA) and water-soluble sodium salt form poly-γ-L-glutamic acid (γ-PGANa) as biosorbents. The maximum adsorption capacities at equilibrium of γ-PGA and γ-PGANa for Cs were 345 mg-Cs(g-γ-PGA)(-1) at pH 6.0 and 290 mg-Cs(g-γ-PGANa)(-1) at pH 9.0, respectively. At lower pH < pKa, the carboxyl groups of γ-PGA primarily remained in the protonated form and adsorption of Cs only slightly occurred. At higher pH > pKa, the adsorption of Cs was significantly facilitated due to ionization of carboxyl groups to carboxylate ion. Adsorption of Cs at pH > 9.0 was inhibited due to the hydrolysis of Cs. The Langmuir model could successfully describe the isotherm data. For γ-PGA and γ-PGANa, the maximum adsorption capacities at equilibrium in the Langmuir model were 446 and 333 mg-Cs(g-adsorbent)(-1), respectively. The high adsorption capacities confirmed a potential utilization of γ-PGA and γ-PGANa for Cs removal. The adsorption of Cs by both γ-PGA and γ-PGANa attained the equilibrium within 0.5 min. The very quick equilibration is a benefit from the viewpoint of practical application. The spectra of FT-IR and XPS before and after adsorption confirmed the adsorption of Cs onto γ-PGA and γ-PGANa via electrostatic interaction with carboxylate anions.

  20. The adsorption behavior of mercury on the hematite (1-102) surface from coal-fired power plant emissions

    NASA Astrophysics Data System (ADS)

    Jung, J. E.; Jew, A. D.; Rupp, E.; Aboud, S.; Brown, G. E.; Wilcox, J.

    2014-12-01

    One of the biggest environmental concerns caused by coal-fired power plants is the emission of mercury (Hg). Worldwide, 475 tons of Hg are released from coal-burning processes annually, comprising 24% of total anthropogenic Hg emissions. Because of the high toxicity of Hg species, US Environmental Protection Agency (EPA) proposed a standard on Hg and air toxic pollutants (Mercury and Air Toxics Standards, MATS) for new and existing coal-fired power plants in order to eliminate Hg in flue gas prior to release through the stack. To control the emission of Hg from coal-derived flue gas, it is important to understand the behavior, speciation of Hg as well as the interaction between Hg and solid materials, such as fly ash or metal oxides, in the flue gas stream. In this study, theoretical investigations using density functional theory (DFT) were carried out in conjunction with experiments to investigate the adsorption behavior of oxidized Hg on hematite (α-Fe2O3), an important mineral component of fly ash which readily sorbes Hg from flue gas. For DFT calculation, the two α-Fe2O3 (1-102) surfaces modeled consisted of two different surface terminations: (1) M2-clean, which corresponds to the oxygen-terminated surface with the first layer of cations removed and with no hydroxyl groups and (2) M2-OH2-OH, which has bihydroxylated top oxygen atoms and a second layer of hydroxylated oxygen atoms. These surface terminations were selected because both surfaces are highly stable in the temperature range of flue gases. The most probable adsorption sites of Hg, Cl and HgCl on the two α-Fe2O3 surface terminations were suggested based on calculated adsorption energies. Additionally, Bader charge and projected density of states (PDOS) analyses were conducted to characterize the oxidation state of adsorbates and their bonding interactions with the surfaces. Results indicate that oxidized Hg physically adsorbs on the M2-clean surface with a binding energy of -0.103 eV and that

  1. Enhancing adsorption capacity of toxic malachite green dye through chemically modified breadnut peel: equilibrium, thermodynamics, kinetics and regeneration studies.

    PubMed

    Chieng, Hei Ing; Lim, Linda B L; Priyantha, Namal

    2015-01-01

    Breadnut skin, in both its unmodified (KS) and base-modified (BM-KS) forms, was investigated for its potential use as a low-cost adsorbent for the removal of toxic dye, malachite green (MG). Characterization of the adsorbents was carried out using scanning electron microscope, X-ray fluorescence and Fourier transform infra-red spectroscopy. Batch adsorption experiments, carried out under optimized conditions, for the adsorption of MG were fitted using five isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin and Sips) and six error functions to determine the best-fit model. The adsorption capacity was greatly enhanced when breadnut skin was chemically modified with NaOH, leading to an adsorption capacity of 353.0 mg g(-1), that was far superior to most reported adsorbents for the removal of MG. Thermodynamics studies indicated that the adsorption of MG was spontaneous on KS and BM-KS, and the reactions were endothermic and exothermic, respectively. Kinetics studies showed that both followed the pseudo-second order. Regeneration experiments on BM-KS indicated that its adsorption capacity was still maintained at>90% even after five cycles. It can be concluded that NaOH-modified breadfruit skin has great potential to be utilized in real-life application as a low-cost adsorbent for the removal of MG in wastewater treatment.

  2. Mercury Adsorption and Oxidation over Cobalt Oxide Loaded Magnetospheres Catalyst from Fly Ash in Oxyfuel Combustion Flue Gas.

    PubMed

    Yang, Jianping; Zhao, Yongchun; Chang, Lin; Zhang, Junying; Zheng, Chuguang

    2015-07-07

    Cobalt oxide loaded magnetospheres catalyst from fly ash (Co-MF catalyst) showed good mercury removal capacity and recyclability under air combustion flue gas in our previous study. In this work, the Hg(0) removal behaviors as well as the involved reactions mechanism were investigated in oxyfuel combustion conditions. Further, the recyclability of Co-MF catalyst in oxyfuel combustion atmosphere was also evaluated. The results showed that the Hg(0) removal efficiency in oxyfuel combustion conditions was relative high compared to that in air combustion conditions. The presence of enriched CO2 (70%) in oxyfuel combustion atmosphere assisted the mercury oxidation due to the oxidation of function group of C-O formed from CO2. Under both atmospheres, the mercury removal efficiency decreased with the addition of SO2, NO, and H2O. However, the enriched CO2 in oxyfuel combustion atmosphere could somewhat weaken the inhibition of SO2, NO, and H2O. The multiple capture-regeneration cycles demonstrated that the Co-MF catalyst also present good regeneration performance in oxyfuel combustion atmosphere.

  3. Investigation of adsorption behavior of mercury on Au(111) from first principles.

    PubMed

    Lim, Dong-Hee; Aboud, Shela; Wilcox, Jennifer

    2012-07-03

    The structural and electronic properties of Hg, SO(2), HgS, and HgO adsorption on Au(111) surfaces have been determined using density functional theory with the generalized gradient approximation. The adsorption strength of Hg on Au(111) increases by a factor of 1.3 (from -9.7 to -12.6 kcal/mol) when the number of surface vacancies increases from 0 to 3; however, the adsorption energy decreases with more than three vacancies. In the case of SO(2) adsorption on Au(111), the Au surface atoms are better able to stabilize the SO(2) molecule when they are highly undercoordinated. The SO(2) adsorption stability is enhanced from -0.8 to -9.3 kcal/mol by increasing the number of vacancies from 0 to 14, with the lowest adsorption energy of -10.2 kcal/mol at 8 Au vacancies. Atomic sulfur and oxygen precovered-Au(111) surfaces lower the Hg stability when Hg adsorbs on the top of S and O atoms. However, a cooperative effect between adjacent Hg atoms is observed as the number of S and Hg atoms increases on the perfect Au(111) surface, resulting in an increase in the magnitude of Hg adsorption. Details of the electronic structure properties of the Hg-Au systems are also discussed.

  4. Preparation of a porous clay heterostructure and study of its adsorption capacity of phenol and chlorinated phenols from aqueous solutions.

    PubMed

    Arellano-Cárdenas, Sofía; Gallardo-Velázquez, Tzayhrí; Osorio-Revilla, Guillermo; López-Cortez, Ma del Socorro

    2008-01-01

    A porous clay heterostructure (PCH) from a Mexican clay was prepared and characterized, and its aqueous phenol and dichlorophenols (DCPs) adsorption capacities were studied using a batch equilibrium technique. The PCH displayed a surface area of 305.5 m2/g, 37.2 A average porous diameter, and a basal space of 23.2 A. The adsorption capacity shown by the PCH for both phenol and DCPs from water (14.5 mg/g for phenol; 48.7 mg/g for 3,4-DCP; and 45.5 mg/g for 2,5-DCP) suggests that the PCH has both hydrophobic and hydrophilic characteristics, as a result of the presence of silanol and siloxane groups formed during the pillaring and calcination of the PCH. The values of maximal adsorption capacity for dichlorophenols were higher than those reported for aluminum pillared clays and some inorgano-organo clays and comparable with some ionic exchange resins.

  5. The effects of urease immobilization on the transport characteristics and protein adsorption capacity of cellulose acetate based hemodialysis membranes.

    PubMed

    Mahlicli, Filiz Yasar; Altinkaya, Sacide Alsoy

    2009-10-01

    In this study, cellulose acetate (CA) based hemodialysis membranes were prepared by a dry phase inversion method and the influences of urease immobilization on the clearing performance and protein adsorption capacity of the membranes were investigated. Permeation experiments have shown that modification of CA membranes with urease immobilization not only enhanced the transport rate of urea but also increased the permeation coefficients of uric acid and creatinine by changing the structure of the membrane. Furthermore, the protein adsorption capacity of the CA membranes decreased. On the other hand, the mechanical strength of the modified CA membrane did not change significantly compared with that of the unmodified one. A mathematical model was derived to determine the rate of mass transfer of urea through modified CA membranes. Model predictions along with the experimental data suggest that urease immobilization can be used as an alternative method in preparing CA based hemodialysis membranes with improved transport characteristics and biocompatibility through reduced protein adsorption capacities.

  6. A geometric pore adsorption model for predicting the drug loading capacity of insoluble drugs in mesoporous carbon.

    PubMed

    Gao, Yikun; Zhu, Wenquan; Liu, Jia; Di, Donghua; Chang, Di; Jiang, Tongying; Wang, Siling

    2015-05-15

    In this work, a simple and accurate geometric pore-adsorption model was established and experimentally validated for predicting the drug loading capacity in mesoporous carbon. The model was designed according to the shape of pore channels of mesoporous carbon and the arrangement of drug molecules loaded in the pores. Three different small molecule drugs (celecoxib, fenofibrate and carvedilol) were respectively loaded in mesoporous carbon with different pore sizes. In order to test the accuracy of the established model, nitrogen adsorption-desorption analysis was employed to confirm the pore structure of mesoporous carbon and to calculate the occupation volume of the adsorbed drugs. The adsorption isotherms of celecoxib were systematically investigated to describe the adsorption process. It was found that the experimental results of adsorption capacity were all in the range of the predicted values for all the tested drugs and mesoporous carbon. The occupation volumes calculated from the model also agreed well with the experimental data. These results demonstrated that the established model could accurately provide the range of drug loading capacity, which may provide a useful option for the prediction of the drug loading capacity of small molecule drugs in mesoporous materials.

  7. Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-09-06

    A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  8. Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J; Dai, Sheng; Oyola, Yatsandra

    2014-05-13

    A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  9. Synthesis of multi-walled carbon nanotubes/β-FeOOH nanocomposites with high adsorption capacity

    NASA Astrophysics Data System (ADS)

    Song, Hao-Jie; Liu, Lei; Jia, Xiao-Hua; Min, Chunying

    2012-12-01

    A hybrid nanostructure of multi-walled carbon nanotubes (CNTs) and β-ferric oxyhydroxide (β-FeOOH) nanoparticles is synthesized by ultrasonic-assisted in situ hydrolysis of the precursor ferric chloride and CNTs. Characterization by X-ray diffraction, scanning electron microscopy , and transmission electron microscopy establishes the nanohybrid structure of the synthesized sample. The results revealed that the surface of CNTs was uniformly assembled by numerous β-FeOOH nanoparticles and had an average diameter of 3 nm. The formation route of anchoring β-FeOOH nanoparticles onto CNTs was proposed as the intercalation and adsorption of iron ions onto the wall of CNTs, followed by the nucleation and growth of β-FeOOH nanoparticles. The values of remanent magnetization ( M r) and coercivity ( H c) of the as-synthesized CNTs/β-FeOOH nanocomposites were 0.1131 emu g, and 490.824 Oe, respectively. Furthermore, CNTs/β-FeOOH nanocomposites showed a very high adsorption capacity of Congo red and thus these nanocomposites can be used as good adsorbents and can be used for the removal of the dye of Congo red from the waste water system.

  10. Copper Accumulation, Availability and Adsorption Capacity in Sandy Soils of Vineyards with Different Cultivation Duration

    NASA Astrophysics Data System (ADS)

    Mallmann, F. J. K.; Miotto, A.; Bender, M. A.; Gubiani, E.; Rheinheimer, D. D. S.; Kaminski, J.; Ceretta, C. A.; Šimůnek, J.

    2015-12-01

    Bordeaux mixture is a copper-based (Cu) fungicide and bactericide applied in vineyards to control plant diseases. Since it is applied several times per year, it accumulates in large quantities on plants and in soil. This study evaluates the Cu accumulation in, and desorption kinetics and adsorption capability of a sandy Ultisol in a natural field and in 3 vineyards for 5 (V1), 11 (V2), and 31 (V3) years in South of Brazil. Soil samples were collected in 8 depths (0-60 cm) of all four soil profiles, which all displayed similar soil properties. The following soil properties were measured: pH, organic matter (OM), soil bulk density, Cu total concentration, and Cu desorption and adsorption curves. A two first-order reactions model and the Langmuir isotherm were fitted to the desorption and adsorption curves, respectively. An increase in the total mass of Cu in the vineyards followed a linear regression curve, with an average annual increase of 7.15 kg ha-1. Cu accumulated down to a depth of 5, 20, and 30 cm in V1, V2 and V3, respectively, with the highest Cu content reaching 138.4 mg kg-1 in the 0-5 cm soil layer of V3. Cu desorption parameters showed a high correlation with its total concentration. Approximately 57 and 19% of total Cu were immediately and slowly available, respectively, indicating a high potential for plant absorption and/or downward movement. Cu concentrations extracted by EDTA from soil layers not affected by anthropogenic Cu inputs were very low. The maximum Cu adsorption capacity of the 0-5 and 5-10 cm soil layers increased with the vineyard age, reaching concentrations higher than 900 mg kg-1. This increase was highly related to OM and pH, which both increased with cultivation duration. Despite of low clay content of these soils, there is low risk of groundwater Cu contamination for actual conditions. However, high Cu concentrations in the surface layer of the long-term vineyards could cause toxicity problems for this and for companion crops.

  11. The adsorption of mercury-species on relaxed and rumpled CaO (0 0 1) surfaces investigated by density functional theory.

    PubMed

    Blowers, Paul; Kim, Bo Gyeong

    2011-03-01

    This research examines the importance of several computational choices in modeling mercury species adsorption on calcium oxide surfaces and is the second in a series of papers. The importance of surface relaxation was tested and it was found that adsorption energies changed for HgCl(2), moving adsorption from being at the borderline of physisorption and chemisorption to being strongly chemisorbed. Results for Hg and HgCl were unaffected. A second computational choice, that of the cluster or periodic model size was tested in both the plane of the model (4 × 4 or 5 × 5 model sizes) and for the depth (two or three layers). It was found that the minimum cluster size for handling mercury adsorption was 5 × 5 and that only two layers of depth were needed. The energetic results show that rumpled CaO surfaces will only weakly physisorb elemental mercury, but could be used to capture HgCl(2) from coal combustion flue gases, which is in agreement with limited experimental data.

  12. Changing the adsorption capacity of coal-based honeycomb monoliths for pollutant removal from liquid streams by controlling their porosity

    NASA Astrophysics Data System (ADS)

    Gatica, José M.; Harti, Sanae; Vidal, Hilario

    2010-09-01

    Coal-based honeycomb monoliths extruded using methods developed for ceramic materials have been used to retain methylene blue and p-nitrophenol from aqueous solutions. The influence of the filters' thermal treatment on their textural properties and performance as adsorbents was examined. Characterization by N 2 physisorption, mercury porosimetry and scanning electron microscopy along with adsorption tests under dynamic conditions suggest that, depending on the pollutant and its initial concentration, it can be more convenient to previously submit the monoliths to a simple carbonization or to an additional activation, with or without preoxidation, as a consequence of their different resulting pore structures. Infrared spectroscopy indicates that their different adsorption behaviour seems not to be related to differences in their surface chemical groups. In addition, axial crushing tests show that the monoliths have an acceptable mechanical resistance for the application investigated.

  13. Effect of the both texture and electrical properties of activated carbon on the CO{sub 2} adsorption capacity

    SciTech Connect

    Djeridi, W.; Ouederni, A.; Mansour, N.Ben; Llewellyn, P.L.; Alyamani, A.; El Mir, L.

    2016-01-15

    Highlights: • A series of activated carbon pellet without binder was prepared by chemical activation. • Carbon dioxide storage isotherm at 30 °C and up to 25 bars was measured for the microporous carbon. • Adsorption enthalpies have been correlated with the carbon dioxide uptake. • Pyrolysis temperature effect on the electrical conductivity of the samples. • Impact of the both texture and electrical properties on CO{sub 2} adsorption capacity have been deducted - Abstract: A series of activated carbon pellets (ACP) based on olive stones were studied for CO{sub 2} storage application. The surface area, pore volume, and pore diameter were evaluated from the analysis of N{sub 2} adsorption isotherm data. The characterization of carbon materials was performed by scanning electron microscopy (SEM), the powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The adsorption enthalpies were obtained by microcalorimetry. The effect of pyrolysis temperature on textural, electrical conductivity and gas adsorption capacities of the ACP were investigated by adsorbing CO{sub 2} at 303 K in the pressure range of 0–2.3 MPa. In fact the electrical conductivity is strongly affected by the microporosity of the samples and the size of the micropore. It increases when the pore size decreases which affect the CO{sub 2} adsorption. Also with increases temperature the free electrons concentration on the surface increases which affect the interaction of the adsorbed gas molecules.

  14. Adsorption characteristics of adsorbent resins and antioxidant capacity for enrichment of phenolics from two-phase olive waste.

    PubMed

    Wang, Zhihong; Wang, Chengzhang; Yuan, Jiaojiao; Zhang, Changwei

    2017-01-01

    In this study, the adsorption properties of nine resins including polyamide resin (30-60), polyamide resin (60-100) AB-8, S-8, D-101, NKA-9, NKA-II, XDA-1 and XDA-4 for enrichment phenolics of the olive waste were investigated. XDA-1 and NKA-II were chosen for further study due to their outstanding adsorption and desorption capacity. XDA-1 and NKA-II had similar adsorption and desorption behaviors for phenolics of olive waste. The adsorption mechanism could be better explained by pseudo second-order kinetics model and Freundlich isotherm model, and the adsorption processes were spontaneously and exothermic. The experiment of gradient elution were carried out through treated XDA-1 resins column, the result indicated the total phenolics were mainly obtained from the 40% and 60% ethanol fraction. The order of antioxidant capacity by DPPH  , ABTS(+) radical and FRAP assay was similar with the content of phenolics from fraction elution. The compositions of phenolics from different elution fractions were determined by reversed phase-HPLC-DAD method. Gallic acid, hydroxytyrosol, tyrosol and ferulic acid were the major constituent in the fraction elute, and the content of hydroxytyrosol reached to the 41.69mg/g. The above results revealed the synergistic effects of the different phenolics contribute to the antioxidant capacity.

  15. Integrated Removal of NOx with Carbon Monoxide as Reductant, and Capture of Mercury in a Low Temperature Selective Catalytic and Adsorptive Reactor

    SciTech Connect

    Neville Pinto; Panagiotis Smirniotis; Stephen Thiel

    2010-08-31

    Coal will likely continue to be a dominant component of power generation in the foreseeable future. This project addresses the issue of environmental compliance for two important pollutants: NO{sub x} and mercury. Integration of emission control units is in principle possible through a Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR) in which NO{sub x} removal is achieved in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The capture of mercury is integrated into the same process unit. Such an arrangement would reduce mercury removal costs significantly, and provide improved control for the ultimate disposal of mercury. The work completed in this project demonstrates that the use of CO as a reductant in LTSCR is technically feasible using supported manganese oxide catalysts, that the simultaneous warm-gas capture of elemental and oxidized mercury is technically feasible using both nanostructured chelating adsorbents and ceria-titania-based materials, and that integrated removal of mercury and NO{sub x} is technically feasible using ceria-titania-based materials.

  16. Cu(II) and Zn(II) adsorption capacity of three different clay liner materials.

    PubMed

    Musso, T B; Parolo, M E; Pettinari, G; Francisca, F M

    2014-12-15

    Sorption of Cu(II) and Zn(II) on three natural clays meeting the international requirements for use as liners was evaluated by means of batch tests. The purpose of this research was to determine the retention capacities of the clays for metal cations commonly present in urban solid waste leachates. The pH and ionic strength conditions were set at values frequently found in real leachates. The changes observed in the XRD patterns and FTIR spectra upon adsorption can be considered an evidence of clay-metal electrostatic interaction. The Langmuir model was found to best describe the sorption processes, offering maximum sorption capacities from 8.16 to 56.89 mg/g for Cu(II) and from 49.59 to 103.83 mg/g for Zn(II). All samples remove more Zn(II) than Cu(II), which may be related to the different geometry of the hydrated Cu(II) cation. The total amount of metal sorption was strongly influenced by the total specific surface area, the presence of carbonates and the smectite content of the clays. In addition to their known quality as physical barriers, the adsorbed amounts obtained indicate the suitability of the tested clays to contribute to the retardation of Cu(II) and Zn(II) transport through clay liners.

  17. Expanded porous MOF-505 analogue exhibiting large hydrogen storage capacity and selective carbon dioxide adsorption.

    PubMed

    Zheng, Baishu; Yun, Ruirui; Bai, Junfeng; Lu, Zhiyong; Du, Liting; Li, Yizhi

    2013-03-18

    An expanded 4,4-paddlewheel-connected porous MOF-505-type metal-organic framework (MOF), [Cu2(PDEB)(H2O)2]·xS (NJU-Bai12; NJU-Bai represents the Nanjing University Bai group and S represents noncoordinated solvent molecules) has been designed from a nanosized rectangular diisophthalate linker containing alkyne groups 5,5'-(1,4-phenylenedi-2,1-ethynediyl)bis(1,3-benzenecarboxylic acid). This MOF material possesses permanent microporosity with the highest Brunauer-Emmett-Teller surface area of 3038 m(2)·g(-1) and the largest unsaturated total hydrogen storage capacity of 62.7 mg·g(-1) at 77 K and 20 bar among reported MOF-505 analogues. Additionally, NJU-Bai12 also exhibits excellent carbon dioxide (CO2) uptake capacity (23.83 and 19.85 mmol·g(-1) at 20 bar for 273 and 298 K, respectively) and selective gas adsorption properties with CO2/CH4 selectivity of 5.0 and CO2/N2 selectivity of 24.6 at room temperature.

  18. Synthesis, characterisation and adsorption properties of a porous copper(II) 3D coordination polymer exhibiting strong binding enthalpy and adsorption capacity for carbon dioxide.

    PubMed

    Eckold, Pierre; Gee, William J; Hill, Matthew R; Batten, Stuart R

    2012-11-21

    The synthesis and characterisation of microporous coordination polymers containing copper(II) or cobalt(II) and 2-(pyridin-4-yl)malonaldehyde (Hpma) is described and the gas adsorption properties evaluated. Single-crystal X-ray structure determinations identified the structures as [M(pma)(2)]·2X (M = Cu, 1; Co, 2; X = MeOH, MeCN), which contain 3D networks with rutile topology and continuous 1D rectangular channels with diameters ranging from 3 to 4 Å. The materials exhibit low BET surface areas of 143 m(2) g(-1), but possess large capacities for carbon dioxide capture of 14.1 wt%. The small pore channels are shown to account for this, delivering a particularly strong binding enthalpy to adsorbed CO(2) of 38 kJ mol(-1), and a very large adsorption capacity relative to the low surface area.

  19. High adsorption capacity of heavy metals on two-dimensional MXenes: an ab initio study with molecular dynamics simulation.

    PubMed

    Guo, Xun; Zhang, Xitong; Zhao, Shijun; Huang, Qing; Xue, Jianming

    2016-01-07

    Density functional theory (DFT) calculation is employed to study the adsorption properties of Pb and Cu on recently synthesized two-dimensional materials MXenes, including Ti3C2, V2C1 and Ti2C1. The influence of surface decoration with functional groups such as H, OH and F have also been investigated. Most of these studied MXenes exhibit excellent capability to adsorb Pb and Cu, especially the adsorption capacity of Pb on Ti2C1 is as high as 2560 mg g(-1). Both the binding energies and the adsorption capacities are sensitive to the functional groups attached to the MXenes' surface. Ab initio molecular dynamics (ab-init MD) simulation confirms that Ti2C1 remains stable at room temperature after adsorbing Pb atoms. Our calculations imply that these newly emerging two-dimensional MXenes are promising candidates for wastewater treatment and ion separation.

  20. EFFECT OF MOLECULAR OXYGEN ON ADSORPTIVE CAPACITY AND EXTRACTION EFFICIENCY OF GRANULATED ACTIVATED CARBON FOR THREE ORTHO-SUBSTITUTED PHENOLS

    EPA Science Inventory

    Adsorptive capacity of activated carbon for several organic compounds was found to be strongly influenced by the presence of molecular oxygen. This influence is manifested by the polymerization of adsorbate on the surface of activated carbon. As a result, GAC exhibits much high...

  1. Mercury species, selenium, metallothioneins and glutathione in two dolphins from the southeastern Brazilian coast: Mercury detoxification and physiological differences in diving capacity.

    PubMed

    Kehrig, Helena A; Hauser-Davis, Rachel A; Seixas, Tercia G; Pinheiro, Ana Beatriz; Di Beneditto, Ana Paula M

    2016-06-01

    In the present study, the concentration of trace elements, total mercury (Hg) and selenium (Se) and mercury forms (MeHg, Hginorg and HgSe) in the vulnerable coastal dolphins Pontoporia blainvillei and Sotalia guianensis were appraised and compared, using metallothioneins (MT) and glutathione (GSH) as biomarkers for trace element exposure. The trace element concentrations varied between muscle and liver tissues, with liver of all dolphin specimens showing higher Hg and Se concentrations than those found in muscle. Hg, MeHg and Hginorg molar concentrations showed a clear increase with Se molar concentrations in the liver of both dolphins, and Se concentrations were higher than those of Hg on a molar basis. Se plays a relevant role in the detoxification of MeHg in the hepatic tissue of both dolphins, forming Hg-Se amorphous crystals in liver. In contrast, MT were involved in the detoxification process of Hginorg in liver. GSH levels in P. blainvillei and S. guianensis muscle tissue suggest that these dolphins have different diving capacities. Muscle Hg concentrations were associated to this tripeptide, which protects dolphin cells against Hg stress.

  2. High adsorption capacity NaOH-activated carbon for dye removal from aqueous solution.

    PubMed

    Wu, Feng-Chin; Tseng, Ru-Ling

    2008-04-15

    In this study, the surface coverage ratio (Sc/Sp) and monolayer cover adsorption amount per unit surface area (qmon/Sp) were employed to investigate the adsorption isotherm equilibrium of the adsorption of dyes (AB74, BB1 and MB) on NaOH-activated carbons (FWNa2, FWNa3 and FWNa4); the adsorption rate of the Elovich equation (1/b) and the ratio of 1min adsorption amount of adsorbate to the monolayer cover amount of adsorbate (q1/qmon) were employed to investigate adsorption kinetics. The qmon/Sp of NaOH-activated carbons was better than that of KOH-activated carbons prepared from the same raw material (fir wood). The Sc/Sp values of the adsorption of all adsorbates on adsorbent FWNa3 in this study were found to be higher than those in related literature. Parameters 1/b and q1 of the adsorption of dyes on activated carbons in this study were higher than those on KOH-activated carbons; the q1/qmon value of FWNa3 was the highest. The pore structure and the TPD measurement of the surface oxide groups were employed to explain the superior adsorption performance of FWNa3. A high surface activated carbon (FWNa3) with excellent adsorption performance on dyes with relation to adsorption isotherm equilibrium and kinetics was obtained in this study. Several adsorption data processing methods were employed to describe the adsorption performance.

  3. Textural characterization of native and n-alky-bonded silica monoliths by mercury intrusion/extrusion, inverse size exclusion chromatography and nitrogen adsorption.

    PubMed

    Thommes, M; Skudas, R; Unger, K K; Lubda, D

    2008-05-16

    Native and n-alkyl-bonded (n-octadecyl) monolithic silica rods with mesopores in the range between 10 and 25 nm and macropores in the range between 1.8 and 6.0 microm were examined by mercury intrusion/extrusion, inverse size exclusion chromatography (ISEC) and nitrogen sorption. Our results reveal very good agreement for the mesopore size distribution obtained from nitrogen adsorption (in combination with an advanced NLDFT analysis) and ISEC. Our studies highlight the importance of mercury porosimetry for the assessment of the macropore size distribution and show that mercury porosimetry is the only method which allows obtaining a combined and comprehensive structural characterization of macroporous/mesoporous silica monoliths. Our data clearly confirm that mercury porosimetry hysteresis and entrapment have different origin, and indicate the intrinsic nature of mercury porosimetry hysteresis in these silica monoliths. Within this context some silica monoliths show the remarkable result of no entrapment of mercury after extrusion from the mesopore system (i.e. for the first intrusion/extrusion cycle). The results of a systematic study of the mercury intrusion/extrusion behavior into native silica monoliths and monoliths with bonded n-alkyl groups reveals that the macro (through) pore structure, which controls the mass transfer to and from the mesopores, here mainly controls the entrapment behavior. Our data suggest that mercury intrusion/extrusion porosimetry does not only allow to obtain a comprehensive pore structure analysis, but can also serve as a tool to estimate the mass transport properties of silica monoliths to be employed in liquid-phase separation processes.

  4. Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity

    PubMed Central

    Huang, Zhujian; Gong, Beini; Dai, Yaping; Chiang, Pen-Chi; Lai, Xiaolin; Yu, Guangwei

    2016-01-01

    To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH2) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt, APTES4.0CEC-Mt) with enhanced adsorption capacity for Co2+. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co2+ by APTES-Mt was evaluated. The results indicated that adsorption of Co2+ onto Ca-Mt, APTES1.0CEC-Mt and APTES2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co2+ onto APTES3.0CEC-Mt and APTES4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt and APTES4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co2+ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co2+-rich wastewater. PMID:27448094

  5. High capacity MnOx:ZrO2 sorbent for elementary mercury capture: preparation, characterization and comparison to other sorbents

    NASA Astrophysics Data System (ADS)

    Lakatos, J.; Snape, C. E.

    2017-02-01

    Manganese oxide-zirconia type (MnOx:ZrO2) sorbents were prepared using the sol-gel technique by co precipitation ZrO(NO3)2.xH2O and Mn(NO3)2 xH2O. The heat treatment below 500°C resulted a high surface area solid structure which consists of amorphous Mn2O3 (Bixbyite) and amorphous ZrO2 phases. This material was found a high capacity oxidative sorbent for mercury removal from gas streams.

  6. Adsorption capacity of poly(ether imide) microparticles to uremic toxins.

    PubMed

    Tetali, Sarada D; Jankowski, Vera; Luetzow, Karola; Kratz, Karl; Lendlein, Andreas; Jankowski, Joachim

    2016-01-01

    Uremia is a phenomenon caused by retention of uremic toxins in the plasma due to functional impairment of kidneys in the elimination of urinary waste products. Uremia is presently treated by dialysis techniques like hemofiltration, dialysis or hemodiafiltration. However, these techniques in use are more favorable towards removing hydrophilic than hydrophobic uremic toxins. Hydrophobic uremic toxins, such as hydroxy hipuric acid (OH-HPA), phenylacetic acid (PAA), indoxyl sulfate (IDS) and p-cresylsulfate (pCRS), contribute substantially to the progression of chronic kidney disease (CKD) and cardiovascular disease. Therefore, objective of the present study is to test adsorption capacity of highly porous microparticles prepared from poly(ether imide) (PEI) as an alternative technique for the removal of uremic toxins. Two types of nanoporous, spherically shaped microparticles were prepared from PEI by a spraying/coagulation process.PEI particles were packed into a preparative HPLC column to which a mixture of the four types of uremic toxins was injected and eluted with ethanol. Eluted toxins were quantified by analytical HPLC. PEI particles were able to adsorb all four toxins, with the highest affinity for PAA and pCR. IDS and OH-HPA showed a partially non-reversible binding. In summary, PEI particles are interesting candidates to be explored for future application in CKD.

  7. Evaluation of the memory effect on gold-coated silica adsorption tubes used for the analysis of gaseous mercury by cold vapor atomic absorption spectrometry.

    PubMed

    Rahman, Mohammad Mahmudur; Brown, Richard J C; Kim, Ki-Hyun; Yoon, Hye-On; Phan, Nhu-Thuc

    2013-01-01

    In an effort to reduce the experimental bias involved in the analysis of gaseous elemental mercury (Hg(o)), the blank response from gold-coated adsorption tubes has been investigated using cold vapor atomic absorption spectrometry (CVAAS). Our study has been compared with our recent investigation on memory effect in a cold vapour atomic fluorescence spectrometry (CVAFS). The pattern of blank responses was quantified after loading different amounts of mercury and after different time intervals of 1, 14, and 45 days. In case of the one day interval, the result of five to six instant blank heating cycles confirmed successful liberation of mercury following the second and third blank heating cycles. The results of 14 or 45 days generally suggest that liberation of excess mercury is affected by both the initial loading amount and the length of storage time prior to analysis. We have demonstrated a possibly effective way to reduce memory effects. Some similarities of these results with those from CVAFS experiment suggests that the blank response is caused by a combination of mercury absorbed within the bulk gold and micro- and nanoparticles liberated during heating and not from coabsorbing interfering gaseous species.

  8. Evaluation of the Memory Effect on Gold-Coated Silica Adsorption Tubes Used for the Analysis of Gaseous Mercury by Cold Vapor Atomic Absorption Spectrometry

    PubMed Central

    Rahman, Mohammad Mahmudur; Brown, Richard J. C.; Yoon, Hye-On; Phan, Nhu-Thuc

    2013-01-01

    In an effort to reduce the experimental bias involved in the analysis of gaseous elemental mercury (Hgo), the blank response from gold-coated adsorption tubes has been investigated using cold vapor atomic absorption spectrometry (CVAAS). Our study has been compared with our recent investigation on memory effect in a cold vapour atomic fluorescence spectrometry (CVAFS). The pattern of blank responses was quantified after loading different amounts of mercury and after different time intervals of 1, 14, and 45 days. In case of the one day interval, the result of five to six instant blank heating cycles confirmed successful liberation of mercury following the second and third blank heating cycles. The results of 14 or 45 days generally suggest that liberation of excess mercury is affected by both the initial loading amount and the length of storage time prior to analysis. We have demonstrated a possibly effective way to reduce memory effects. Some similarities of these results with those from CVAFS experiment suggests that the blank response is caused by a combination of mercury absorbed within the bulk gold and micro- and nanoparticles liberated during heating and not from coabsorbing interfering gaseous species. PMID:23589708

  9. Elemental mercury oxidation and adsorption on magnesite powder modified by Mn at low temperature.

    PubMed

    Xu, Yalin; Zhong, Qin; Liu, Xinya

    2015-01-01

    Mn modified the commercial magnesite powder prepared by wet impregnation method has been shown to be effective for gas-phase elemental mercury (Hg(0)) removal at low temperatures. The prepared samples are characterized in detail across multiform techniques: XRF, BET, SEM-EDX, XRD, H2-TPR, and XPS, and all the results show that the amorphous MnO2 impregnated on magnesite powder improves the removal efficiency of Hg(0). Through further analysis by TG and in situ FTIR, the reasonable removal mechanism is also speculated. The results indicate that chemisorbed oxygen is an important reactant in the heterogeneous reaction, and gas-phase Hg(0) is adsorbed and then oxidized to solid MnHgO3 on the surface of the adsorbent.

  10. Determination of Xanthine in the Presence of Hypoxanthine by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

    PubMed Central

    Farias, Percio Augusto Mardini; Castro, Arnaldo Aguiar

    2014-01-01

    A stripping method for the determination of xanthine in the presence of hypoxanthine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10−3 mol L−1 NaOH solution as supporting electrolyte, an accumulation potential of 0.00 V for xanthine and −0.50 V for hypoxanthine–copper, and a linear scan rate of 200 mV second−1. The response of xanthine is linear over the concentration ranges of 20–140 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 36 ppt (2.3 × 10−10 mol L−1). Adequate conditions for measuring the xanthine in the presence of hypoxanthine, copper and other metals, uric acid, and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of xanthine associated with hypoxanthine, uric acid, nitrogenated bases, ATP, and ssDNA. PMID:24940040

  11. Effect of different carbon nanotubes on cadmium toxicity to Daphnia magna: The role of catalyst impurities and adsorption capacity.

    PubMed

    Wang, Xinghao; Qu, Ruijuan; Liu, Jiaoqin; Wei, Zhongbo; Wang, Liansheng; Yang, Shaogui; Huang, Qingguo; Wang, Zunyao

    2016-01-01

    Experiments were conducted to investigate the effect of four different carbon nanotubes single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs) and hydroxylated and carboxylated multi-walled carbon nanotubes (OH-MWCNTs and COOH-MWCNTs) on Cd toxicity to the aquatic organism Daphnia magna. The acute toxicity results indicated that all CNTs could enhance the toxicity of Cd to D. magna. Furthermore, the filtrate toxicity and adsorption tests showed that the toxicity-increasing effect of SWCNTs and MWCNTs in the overall system was mainly caused by catalysts impurities from the pristine CNTs, whereas the greater adsorption of Cd onto OH-MWCNTs (30.52 mg/g) and COOH-MWCNTs (24.93 mg/g) was the key factor contributing to the enhanced toxicity. This result raised a concern that the metal catalyst impurities, adsorption capacities, and accumulation of waterborne CNTs were responsible for the toxicity of Cd to aquatic organism.

  12. Square wave adsorptive stripping voltammetry of molybdenum(VI) in continuous flow at a wall-jet mercury film electrode sensor.

    PubMed

    Neto, M M; Rocha, M M; Brett, C M

    1994-09-01

    An adsorptive stripping voltammetry method for the determination of traces of molybdenum(VI) in flowing solution at a wall-jet electrode sensor has been developed. After adsorption of a molybdenum complex on a wall-jet mercury film electrode, the complex is reduced by a square wave scan. More satisfactory results were obtained using 8-hydroxyquinoline as a complexing agent in nitrate medium than using Toluidine Blue in oxalic acid. Enhanced sensitivity was achieved by optimizing adsorption time and square wave parameter values. The detection limit of Mo(VI) was found to be at the nanomolar level. Interference of some other metallic species in the determination of nanomolar Mo(VI) was also investigated: Cu(II), Zn(II), Mn(II) do not interfere at 10 muM, whereas 1 muM FeEDTA(-) causes an increase in peak current. This iron interference was removed effectively with citric acid.

  13. Dye-adsorption capacity of high surface-area hydrogen titanate nanosheets processed via modified hydrothermal method.

    PubMed

    Padinhattayil, Hareesh; Augustine, Rimesh; Shukla, Satyajit

    2013-04-01

    High surface-area (380 m2 x g(-1)) hydrogen titanate nanosheets (HTNS) processed via the modified hydrothermal method have been utilized for the removal of methylene blue (MB) dye from an aqueous solution via the surface-adsorption process involving the electrostatic attraction mechanism. The HTNS have been characterized using the transmission electron microscope (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) specific surface-area measurement techniques. The amount of MB dye adsorbed on the surface of HTNS at equilibrium (q(e)) has been examined as a function of contact time, initial dye-concentration, and initial solution-pH. Within the investigated range of initial solution-pH (2.5-11), the MB dye adsorption on the surface of HTNS has been observed to follow the pseudo-second-order kinetics with the dye-adsorption capacity of 119 mg x g(-1) at the initial solution-pH of - 10. The adsorption equilibrium follows the Langmuir isotherm within the initial solution-pH range of 2.5-10. However, in a highly basic solution (initial solution-pH -11), the adsorption equilibrium has been observed to follow the Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DKR) models in the different ranges of initial MB dye concentration. The mere dependence on the DKR model has not been observed within the investigated range of initial solution-pH. The differences in the dye-adsorption characteristics and capacity of HTNS, compared with those of hydrogen titanate nanotubes, have been attributed to the difference in their specific surface-area. Irrespective of the morphology, the maximum coverage of MB dye on the surface of hydrogen titanate has been noted to be the same (52%).

  14. Effective mercury(II) bioremoval from aqueous solution, and its electrochemical determination.

    PubMed

    Balderas-Hernández, Patricia; Roa-Morales, Gabriela; Ramírez-Silva, María Teresa; Romero-Romo, Mario; Rodríguez-Sevilla, Erika; Esparza-Schulz, Juan Marcos; Juárez-Gómez, Jorge

    2017-01-01

    This work proposed mercury elimination using agricultural waste (Allium Cepa L.). The biomass removed 99.4% of mercury, following a pseudo-second order kinetics (r(2) = 0.9999). The Langmuir model was adequately fitted to the adsorption isotherm, thereby obtaining the maximum mercury adsorption capacity of 111.1 ± 0.3 mg g(-1). The biomass showed high density of strong mercury chelating groups, thus making it economically attractive. Also, the implementation of a mercury-selective electrode for continuous determination in real time is proposed; this electrode replaces techniques like atomic absorption spectroscopy, thus it can be applied to real time studies. This work therefore presents a new perspective for removing mercury(II) from contaminated water for environmental remediation.

  15. Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

    NASA Astrophysics Data System (ADS)

    Zhao, Chunjiang; Wu, Huarui

    2017-03-01

    Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pdn (n = 1-6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH3 adsorption on PNG. The adsorption ability of Hg on Pdn decorated PNG is found to be related to the d-band center (εd) of the Pdn, in which the closer εd of Pdn to the Fermi level, the higher adsorption strength for Hg on Pdn decorated PNG. Moreover, the charge transfer between Pdn and arsenic may constitute arsenic adsorption on Pdn decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring εd of adsorbed metals.

  16. Characterization of the cation-binding capacity of a potassium-adsorption filter used in red blood cell transfusion.

    PubMed

    Suzuki, Takao; Muto, Shigeaki; Miyata, Yukio; Maeda, Takao; Odate, Takayuki; Shimanaka, Kimio; Kusano, Eiji

    2015-06-01

    A K(+) -adsorption filter was developed to exchange K(+) in the supernatant of stored irradiated red blood cells with Na(+) . To date, however, the filter's adsorption capacity for K(+) has not been fully evaluated. Therefore, we characterized the cation-binding capacity of this filter. Artificial solutions containing various cations were continuously passed through the filter in 30 mL of sodium polystyrene sulfonate at 10 mL/min using an infusion pump at room temperature. The cation concentrations were measured before and during filtration. When a single solution containing K(+) , Li(+) , H(+) , Mg(2+) , Ca(2+) , or Al(3+) was continuously passed through the filter, the filter adsorbed K(+) and the other cations in exchange for Na(+) in direct proportion to the valence number. The order of affinity for cation adsorption to the filter was Ca(2+) >Mg(2+) >K(+) >H(+) >Li(+) . In K(+) -saturated conditions, the filter also adsorbed Na(+) . After complete adsorption of these cations on the filter, their concentration in the effluent increased in a sigmoidal manner over time. Cations that were bound to the filter were released if a second cation was passed through the filter, despite the different affinities of the two cations. The ability of the filter to bind cations, especially K(+) , should be helpful when it is used for red blood cell transfusion at the bedside. The filter may also be useful to gain a better understanding of the pharmacological properties of sodium polystyrene sulfonate.

  17. Predicting CH4 adsorption capacity of microporous carbon using N2 isotherm and a new analytical model

    USGS Publications Warehouse

    Sun, Jielun; Chen, S.; Rostam-Abadi, M.; Rood, M.J.

    1998-01-01

    A new analytical pore size distribution (PSD) model was developed to predict CH4 adsorption (storage) capacity of microporous adsorbent carbon. The model is based on a 3-D adsorption isotherm equation, derived from statistical mechanical principles. Least squares error minimization is used to solve the PSD without any pre-assumed distribution function. In comparison with several well-accepted analytical methods from the literature, this 3-D model offers relatively realistic PSD description for select reference materials, including activated carbon fibers. N2 and CH4 adsorption data were correlated using the 3-D model for commercial carbons BPL and AX-21. Predicted CH4 adsorption isotherms, based on N2 adsorption at 77 K, were in reasonable agreement with the experimental CH4 isotherms. Modeling results indicate that not all the pores contribute the same percentage Vm/Vs for CH4 storage due to different adsorbed CH4 densities. Pores near 8-9 A?? shows higher Vm/Vs on the equivalent volume basis than does larger pores.

  18. [Effect of KI modified clay on elemental mercury removal efficiency].

    PubMed

    Shen, Bo-Xiong; Chen, Jian-Hong; Cai, Ji; He, Chuan; Li, Zhuo

    2014-08-01

    Adsorption tests of elemental mercury were carried out by using KI modified clay (bentonite) in simulated flue gas under different conditions. Brunauer-Emett-Teller measurement (BET), Fourier Transform Infraredspectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used to analyze the physical and chemical properties of the materials. Compared with the original bentonite, Hg(0) removal efficiency and Hg(0) adsorption capacity were drastically improved by the KI treatment. The experiment results also indicated that temperature could enhance the property of Hg(0) adsorption. Chemical adsorption was the dominant part in the process of Hg(0) adsorption. O2 was a beneficial factor for Hg(0) adsorption. SO2 was found to have a slight promotional effect on Hg(0) adsorption. The existence of H2O exhibited a dramatic inhibitory effect on Hg(0) adsorption.

  19. Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Wood, Jordana R.; Schlafer, Nicholas J.; Janke, Christopher J.; Das, Sadananda; Mayes, Richard; Saito, Tomonori; Brown, Suree S.; Tsouris, Constantinos; Tsouris, Costas; Wai, Chien M.; Pan, Horng-Bin

    2016-09-29

    The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a

  20. Relationship between the adsorption capacity of pesticides by wood residues and the properties of woods and pesticides.

    PubMed

    Rodriguez-Cruz, Sonia; Andrades, Maria S; Sanchez-Camazano, Maria; Sanchez-Martin, Maria J

    2007-05-15

    With the aim to explore the potential use of wood residues in technologies aimed at preventing the pollution of soil and water, we studied the adsorption of four non-ionic pesticides (linuron, alachlor, metalaxyl, and chlorpyrifos) and two ionic pesticides (dicamba and paraquat) with a Kow range of -4.5 to 4.7 by nine types of wood with lignin content in the 18.2-26.9% range. The Freundlich Kf values were considered as indicators of the adsorption capacity. A statistical study was carried out using simple and multiple correlations to establish the degree to which the different parameters of the woods and of the pesticides were involved in adsorption. In the case of the non-ionic pesticides, positive and negative significant correlations were observed between Kf and the lignin (r = 0.73-0.83, p < 0.05-0.01), and soluble C contents of the woods (r = 0.66-0.84), p < 0.1-0.01). For dicamba, a correlation between Kf and pH (r = -0.66, p < 0.1) of the woods was found, while for paraquat, this was seen between Kf and the cation exchange capacity (r = 0.71, p < 0.1) of the woods. No significant correlation was observed between Kf and the total C content of the woods. A highly significant correlation between Kf and Kow values (r > or = 0.93, p < 0.01) was found in the adsorption of the pesticides by the woods (with the exception of paraquat) showing that this parameter is very important in this adsorption process. The determination coefficient of the multiple correlation between Kf and the parameters Kow, soluble C, and lignin contents accounts for nearly 100% of the variability in adsorption for non-ionic pesticides. Based on the results of our study and of those of the literature related to the adsorption of aromatic hydrocarbons, we used the Kow values to define a predictive model of adsorption of hydrophobic organic compounds in general by the woods.

  1. Molecular basis for the high CO2 adsorption capacity of chabazite zeolites.

    PubMed

    Pham, Trong D; Hudson, Matthew R; Brown, Craig M; Lobo, Raul F

    2014-11-01

    CO2 adsorption in Li-, Na-, K-CHA (Si/Al=6,=12), and silica chabazite zeolites was investigated by powder diffraction. Two CO2 adsorption sites were found in all chabazites with CO2 locating in the 8-membered ring (8MR) pore opening being the dominant site. Electric quadrupole-electric field gradient and dispersion interactions drive CO2 adsorption at the middle of the 8 MRs, while CO2 polarization due to interaction with cation sites controls the secondary CO2 site. In Si-CHA, adsorption is dominated by dispersion interactions with CO2 observed on the pore walls and in 8 MRs. CO2 adsorption complexes on dual cation sites were observed on K-CHA, important for K-CHA-6 samples due to a higher probability of two K(+) cations bridging CO2. Trends in isosteric heats of CO2 adsorption based on cation type and concentration can be correlated with adsorption sites and CO2 quantity. A decrease in the hardness of metal cations results in a decrease in the direct interaction of these cations with CO2.

  2. Quantitative evaluation of the effect of moisture contents of coconut shell activated carbon used for respirators on adsorption capacity for organic vapors.

    PubMed

    Abiko, Hironobu; Furuse, Mitsuya; Takano, Tsuguo

    2010-01-01

    Activated carbon is an elemental material used for hygienic applications, particularly as an adsorbent for harmful gases and vapors. In Japanese industrial and occupational hygiene, activated carbon produced from coconut shell is a traditional and popular adsorbent material due to its excellent adsorption ability and cost advantage. In this research, in order to clarify the effect of the preliminary content of moisture on the adsorption capacity in detail, we prepared several coconut shell activated carbons which were preconditioned by equilibration with moisture at different relative humidities. We measured their adsorption capacities as breakthrough times for 6 kinds of organic vapor, and attempted to determine the relationships between the relative weight increase of water adsorption and the decrease of adsorption capacities of the activated carbon specimens for the organic vapors. The procedure of the quantitative evaluation of the effect of moisture and the results are useful for practical applications of activated carbon, particularly those used as adsorbents in workplaces.

  3. Adsorption of chromium(III), mercury(II) and lead(II) ions onto 4-aminoantipyrine immobilized bentonite.

    PubMed

    Wang, Qihui; Chang, Xijun; Li, Dandan; Hu, Zheng; Li, Ruijun; He, Qun

    2011-02-28

    In this work, the immobilization of 4-aminoantipyrine onto bentonite was carried out and it was then used to investigate the adsorption behavior of Cr(III), Hg(II) and Pb(II) ions from aqueous solutions. The separation and preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the interfering ions. Under optimum pH value (pH 4.0), the maximum static adsorption capacity of the sorbent was found to be 38.8, 52.9 and 55.5 mg g(-1) for Cr(III), Hg(II) and Pb(II), respectively. 2.0 mL of 2% thiourea in 1.0 M HCl solution effectively eluted the adsorbed metal ions. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.09 and 0.23 ng mL(-1) for Cr(III), Hg(II) and Pb(II), respectively. The relative standard deviation (RSD) was lower 3.0% (n=8). The developed method has been validated by analyzing certified reference materials and successfully applied to the determination of trace Cr(III), Hg(II) and Pb(II) in water samples with satisfactory results.

  4. Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: Adsorption capacity, kinetic and isotherm studies

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Chen, Jianhua; Zhang, Xueliang; Chen, Yiping

    2014-02-01

    Activated carbons with high mesoporosity and abundant oxygen-containing functional groups were prepared from water hyacinth using H3PO4 activation (WHAC) to eliminate Pb(II) in water. Characterizations of the WHAC were performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The BET analysis showed that WHAC possesses a high mesoporosity (93.9%) with a BET surface area of 423.6 m2/g. The presence of oxygen-containing functional groups including hydroxyl, carbonyl, carboxyl and phosphate groups renders the WHAC a favorable adsorbent for Pb(II) with the maximum monolayer capacity (qm) 118.8 mg/g. The adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm. The desorption study demonstrated that the WHAC could be readily regenerated using 0.1 M HCl (pH = 1.0). The desorbed WHAC could be reused at least six times without significant adsorption capacity reduction. The adsorption process was spontaneous and endothermic with ΔG (-0.27, -1.13, -3.02, -3.62, -5.54, and -9.31 kJ/mol) and ΔH (38.72 kJ/mol). Under the optimized conditions, a small amount of the adsorbent (1.0 g/L) could remove as much as 90.1% of Pb(II) (50 mg/L) in 20 min at pH 6.0 and temperature of 298 K. Therefore, the WHAC has a great potential to be an economical and efficient adsorbent in the treatment of lead-contaminated water.

  5. High gas storage capacities and stepwise adsorption in a UiO type metal-organic framework incorporating Lewis basic bipyridyl sites.

    PubMed

    Li, Liangjun; Tang, Sifu; Wang, Chao; Lv, Xiaoxia; Jiang, Min; Wu, Huaizhi; Zhao, Xuebo

    2014-03-04

    A UiO type MOF with Lewis basic bipyridyl sites was synthesized and structurally characterized. After being activated by Soxhlet-extraction, this MOF exhibits high storage capacities for H2, CH4 and CO2, and shows unusual stepwise adsorption for liquid CO2 and solvents, indicating a sequential filling mechanism on different adsorption sites.

  6. Method and apparatus for sampling atmospheric mercury

    DOEpatents

    Trujillo, Patricio E.; Campbell, Evan E.; Eutsler, Bernard C.

    1976-01-20

    A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

  7. Simultaneous activation/sulfurization method for production of sulfurized activated carbons: characterization and Hg(II) adsorption capacity.

    PubMed

    Shamsijazeyi, Hadi; Kaghazchi, Tahereh

    2014-01-01

    As an inexpensive method for modification of activated carbons (ACs), sulfurization has attracted significant attention. However, the resulting sulfurized activated carbons (SACs) often are less porous than the original ACs. In this work, we propose a new method for concurrent sulfurization/activation that can lead to preparation of SACs with more porosity than the corresponding non-sulfurized ACs. By using scanning electron microscopy, nitrogen adsorption/desorption, and iodine number experiments, the porous structure of the SACs has been compared with that of non-sulfurized ACs. The specific surface areas of SACs are higher than the corresponding ACs, regardless of the type of activation agents used. For instance, the specific surface area of SAC and AC activated with phosphoric acid is 1,637 and 1,338 m(2)/g, respectively. Additionally, sulfur contents and surface charges (pHpzc) of the SACs and non-sulfurized ACs are compared. In fact, the SACs have higher sulfur contents and more acidic surfaces. Furthermore, the Hg(II) adsorption capacity of SACs has been compared with the corresponding non-sulfurized ACs. The Hg(II) adsorption isotherms on a selected SAC is measured at different pH values and temperatures. Hg(II) adsorptions as high as 293 mg/g are observed by using SACs prepared by the method proposed in this study.

  8. Effects of Igneous Intrusion on Microporosity and Gas Adsorption Capacity of Coals in the Haizi Mine, China

    PubMed Central

    2014-01-01

    This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (Ro) increased from 2.30% to 2.78%, forming devolatilization vacuoles and a fine mosaic texture. Volatile matter (VM) decreased from 17.6% to 10.0% and the moisture decreased from 3.0% to 1.6%. With decreasing distance to the sill, the micropore volumes initially increased from 0.0054 cm3/g to a maximum of 0.0146 cm3/g and then decreased to 0.0079 cm3/g. The results show that the thermal evolution of the sill obviously changed the coal geochemistry and increased the micropore volume and adsorption capacity of heat-affected coal (60–160 m from the sill) compared with the unaltered coals. The trap effect of the sill prevented the high-pressure gas from being released, forming gas pocket. Mining activities near the sill created a low pressure zone leading to the rapid accumulation of methane and gas outbursts in the Haizi Mine. PMID:24723841

  9. Effects of igneous intrusion on microporosity and gas adsorption capacity of coals in the Haizi Mine, China.

    PubMed

    Jiang, Jingyu; Cheng, Yuanping

    2014-01-01

    This paper describes the effects of igneous intrusions on pore structure and adsorption capacity of the Permian coals in the Huaibei Coalfield, China. Twelve coal samples were obtained at different distances from a ~120 m extremely thick sill. Comparisons were made between unaltered and heat-affected coals using geochemical data, pore-fracture characteristics, and adsorption properties. Thermal alteration occurs down to ~1.3 × sill thickness. Approaching the sill, the vitrinite reflectance (R(o)) increased from 2.30% to 2.78%, forming devolatilization vacuoles and a fine mosaic texture. Volatile matter (VM) decreased from 17.6% to 10.0% and the moisture decreased from 3.0% to 1.6%. With decreasing distance to the sill, the micropore volumes initially increased from 0.0054 cm(3)/g to a maximum of 0.0146 cm(3)/g and then decreased to 0.0079 cm(3)/g. The results show that the thermal evolution of the sill obviously changed the coal geochemistry and increased the micropore volume and adsorption capacity of heat-affected coal (60-160 m from the sill) compared with the unaltered coals. The trap effect of the sill prevented the high-pressure gas from being released, forming gas pocket. Mining activities near the sill created a low pressure zone leading to the rapid accumulation of methane and gas outbursts in the Haizi Mine.

  10. Development of dry control technology for emissions of mercury in flue gas

    SciTech Connect

    Huang, Hann S.; Wu, Jiann M.; Livengood, C.D.

    1995-06-01

    In flue gases from coal-combustion systems, mercury in either the elemental state or its chloride form (HgCl{sub 2}) can be predominant among all the possible mercury species present; this predominance largely depends on the chlorine-to-mercury ratio in the coal feeds. Conventional flue-gas cleanup technologies are moderately effective in controlling HgCl{sub 2} but are very poor at controlling elemental mercury. Experiments were conducted on the removal of elemental mercury vapor by means of a number of different types of sorbents, using a fixed-bed adsorption system. Of the four commercial activated carbons evaluated, the sulfur-treated carbon sample gives the best removal performance, with good mercury-sorption capacities. Promising removal results also have been obtained with low-cost minerals after chemical treatments. These inorganic sorbents could potentially be developed into a cost-effective alternative to activated carbons for mercury removal.

  11. Effect of the concentration of inherent mineral elements on the adsorption capacity of coconut shell-based activated carbons.

    PubMed

    Afrane, G; Achaw, Osei-Wusu

    2008-09-01

    Coconut shells of West Africa Tall, a local variety of the coconut species Cocos nucifera L., were taken from five different geographical locations in Ghana and examined for the presence and concentration levels of some selected mineral elements using atomic absorption spectrometer. Activated carbons were subsequently made from the shells by the physical method. The iodine adsorption characteristics of the activated carbons measured showed a definite relationship to the concentration levels of potassium and other mineral elements in the precursor shell. Samples with lower total minerals content recorded higher iodine numbers. It was observed that the origin of the shells was related to the concentration levels of the analyzed mineral elements in the shells, which in turn affected the adsorption capacity of the activated carbons. The results of this study have important implications for the sourcing of coconuts whose shells are used in the manufacture of activated carbons.

  12. Effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing yellow zein.

    PubMed

    Sessa, D J; Palmquist, D E

    2008-09-01

    The Freundlich model was evaluated for use to assess the effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing corn zein. Because zein protein and its color/odor components are all adsorbed by activated carbon, a method to monitor their removal was needed. Yellow color is due to xanthophylls; a contributor to off-odor is diferuloylputrescine. The off-odor component absorbs ultraviolet (UV) light at about 325 nm and its removal coincides with removal of yellow color. A spectrophotometric method based on UV absorbances 280 nm for protein and 325 nm for the off-odor component was used to monitor their adsorptions onto activated carbon. Equilibrium studies were performed over temperature range from 25 to 60 degrees C for zein dissolved in 70% aqueous ethanol. Runs made at 55 degrees C adsorbed significantly more of the color/odor components than the protein.

  13. KINETIC STUDY OF ADSORPTION AND TRANSFORMATION OF MERCURY ON FLY ASH PARTICLES IN AN ENTRAINED FLOW REACTOR

    EPA Science Inventory

    Experimental studies were performed to investigate the interactions of elemental mercury vapor with entrained fly ash particles from coal combustion in a flow reactor. The rate of transformation of elemental mercury on fly ash particles was evauated over the temperature range fro...

  14. 2,4-D adsorption to biochars: effect of preparation conditions on equilibrium adsorption capacity and comparison with commercial activated carbon literature data.

    PubMed

    Kearns, J P; Wellborn, L S; Summers, R S; Knappe, D R U

    2014-10-01

    Batch isotherm experiments were conducted with chars to study adsorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Chars generated from corncobs, bamboo and wood chips in a laboratory pyrolyzer at 400-700 °C were compared with traditional kiln charcoals collected from villages in S/SE Asia and with activated carbons (ACs). 2,4-D uptake by laboratory chars obtained from bamboo and wood chips after 14 h of pyrolysis at 700 °C, from wood chips after 96 h of pyrolysis at 600 °C, and one of the field-collected chars (basudha) was comparable to ACs. H:C and O:C ratios declined with pyrolysis temperature and duration while surface area increased to >500 m(2)/g. Increasing pyrolysis intensity by increasing temperature and/or duration of heating was found to positively influence adsorption capacity yield (mg(2,4-D/g(feedstock))) over the range of conditions studied. Economic analysis showed that high temperature chars can be a cost-effective alternative to ACs for water treatment applications.

  15. Fate and aqueous transport of mercury in light of the Clean Air Mercury Rule for coal-fired electric power plants

    NASA Astrophysics Data System (ADS)

    Arzuman, Anry

    Mercury is a hazardous air pollutant emitted to the atmosphere in large amounts. Mercury emissions from electric power generation sources were estimated to be 48 metric tons/year, constituting the single largest anthropogenic source of mercury in the U.S. Settled mercury species are highly toxic contaminants of the environment. The newly issued Federal Clean Air Mercury Rule requires that the electric power plants firing coal meet the new Maximum Achievable Mercury Control Technology limit by 2018. This signifies that all of the air-phase mercury will be concentrated in solid phase which, based on the current state of the Air Pollution Control Technology, will be fly ash. Fly ash is utilized by different industries including construction industry in concrete, its products, road bases, structural fills, monifills, for solidification, stabilization, etc. Since the increase in coal combustion in the U.S. (1.6 percent/year) is much higher than the fly ash demand, large amounts of fly ash containing mercury and other trace elements are expected to accumulate in the next decades. The amount of mercury transferred from one phase to another is not a linear function of coal combustion or ash production, depends on the future states of technology, and is unknown. The amount of aqueous mercury as a function of the future removal, mercury speciation, and coal and aquifer characteristics is also unknown. This paper makes a first attempt to relate mercury concentrations in coal, flue gas, fly ash, and fly ash leachate using a single algorithm. Mercury concentrations in all phases were examined and phase transformation algorithms were derived in a form suitable for probabilistic analyses. Such important parameters used in the transformation algorithms as Soil Cation Exchange Capacity for mercury, soil mercury selectivity sequence, mercury activity coefficient, mercury retardation factor, mercury species soil adsorption ratio, and mercury Freundlich soil adsorption isotherm

  16. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR ORGANIC CONTAMINANTS FROM ADSORBENT AND ADSORBATE PROPERTIES

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  17. Separation of mercury from aqueous mercuric chloride solutions by onion skins

    SciTech Connect

    Asai, S.; Konishi, Y.; Tomisaki, H.; Nakanishi, M.

    1986-01-01

    The separation of mercury from aqueous HgCl/sub 2/ solutions by onion skins (outermost coat) was studied both experimentally and theoretically. The distribution equilibria were measured by the batchwise method. The experimental results revealed that onion skin is a useful material for separating mercury from aqueous systems. The distribution data obtained at 25/sup 0/C were analyzed by using the theory based on the law of mass action. The separation of dissolved mercury by onion skins was found to be a process accompanied by an ion-exchange reaction of the cationic complex HgCl/sup +/ and an adsorption of the neutral complex HgCl/sub 2/. The equilibrium constants of the ion-exchange and adsorption processes at 25/sup 0/C and the mercury-binding capacity of onion skins were determined. Further, it was found that the distribution equilibrium of mercury is comparatively insensitive to temperature.

  18. Properties of poly(1-naphthylamine)/Fe3O4 composites and arsenic adsorption capacity in wastewater

    NASA Astrophysics Data System (ADS)

    Tran, Minh Thi; Nguyen, Thi Huyen Trang; Vu, Quoc Trung; Nguyen, Minh Vuong

    2016-03-01

    The research results of poly(1-naphthylamine)/Fe3O4 (PNA/Fe3O4) nanocomposites synthesized by a chemical method for As(III) wastewater treatment are presented in this paper. XRD patterns and TEM images showed that the Fe3O4 grain size varied from 13 to 20 nm. The results of Raman spectral analysis showed that PNA participated in part of the PNA/Fe3O4 composite samples. The grain size of PNA/Fe3O4 composite samples is about 25-30 nm measured by SEM. The results of vibrating sample magnetometer measurements at room temperature showed that the saturation magnetic moment of PNA/Fe3O4 samples decreased from 63.13 to 43.43 emu/g, while the PNA concentration increased from 5% to 15%. The nitrogen adsorption-desorption isotherm of samples at 77 K at a relative pressure P/ P 0 of about 1 was studied in order to investigate the surface and porous structure of nanoparticles by the BET method. Although the saturation magnetic moments of samples decreased with the polymer concentration increase, the arsenic adsorption capacity of the PNA/Fe3O4 sample with the PNA concentration of 5% is better than that of Fe3O4 in a solution with pH = 7. In the solution with pH > 14, the arsenic adsorption of magnetic nanoparticles is insignificant.

  19. Hyperbranched-polyol-tethered poly (amic acid) electrospun nanofiber membrane with ultrahigh adsorption capacity for boron removal

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Wu, Zhongyu; Zhang, Yufeng; Meng, Jianqiang

    2017-04-01

    The development of efficient adsorbents with high sorption capacity remains as a challenge for the removal of micropollutants occurred globally in water resources. In this work, poly (amic acid) (PAA) electrospun nanofiber membranes grafted with hyperbranched polyols were synthesized and used for boron removal. The PAA nanofiber was reacted with hyperbranched polyethylenimine (HPEI) and further with glycidol to introduce the vicinal hydroxyl groups. The chemical composition and surface characteristics of the obtained PAA-g-PG membranes were evaluated by FESEM, FTIR, XPS and water contact angles (WCA) measurements. The boron adsorption thermodynamics and kinetics were investigated systematically. The results showed that the PAA nanofiber spun from concentration of 15% had uniform morphology and narrow diameter distribution. The PAA-g-PG nanofiber membrane had a maximum boron uptake of 5.68 mmol/g and could adsorb 0.82 mmol/g boron from a 5 mg/L solution in 15 min. Both the high surface area of nanofibers and the hyperbranched structure should contribute to the high boron uptake and high adsorption rate. The nanofiber membrane obeyed the Langmuir adsorption model and the pseudo-first-order kinetic model. The regeneration efficiency of the nanofiber membrane remained 93.9% after 10 cycled uses, indicating good regenerability of the membrane.

  20. Biochar characteristics produced from food-processing products and their sorptive capacity for mercury and phenanthrene

    NASA Astrophysics Data System (ADS)

    Fotopoulou, Kalliopi N.; Karapanagioti, Hrissi K.; Manariotis, Ioannis D.

    2015-04-01

    Various organic-rich wastes including wood chips, animal manure, and crop residues have been used for biochar production. Biochar is used as an additive to soils to sequester carbon and improve soil fertility but its use as a sorbent for environmental remediation processes is gaining increased attention. Surface properties such as point of zero charge, surface area and pore volume, surface topography, surface functional groups and acid-base behavior are important factors, which affect sorption efficiency. Understanding the surface alteration of biochars increases our understanding of the pollutant-sorbent interaction. The scope of the present work was to evaluate the effect of key characteristics of biochars on their sorptive properties. Raw materials for biochar production were evaluated including byproducts from brewering, coffee, wine, and olive oil industry. The charring process was performed at different temperatures under limited-oxygen conditions using specialized containers. The surface area, the pore volume, and the average pore size of the biochars were determined. Open surface area and micropore volume were determined using t-plot method and Harkins & Jura equation. Raw food-processing waste demonstrates low surface area that increases by 1 order of magnitude by thermal treatment up to 750oC. At temperatures from 750 up to 900oC, pyrolysis results to biochars with surface areas 210-700 m2/g. For the same temperature range, a high percentage (46 to73%) of the pore volume of the biochars is due to micropores. Positive results were obtained when high surface area biochars were tested for their ability to remove organic (i.e. phenanthrene) and inorganic (i.e. mercury) compounds from aqueous solutions. All these properties point to new materials that can effectively be used for environmental remediation.

  1. Evaluation of phosphorus adsorption capacity of sesame straw biochar on aqueous solution: influence of activation methods and pyrolysis temperatures.

    PubMed

    Park, J H; Ok, Y S; Kim, S H; Cho, J S; Heo, J S; Delaune, R D; Seo, D C

    2015-12-01

    The phosphorus (P) adsorption characteristic of sesame straw biochar prepared with different activation agents and pyrolysis temperatures was evaluated. Between 0.109 and 0.300 mg L(-1) in the form of inorganic phosphate was released from raw sesame straw biochar in the first 1 h. The release of phosphate was significantly enhanced from 62.6 to 168.2 mg g(-1) as the pyrolysis temperature increased. Therefore, sesame straw biochar cannot be used as an adsorbent for P removal without change in the physicochemical characteristics. To increase the P adsorption of biochar in aqueous solution, various activation agents and pyrolysis temperatures were applied. The amount of P adsorbed from aqueous solution by biochar activated using different activation agents appeared in the order ZnCl2 (9.675 mg g(-1)) > MgO (8.669 mg g(-1)) ⋙ 0.1N-HCl > 0.1N-H2SO4 > K2SO4 ≥ KOH ≥ 0.1N-H3PO4, showing ZnCl2 to be the optimum activation agent. Higher P was adsorbed by the biochar activated using ZnCl2 under different pyrolysis temperatures in the order 600 °C > 500 °C > 400 °C > 300 °C. Finally, the amount of adsorbed P by activated biochar at different ratios of biochar to ZnCl2 appeared in the order 1:3 ≒ 1:1 > 3:1. As a result, the optimum ratio of biochar to ZnCl2 and pyrolysis temperature were found to be 1:1 and 600 °C for P adsorption, respectively. The maximum P adsorption capacity by activated biochar using ZnCl2 (15,460 mg kg(-1)) was higher than that of typical biochar, as determined by the Langmuir adsorption isotherm. Therefore, the ZnCl2 activation of sesame straw biochar was suitable for the preparation of activated biochar for P adsorption.

  2. Synthesis, characterisation and methyl orange adsorption capacity of ferric oxide-biochar nano-composites derived from pulp and paper sludge

    NASA Astrophysics Data System (ADS)

    Chaukura, Nhamo; Murimba, Edna C.; Gwenzi, Willis

    2016-02-01

    A Fe2O3-biochar nano-composite (Fe2O3-BC) was prepared from FeCl3-impregnated pulp and paper sludge (PPS) by pyrolysis at 750 °C. The characteristics and methyl orange (MO) adsorption capacity of Fe2O3-BC were compared to that of unactivated biochar (BC). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the composite material was nano-sized. Fourier transform infrared (FTIR) spectroscopy revealed the presence of hydroxyl and aromatic groups on BC and on Fe2O3-BC, but Brunauer-Emmett-Teller (BET) surface area and Barrett-Joyner-Halenda (BJH) porosity were lower for Fe2O3-BC than BC. Despite the lower BET surface area and porosity of Fe2O3-BC, its MO adsorption capacity was 52.79 % higher than that of BC. The equilibrium adsorption data were best represented by the Freundlich model with a maximum adsorption capacity of 20.53 mg g-1 at pH 8 and 30 min contact time. MO adsorption obeyed pseudo-second-order kinetics for both BC and Fe2O3-BC with R 2 values of 0.996 and 0.999, respectively. Higher MO adsorption capacity for Fe2O3-BC was attributed to the hybrid nature of the nano-composites; adsorption occurred on both biochar matrix and Fe2O3 nanocrystals. Gibbs free energy calculations confirmed the adsorption is energetically favourable and spontaneous with a high preference for adsorption on both adsorbents. The nano-composite can be used for the efficient removal of MO (>97 %) from contaminated wastewater.

  3. Synthesis of bilayer MoS{sub 2} nanosheets by a facile hydrothermal method and their methyl orange adsorption capacity

    SciTech Connect

    Ye, Lijuan; Xu, Haiyan; Zhang, Dingke; Chen, Shijian

    2014-07-01

    Highlights: • Hexagonal phase of MoS{sub 2} nanosheets was synthesized by a facile hydrothermal method. • FE-SEM and TEM images show the sheets-like morphology of MoS{sub 2}. • Bilayer MoS{sub 2} can be grown under the optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. • The MoS{sub 2} nanosheets possess high methyl orange adsorption capacity due to the large surface area. - Abstract: Molybdenum disulfide (MoS{sub 2}) nanosheets have received significant attention recently due to the potential applications for exciting physics and technology. Here we show that MoS{sub 2} nanosheets can be prepared by a facile hydrothermal method. The study of the properties of the MoS{sub 2} nanosheets prepared at different conditions suggests that the mole ratio of precursors and hydrothermal time significantly influences the purity, crystalline quality and thermal stability of MoS{sub 2}. X-ray diffraction, Raman spectra and transmission electron microscopy results indicate that bilayer MoS{sub 2} can be grown under an optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. Moreover, such ultrathin nanosheets exhibit a prominent photoluminescence and possess high methyl orange adsorption capacity due to the large surface area, which can be potentially used in photodevice and photochemical catalyst.

  4. Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps.

    PubMed

    Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K; Ong, Ta-Chung; Keeler, Eric G; Kim, Hyunho; McKay, Ian S; Griffin, Robert G; Wang, Evelyn N

    2015-01-01

    Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg(2+) ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, (27)Al/(29)Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2(nd) law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications.

  5. Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps

    PubMed Central

    Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K.; Ong, Ta-Chung; Keeler, Eric G.; Kim, Hyunho; McKay, Ian S.; Griffin, Robert G.; Wang, Evelyn N.

    2014-01-01

    Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N2 sorption, 27Al/29Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick’s 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. PMID:25395877

  6. Zeolite Y adsorbents with high vapor uptake capacity and robust cycling stability for potential applications in advanced adsorption heat pumps

    SciTech Connect

    Li, XS; Narayanan, S; Michaelis, VK; Ong, TC; Keeler, EG; Kim, H; Mckay, IS; Griffin, RG; Wang, EN

    2015-01-01

    Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg, Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the lab-scale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N-2 sorption, Al-27/Si-29 MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H2O and N-2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications. (C) 2014 Elsevier Inc. All rights reserved.

  7. Determination of coalbed methane potential and gas adsorption capacity in Western Kentucky coals

    USGS Publications Warehouse

    Mardon, S.M.; Takacs, K.G.; Hower, J.C.; Eble, C.F.; Mastalerz, Maria

    2006-01-01

    The Illinois Basin has not been developed for Coalbed Methane (CBM) production. It is imperative to determine both gas content and other parameters for the Kentucky portion of the Illinois Basin if exploration is to progress and production is to occur in this area. This research is part of a larger project being conducted by the Kentucky Geological Survey to evaluate the CBM production of Pennsylvanian-age western Kentucky coals in Ohio, Webster, and Union counties using methane adsorption isotherms, direct gas desorption measurements, and chemical analyses of coal and gas. This research will investigate relationships between CBM potential and petrographic, surface area, pore size, and gas adsorption isotherm analyses of the coals. Maceral and reflectance analyses are being conducted at the Center for Applied Energy Research. At the Indiana Geological Survey, the surface area and pore size of the coals will be analyzed using a Micrometrics ASAP 2020, and the CO2 isotherm analyses will be conducted using a volumetric adsorption apparatus in a water temperature bath. The aforementioned analyses will be used to determine site specific correlations for the Kentucky part of the Illinois Basin. The data collected will be compared with previous work in the Illinois Basin and will be correlated with data and structural features in the basin. Gas composition and carbon and hydrogen isotopic data suggest mostly thermogenic origin of coalbed gas in coals from Webster and Union Counties, Kentucky, in contrast to the dominantly biogenic character of coalbed gas in Ohio County, Kentucky.

  8. Superfine powdered activated carbon incorporated into electrospun polystyrene fibers preserve adsorption capacity.

    PubMed

    Apul, Onur G; Hoogesteijn von Reitzenstein, Natalia; Schoepf, Jared; Ladner, David; Hristovski, Kiril D; Westerhoff, Paul

    2017-03-17

    A composite material consisted of superfine powdered activated carbon (SPAC) and fibrous polystyrene (PS) was fabricated for the first time by electrospinning. SPAC is produced by pulverizing powdered activated carbon. The diameter of SPAC (100-400nm) is more than one hundred times smaller than conventional powdered activated carbon, but it maintains the internal pore structure based on organic micropollutant adsorption isotherms and specific surface area measurements. Co-spinning SPAC into PS fibers increased specific surface area from 6m(2)/g to 43m(2)/g. Unlike metal oxide nanoparticles, which are non-accessible for sorption from solution, electrospinning with SPAC created porous fibers. Composite SPAC-PS electrospun fibers, containing only 10% SPAC, had 30% greater phenanthrene sorption compared against PS fibers alone. SPAC particles embedded within the polymer were either partially or fully incorporated, and the accessibility of terminal adsorption sites were conserved. Conserving the adsorptive functionality of SPAC particles in electrospun non-woven polymeric fiber scaffolding can enable their application in environmental applications such as drinking water treatment.

  9. Removal of mercury species with dithiocarbamate-anchored polymer/organosmectite composites.

    PubMed

    Say, Ridvan; Birlik, Ebru; Erdemgil, Zerrin; Denizli, Adil; Ersöz, Arzu

    2008-02-11

    Mercury is one of the most toxic heavy metals found in solid and liquid waste disposed by chloro-alkali, paint, paper/pulp, battery, pharmaceutical, oil refinery and mining companies. Any form of mercury introduced to nature through any means is converted into a more toxic form such as methylmercury chloride (as produced by aquatic organisms) which usually accumulates in the tissue of fish and birds. The primary aim of this study was to investigate performance of dithiocarbamate-anchored polymer/organosmectite composites as sorbents for removal of mercury from aqueous solution. The modified smectite nanocomposites then were reacted with carbondisulfide to incorporate dithiocarbamate functional groups into the nanolayer of the organoclay. These dithiocarbamate-anchored composites were used for the removal of mercury species [Hg(II), CH(3)Hg(I) and C(6)H(5)Hg(I)]. Mercury adsorption was found to be dependent on the solution pH, mercury concentration and the type of mercury species to be adsorbed. The maximum adsorption capacities were equal to 157.3 mg g(-1) (782.5 micromol g(-1)) for Hg(II); 214.6 mg g(-1) (993.9 micromol g(-1)) for CH(3)Hg(I); 90.3 mg g(-1) (325 micromol g(-1)) for C(6)H(5)Hg(I). The competitive adsorption capacities (i.e. adsorption capacities based on solutions containing all three mercuric ions) are 7.7 mg g(-l) (38.3 micromol g(-1)), 9.2 mg g(-l) (42.6 micromol g(-1)) and 12.7 mg g(-1) (45.7 micromol g(-1)) for Hg(II), CH(3)Hg(I) and C(6)H(5)Hg(I), respectively, at 10 ppm initial concentration. The adsorption capacities on molar basis were in order of C(6)H(5)Hg(I)>CH(3)Hg(I)>Hg(II).

  10. Enhancing gas adsorption and separation capacity through ligand functionalization of microporous metal-organic framework structures.

    PubMed

    Zhao, Yonggang; Wu, Haohan; Emge, Thomas J; Gong, Qihan; Nijem, Nour; Chabal, Yves J; Kong, Lingzhu; Langreth, David C; Liu, Hui; Zeng, Heping; Li, Jing

    2011-04-26

    Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials.

  11. Mercury Emission and Removal of a 135MW CFB Utility Boiler

    NASA Astrophysics Data System (ADS)

    Duan, Y. F.; Zhuo, Y. Q.; Wang, Y. J.; Zhang, L.; Yang, L. G.; Zhao, C. S.

    To evaluate characteristic of the mercury emission and removal from a circulating fluidized bed (CFB) boiler, a representative 135 MW CFB utility boiler was selected to take the onsite measurement of mercury concentrations in feeding coal, bottom ash, fly ash and flue gas using the US EPA recommended Ontario Hydro Method (OHM). The results show that particulate mercury is of majority in flue gas of the CFB boiler. Mercury removal rate of the electrostatic precipitator (ESP) reaches 98%. Mercury emission concentration in stack is only 0.062μg/Nm3, and the mass proportion of mercury in bottom ash is less than 1%. It was found that the fly ashes were highly adsorptive to flue gas mercury because of its higher unburned carbon content. Adsorption effect is related to carbon pore structural properties of fly ash and temperature of flue gas. However mercury adsorption capacity by fly ash can not be improved any more when unburned carbon content in fly ash increases further.

  12. Effect of carboxyethylation degree on the adsorption capacity of Cu(II) by N-(2-carboxyethyl)chitosan from squid pens.

    PubMed

    Huang, Jun; Xie, Haihua; Ye, Hui; Xie, Tian; Lin, Yuecheng; Gong, Jinyan; Jiang, Chengjun; Wu, Yuanfeng; Liu, Shiwang; Cui, Yanli; Mao, Jianwei; Mei, Lehe

    2016-03-15

    Chitosan was prepared by N-deacetylation of squid pens β-chitin, and N-carboxyethylated chitosan (N-CECS) with different degrees of substitution (DS) were synthesized. DS values of N-CECS derivatives calculated by (1)H nuclear magnetic resonance (NMR) spectroscopy were 0.60, 1.02 and 1.46, respectively. The adsorption capacity of Cu(II) by N-CECS correlated well with the DS and pH ranging from 3.2 to 5.8. The maximum Cu(II) adsorption capacity (qm) of all three N-CECS at pH 5.4 was 207.5mg g(-1), which was 1.4-fold higher than that of chitosan. The adsorption equilibrium process was better described by the Langmuir than Freundlich isotherm model. Adsorption of Cu(II) ion onto N-CECS followed a pseudo-second order mechanism with chemisorption as the rate-limiting step. In a ternary adsorption system, the adsorption capacity of Cu(II) by N-CECS also presented high values, and qm for Cu(II), Cd(II), and Pb(II) were 150.2, 28.8, and 187.9mg g(-1), respectively.

  13. One-step synthesis of a novel N-doped microporous biochar derived from crop straws with high dye adsorption capacity.

    PubMed

    Lian, Fei; Cui, Guannan; Liu, Zhongqi; Duo, Lian; Zhang, Guilong; Xing, Baoshan

    2016-07-01

    N-doping is one of the most promising strategies to improve the adsorption capacity and selectivity of carbon adsorbents. Herein, synthesis, characterization and dye adsorption of a novel N-doped microporous biochar derived from direct annealing of crop straws under NH3 is presented. The resultant products exhibit high microporosity (71.5%), atomic percentage of nitrogen (8.81%), and adsorption capacity to dyes, which is about 15-20 times higher than that of original biochar. Specifically, for the sample NBC800-3 pyrolyzed at 800°C in NH3 for 3 h, its adsorption for acid orange 7 (AO7, anionic) and methyl blue (MB, cationic) is up to 292 mg g(-1) and 436 mg g(-1), respectively, which is among the highest ever reported for carbonaceous adsorbents. The influences of N-doping and porous structure on dye adsorption of the synthesized carbons are also discussed, where electrostatic attraction, π-π electron donor-accepter interaction, and Lewis acid-base interaction mainly contribute to AO7 adsorption, and surface area (especially pore-filling) dominates MB adsorption. The N-doped biochar can be effectively regenerated and reused through direct combustion and desorption approaches.

  14. The Relative Influence of Turbulence and Turbulent Mixing on the Adsorption of Mercury within a Gas-Sorbent Suspension

    EPA Science Inventory

    Our previous investigations demonstrated that entrained flow or in-flight adsorption can be a more effective and flexible approach to trace gas adsorption than fixed sorbent beds. The present investigation establishes the turbulent mixing that accompanies sorbent injection is an ...

  15. Preparation and evaluation of coal-derived activated carbons for removal of mercury vapor from simulated coal combustion flue fases

    USGS Publications Warehouse

    Hsi, H.-C.; Chen, S.; Rostam-Abadi, M.; Rood, M.J.; Richardson, C.F.; Carey, T.R.; Chang, R.

    1998-01-01

    Coal-derived activated carbons (CDACs) were tested for their suitability in removing trace amounts of vapor-phase mercury from simulated flue gases generated by coal combustion. CDACs were prepared in bench-scale and pilot-scale fluidized-bed reactors with a three-step process, including coal preoxidation, carbonization, and then steam activation. CDACs from high-organicsulfur Illinois coals had a greater equilibrium Hg0 adsorption capacity than activated carbons prepared from a low-organic-sulfur Illinois coal. When a low-organic-sulfur CDAC was impregnated with elemental sulfur at 600 ??C, its equilibrium Hg0 adsorption capacity was comparable to the adsorption capacity of the activated carbon prepared from the high-organicsulfur coal. X-ray diffraction and sulfur K-edge X-ray absorption near-edge structure examinations showed that the sulfur in the CDACs was mainly in organic forms. These results suggested that a portion of the inherent organic sulfur in the starting coal, which remained in the CDACs, played an important role in adsorption of Hg0. Besides organic sulfur, the BET surface area and micropore area of the CDACs also influenced Hg0 adsorption capacity. The HgCl2 adsorption capacity was not as dependent on the surface area and concentration of sulfur in the CDACs as was adsorption of Hg0. The properties and mercury adsorption capacities of the CDACs were compared with those obtained for commercial Darco FGD carbon.

  16. Effects of Dendropanax morbifera Léveille extracts on cadmium and mercury secretion as well as oxidative capacity: A randomized, double-blind, placebo-controlled trial

    PubMed Central

    SEO, JAE SAM; YOO, DAE YOUNG; JUNG, HYO YOUNG; KIM, DONG-WOO; HWANG, IN KOO; LEE, JONG YOUNG; MOON, SEUNG MYUNG

    2016-01-01

    In this randomized, double-blind, placebo controlled clinical trial, the effects of Dendropanax morbifera (D. morbifera) Léveille on heavy metal (cadmium and mercury) excretion as well as on lipid peroxidation and Cu, Zn-superoxide dismutase (SOD1) activity were investigated. For this study, tablets containing placebo or 300 mg of the leaf extract from D. morbifera Léveille were used. A total of 60 eligible healthy subjects were enrolled in this randomized, double-blind, placebo-controlled study. The differences in cadmium, mercury, and malondialdehyde (MDA) levels and SOD1 activity were measured in the serum 60 days after treatment with placebo or D. morbifera Léveille extracts. No significant differences between baseline characteristics and biochemical values were identified in subjects in the placebo and D. morbifera Léveille groups. Serum levels of cadmium, mercury and MDA decreased following consumption of D. morbifera Léveille extracts; however, no significant differences were identified. In addition, female, but not male, subjects who consumed D. morbifera Léveille extracts showed a significant increase in SOD1 activity. This result suggests that chronic consumption of D. morbifera Léveille extract can help to facilitate excretion of cadmium and mercury from serum and increase the antioxidant capacity in humans. PMID:27123258

  17. Effects of Dendropanax morbifera Léveille extracts on cadmium and mercury secretion as well as oxidative capacity: A randomized, double-blind, placebo-controlled trial.

    PubMed

    Seo, Jae Sam; Yoo, Dae Young; Jung, Hyo Young; Kim, Dong-Woo; Hwang, In Koo; Lee, Jong Young; Moon, Seung Myung

    2016-05-01

    In this randomized, double-blind, placebo controlled clinical trial, the effects of Dendropanax morbifera (D. morbifera) Léveille on heavy metal (cadmium and mercury) excretion as well as on lipid peroxidation and Cu, Zn-superoxide dismutase (SOD1) activity were investigated. For this study, tablets containing placebo or 300 mg of the leaf extract from D. morbifera Léveille were used. A total of 60 eligible healthy subjects were enrolled in this randomized, double-blind, placebo-controlled study. The differences in cadmium, mercury, and malondialdehyde (MDA) levels and SOD1 activity were measured in the serum 60 days after treatment with placebo or D. morbifera Léveille extracts. No significant differences between baseline characteristics and biochemical values were identified in subjects in the placebo and D. morbifera Léveille groups. Serum levels of cadmium, mercury and MDA decreased following consumption of D. morbifera Léveille extracts; however, no significant differences were identified. In addition, female, but not male, subjects who consumed D. morbifera Léveille extracts showed a significant increase in SOD1 activity. This result suggests that chronic consumption of D. morbifera Léveille extract can help to facilitate excretion of cadmium and mercury from serum and increase the antioxidant capacity in humans.

  18. Facile synthesis of hydroxy-modified MOF-5 for improving the adsorption capacity of hydrogen by lithium doping.

    PubMed

    Kubo, Masaru; Hagi, Hayato; Shimojima, Atsushi; Okubo, Tatsuya

    2013-11-01

    A facile synthesis of partially hydroxy-modified MOF-5 and its improved H2-adsorption capacity by lithium doping are reported. The reaction of Zn(NO3)2·6H2O with a mixture of terephthalic acid (H2BDC) and 2-hydroxyterephthalic acid (H2BDC-OH) in DMF gave hydroxy-modified MOF-5 (MOF-5-OH-x), in which the molar fraction (x) of BDC-OH(2-) was up to 0.54 of the whole ligand. The MOF-5-OH-x frameworks had high BET surface areas (about 3300 m(2) g(-1)), which were comparable to that of MOF-5. We suggest that the MOF-5-OH-x frameworks are formed by the secondary growth of BDC(2-)-rich MOF-5 seed crystals, which are nucleated during the early stage of the reaction. Subsequent Li doping into MOF-5-OH-x results in increased H2 uptake at 77 K and 0.1 MPa from 1.23 to 1.39 wt.% and an increased isosteric heat of H2 adsorption from 5.1-4.2 kJ mol(-1) to 5.5-4.4 kJ mol(-1).

  19. Separation of complexed mercury from aqueous wastes using self-assembled mercaptan on mesoporous silica

    SciTech Connect

    Mattigod, S.V.; Feng, X.; Fryxell, G.E.; Liu, J.; Gong, M.

    1999-09-01

    Separation of Hg(II) from potassium iodide/sulfate wastes was studied using a novel mesoporous silica material containing self-assembled mercaptan groups. The adsorbent, consisting of self-assembled mercaptan on mesoporous silica (SAMMS) developed at Pacific Northwest National Laboratory (PNNL), was characterized as to its specificity, adsorption capacity, and kinetics for separation of mercury from potassium iodide/sulfate solutions. Aqueous speciation calculations indicated that a major fraction (92--99%) of dissolved mercury in the potassium iodide/sulfate wastes solutions existed as HgI{sub 4}{sup 2{minus}} species. The adsorption data showed that the mercury adsorption capacity of SAMMS material increased with decreasing iodide concentrations. The magnitude of calculated free energy of adsorption indicated that mercury adsorption on this adsorbent is typical of soft acid-soft base interactions. High specificity for anionic complexes of Hg(II) by the SAMMS material was confirmed by distribution coefficient measurements. The kinetics data indicated that the adsorption reactions occur very rapidly independent of Hg(II) concentrations and pH. These tests confirmed that SAMMS material can very effectively remove strongly complexed Hg(II) from aqueous wastes.

  20. MOF-derived ZnO and ZnO@C composites with high photocatalytic activity and adsorption capacity.

    PubMed

    Yang, Seung Jae; Im, Ji Hyuk; Kim, Taehoon; Lee, Kunsil; Park, Chong Rae

    2011-02-15

    Nanostructured ZnO materials have unique and highly attractive properties and have inspired interest in their research and development. This paper presents a facile method for the preparation of novel ZnO-based nanostructured architectures using a metal organic framework (MOF) as a precursor. In this approach, ZnO nanoparticles and ZnO@C hybrid composites were produced under several heating and atmospheric (air or nitrogen) conditions. The resultant ZnO nanoparticles formed hierarchical aggregates with a three-dimensional cubic morphology, whereas ZnO@C hybrid composites consisted of faceted ZnO crystals embedded within a highly porous carbonaceous species, as determined by several characterization methods. The newly synthesized nanomaterials showed relatively high photocatalytic decomposition activity and significantly enhanced adsorption capacities for organic pollutants.

  1. Novel regenerable sorbent based on Zr-Mn binary metal oxides for flue gas mercury retention and recovery.

    PubMed

    Xie, Jiangkun; Qu, Zan; Yan, Naiqiang; Yang, Shijian; Chen, Wanmiao; Hu, Lingang; Huang, Wenjun; Liu, Ping

    2013-10-15

    To capture and recover mercury from coal-fired flue gas, a series of novel regenerable sorbents based on Zr-Mn binary metal oxides were prepared and employed at a relatively low temperature. PXRD, TEM, TPR, XPS, and N2-adsorption methods were employed to characterize the sorbents. The Hg(0) adsorption performance of the sorbents was tested, and the effects of the main operation parameters and the gas components on the adsorption were investigated. Zr significantly improved the sorbent's mercury capacity, which was nearly 5mg/g for Zr0.5Mn0.5Oy. Furthermore, the spent sorbent could be regenerated by heating to 350°C, and the highly concentrated elemental mercury released could be facilely recycled. Therefore, a much greener process for mercury capture and recovery could be anticipated based on this regenerable sorbent.

  2. Trace vanadium analysis by catalytic adsorptive stripping voltammetry using mercury-coated micro-wire and polystyrene-coated bismuth film electrodes.

    PubMed

    Dansby-Sparks, Royce; Chambers, James Q; Xue, Zi-Ling

    2009-06-08

    An electrochemical technique has been developed for ultra-trace (ng L(-1)) vanadium (V) measurement. Catalytic adsorptive stripping voltammetry for V analysis was developed at mercury-coated gold micro-wire electrodes (MWEs, 100 microm) in the presence of gallic acid (GA) and bromate ion. A potential of -0.275 V (vs Ag/AgCl) was used to accumulate the complex in acetate buffer (pH 5.0) at the electrode surface followed by a differential pulse voltammetric scan. Parameters affecting the electrochemical response, including pH, concentration of GA and bromate, deposition potential and time have been optimized. Linear response was obtained in the 0-1000 ng L(-1) range (2 min deposition), with a detection limit of 0.88 ng L(-1). The method was validated by comparison of results for an unknown solution of V by atomic absorption measurement. The protocol was evaluated in a real sample by measuring the amount of V in river water samples. Thick bismuth film electrodes with protective polystyrene films have also been made and evaluated as a mercury free alternative. However, ng L(-1) level detection was only attainable with extended (10 min) deposition times. The proposed use of MWEs for the detection of V is sensitive enough for future use to test V concentration in biological fluids treated by the advanced oxidation process (AOP).

  3. Dendritic silica nanomaterials (KCC-1) with fibrous pore structure possess high DNA adsorption capacity and effectively deliver genes in vitro.

    PubMed

    Huang, Xiaoxi; Tao, Zhimin; Praskavich, John C; Goswami, Anandarup; Al-Sharab, Jafar F; Minko, Tamara; Polshettiwar, Vivek; Asefa, Tewodros

    2014-09-16

    The pore size and pore structure of nanoporous materials can affect the materials' physical properties, as well as potential applications in different areas, including catalysis, drug delivery, and biomolecular therapeutics. KCC-1, one of the newest members of silica nanomaterials, possesses fibrous, large pore, dendritic pore networks with wide pore entrances, large pore size distribution, spacious pore volume and large surface area--structural features that are conducive for adsorption and release of large guest molecules and biomacromolecules (e.g., proteins and DNAs). Here, we report the results of our comparative studies of adsorption of salmon DNA in a series of KCC-1-based nanomaterials that are functionalized with different organoamine groups on different parts of their surfaces (channel walls, external surfaces or both). For comparison the results of our studies of adsorption of salmon DNA in similarly functionalized, MCM-41 mesoporous silica nanomaterials with cylindrical pores, some of the most studied silica nanomaterials for drug/gene delivery, are also included. Our results indicate that, despite their relatively lower specific surface area, the KCC-1-based nanomaterials show high adsorption capacity for DNA than the corresponding MCM-41-based nanomaterials, most likely because of KCC-1's large pores, wide pore mouths, fibrous pore network, and thereby more accessible and amenable structure for DNA molecules to diffuse through. Conversely, the MCM-41-based nanomaterials adsorb much less DNA, presumably because their outer surfaces/cylindrical channel pore entrances can get blocked by the DNA molecules, making the inner parts of the materials inaccessible. Moreover, experiments involving fluorescent dye-tagged DNAs suggest that the amine-grafted KCC-1 materials are better suited for delivering the DNAs adsorbed on their surfaces into cellular environments than their MCM-41 counterparts. Finally, cellular toxicity tests show that the KCC-1-based

  4. Functionalized diatom silica microparticles for removal of mercury ions

    PubMed Central

    Yu, Yang; Addai-Mensah, Jonas; Losic, Dusan

    2012-01-01

    Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH2) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g−1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions. PMID:27877475

  5. Adsorption of 2,4,6-trinitrotoluene on carboxylated porous polystyrene microspheres

    NASA Astrophysics Data System (ADS)

    Ye, Zhengfang; Meng, Qingqiang; Lu, Shengtao

    2012-02-01

    Large-pore-size (150 nm) polystyrene (PSt) microspheres were carboxylated with phthalic anhydride (PA) through Friedel-Crafts acetylation to study the adsorption of 2,4,6-trinitrotoluene (TNT) on this material from aqueous solution. The scanning electron microscope (SEM) images and mercury porosimetry measurements (MPM) of the microspheres showed that the pore structure was unchanged during the reaction. High adsorption capacity (11.2 mg g-1 of suction-dried adsorbent) and adsorption rate (33.9 mg g-1 h-1) for TNT were observed during the study. As shown by the adsorption isotherm, the adsorption of TNT on PA-PSt can be described by the Freundlich adsorption equation, indicating heterogeneous adsorption process. On-column adsorption of TNT on PA-PSt and elution indicated that TNT can be completely removed from aqueous solution and condensed into acetone.

  6. CO2 Adsorption in Low-Rank Coals: Progress Toward Assessing the National Capacity to Store CO2 in the Subsurface

    NASA Astrophysics Data System (ADS)

    Stanton, R. W.; Burruss, R. C.; Flores, R. M.; Warwick, P. D.

    2001-05-01

    Subsurface environments for geologic storage of CO2 from combustion of fossil fuel include saline formations, depleted oil and gas reservoirs, and unmineable coalbeds. Of these environments, storage in petroleum reservoirs and coal beds offers a potential economic benefit of enhanced recovery of energy resources. Meaningful assessment of the volume and geographic distribution of storage sites requires quantitative estimates of geologic factors that control storage capacity. The factors that control the storage capacity of unmineable coalbeds are poorly understood. In preparation for a USGS assessment of CO2 storage capacity we have begun new measurements of CO2 and CH4 adsorption isotherms of low-rank coal samples from 4 basins. Initial results for 13 samples of low-rank coal beds from the Powder River Basin (9 subbituminous coals), Greater Green River Basin (1 subbituminous coal), Williston Basin (2 lignites) and the Gulf Coast (1 lignite) indicate that their adsorption capacity is up to 10 times higher than it is for CH4. These values contrast with published measurements of the CO2 adsorption capacity of bituminous coals from the Fruitland Formation, San Juan basin, and Gates Formation, British Columbia, that indicate about twice as much carbon dioxide as methane can be adsorbed on coals. Because CH4 adsorption isotherms are commonly measured on coals, CO2 adsorption capacity can be estimated if thecorrect relationship between the gases is known. However, use a factor to predict CO2 adsorption that is twice that of CH4 adsorption, which is common in the published literature, grossly underestimates the storage capacity of widely distributed, thick low-rank coal beds. Complete petrographic and chemical characterization of these low-rank coal samples is in progress. Significant variations in adsorption measurements among samples are depicted depending on the reporting basis used. Properties were measured on an "as received" (moist) basis but can be converted to a

  7. Regenerative process for removal of mercury and other heavy metals from gases containing H.sub.2 and/or CO

    DOEpatents

    Jadhav, Raja A.

    2009-07-07

    A method for removal of mercury from a gaseous stream containing the mercury, hydrogen and/or CO, and hydrogen sulfide and/or carbonyl sulfide in which a dispersed Cu-containing sorbent is contacted with the gaseous stream at a temperature in the range of about 25.degree. C. to about 300.degree. C. until the sorbent is spent. The spent sorbent is contacted with a desorbing gaseous stream at a temperature equal to or higher than the temperature at which the mercury adsorption is carried out, producing a regenerated sorbent and an exhaust gas comprising released mercury. The released mercury in the exhaust gas is captured using a high-capacity sorbent, such as sulfur-impregnated activated carbon, at a temperature less than about 100.degree. C. The regenerated sorbent may then be used to capture additional mercury from the mercury-containing gaseous stream.

  8. The role of counter ions in nano-hematite synthesis: Implications for surface area and selenium adsorption capacity.

    PubMed

    Lounsbury, Amanda W; Yamani, Jamila S; Johnston, Chad P; Larese-Casanova, Philip; Zimmerman, Julie B

    2016-06-05

    Nano metal oxides are of interest for aqueous selenium (Se) remediation, and as such, nano-hematite (nα-Fe2O3) was examined for use as a Se adsorbent. The effect of surface area on adsorption was also studied. nα-Fe2O3 particles were synthesized from Fe(NO3)3 and FeCl3 via forced hydrolysis. The resulting particles have similar sizes, morphologies, aggregate size, pore size, and PZC. The nα-Fe2O3 from FeCl3 (nα-Fe2O3-C) differs from the nα-Fe2O3 from Fe(NO3)3 (nα-Fe2O3-N) with a ∼25±2m(2)/g greater surface area. Selenite Se(IV) adsorption capacity on nα-Fe2O3 has a qmax ∼17mg/g for the freeze-dried and re-suspended nα-Fe2O3. The Δqmax for nα-Fe2O3 from Fe(NO3)3 and FeCl3 that remained in suspension was 4.6mg/g. For selenate Se(VI), the freeze-dried and re-suspended particles realize a Δqmax= 1.5mg/g for nα-Fe2O3 from Fe(NO3)3 and FeCl3. The nα-Fe2O3 from Fe(NO3)3 and FeCl3 that remained in suspension demonstrated Se(VI) Δqmax=5.4mg/g. In situ ATR-FTIR isotherm measurements completed for Se(VI) at a pH 6 suggest that Se(VI) forms primarily outer-sphere complexes with nα-Fe2O3 synthesized from both salts.

  9. Determination of Adsorption Capacity and Kinetics of Amidoxime-Based Uranium Adsorbent Braided Material in Unfiltered Seawater Using a Flume Exposure System

    SciTech Connect

    Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.; Park, Jiyeon; Bonheyo, George T.; Jeters, Robert T.; Schlafer, Nicholas J.; Wood, Jordana R.

    2015-08-31

    PNNL has developed a recirculating flume system for exposing braided adsorbent material to natural seawater under realistic temperature and flow-rate exposure conditions. The flumes are constructed of transparent acrylic material they allow external light to pass into the flumes and permit photosynthetic growth of naturally present marine organisms (biofouling). Because the system consists of two flumes, replicate experiments can be conducted in which one of the flumes can be manipulated relative to the other. For example, one flume can be darkened to eliminate light exposure by placing a black tarp over the flume such that dark/light experiments can be conducted. Alternatively, two different braided adsorbents can be exposed simultaneously with no potential cross contamination issues. This report describes the first use of the PNNL flume system to study the impact of biofouling on adsorbent capacity. Experiments were conducted with the ORNL AI8 braided adsorbent material in light exposed and darkened flumes for a 42 day exposure experiment. The major objective of this effort is to develop a system for the exposure of braided adsorbent material to unfiltered seawater and to demonstrate the system by evaluating the performance of adsorption material when it is exposed to natural marine biofouling as it would be when the technology is used in the marine environment. Exposures of amidoxime-based polymeric braid adsorbents prepared by Oak Ridge Natural Laboratory (ORNL) were exposed to ambient seawater at 20°C in a flume system. Adsorption kinetics and adsorption capacity were assessed using time series determinations of uranium adsorption and one-site ligand saturation modeling. Biofouling in sunlight surface seawater has the potential to significantly add substantial biogenic mass to adsorption material when it is exposed for periods greater than 21 days. The observed biomass increase in the light flume was approximately 80 % of the adsorbent mass after 42 days. The

  10. Sn-Mn binary metal oxides as non-carbon sorbent for mercury removal in a wide-temperature window.

    PubMed

    Xie, Jiangkun; Xu, Haomiao; Qu, Zan; Huang, Wenjun; Chen, Wanmiao; Ma, Yongpeng; Zhao, Songjian; Liu, Ping; Yan, Naiqiang

    2014-08-15

    A series of Sn-Mn binary metal oxides were prepared through co-precipitation method. The sorbents were characterized by powder X-ray diffraction (powder XRD), transmission electronic microscopy (TEM), H2-temperature-programmed reduction (H2-TPR) and NH3-temperature-programmed desorption (NH3-TPD) methods. The capability of the prepared sorbents for mercury adsorption from simulated flue gas was investigated by fixed-bed experiments. Results showed that mercury adsorption on pure SnO2 particles was negligible in the test temperature range, comparatively, mercury capacity on MnOx at low temperature was relative high, but the capacity would decrease significantly when the temperature was elevated. Interestingly, for Sn-Mn binary metal oxide, mercury capacity increased not only at low temperature but also at high temperature. Furthermore, the impact of SO2 on mercury adsorption capability of Sn-Mn binary metal oxides was also investigated and it was noted that the effect at low temperature was different comparing with that of high temperature. The mechanism was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs). Moreover, a mathematic model was built to calculate mercury desorption activation energy from Sn to Mn binary metal oxides.

  11. Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions.

    PubMed

    Lei, Chunsheng; Zhu, Xiaofeng; Zhu, Bicheng; Jiang, Chuanjia; Le, Yao; Yu, Jiaguo

    2017-01-05

    The preparation of hierarchical porous materials as catalysts and sorbents has attracted much attention in the field of environmental pollution control. Herein, Ni/Mg/Al layered double hydroxides (NMA-LDHs) hierarchical flower-like hollow microspheres were synthesized by a hydrothermal method. After the NMA-LDHs was calcined at 600°C, NMA-LDHs transformed into Ni/Mg/Al layered double oxides (NMA-LDOs), which maintained the hierarchical flower-like hollow structure. The crystal phase, morphology, and microstructure of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy elemental mapping, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption methods. Both the calcined and non-calcined NMA-LDHs were examined for their performance to remove Congo red (CR) and hexavalent chromium (Cr(VI)) ions in aqueous solution. The maximum monolayer adsorption capacities of CR and Cr(VI) ions over the NMA-LDOs sample were 1250 and 103.4mg/g at 30°C, respectively. Thermodynamic studies indicated that the adsorption process was endothermic in nature. In addition, the addition of coexisting anions negatively influenced the adsorption capacity of Cr(VI) ions, in the following order: CO3(2-)>SO4(2-)>H2PO4(-)>Cl(-). This work will provide new insight into the design and fabrication of advanced adsorption materials for water pollutant removal.

  12. Alkenyl/thiol-derived metal-organic frameworks (MOFs) by means of postsynthetic modification for effective mercury adsorption.

    PubMed

    Liu, Tao; Che, Jin-Xin; Hu, Yong-Zhou; Dong, Xiao-Wu; Liu, Xin-Yuan; Che, Chi-Ming

    2014-10-20

    The synthesis of new functionally diverse alkenyl-derived Cr-MIL-101s (MIL=material of Institute Lavoisier) was realized by a novel and convenient postsynthetic modification (PSM) protocol by means of the carbon-carbon bond-forming Mizoroki-Heck reaction. The new PSM protocol demonstrates a broad scope of substrates with excellent tolerance of functionality under mild reaction conditions. Moreover, a new metal-organic framework (MOF) that bears both alkenyl and thiol side chains prepared by means of the tandem PSM method has shown excellent adsorbent ability in removing mercury ions from water.

  13. Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk.

    PubMed

    Johari, Khairiraihanna; Alias, Afidatul Shazwani; Saman, Norasikin; Song, Shiow Tien; Mat, Hanapi

    2015-01-01

    The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.

  14. A study of the alumina-silica gel adsorbent for the removal of silicic acid from geothermal water: increase in adsorption capacity of the adsorbent due to formation of amorphous aluminosilicate by adsorption of silicic acid.

    PubMed

    Yokoyama, Takushi; Ueda, Akira; Kato, Koichi; Mogi, Katsumi; Matsuo, Shorin

    2002-08-01

    Two kinds of adsorbents (Si adsorbent and Al adsorbent) for the removal of silicic acid from geothermal water to retard the formation of silica scales were prepared using silicic acid contained in geothermal water. The Si adsorbent was prepared by evaporating geothermal water, and the Al adsorbent was prepared by evaporating geothermal water after the addition of aluminum chloride. The specific surface area of the Si adsorbent was small and it's adsorption capacity of silicic acid was low. Although the specific surface area of the Al adsorbent was also small, it was significantly increased by the adsorption of silicic acid and it's adsorption capacity was high. Based on the change in the local structure of aluminum ion by the adsorption of silicic acid, the Al adsorbent was considered to be silica particles covered with crystalline aluminum hydroxide. Moreover, it was concluded that the increase in the specific surface area of the Al adsorbent and the decrease in the zeta potential were due to the formation of an amorphous aluminosilicate with a large surface area and a negative charge (one 4-coordinated Al) by the reaction between aluminum ions and silicic acids.

  15. Fourier transform infra-red (FTIR) spectroscopy investigation, dose effect, kinetics and adsorption capacity of phosphate from aqueous solution onto laterite and sandstone.

    PubMed

    Coulibaly, Lassina Sandotin; Akpo, Sylvain Kouakou; Yvon, Jacques; Coulibaly, Lacina

    2016-12-01

    Environmental pollution by phosphate in developing countries is growing with extensive and diffuse pollution. Solving these problem with intensive technologies is very expensive. Using natural sorbent such as laterite and sandstone could be a solution. The main objective of the study is to evaluate the P-removal efficiency of these materials under various solution properties. Laterite and sandstone used mainly contain very high levels of finely grained iron and aluminum oxy-hydroxides and diverse dioctahedral clays. Phosphate adsorption tests were carried out using crushed laterite and sandstone. Optimal doses and pH effects on phosphate adsorption were studied with a potassium hydrogeno-phosphate solution of 5 mg/L at 30 °C. The main results were that the optimal dosage is 15 and 20 mg/L respectively for laterite and sandstone. The phosphate adsorptions efficiency of laterite and sandstone are pH-dependent, they increase when the pH grows up to the Point of Zero Charge (PZC) and slowly decrease beyond. The adsorption capacities of the materials also increase proportionally with the initial phosphate concentration. The pseudo-second-order successfully described the kinetics of the phosphate adsorption on the two adsorbents. With this model, the adsorption capacity values are obtained, which give an idea of the maximum phosphate uptake that the laterite and sandstone could achieve. The changes on the FTIR spectra of raw materials and phosphate adsorbed material confirm the mechanism of chemisorptions. Considering the above, laterite and sandstone could be used as efficient and cheap adsorbent for the removal of phosphate in aqueous solution.

  16. A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Li, Wenting; Shang, Chunli; Li, Xue

    2015-12-01

    Anatase TiO2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption analysis, UV-vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO2 NSs possess high surface area up to 378 m2 g-1. The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

  17. Using the Novel Method of Nonthermal Plasma To Add Cl Active Sites on Activated Carbon for Removal of Mercury from Flue Gas.

    PubMed

    Zhang, Bi; Zeng, Xiaobo; Xu, Ping; Chen, Juan; Xu, Yang; Luo, Guangqian; Xu, Minghou; Yao, Hong

    2016-11-01

    A new method using nonthermal plasma to add Cl active sites on activated carbon was proposed to improve the efficiency of activated carbon (AC) for removal of mercury from flue gas. The experiments were conducted via a lab-scale dielectric barrier discharge nonthermal plasma system and a vertical adsorption reactor. The results showed that the nonthermal plasma treatment with a small amount of Cl2 successfully added Cl active sites on AC and greatly increased the mercury removal efficiency of AC by chemisorption in a very short treatment time. The increase in Cl2 concentration for AC treatment promoted the efficiency of AC. The capacity of mercury adsorption positively correlated with the content of Cl2 for AC treatment, which depends on the number of Cl active sites on activated carbon. The treated AC maintained a high mercury removal efficiency within a temperature range of 30-210 °C. SO2 and H2O in flue gas inhibited the removal of mercury by AC, while HCl had a promotional effect. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis indicated the chemisorption of mercury was attributed to the C-Cl groups generated on AC surfaces during Cl2 nonthermal plasma treatment. The C-Cl groups as active sites had strong adsorption energy for mercury, which converted elemental mercury to HgCl2.

  18. Combined electron-beam and adsorption purification of water from mercury and chromium using materials of vegetable origin as sorbents

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. V.; Bludenko, A. V.; Makarov, I. E.; Pikaev, A. K.; Kyung Kim, Duk; Kim, Yuri; Han, Bumsoo

    1997-04-01

    Combined electron-beam and adsorption method of purification of water from Hg(II) and Cr(VI) using materials of vegetable origin as sorbents was developed. It consists in the addition of materials of vegetable origin (e.g. cellulose, carboxymethyl cellulose, starch, and wheat flour) into water, subsequent electron-beam irradiation, sedimentation and filtration of additives with captured Hg(II) or Cr(VI). The method is based on the synergistic effect of the combined action of irradiation and sorbent. The best results were obtained with the wheat flour. For example, the addition of 25 mg/I of the flour to the water containing 1 mg/I Hg(II) and irradiation with dose 1.1 kGy upon bubbling inert gas through the system led to the 98% removal of the pollutant. The possible mechanism of the processes causing the purification of water is discussed.

  19. Mercury emissions from coal combustion: modeling and comparison of Hg capture in a fabric filter versus an electrostatic precipitator.

    PubMed

    Scala, Fabrizio; Clack, Herek L

    2008-04-01

    Mercury emissions from coal combustion must be reduced, in response to new air quality regulations in the U.S. Although the most mature control technology is adsorption across a dust cake of powdered sorbent in a fabric filter (FF), most particulate control in the U.S. associated with coal combustion takes the form of electrostatic precipitation (ESP). Using recently developed models of mercury adsorption within an ESP and within a growing sorbent bed in a FF, parallel analyses of elemental mercury (Hg(0)) uptake have been conducted. The results show little difference between an ESP and a FF in absolute mercury removal for a low-capacity sorbent, with a high-capacity sorbent achieving better performance in the FF. Comparisons of fractional mercury uptake per-unit-pressure-drop provide a means for incorporating and comparing the impact of the much greater pressure drop of a FF as compared to an ESP. On a per-unit-pressure-drop basis, mercury uptake within an ESP exhibited better performance, particularly for the low-capacity sorbent and high mass loadings of both sorbents.

  20. Removal of mercury from an alumina refinery aqueous stream.

    PubMed

    Mullett, Mark; Tardio, James; Bhargava, Suresh; Dobbs, Charles

    2007-06-01

    Digestion condensate is formed as a by-product of the alumina refinery digestion process. The solution exhibits a high pH and is chemically reducing, containing many volatile species such as water, volatile organics, ammonia, and mercury. Because digestion condensate is chemically unique, an innovative approach was required to investigate mercury removal. The mercury capacity and adsorption kinetics were investigated using a number of materials including gold, silver and sulphur impregnated silica and a silver impregnated carbon. The results were compared to commercial sorbents, including extruded and powdered virgin activated carbons and a sulphur impregnated mineral. Nano-gold supported on silica (88% removal under batch conditions and 95% removal under flow conditions) and powdered activated carbon (91% under batch conditions and 98% removal under flow conditions) were the most effective materials investigated. The silver and sulphur impregnated materials were unstable in digestion condensate under the test conditions used.

  1. Sol-gel synthesized adsorbents for mercury(II), chromium(III) and cobalt(II) separations

    NASA Astrophysics Data System (ADS)

    Nam, Kwan-Hyun

    Novel organo-ceramic adsorbents are synthesized and characterized for mercury(II), chromium(III) and cobalt(II) separations from aqueous streams. Mercury(II) adsorption on thiol functional adsorbents (SOL-AD-IV) is studied for two systems: (1) coal-fired utility plant scrubber water, and (2) acidic nuclear wastes. To exemplify the removal of mercury from these systems, simulants are prepared and used. Results show that the mercury adsorption capacity is higher than reported in the literature. In addition, the adsorbent exhibits high adsorption capacity even at 4 M HNO3. In column operation, flow rates as high as 1100 BV/h could be employed with effluent concentrations reaching below 0.06 mug/L. This adsorbent is found to exhibit superior mercury adsorption characteristics with a demonstrated long life cycle. Chromium(III) and cobalt(II) adsorption is evaluated using phosphonic acid (SOL-PHONIC) and phosphinic acid (SOL-PHINIC) functional adsorbents synthesized via sol-gel processing by co-condensation of clusters of functional precursor (FPS) and cross-linking (CA) silanes. Nuclear magnetic resonance (NMR) spectroscopy is used to examine the evolution of oligomeric species with hydrolysis and condensation reaction times. The effects of both the FPS and CA oligomeric species on the physicochemical properties of the resulting adsorbent materials are evaluated and explained in terms of structural and adsorption capacity characteristics. The adsorbents are further characterized by solid-state NMR spectroscopy to elucidate the incorporation of the FPS and the nature of the functional groups in the adsorbent matrix. SOL-PHONIC is employed for the removal of chromium, and both SOL-PHONIC and SOL-PHINIC are employed for the removal of cobalt. Results show that chromium and cobalt adsorptions are solution pH dependent. Cobalt adsorption tests evaluated using the two adsorbents show that SOL-PHONIC exhibits a higher selectivity towards cobalt over nickel. The adsorption

  2. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

    NASA Astrophysics Data System (ADS)

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-05-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g‑1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment.

  3. Ultrasond-assisted synthesis of Fe3O4/SiO2 core/shell with enhanced adsorption capacity for diazinon removal

    NASA Astrophysics Data System (ADS)

    Farmany, Abbas; Mortazavi, Seyede Shima; Mahdavi, Hossein

    2016-10-01

    Fe3O4/SiO2 core/shell nanocrystals were synthesized by ultrasond-assisted procedure. The core/shell nanocrystals were characterized using XRD, FT-IR spectroscopy, SEM and BET. The BET analysis confirmed that iron oxide nanocrystal with the surface area of 208.0 m2/g can be used as an excellent adsorbent for organic and inorganic pollutants. The core/shell nanocrystal was used as an adsorbent for removal of insecticide O,O-diethyl-O[2-isopropyl-6-methylpyridimidinyl] phosphorothioate (diazinon). In continue the influence of different parameters such as pH, adsorbent dosage and shaking time on the adsorption capacity were studied. The experimental data were fitted well with the pseudo-second-order kinetic model (R2=0.9706). The adsorption isotherm was described well by Langmuir isotherm.

  4. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

    PubMed Central

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-01-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g−1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment. PMID:27142194

  5. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR EMERGING ORGANIC CONTAMINANTS FROM FUNDAMENTAL ADSORBENT AND ADSORBATE PROPERTIES - PRESENTATION

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  6. High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water.

    PubMed

    Wei, Yan; Yang, Ran; Zhang, Yong-Xing; Wang, Lun; Liu, Jin-Huai; Huang, Xing-Jiu

    2011-10-21

    γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.

  7. High-efficient mercury removal from environmental water samples using di-thio grafted on magnetic mesoporous silica nanoparticles.

    PubMed

    Mehdinia, Ali; Akbari, Maryam; Baradaran Kayyal, Tohid; Azad, Mohammad

    2015-02-01

    In this work, magnetic di-thio functionalized mesoporous silica nanoparticles (DT-MCM-41) were prepared by grafting dithiocarbamate groups within the channels of magnetic mesoporous silica nanocomposites. The functionalized nanoparticles exhibited proper magnetic behavior. They were easily separated from the aqueous solution by applying an external magnetic field. The results indicated that the functionalized nanoparticles had a potential for high-efficient removal of Hg(2+) in environmental samples. The maximum adsorption capacity of the sorbent was 538.9 mg g(-1), and it took about 10 min to achieve the equilibrium adsorption. The resulted adsorption capacity was higher than similar works for adsorption of mercury. It can be due to the presence of di-thio and amine active groups in the structure of sorbent. The special properties of MCM-41 like large surface area and high porosity also provided a facile accessibility of the mercury ions into the ligand sites. The complete removal of mercury ions was attained with dithiocarbamate groups in a wide range of mercury concentrations. The recovery studies were also applied for the river water, seawater, and wastewater samples, and the values were over of 97 %.

  8. Adsorption of Hg(II) from aqueous solutions using TiO2 and titanate nanotube adsorbents

    NASA Astrophysics Data System (ADS)

    López-Muñoz, María-José; Arencibia, Amaya; Cerro, Luis; Pascual, Raquel; Melgar, Álvaro

    2016-03-01

    Titania and titanate nanotubes were evaluated as adsorbents for the removal of Hg(II) from aqueous solution. Commercial titanium dioxide (TiO2-P25, Evonik), a synthesized anatase sample obtained by the sol-gel method (TiO2-SG) and titanate nanotubes (TNT) prepared via hydrothermal treatment were compared. Mercury adsorption was analysed by kinetic and equilibrium experiments, studying the influence of pH and the type of adsorbents. The kinetics of Hg(II) adsorption on titania and titanate nanotubes could be well described by the pseudo-second order model. It was found that the process is generally fast with small differences between adsorbents, which cannot be explained by their dissimilarities in textural properties. Equilibrium isotherm data were best fitted with the Sips isotherm model. The maximum adsorption capacities of Hg(II) were achieved with titanate nanotubes sample, whereas between both titania samples, TiO2-SG exhibited the highest mercury uptake. For all adsorbents, adsorption capacities were enhanced as pH was increased, achieving at pH 10 Hg(II) adsorption capacities of 100, 121, and 140 mg g-1 for TiO2-P25, TiO2-SG, and TNT, respectively. Differences between samples were discussed in terms of their crystalline phase composition and chemical nature of both, mercury species and surface active sites.

  9. Effect of immobilized amine density on cadmium(II) adsorption capacities for ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres

    NASA Astrophysics Data System (ADS)

    Dong, Tingting; Yang, Liangrong; Pan, Feng; Xing, Huifang; Wang, Li; Yu, Jiemiao; Qu, Hongnan; Rong, Meng; Liu, Huizhou

    2017-04-01

    A series of ethanediamine (EDA) - modified magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined. The results showed that the cadmium saturation adsorption capacity increased with the immobilized amine density. However, they did not show strong positive linear correlation in the whole range of amine density examined. The molar ratio of amine groups to the adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4. It suggested that low immobilized amine density led to low coordination efficiency of the amine. It is hypothesized that the immobilized amine groups needed to be physically close enough to form stable amine-metal complex. When the amine density reached to a critical value 1.25 m mol m-2, stable amine-cadmium complex (4:1 N/Cd) was proposed to form. To illustrate the coordination mechanism (structure and number) of amine and Cd, FT-IR spectra of m-PGMA-EDA and m-PGMA-EDA-Cd , and X-ray photoelectron spectroscopy (XPS) of PGMA-EDA and PGMA-EDA-Cd were examined and analyzed.

  10. Granular activated carbon adsorption of organic micro-pollutants in drinking water and treated wastewater--Aligning breakthrough curves and capacities.

    PubMed

    Zietzschmann, Frederik; Stützer, Christian; Jekel, Martin

    2016-04-01

    Small-scale granular activated carbon (GAC) tests for the adsorption of organic micro-pollutants (OMP) were conducted with drinking water and wastewater treatment plant (WWTP) effluent. In both waters, three influent OMP concentration levels were tested. As long as the influent OMP concentrations are below certain thresholds, the relative breakthrough behavior is not impacted in the respective water. Accordingly, the GAC capacity for OMP is directly proportional to the influent OMP concentration in the corresponding water. The differences between the OMP breakthrough curves in drinking water and WWTP effluent can be attributed to the concentrations of the low molecular weight acid and neutral (LMW) organics of the waters. Presenting the relative OMP concentrations (c/c0) over the specific throughput of the LMW organics (mg LMW organics/g GAC), the OMP breakthrough curves in drinking water and WWTP effluent superimpose each other. This superimposition can be further increased if the UV absorbance at 254 nm (UV254) of the LMW organics is considered. In contrast, using the specific throughput of the dissolved organic carbon (DOC) did not suffice to obtain superimposed breakthrough curves. Thus, the LMW organics are the major water constituent impacting OMP adsorption onto GAC. The results demonstrate that knowing the influent OMP and LMW organics concentrations (and UV254) of different waters, the OMP breakthroughs and GAC capacities corresponding to any water can be applied to all other waters.

  11. LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

    PubMed

    Economou, Anastasios; Voulgaropoulos, Anastasios

    2003-01-01

    The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

  12. Effect of Heat Treatment on the Nitrogen Content and Its Role on the Carbon Dioxide Adsorption Capacity of Highly Ordered Mesoporous Carbon Nitride.

    PubMed

    Lakhi, Kripal S; Park, Dae-Hwan; Joseph, Stalin; Talapaneni, Siddulu N; Ravon, Ugo; Al-Bahily, Khalid; Vinu, Ajayan

    2017-03-02

    Mesoporous carbon nitrides (MCNs) with rod-shaped morphology and tunable nitrogen contents have been synthesized through a calcination-free method by using ethanol-washed mesoporous SBA-15 as templates at different carbonization temperatures. Carbon tetrachloride and ethylenediamine were used as the sources of carbon and nitrogen, respectively. The resulting MCN materials were characterized with low- and high-angle powder XRD, nitrogen adsorption, high-resolution (HR) SEM, HR-TEM, elemental analysis, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure techniques. The carbonization temperature plays a critical role in controlling not only the crystallinity, but also the nitrogen content and textural parameters of the samples, including specific surface area and specific pore volume. The nitrogen content of MCN decreases with a concomitant increase in specific surface area and specific pore volume, as well as the crystallinity of the samples, as the carbonization temperature is increased. The results also reveal that the structural order of the materials is retained, even after heat treatment at temperatures up to 900 °C with a significant reduction of the nitrogen content, but the structure is partially damaged at 1000 °C. The carbon dioxide adsorption capacity of these materials is not only dependent on the textural parameters, but also on the nitrogen content. The MCN prepared at 900 °C, which has an optimum BET surface area and nitrogen content, registers a carbon dioxide adsorption capacity of 20.1 mmol g(-1) at 273 K and 30 bar, which is much higher than that of mesoporous silica, MCN-1, activated carbon, and multiwalled carbon nanotubes.

  13. Synthesis and evaluation of a thiourea-modified chitosan derivative applied for adsorption of Hg(II) from synthetic wastewater.

    PubMed

    Wang, Lin; Xing, Ronge; Liu, Song; Cai, Shengbao; Yu, Huahua; Feng, Jinhua; Li, Rongfeng; Li, Pengcheng

    2010-06-01

    In this work, a thiourea-modified chitosan derivative (TMCD) was synthesized through two steps, O-carboxymethylated first and then modified by a polymeric Schiff's base of thiourea/glutaraldehyde. The adsorption behavior of mercury (II) ions onto TMCD was investigated through batch method. The maximum adsorption capacity for Hg(II) was found to be 6.29 mmol/g at pH 5.0 and both kinetic and thermodynamic parameters of the adsorption process were obtained. The results indicated that adsorption process was spontaneous exothermic reaction and kinetically followed pseudo-second-order model. The adsorption experiments also demonstrated TMCD had high adsorption selectivity towards Hg(II) ions when coexisted with Cu(II), Zn(II), Cd(II) and Ca(II) in solution and it could be easily regenerated and efficiently reused.

  14. Surface catalyzed mercury transformation reactions

    NASA Astrophysics Data System (ADS)

    Varanasi, Patanjali

    /m 3 using a diffusion tube as the source of Hg0(g). All experiments were conducted using 4% O2 in nitrogen mix as a reaction gas, and other reactants (HCl, H2O and SO2, NO 2, Br2) were added as required. The fixed bed reactor was operated over a temperature range of 200 to 400°C. In each experiment, the reactor effluent was analyzed using the modified Ontario-Hydro method. After each experiment, fly ash particles were also analyzed for mercury. The results show that the ability of fly ash to adsorb and/or oxidize mercury is primarily dependent on its carbon, iron and calcium content. There can be either one or more than one key component at a particular temperature and flue gas condition. Surface area played a secondary role in effecting the mercury transformations when compared to the concentration of the key component in the fly ash. Amount carbon and surface area played a key important role in the adsorption of mercury. Increased concentration of gases in the flue gas other than oxygen and nitrogen caused decreased the amount of mercury adsorbed on carbon surface. Mercury adsorption by iron oxide primarily depended on the crystalline structure of iron oxide. alpha-iron oxide had no effect on mercury adsorption or oxidation under most of the flue gas conditions, but gamma-iron oxide adsorbed mercury under most of the flue gas conditions. Bromine is a very good oxidizing agent for mercury. But in the presence of calcium oxide containing fly ashes, all the oxidized mercury would be reduced to elemental form. Among the catalysts, it was observed that presence of free lattice chlorine in the catalyst was very important for the oxidation of mercury. But instead of using the catalyst alone, using it along with carbon may better serve the purpose by providing the adsorption surface for mercury and also some extra surface area for the reaction to occur (especially for fly ashes with low surface area).

  15. The effect of moisture on the methane adsorption capacity of shales: A study case in the eastern Qaidam Basin in China

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Yu, Qingchun

    2016-11-01

    This study investigated the effects of moisture on high-pressure methane adsorption in carboniferous shales from the Qaidam Basin, China. The shale characteristics, including the organic/inorganic compositions and pore structure (volume and surface) distribution, were obtained using various techniques. Gibbs adsorption measurements were performed over a pressure range up to 6 MPa and temperatures of 308.15 K on dry samples and moisture-equilibrated samples to analyze the correlations between organic/inorganic matter, pore structure, and moisture content on the methane sorption capacity. Compared to dry samples, the sorption capacity of wet samples (0.44-2.52% of water content) is reduced from 19.7 ± 5.3% to 36.1% ± 6.1%. Langmuir fitting is conducted to investigate moisture-dependent variations of adsorbed methane density, Langmuir pressure, and volume. By combining the pore volume and surface distribution analyses, our observations suggested that the main competition sites for CH4-H2O covered pores of approximately 2-7 nm, whereas the effective sites for methane and water were predominantly distributed within smaller (<4 nm) and larger pores (>10 nm), respectively. Regarding the compositional correlations, the impact of moisture on the amount of adsorbed methane shows a roughly linearly decreasing trend with increasing TOC content ranging from 0.62 to 2.88%, whereas the correlation between the moisture effect and various inorganic components is more complicated. Further fitting results indicate that illite/smectite mixed formations are closely related to the methane capacity, whereas the illite content show an evident connection to the pore structural (volume and surface) variations in the presence of moisture.

  16. The Effect of Oxidation on the Surface Chemistry of Sulfur-Containing Carbons and their Arsine Adsorption Capacity

    DTIC Science & Technology

    2010-01-01

    hydrogen sulfide . Carbon 2004;42(3):469–76. Fig. 6 – Water adsorption isotherms of the samples studied. 1786 C A R B O N 4 8 ( 2 0 1 0 ) 1 7 7 9 –1 7 8...that oxygen- and sulfur-containing groups participate in arsine oxida- tion to arsenic tri- and pentoxide and/or in the formation of arsenic sulfides ...technological difficulties, arsine is also a powerful toxin susceptible to oxidation with a strong exothermic effect. Of all the methods to separate

  17. Mercury (II) removal from water by coconut shell based activated carbon: batch and column studies.

    PubMed

    Goel, Jyotsna; Kadirvelu, K; Rajagopal, C

    2004-02-01

    This study was undertaken to investigate adsorption behavior of Hg (II) from aqueous systems on activated carbon in static and dynamic mode by varying initial Hg (II) concentration, adsorbent dose and pH. Langmuir and Freundlich adsorption isotherm were applied to model the adsorption data. Removal of mercury obeyed the Langmuir and Freundlich adsorption isotherm models. The extent of removal of Hg (II) was found to be dependent on sorbent dose, pH and initial Hg (II) concentration. Mercury uptake increased from 72 to 100 percent with increasing pH from 2 to 10. A set of desorption studies was also performed for the metal ions with the aim of investigating the mechanism involved. Moreover, the competing effects of various ions like Pb (II) and Cu (II) is also described. The column capacity for a column diameter of 20 mm, bed height of 0.4 m, hydraulic loading rate of 7.5 m3 h(-1) m(-2) and a feed concentration of 3 mg l(-1) were found to be 3.02 mg g(-1). Breakthrough curves were plotted for the adsorption of mercury on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3-10.5 m3 h(-1) m(-2)), bed height (0.3-0.5 m), and feed concentrations (2-6 mg l(-1)). The aim was to assess the effect of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity, which helped in ascertaining the practical applicability of the adsorbent. At the end an attempt has been made to develop empirical relationship from the data generated from column studies for designing the adsorption column, based on the Bohart-Adams model.

  18. Characterization of Fly Ash from Coal-Fired Power Plant and Their Properties of Mercury Retention

    NASA Astrophysics Data System (ADS)

    He, Ping; Jiang, Xiumin; Wu, Jiang; Pan, Weiguo; Ren, Jianxing

    2015-12-01

    Recent research has shown that fly ash may catalyze the oxidation of elemental mercury and facilitate its removal. However, the nature of mercury-fly ash interaction is still unknown, and the mechanism of mercury retention in fly ash needs to be investigated more thoroughly. In this work, a fly ash from a coal-fired power plant is used to characterize the inorganic and organic constituents and then evaluate its mercury retention capacities. The as-received fly ash sample is mechanically sieved to obtain five size fractions. Their characteristics are examined by loss on ignition (LOI), scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), X-ray diffraction (XRD), and Raman spectra. The results show that the unburned carbon (UBC) content and UBC structural ordering decrease with a decreasing particle size for the five ashes. The morphologies of different size fractions of as-received fly ash change from the glass microspheres to irregular shapes as the particle size increases, but there is no correlation between particle size and mineralogical compositions in each size fraction. The adsorption experimental studies show that the mercury-retention capacity of fly ash depends on the particle size, UBC, and the type of inorganic constituents. Mercury retention of the types of sp2 carbon is similar to that of sp3 carbon.

  19. New V(IV)-based metal-organic framework having framework flexibility and high CO2 adsorption capacity.

    PubMed

    Liu, Ying-Ya; Couck, Sarah; Vandichel, Matthias; Grzywa, Maciej; Leus, Karen; Biswas, Shyam; Volkmer, Dirk; Gascon, Jorge; Kapteijn, Freek; Denayer, Joeri F M; Waroquier, Michel; Van Speybroeck, Veronique; Van Der Voort, Pascal

    2013-01-07

    A vanadium based metal-organic framework (MOF), VO(BPDC) (BPDC(2-) = biphenyl-4,4'-dicarboxylate), adopting an expanded MIL-47 structure type, has been synthesized via solvothermal and microwave methods. Its structural and gas/vapor sorption properties have been studied. This compound displays a distinct breathing effect toward certain adsorptives at workable temperatures. The sorption isotherms of CO(2) and CH(4) indicate a different sorption behavior at specific temperatures. In situ synchrotron X-ray powder diffraction measurements and molecular simulations have been utilized to characterize the structural transition. The experimental measurements clearly suggest the existence of both narrow pore and large pore forms. A free energy profile along the pore angle was computationally determined for the empty host framework. Apart from a regular large pore and a regular narrow pore form, an overstretched narrow pore form has also been found. Additionally, a variety of spectroscopic techniques combined with N(2) adsorption/desorption isotherms measured at 77 K demonstrate that the existence of the mixed oxidation states V(III)/V(IV) in the titled MOF structure compared to pure V(IV) increases the difficulty in triggering the flexibility of the framework.

  20. Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

    NASA Astrophysics Data System (ADS)

    Hlaing, Nwe Ni; Vignesh, K.; Sreekantan, Srimala; Pung, Swee-Yong; Hinode, Hirofumi; Kurniawan, Winarto; Othman, Radzali; Thant, Aye Aye; Mohamed, Abdul Rahman; Salim, Chris

    2016-02-01

    Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2-0.8 M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG-DTA) techniques. The phase purity, crystallite size, Brunauer-Emmett-Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8 M. TGA results exhibited that 0.8 M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

  1. EVALUATING REGIONAL PREDICTIVE CAPACITY OF A PROCESS-BASED MERCURY EXPOSURE MODEL, REGIONAL-MERCURY CYCLING MODEL (R-MCM), APPLIED TO 91 VERMONT AND NEW HAMPSHIRE LAKES AND PONDS, USA

    EPA Science Inventory

    Regulatory agencies must develop fish consumption advisories for many lakes and rivers with limited resources. Process-based mathematical models are potentially valuable tools for developing regional fish advisories. The Regional Mercury Cycling model (R-MCM) was specifically d...

  2. Synthesis and Characterization of Novel Sulfur-Functionalized Silica Gels as Mercury Adsorbents

    NASA Astrophysics Data System (ADS)

    Johari, Khairiraihanna; Saman, Norasikin; Mat, Hanapi

    2014-03-01

    This paper describes the synthesis, functionalization, and characterization of silica gels as mercury adsorbents. The synthesis was carried out according to the modified Stöber method using tetraethyl orthosilicate [TEOS], 3-mercaptopropyl trimethoxysilane [MPTMS] and bis(triethoxysilylpropyl) tetrasulfide [BTEPST] as precursors. The functionalization was carried out via co-condensation and impregnation methods using MPTMS, BTESPT, elemental sulfur [ES], and carbon disulfide [CS2] as sulfur ligands. The choice of the sulfur ligands as precursors and functionalization agents was due to the existence of sulfur active groups in their molecular structures which were expected to have high affinity toward Hg(II) ions. The synthesized adsorbents were characterized by using scanning electron microscope, fourier transform infrared spectrophotometer, nitrogen adsorption/desorption, and energy dispersive X-ray diffractometer. The batch Hg(II) adsorption experiments were employed to evaluate the Hg(II) adsorption performances of the synthesized adsorbents under different pH values. The results revealed that the highest Hg(II) adsorption capacity was obtained for the SG-MPTMS(10) which was 47.83 mg/g at pH 8.5. In general, the existence of sulfur functional groups, especially MPTMS in the silica matrices, gave a significant enhancement of Hg(II) adsorption capacity and the sulfur functionalization via co-condensation method, which is potential as a superior approach in the mercury adsorbent synthesis.

  3. Application of a novel magnetic carbon nanotube adsorbent for removal of mercury from aqueous solutions.

    PubMed

    Homayoon, Farshid; Faghihian, Hossein; Torki, Firoozeh

    2017-04-01

    In this research, multiwall carbon nanotube was magnetized and subsequently functionalized by thiosemicarbazide. After characterization by FTIR, BET, SEM, EDAX, and VSM techniques, the magnetized adsorbent (multi-walled carbon nanotubes (MWCNTs)/Fe3O4) was used for removal of Hg(2+) from aqueous solutions and the experimental conditions were optimized. The adsorption capacity of 172.83 mg g(-1) was obtained at 25 °C and pH = 3 which was superior to the value obtained for initial multiwall carbon nanotube, magnetized sample, and many previously reported values. In the presence of Pb(+2) and Cd(+2), the adsorbent was selective towards mercury when their concentration was respectively below 50 and 100 mg L(-1). The adsorption process was kinetically fast and the equilibration was attained within 60 min with 69.5% of the capacity obtained within 10 min. The used adsorbent was regenerated by HNO3 solution, and the regenerated adsorbent retained 92% of its initial capacity. The magnetic sensitivity of the adsorbent allowed the simple separation of the used adsorbent from the solution by implying an appropriate external magnetic field. The adsorption data was well fitted to the Langmuir isotherm model, indicating homogeneous and monolayer adsorption of mercury by the adsorbent.

  4. Importance of elemental mercury in lake sediments.

    PubMed

    Bouffard, Ariane; Amyot, Marc

    2009-02-01

    Mercury (Hg) redox changes in sediments are poorly studied and understood, even though they potentially control Hg availability for methylation and can alter sediment-water Hg exchange. Elemental Hg (Hg(0)) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg(0) concentrations in sediments varied between 6.3 and 60.3 pg g(-1) (wet weight) which represented 7.4-28.4% of total mercury (HgT) concentration. Hg(0) concentrations were similar in both lakes. Hg(0) was rapidly adsorbed on sediments in controlled adsorption experiments and surface sediments sampled in summer had a stronger affinity for Hg(0) than deeper sediments and sediments sampled in fall. This adsorption was positively correlated to organic matter content and negatively related to particle grain size, pH and oxygen concentration in overlying water. This study demonstrates that Hg(0) is a prevalent species in sediments, but not in porewater, because of the high sorptive capacity of sediments towards Hg(0). Its potential availability towards Hg methylating bacteria remains to be determined.

  5. Mesoporous silica functionalized with 1-furoyl thiourea urea for Hg(II) adsorption from aqueous media.

    PubMed

    Mureseanu, Mihaela; Reiss, Aurora; Cioatera, Nicoleta; Trandafir, Ion; Hulea, Vasile

    2010-10-15

    New organic-inorganic hybrid materials were prepared by covalently anchoring 1-furoyl thiourea on mesoporous silica (SBA-15). By means of various characterization techniques (X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, and FTIR spectroscopy) it has been established that the organic groups were successfully anchored on the SBA-15 surfaces and the ordering of the inorganic support was preserved during the chemical modifications. The hybrid sorbents exhibited good ability to remove Hg(II) from aqueous solution. Thus, at pH 6, the adsorption capacity of mercury ions reached 0.61 mmol g(-1).

  6. Long-Life and High-Areal-Capacity Li-S Batteries Enabled by a Light-Weight Polar Host with Intrinsic Polysulfide Adsorption.

    PubMed

    Pang, Quan; Nazar, Linda F

    2016-04-26

    Lithium-sulfur batteries are attractive electrochemical energy storage systems due to their high theoretical energy density and very high natural abundance of sulfur. However, practically, Li-S batteries suffer from short cycling life and low sulfur utilization, particularly in the case of high-sulfur-loaded cathodes. Here, we report on a light-weight nanoporous graphitic carbon nitride (high-surface-area g-C3N4) that enables a sulfur electrode with an ultralow long-term capacity fade rate of 0.04% per cycle over 1500 cycles at a practical C/2 rate. More importantly, it exhibits good high-sulfur-loading areal capacity (up to 3.5 mAh cm(-2)) with stable cell performance. We demonstrate the strong chemical interaction of g-C3N4 with polysulfides using a combination of spectroscopic experimental studies and first-principles calculations. The 53.5% concentration of accessible pyridinic nitrogen polysulfide adsorption sites is shown to be key for the greatly improved cycling performance compared to that of N-doped carbons.

  7. Immobilization of mercury by carboxymethyl cellulose stabilized iron sulfide nanoparticles: reaction mechanisms and effects of stabilizer and water chemistry.

    PubMed

    Gong, Yanyan; Liu, Yuanyuan; Xiong, Zhong; Zhao, Dongye

    2014-04-01

    Iron sulfide (FeS) nanoparticles were prepared with sodium carboxymethyl cellulose (CMC) as a stabilizer, and tested for enhanced removal of aqueous mercury (Hg(2+)). CMC at ≥0.03 wt % fully stabilized 0.5 g/L of FeS (i.e., CMC-to-FeS molar ratio ≥0.0006). FTIR spectra suggested that CMC molecules were attached to the nanoparticles through bidentate bridging and hydrogen bonding. Increasing the CMC-to-FeS molar ratio from 0 to 0.0006 enhanced mercury sorption capacity by 20%; yet, increasing the ratio from 0.0010 to 0.0025 diminished the sorption by 14%. FTIR and XRD analyses suggested that precipitation (formation of cinnabar and metacinnabar), ion exchange (formation of Hg0.89Fe0.11S), and surface complexation were important mechanisms for mercury removal. A pseudo-second-order kinetic model was able to interpret the sorption kinetics, whereas a dual-mode isotherm model was proposed to simulate the isotherms, which considers precipitation and adsorption. High mercury uptake was observed over the pH range of 6.5-10.5, whereas significant capacity loss was observed at pH < 6. High concentrations of Cl(-) (>106 mg/L) and organic matter (5 mg/L as TOC) modestly inhibited mercury uptake. The immobilized mercury remained stable when preserved for 2.5 years at pH above neutral.

  8. Single-Walled Carbon Nanotubes (SWCNTs), as a Novel Sorbent for Determination of Mercury in Air

    PubMed Central

    Golbabaei, Farideh; Ebrahimi, Ali; Shirkhanloo, Hamid; Koohpaei, Alireza; Faghihi-Zarandi, Ali

    2016-01-01

    Background: Based on the noticeable toxicity and numerous application of mercury in industries, removal of mercury vapor through sorbent is an important environmental challenge. Purpose of the Study: Due to their highly porous and hollow structure, large specific surface area, light mass density and strong interaction, Single-Walled Carbon Nanotubes (SWCNTs) sorbent were selected for this investigation. Methods: In this study, instrumental conditions, method procedure and different effective parameters such as adsorption efficiency, desorption capacity, time, temperature and repeatability as well as retention time of adsorbed mercury were studied and optimized. Also, mercury vapor was determined by cold vapor atomic absorption spectrometry (CV-AAS). Obtained data were analyzed by Independent T- test, Multivariate linear regression and one way–ANOVA finally. Results: For 80 mg nanotubes, working range of SWCNT were achieved 0.02-0.7 μg with linear range (R2=0.994). Our data revealed that maximum absorption capacity was 0.5 μg g-1 as well as limit of detection (LOD) for studied sorbent was 0.006 μg. Also, optimum time and temperature were reported, 10 min and 250 °C respectively. Retention time of mercury on CNTs for three weeks was over 90%. Results of repeated trials indicated that the CNTs had long life, so that after 30 cycles of experiments, efficiency was determined without performance loss. Conclusion: Results showed that carbon nanotubes have high potential for efficient extraction of mercury from air and can be used for occupational and environmental purposes. The study of adsorption properties of CNTs is recommended. PMID:26925918

  9. Control of mercury pollution.

    PubMed

    Noyes, O R; Hamdy, M K; Muse, L A

    1976-01-01

    When a 203Ng(NO3)2 solution was kept at 25 degrees C in glass or polypropylene containers, 50 and 80% of original radioactivity was adsorbed to the containers' walls after 1 and 4 days, respectively. However, no loss in radioactivity was observed if the solution was supplemented with HgCl as carrier (100 mug Hg2+/ml) and stored in either container for 13 days. When 203Hg2+ was dissolved in glucose basal salt broth with added carrier, levels of 203Hg2+ in solution (kept in glass) decreased to 80 and 70% of original after 1 and 5 days and decreased even more if stored in polypropylene (60 and 40% of original activity after 1 and 4 days, respectively). In the absence of carrier, decreases of 203Hg2+ activities in media stored in either container were more pronounced due to chemisorption (but) not diffusion. The following factors affecting the removal of mercurials from aqueous solution stored in glass were examined: type and concentration of adsorbent (fiber glass and rubber powder); pH; pretreatment of the rubber; and the form of mercury used. Rubber was equally effective in the adsorption of organic and inorganic mercury. The pH of the aqueous 203Hg2+ solution was not a critical factor in the rate of adsorption of mercury by the rubber. In addition, the effect of soaking the rubber in water for 18 hr did not show any statistical difference when compared with nontreated rubber. It can be concluded that rubber is a very effective adsorbent of mercury and, thus, can be used as a simple method for control of mercury pollution.

  10. Mercury and Your Health

    MedlinePlus

    ... the Risk of Exposure to Mercury Learn About Mercury What is Mercury What is Metallic mercury? Toxicological Profile ToxFAQs Mercury Resources CDC’s National Biomonitoring Program Factsheet on Mercury ...

  11. Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria.

    PubMed

    Kis, Mariann; Sipka, Gábor; Maróti, Péter

    2017-03-04

    Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism (1) has two kinetically distinguishable components, (2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca(2+) channel blockers, (3) shows complex pH dependence demonstrating the competition of ligand binding of Hg(II) ions with H(+) ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH), and (4) is not a passive but an energy-dependent process as evidenced by light activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 10(5)) greater than their own masses by well-defined strong and weak binding sites with equilibrium binding constants in the range of 1 (μM)(-1) and 1 (mM)(-1), respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g., Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as a sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury-contaminated aqueous cultures.

  12. [Mercury poisoning].

    PubMed

    Bensefa-Colas, L; Andujar, P; Descatha, A

    2011-07-01

    Mercury is a widespread heavy metal with potential severe impacts on human health. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds. This article aims to reviewing and synthesizing the main knowledge of the mercury toxicity and its organic compounds that clinicians should know. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases, whereas chronic inhalation rather induces neurological or renal disorders (encephalopathy and interstitial or glomerular nephritis). Methylmercury poisonings from intoxicated food occurred among some populations resulting in neurological disorders and developmental troubles for children exposed in utero. Treatment using chelating agents is recommended in case of symptomatic acute mercury intoxication; sometimes it improves the clinical effects of chronic mercury poisoning. Although it is currently rare to encounter situations of severe intoxication, efforts remain necessary to decrease the mercury concentration in the environment and to reduce risk on human health due to low level exposure (dental amalgam, fish contamination by organic mercury compounds…). In case of occupational exposure to mercury and its compounds, some disorders could be compensated in France. Clinicians should work with toxicologists for the diagnosis and treatment of mercury intoxication.

  13. A first-principles study of Hg adsorption on Pd(1 1 1) and Pd/γ-Al2O3(1 1 0) surfaces

    NASA Astrophysics Data System (ADS)

    Geng, Lu; Han, Lina; Cen, Wanglai; Wang, Jiancheng; Chang, Liping; Kong, Dejin; Feng, Gang

    2014-12-01

    Spin-polarized density functional theory calculations were carried out to investigate the adsorption of Hgn (n = 1-3) on the perfect, step and vacancy-defective Pd(1 1 1) surfaces as well as the Pd/γ-Al2O3(1 1 0) surface. It is found that Hg atoms prefer to adsorb on the hollow sites on Pd(1 1 1) surfaces. The adsorption of Hg on the step and vacancy-defective Pd(1 1 1) surfaces is stronger than on the perfect Pd(1 1 1) surface, which indicates that the existence of vacancy and step defects can enhance the mercury adsorption activity of Pd adsorbents. As indicated by the calculated adsorption energies, the mercury adsorption on γ-Al2O3 is weak. The γ-Al2O3 supported single Pd atom shows as good Hg adsorption activity as the perfect Pd(1 1 1) surface at low Hg coverage, while more coordination unsaturated active Pd atoms is needed to achieve high Hg adsorption capacity. In addition, it was also found that the Hg adsorption on Pd/γ-Al2O3 weakens the binding of Pd to the γ-Al2O3 surface.

  14. Reduction of mercury, copper, nickel, cadmium, and zinc levels in solution by competitive adsorption onto peanut hulls, and raw and aged bark.

    PubMed

    Henderson, R W; Andrews, D S; Lightsey, G R; Poonawala, N A

    1977-03-01

    The competitive adsorption of common heavy metal ions by peanut hulls, raw bark, and composted bark was studied. These solid wastes were found to adsorb significant amounts of one or more of the heavy metals (Hg, Cu, Ni, Cd, Zn) commonly found in municipal sludge and wastewater.

  15. Adsorption of Ag, Cu and Hg from aqueous solutions using expanded perlite.

    PubMed

    Ghassabzadeh, Hamid; Mohadespour, Ahmad; Torab-Mostaedi, Meisam; Zaheri, Parisa; Maragheh, Mohammad Ghannadi; Taheri, Hossein

    2010-05-15

    The aim of the present work was to investigate the ability of expanded perlite (EP) to remove of silver, copper and mercury ions from aqueous solutions. Batch adsorption experiments were carried out and the effect of pH, adsorbent dosage, contact time and temperature of solution on the removal process has been investigated. The optimum pH for the adsorption was found to be 6.5. Adsorption of these metal ions reached their equilibrium concentration in 120, 240 and 180 min for Ag (I), Cu (II) and Hg (II) ions, respectively. Experimental data were also evaluated in terms of kinetic characteristics of adsorption and it was found that adsorption process for these metal ions followed well pseudo-second-order kinetics. Using Langmuir isotherm model, maximum adsorption capacity of EP was found to be 8.46, 1.95 and 0.35 mg/g for Ag (I), Cu (II) and Hg (II) ions, respectively. Finally, the thermodynamic parameters including, the change of free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) of adsorption were calculated for each metal ion. The results showed that the adsorption of these metal ions on EP was feasible and exothermic at 20-50 degrees C.

  16. Preparation, characterization, and application of modified chitosan sorbents for elemental mercury removal

    SciTech Connect

    Zhang, A.C.; Xiang, J.; Sun, L.S.; Hu, S.; Li, P.S.; Shi, J.M.; Fu, P.; Su, S.

    2009-05-15

    A series of raw, iodine (bromide) or/and sulfuric acid-modified chitosan sorbents were synthesized and comprehensively characterized by N{sub 2} isotherm adsorption/desorption method, TGA, FTIR, XRD, and XPS et al. Adsorption experiments of vapor-phase elemental mercury (Hg{sup 0}) were studied using the sorbents in a laboratory-scale fixed-bed reactor. The results revealed that porosities and specific surface areas of the sorbents decreased after modification. The sorbents operated stably at flue-gas temperature below 140{sup o}C. The chemical reactions of iodine and sulfate ion with the amide of chitosan occurred, and the I{sub 2} was found in the sorbents due to the presence of H{sub 2}SO{sub 4}. Fixed-bed adsorber tests showed that compared to raw chitosan, the bromide or iodine-modified chitosan could promote the efficiency of Hg{sub 0} capture more or less. Mercury removal efficiency could be significantly promoted when an appropriate content of H{sub 2}SO{sub 4} was added, and the iodine and H{sub 2}SO{sub 4} modified sorbents almost had a mercury removal efficiency of 100% for 3 h. The presence of moisture can increase the sorbent's capacity for mercury uptake due to the existence of active sites, such as sulfonate and amino group. The mercury breakthrough of modified chitosan sorbents decreased with increasing temperature. A reaction scheme that could explain the experimental results was presumed based on the characterizations and adsorption study.

  17. Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

    NASA Astrophysics Data System (ADS)

    Bao, Shuangyou; Li, Kai; Ning, Ping; Peng, Jinhui; Jin, Xu; Tang, Lihong

    2017-01-01

    A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R2 > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5-6 and 6-7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298-318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.

  18. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  19. Enhancement of the adsorption capacity of the light-weight expanded clay aggregate surface for the metronidazole antibiotic by coating with MgO nanoparticles: Studies on the kinetic, isotherm, and effects of environmental parameters.

    PubMed

    Kalhori, Ebrahim Mohammadi; Al-Musawi, Tariq J; Ghahramani, Esmaeil; Kazemian, Hossein; Zarrabi, Mansur

    2017-02-09

    The synthesized MgO nanoparticles were used to coat the light-weight expanded clay aggregates (LECA) and as a metronidazole (MNZ) adsorbent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transformed infrared (FTIR) techniques were employed to study the surface morphology and characteristics of the adsorbents. MgO/LECA clearly revealed the advantages of the nanocomposite particles, showing high specific surface area (76.12 m(2)/g), significant adsorption sites and functional groups. Between pH 5 and 9, the MNZ sorption was not significantly affected. Kinetic studies revealed that the MNZ adsorption closely followed the Avrami model, with no dominant process controlling the sorption rate. The study of the effects of foreign ions revealed that the addition of carbonate raised the MNZ removal efficiency of LECA by 8% and the total removal of MNZ by MgO/LECA. Furthermore, nitrate and hardness only marginally influenced the MNZ removal efficiency and their effects can be ranked in the order of carbonate>nitrate>hardness. The isotherm adsorption of MNZ was best fitted with the Langmuir model enlighten the monolayer MNZ adsorption on the homogeneous LECA and MgO/LECA surfaces. The maximum adsorption capacity under optimum conditions was enhanced from 56.31 to 84.55 mg/g for LECA and MgO/LECA, respectively. These findings demonstrated that the MgO/LECA nanocomposite showed potential as an efficient adsorbent for MNZ removal.

  20. Adsorption of peptide nucleic acid and DNA decamers at electrically charged surfaces.

    PubMed Central

    Fojta, M; Vetterl, V; Tomschik, M; Jelen, F; Nielsen, P; Wang, J; Palecek, E

    1997-01-01

    Adsorption behavior of peptide nucleic acid (PNA) and DNA decamers (GTAGATCACT and the complementary sequence) on a mercury surface was studied by means of AC impedance measurements at a hanging mercury drop electrode. The nucleic acid was first attached to the electrode by adsorption from a 5-microliter drop of PNA (or DNA) solution, and the electrode with the adsorbed nucleic acid layer was then washed and immersed in the blank background electrolyte where the differential capacity C of the electrode double layer was measured as a function of the applied potential E. It was found that the adsorption behavior of the PNA with an electrically neutral backbone differs greatly from that of the DNA (with a negatively charged backbone), whereas the DNA-PNA hybrid shows intermediate behavior. At higher surface coverage PNA molecules associate at the surface, and the minimum value of C is shifted to negative potentials because of intermolecular interactions of PNA at the surface. Prolonged exposure of PNA to highly negative potentials does not result in PNA desorption, whereas almost all of the DNA is removed from the surface at these potentials. Adsorption of PNA decreases with increasing NaCl concentration in the range from 0 to 50 mM NaCl, in contrast to DNA, the adsorption of which increases under the same conditions. PMID:9129832

  1. Adsorption kinetics, thermodynamics and isotherm of Hg(II) from aqueous solutions using buckwheat hulls from Jiaodong of China.

    PubMed

    Wang, Zengdi; Yin, Ping; Qu, Rongjun; Chen, Hou; Wang, Chunhua; Ren, Shuhua

    2013-02-15

    The adsorption kinetics and adsorption isotherms of buckwheat hulls in the region of Jiaodong, China (BHJC) for Hg(II) were investigated. Results revealed that the adsorption kinetics of BHJC for Hg(II) were well described by a pseudo second-order reaction model, and the adsorption thermodynamic parameters ΔG, ΔH and ΔS were -5.83 kJ mol(-1)(35°C), 73.1, and 256 JK(-1) mol(-1), respectively. Moreover, Langmuir, Freundlich and Redlich-Peterson isotherm models were applied to analyse the experimental data and to predict the relevant isotherm parameters. The best interpretation for the experimental data was given by the Langmuir isotherm equation, and the maximum adsorption capacity for Hg(II) is 243.90 mg/g at 35°C. Furthermore, investigation of the adsorption selectivity showed that BHJC displayed strong affinity for mercury in the aqueous solutions and exhibited 100% selectivity for mercury in the presence of Zn(II) and Cd(II).

  2. Mercury emissions control technologies for mixed waste thermal treatment

    SciTech Connect

    Chambers, A.; Knecht, M.; Soelberg, N.; Eaton, D.; Roberts, D.; Broderick, T.

    1997-12-31

    EPA has identified wet scrubbing at low mercury feedrates, as well as carbon adsorption via carbon injection into the offgas or via flow through fixed carbon beds, as control technologies that can be used to meet the proposed Maximum Achievable Control Technology (MACT) rule limit for mercury emissions from hazardous waste incinerators. DOE is currently funding demonstrations of gold amalgamation that may also control mercury to the desired levels. Performance data from a variety of sources was reviewed to determine ranges of achievable mercury control. Preliminary costs were estimated for using these technologies to control mercury emissions from mixed waste incineration. Mercury emissions control for mixed waste incineration may need to be more efficient than for incineration of other hazardous wastes because of higher mercury concentrations in some mixed waste streams. However, mercury control performance data for wet scrubbing and carbon adsorption is highly variable. More information is needed to demonstrate control efficiencies that are achievable under various design and operating conditions for wet scrubbing, carbon adsorption, and gold amalgamation technologies. Given certain assumptions made in this study, capital costs, operating costs, and lifecycle costs for carbon injection, carbon beds, and gold amalgamation generally vary for different assumed mercury feedrates and for different offgas flowrates. Assuming that these technologies can in fact provide the necessary mercury control performance, each of these technologies may be less costly than the others for certain mercury feedrates and the offgas flowrates.

  3. Construction and evaluation of a flow-through cell adapted to a commercial static mercury drop electrode (SMDE) to study the adsorption of Cd(II) and Pb(II) on vermiculite.

    PubMed

    Abate, Gilberto; Lichtig, Jaim; Masini, Jorge C

    2002-09-12

    This paper describes the construction and application of a robust flow-through cell for use with the capillary of a commercial static mercury drop electrode. Linearity of peak current was observed up to 0.50 mumol l(-1) for Cd(II) or Pb(II) in anodic stripping voltammetry experiments performed under continuous flow during the deposition step, using 120 s of deposition time and flow rate of 4.0 ml min(-1). Under these conditions the limits of detection for Cd(II) and Pb(II) were 13 and 17 nmol l(-1), respectively. An analytical throughput of 20 analyses per h was possible using 10 s for cleaning the cell between two samples and including the time needed for the potential scan, which was performed with the flow stopped, using the differential pulse mode for current sampling. The linear dynamic range can be extended up to 5 mumol l(-1) for both cations if the deposition time is decreased to 30 s, a condition in which the sampling throughput is 35 analyses per h. The proposed manifold was used to study the adsorption rates of Cd(II) and Pb(II) onto vermiculite at different pHs, allowing one to perform high sensitivity measurements at high sampling frequency, using low cost instrumentation.

  4. Preconcentration of total mercury from river water by anion exchange mechanism.

    PubMed

    Daye, Mirna; Ouddane, Baghdad; Halwani, Jalal; Hamze, Mariam

    2013-01-01

    A simple and cheap analytical technique was developed for the measurement of total mercury in river water samples using inductively coupled plasma-mass spectrometry (ICP-MS). It is based on the direct complexation of mercury ions using iodide and a cationic surfactant in water for its subsequent solid-phase extraction. Mercury ions are retained on the silica phase as ion pairs in the presence of iodide ions and dodecyltrimethylammonium bromide. Parameters having influential influence on the retention of Hg(II) were investigated: sample flowrate, eluent type, sample volume, iodide and surfactant concentrations. The retained mercury ions are stripped off from silica phase using 10 mL of 8 mol L(-1) HNO3 and quantified by ICP-MS. An enrichment factor of 50 was achieved with a maximum adsorption capacity of 718 μg Hg(II) g(-1). The limit of detection of Hg(II) was 8 pg mL(-1). The developed method was applied for the determination of total mercury in river and tap-water samples.

  5. COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACOUES SURFACES

    SciTech Connect

    Radisav D. Vidic

    2002-05-01

    The first part of this study evaluated the application of a versatile optical technique to study the adsorption and desorption of model adsorbates representative of volatile polar (acetone) and non-polar (propane) organic compounds on a model carbonaceous surface under ultra high vacuum (UHV) conditions. The results showed the strong correlation between optical differential reflectance (ODR) and adsorbate coverage determined by temperature programmed desorption (TPD). ODR technique was proved to be a powerful tool to investigate surface adsorption and desorption from UHV to high pressure conditions. The effects of chemical functionality and surface morphology on the adsorption/desorption behavior of acetone, propane and mercury were investigated for two model carbonaceous surfaces, namely air-cleaved highly oriented pyrolytic graphite (HOPG) and plasma-oxidized HOPG. They can be removed by thermal treatment (> 500 K). The presence of these groups almost completely suppresses propane adsorption at 90K and removal of these groups leads to dramatic increase in adsorption capacity. The amount of acetone adsorbed is independent of surface heat treatment and depends only on total exposure. The effects of morphological heterogeneity is evident for plasma-oxidized HOPG as this substrate provides greater surface area, as well as higher energy binding sites. Mercury adsorption at 100 K on HOPG surfaces with and without chemical functionalities and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from HOPG surface enhances mercury physisorption. Plasma oxidation of HOPG provides additional surface area for mercury adsorption. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms, physisorption below 348 K and chemisorption above 348 K. No significant impact of oxygen functionalities was observed in the chemisorption region. The key findings of this study

  6. Bone char surface modification by nano-gold coating for elemental mercury vapor removal

    NASA Astrophysics Data System (ADS)

    Assari, Mohamad javad; Rezaee, Abbas; Rangkooy, Hossinali

    2015-07-01

    The present work was done to develop a novel nanocomposite using bone char coated with nano-gold for capture of elemental mercury (Hg0) from air. The morphologies, structures, and chemical constitute of the prepared nanocomposite were evaluated by UV-VIS-NIR, dynamic light-scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, and energy dispersive X-ray spectroscopy (EDS). The capture performance of nanocomposite was evaluated in a needle trap for mercury vapor. An on-line setup based on cold vapor atomic absorption spectrometry (CVAAS) was designed for Hg0 determination. Dynamic capacity of nanocomposite for Hg0 was shown high efficient operating capacity of 586.7 μg/g. As temperature increases, the dynamic adsorption capacity of the nanocomposite was decreased, which are characteristics of physicosorption processes. It was found that the surface modification of bone char with nano-gold has various advantages such as high operating dynamic adsorption capacity and low cost preparation. It was also demonstrated that the developed nanocomposite is suitable for on-line monitoring of Hg0. It could be applied for the laboratory and field studies.

  7. Sulfathiazole-based novel UV-cured hydrogel sorbents for mercury removal from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Yetimoğlu, Ece Kök; Kahraman, Memet Vezir; Bayramoğlu, Gülay; Ercan, Özgen; Apohan, Nilhan Kayaman

    2009-02-01

    Sulfathiazole-based novel hydrogel sorbents P(Sulti/hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc)) were prepared by UV irradiation and used for the removal of mercury(II) ion from aqueous media. Hydrogels have been characterized by SEM and thermogravimetric analysis (TGA) techniques. The influence of the uptake conditions was investigated; maximum Hg(II) ion adsorption capacity obtained was 13.46±1.15 mg g -1 at pH 5.0. The hydrogels were tested several times without loss of adsorption capacity. The selectivity of the hydrogel towards to Hg(II), Cd(II) and Zn(II) ions tested was Hg>Cd>Zn.

  8. Electronic storage capacity of ceria: role of peroxide in Aux supported on CeO2(111) facet and CO adsorption.

    PubMed

    Liu, Yinli; Li, Huiying; Yu, Jun; Mao, Dongsen; Lu, Guanzhong

    2015-11-07

    Density functional theory (DFT+U) was used to study the adsorption of Aux (x = 1-4) clusters on the defective CeO2(111) facet and CO adsorption on the corresponding Aux/CeO2-x catalyst, in this work Aux clusters are adsorbed onto the CeO2-x + superoxide/peroxide surface. When Au1 is supported on the CeO2(111) facet with an O vacancy, the strong electronegative Au(δ-) formed is not favorable for CO adsorption. When peroxide is adsorbed on the CeO2(111) facet with the O vacancy, Aux was oxidized, resulting in stable Aux adsorption on the defective ceria surface with peroxide, which promotes CO adsorption on the Aux/CeO2-x catalyst. With more Au atoms in supported Aux clusters, CO adsorption on this surface becomes stronger. During both the Au being supported on CeO2-x and CO being adsorbed on Aux/CeO2-x, CeO2 acts as an electron buffer that can store/release the electrons. These results provide a scientific understanding for the development of high-performance rare earth catalytic materials.

  9. Potential anthropogenic mobilisation of mercury and arsenic from soils on mineralised rocks, Northland, New Zealand.

    PubMed

    Craw, D

    2005-02-01

    Eroded roots of hot spring systems in Northland, New Zealand consist of mineralised rocks containing sulfide minerals. Marcasite and cinnabar are the dominant sulfides with subordinate pyrite. Deep weathering and leached soil formation has occurred in a warm temperate to subtropical climate with up to 3 m/year rainfall. Decomposition of the iron sulfides in natural and anthropogenic rock exposures yields acid rock drainage with pH typically between 2 and 4, and locally down to pH 1. Soils and weathered rocks developed on basement greywacke have negligible acid neutralisation capacity. Natural rainforest soils have pH between 4 and 5 on unmineralised greywacke, and pH is as low as 3.5 in soils on mineralised rocks. Roads with aggregate made from mineralised rocks have pH near 3, and quarries from which the rock was extracted can have pH down to 1. Mineralised rocks are enriched in arsenic and mercury, both of which are environmentally available as solid solution impurities in iron sulfides and phosphate minerals. Base metals (Cu, Pb, Zn) are present at low levels in soils, at or below typical basement rock background. Decomposition of the iron sulfides releases the solid solution arsenic and mercury into the acid rock drainage solutions. Phosphate minerals release their impurities only under strongly acid conditions (pH<1). Arsenic and mercury are adsorbed on to iron oxyhydroxides in soils, concentrated in the C horizon, with up to 4000 ppm arsenic and 100 ppm mercury. Waters emanating from acid rock drainage areas have arsenic and mercury below drinking water limits. Leaching experiments and theoretical predictions indicate that both arsenic and mercury are least mobile in acid soils, at pH of c. 3-4. This optimum pH range for fixation of arsenic and mercury on iron oxyhydroxides in soils is similar to natural pH at the field site of this study. However, neutralisation of acid soils developed on mineralised rocks is likely to decrease adsorption and enhance

  10. Insights into the adsorption capacity and breakthrough properties of a synthetic zeolite against a mixture of various sulfur species at low ppb levels.

    PubMed

    Vellingiri, Kowsalya; Kim, Ki-Hyun; Kwon, Eilhann E; Deep, Akash; Jo, Sang-Hee; Szulejko, Jan E

    2016-01-15

    The sorptive removal properties of a synthetic A4 zeolite were evaluated against sulfur dioxide (SO2) and four reference reduced sulfur compounds (RSC: hydrogen sulfide (H2S), methanethiol (CH3SH), dimethyl sulfide (DMS, (CH3)2S), and dimethyl disulfide (DMDS, CH3SSCH3). To this end, a sorbent bed of untreated (as-received) A4 zeolite was loaded with gaseous standards at four concentration levels (10-100 part-per-billion (ppb (v/v)) at four different volumes (0.1, 0.2, 0.5, and 1 L increments) in both increasing (IO: 0.1-1.0 L) and decreasing volume order (DO: 1.0 to 0.1 L). Morphological properties were characterized by PXRD, FTIR, and BET analysis. The removal efficiency of SO2 decreased from 100% for all concentrations at 0.1 L (initial sample volume) to ∼82% (100 ppb) or ∼96% (10 ppb) at 3.6 L. In contrast, removal efficiency of RSC was near 100% at small loading volumes but then fell sharply, irrespective of concentration (10-100 ppb) (e.g., 32% (DMS) to 52% (H2S) at 100 ppb). The adsorption capacity of zeolite, if expressed in terms of solid-gas partition coefficient (e.g., similar to the Henry's law constant (mmol kg(-1) Pa(-1))), showed moderate variabilities with the standard concentration levels and S compound types such as the minimum of 2.03 for CH3SH (at 20 ppb) to the maximum of 13.9 for SO2 (at 10 ppb). It clearly demonstrated a notable distinction in the removal efficiency of A4 zeolite among the different S species in a mixture with enhanced removal efficiency of SO2 compared to the RSCs.

  11. Development of Nano-Sulfide Sorbent for Efficient Removal of Elemental Mercury from Coal Combustion Fuel Gas.

    PubMed

    Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Shih, Kaimin

    2016-09-06

    The surface area of zinc sulfide (ZnS) was successfully enlarged using nanostructure particles synthesized by a liquid-phase precipitation method. The ZnS with the highest surface area (named Nano-ZnS) of 196.1 m(2)·g(-1) was then used to remove gas-phase elemental mercury (Hg(0)) from simulated coal combustion fuel gas at relatively high temperatures (140 to 260 °C). The Nano-ZnS exhibited far greater Hg(0) adsorption capacity than the conventional bulk ZnS sorbent due to the abundance of surface sulfur sites, which have a high binding affinity for Hg(0). Hg(0) was first physically adsorbed on the sorbent surface and then reacted with the adjacent surface sulfur to form the most stable mercury compound, HgS, which was confirmed by X-ray photoelectron spectroscopy analysis and a temperature-programmed desorption test. At the optimal temperature of 180 °C, the equilibrium Hg(0) adsorption capacity of the Nano-ZnS (inlet Hg(0) concentration of 65.0 μg·m(-3)) was greater than 497.84 μg·g(-1). Compared with several commercial activated carbons used exclusively for gas-phase mercury removal, the Nano-ZnS was superior in both Hg(0) adsorption capacity and adsorption rate. With this excellent Hg(0) removal performance, noncarbon Nano-ZnS may prove to be an advantageous alternative to activated carbon for Hg(0) removal in power plants equipped with particulate matter control devices, while also offering a means of reusing fly ash as a valuable resource, for example as a concrete additive.

  12. Efficient removal of mercury from aqueous solutions and industrial effluent.

    PubMed

    Dos Santos, Maria B P; Leal, Katia Z; Oliveira, Fernando J S; Sella, Silvia M; Vieira, Méri D; Marques, Elisa M D; Gomes, Vanessa A C

    2015-01-01

    The objective of this study was to examine the ability of a solid waste produced during beneficiation of ornamental rocks to remove mercury (Hg) from an industrial effluent and aqueous solutions under various conditions. Batch studies have been carried out by observing the effects of pH, concentration of the adsorbate, contact time, and so on. Various sorption isotherm models such as Langmuir, Freundlich, and Tóth have been applied for the adsorbent. Film and intraparticle diffusion were both found to be rate-limiting steps. Adsorption was properly described by the Freundlich model (capacity constant of 0.3090 (mg g(-1))(mg L(-1))(-1/n) and adsorption intensity indicator of 2.2939), which indicated a favorable sorption and encouraged subsequent studies for treatment of Hg-containing industrial effluent. Industrial effluent treatment efficiency reached Hg removals greater than 90% by using ornamental rock solid waste (ORSW). Besides, desorption studies indicated that the maximum recovery of mercury was 100 ± 2% for 1 mol L(-1) HNO3 and 74 ± 8% for 0.1 mol L(-1) HNO3. The ORSW could be reused thrice without significant difference on the Hg removal rate from industrial effluent. These findings place ORSW as a promising efficient and low-cost adsorbent for the removal of Hg from aqueous solutions and industrial effluent.

  13. Mercury emissions from municipal solid waste combustors

    SciTech Connect

    Not Available

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  14. Disposable mercury-free cell-on-a-chip devices with integrated microfabricated electrodes for the determination of trace nickel(II) by adsorptive stripping voltammetry.

    PubMed

    Kokkinos, Christos; Economou, Anastasios; Raptis, Ioannis; Speliotis, Thanassis

    2008-08-01

    This work reports the fabrication of disposable three-electrode cells with integrated sputtered metal-film electrodes. The working electrode was a bismuth-film electrode (BiFE) while the reference and counter electrodes were made of Ag and Pt, respectively. The deposition of the metal layers was carried out by sputtering of the respective metals on a silicon substrate while the exact geometry of the electrodes was defined via a metal mask placed on the substrate during the deposition process. Initially, the electrodes were characterised by cyclic voltammetry. The utility of these devices was tested for the trace determination of Ni(II) by square wave adsorptive stripping voltammetry (SWAdSV) after complexation with dimethylglyoxime (DMG). The experimental variables (the presence of oxygen, the DMG concentration, the preconcentration potential, the accumulation time and the SW parameters), as well as potential interferences, were investigated. Using the selected conditions, the 3sigma limit of detection was 100 ng L(-1) for Ni(II) (for 90 s of preconcentration) and the relative standard deviation for Ni(II) was 2.3% at the 10 microg L(-1) level (n=8). Finally, the method was applied to the determination of Ni(II) in a certified river water sample.

  15. Mercury capture in bench-scale absorbers

    SciTech Connect

    Livengood, C.D.; Huang, H.S.; Mendelsohn, M.H.; Wu, J.M.

    1994-08-01

    This paper gives,a brief overview of research being conducted at Argonne National Laboratory on the capture of mercury by both dry sorbents and wet scrubbers. The emphasis in the research is on development of a better understanding of the key factors that control the capture of mercury. Future work is expected to utilize that information for the development of new or modified process concepts featuring enhanced mercury capture capabilities. The results and conclusions to date from the Argonne -research on dry sorbents can be summarized as follows: lime hydrates, either regular or high-surface-area, are `not effective in removing mercury; mercury removals are enhanced by the addition of activated carbon; mercury removals with activated carbon decrease with increasing temperature, larger particle size, and decreasing mercury concentration in the gas; and chemical pretreatment (e.g., with sulfur or (CaCl{sub 2}) can greatly increase the removal capacity of activated carbon. Preliminary results from the wet scrubbing research include: no removal of elemental mercury is obtained under normal scrubber operating conditions; mercury removal is improved by the addition of packing or production of smaller gas bubbles to increase the gas-liquid contact area; polysulfide solutions do not appear promising for enhancing mercury removal in typical FGC systems; stainless steel packing appears to have beneficial properties for mercury removal and should be investigated further; and other chemical additives may offer greatly enhanced removals.

  16. Biochar from malt spent rootlets for the removal of mercury from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Boutsika, Lamprini; Manariotis, Ioannis; Karapanagioti, Hrissi K.

    2013-04-01

    Biochar is receiving increased attention as a promising material in environmental applications. It is obtained from the incomplete combustion of carbon-rich biomass under oxygen-limited conditions. One of the many proposed applications of biochars is the removal of metals (e.g., lead, mercury, etc.) from aqueous solutions. Mercury is one of the heavy metals of particular concern due to its toxicity even at relatively low concentration and thus, its removal from aqueous systems is desirable. Malt spent rootlets is a by-product formed during beer production, it is inexpensive and it is produced in high quantities. The objective of the present study was to evaluate the potential use of biochar, produced from malt spent rootlets, to remove mercury from aqueous solutions. Batch experiments were conducted at room temperature (25oC) to obtain the optimum sorption conditions under different pH values, biomass dose, contact time, and solution ionic strength. Sorption kinetics and equilibrium capacity constants were determined at the optimum pH value. Furthermore, the effect of different leaching solutions on mercury desorption from the biochar was examined. All studies with mercury and biochar were conducted at pH 5 that was determined to be the optimum pH for sorption. The proportion of mercury removal increased with the increased dose of the biochar, i.e. from 71% removal for biochar dose of 0.3 g/L, it reached almost 100% removal for biochar dose ˜1 g/L. Based on the isotherm data, the maximum biochar sorption capacity (qmax) for mercury was 99 mg/g. Based on the sorption kinetic data, (qmax) was achieved after 2 h; it should be mentioned that 30% of the (qmax) was observed within the first 5 min. Five leaching solutions were tested for mercury desorption (H2O, HCl, EDTA, NaCl and HNO3). HCl resulted in the highest extraction percentage of the sorbed mercury. The desorbing mercury percentages at 24 h for HCl concentrations 0.1, 0.2, 0.4, 0.8, and 2 M were 62, 59, 62, 69

  17. ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR

    EPA Science Inventory


    The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

  18. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal reservoir, California, was measured at 150, 200, and 250 C as a function of pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption (increasing pressure) and desorption (decreasing pressure) runs were made in order to investigate the nature and the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were performed on the same rock samples. Nitrogen or krypton adsorption and desorption isotherms at 77 K were used to obtain BET specific surface areas, pore volumes and their distributions with respect to pore sizes. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there is in general no proportionality between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The results indicate that multilayer adsorption rather than capillary condensation is the dominant water storage mechanism at high temperatures.

  19. Biosorption of mercury by Macrocystis pyrifera and Undaria pinnatifida: influence of zinc, cadmium and nickel.

    PubMed

    Plaza, Josefina; Viera, Marisa; Donati, Edgardo; Guibal, Eric

    2011-01-01

    This study investigated the adsorption of Hg(II) on Macrocystis pyrifera and Undaria pinnatifida in monometallic system in the presence of Zn(II), Cd(II) and Ni(II). The two biosorbents reached the same maximum sorption capacity (q(m) = 0.8 mmol/g) for mercury. U. pinnatifida showed a greater affinity (given by the coefficient b of the Langmuir equation) for mercury compared to M. pyrifera (4.4 versus 2.7 L/mmol). Mercury uptake was significantly reduced (by more than 50%) in the presence of competitor heavy metals such as Zn(II), Cd(II) and Ni(II). Samples analysis using an environmental scanning electron microscopy equipped with an energy dispersive X-ray microanalysis showed that mercury was heterogeneously adsorbed on the surface of both biomaterials, while the other heavy metals were homogeneous distributed. The analysis of biosorbents by Fourier transform infrared spectrometry indicated that Hg(II) binding occurred on S = O (sulfonate) and N-H (amine) functional groups.

  20. 2-Mercaptothiazoline modified mesoporous silica for mercury removal from aqueous media.

    PubMed

    Pérez-Quintanilla, Damián; del Hierro, Isabel; Fajardo, Mariano; Sierra, Isabel

    2006-06-30

    Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl-SBA-15 or Cl-MCM-41. In a second step a multifunctionalized N, S donor compound (2-mercaptothiazoline, MTZ) was incorporated to obtain the functionalized silicas denoted as MTZ-SBA-15-Het or MTZ-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MTZ-SBA-15-Hom or MTZ-MCM-41-Hom. The functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg (II) at room temperature. SBA-15 and MCM-41 functionalized with MTZ by the homogeneous method present good mercury adsorption values (1.10 and 0.7mmolHg (II)/g of silica, respectively). This fact suggests a better applicability of such mesoporous silica supports to extract Hg (II) from aqueous solutions. In addition, it was observed the existence of a correlation between mercury adsorption with pore size and volume since, SBA-15 with lower areas and higher pore sizes functionalized with sterically demanding ligands, show better adsorption capacities than functionalized MCM-41.

  1. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie; James, John T.; McCoy, Torin; Garcia, Hector

    2010-01-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.

  2. Removal of elemental mercury by iodine-modified rice husk ash sorbents.

    PubMed

    Zhao, Pengfei; Guo, Xin; Zheng, Chuguang

    2010-01-01

    Iodine-modified calcium-based rice husk ash sorbents (I2/CaO/RHA) were synthesized and characterized by X-ray diffraction, X-ray fluorescence, and N2 isotherm adsorption/desorption. Adsorption experiments of vapor-phase elemental mercury (Hg0) were performed in a laboratory-scale fixed-bed reactor. I2/CaO/RHA performances on Hg0 adsorption were compared with those of modified Ca-based fly ash sorbents (I2/CaO/FA) and modified fly ash sorbents (I2/FA). Effects of oxidant loading, supports, pore size distribution, iodine impregnation modes, and temperature were investigated as well to understand the mechanism in capturing Hg0. The modified sorbents exhibited reasonable efficiency for Hg0 removal under simulated flue gas. The surface area, pore size distribution, and iodine impregnation modes of the sorbents did not produce a strong effect on Hg0 capture efficiency, while fair correlation was observed between Hg0 uptake capacity and iodine concentration. Therefore, the content of I2 impregnated on the sorbents was identified as the most important factor influencing the capacity of these sorbents for Hg0 uptake. Increasing temperature in the range of 80-140 degrees C caused a rise in Hg0 removal. A reaction mechanism that may explain the experimental results was presumed based on the characterizations and adsorption study.

  3. Mercury control in 2009

    SciTech Connect

    Sjostrom, S.; Durham, M.; Bustard, J.; Martin, C.

    2009-07-15

    Although activated carbon injection (ACI) has been proven to be effective for many configurations and is a preferred option at many plants sufficient quantities of powdered activated coking (PAC) must be available to meet future needs. The authors estimate that upcoming federal and state regulations will result in tripling the annual US demand for activated carbon to nearly 1.5 billion lb from approximately 450 million lb. Rapid expansion of US production capacity is required. Many PAC manufacturers are discussing expansion of their existing production capabilities. One company, ADA Carbon Solutions, is in the process of constructing the largest activated carbon facility in North America to meet the future demand for PAC as a sorbent for mercury control. Emission control technology development and commercialization is driven by regulation and legislation. Although ACI will not achieve > 90% mercury control at every plant, the expected required MACT legislation level, it offers promise as a low-cost primary mercury control technology option for many configurations and an important trim technology for others. ACI has emerged as the clear mercury-specific control option of choice, representing over 98% of the commercial mercury control system orders to date. As state regulations are implemented and the potential for a federal rule becomes more imminent, suppliers are continuing to develop technologies to improve the cost effectiveness and limit the balance of plant impacts associated with ACI and are developing additional PAC production capabilities to ensure that the industry's needs are met. The commercialisation of ACI is a clear example of industry, through the dedication of many individuals and companies with support from the DOE and EPRI, meeting the challenge of developing cost-effectively reducing emissions from coal-fired power plants. 7 refs., 1 fig.

  4. Effect of functionalized groups on gas-adsorption properties: syntheses of functionalized microporous metal-organic frameworks and their high gas-storage capacity.

    PubMed

    Wang, Yanlong; Tan, Chunhong; Sun, Zhihao; Xue, Zhenzhen; Zhu, Qilong; Shen, Chaojun; Wen, Yuehong; Hu, Shengmin; Wang, Yong; Sheng, Tianlu; Wu, Xintao

    2014-01-27

    The microporous metal-organic framework (MMOF) Zn4O(L1)2⋅9 DMF⋅9 H2O (1-H) and its functionalized derivatives Zn4O(L1-CH3)2⋅9 DMF⋅9 H2O (2-CH3) and Zn4O(L1-Cl)2⋅9 DMF⋅9 H2O (3-Cl) have been synthesized and characterized (H3L1=4-[N,N-bis(4-methylbenzoic acid)amino]benzoic acid, H3L1-CH3=4-[N,N-bis(4-methylbenzoic acid)amino]-2-methylbenzoic acid, H3L1-Cl=4-[N,N-bis(4-methylbenzoic acid)amino]-2-chlorobenzoic acid). Single-crystal X-ray diffraction analyses confirmed that the two functionalized MMOFs are isostructural to their parent MMOF, and are twofold interpenetrated three-dimensional (3D) microporous frameworks. All of the samples possess enduring porosity with Langmuir surface areas over 1950 cm(2) g(-1). Their pore volumes and surface areas decrease in the order 1-H>2-CH3 >3-Cl. Gas-adsorption studies show that the H2 uptakes of these samples are among the highest of the MMOFs (2.37 wt% for 3-Cl at 77 K and 1 bar), although their structures are interpenetrating. Furthermore, this work reveals that the adsorbate-adsorbent interaction plays a more important role in the gas-adsorption properties of these samples at low pressure, whereas the effects of the pore volumes and surface areas dominate the gas-adsorption properties at high pressure.

  5. Determination of binding capacity and adsorption enthalpy between Human Glutamate Receptor (GluR1) peptide fragments and kynurenic acid by surface plasmon resonance experiments.

    PubMed

    Csapó, E; Majláth, Z; Juhász, Á; Roósz, B; Hetényi, A; Tóth, G K; Tajti, J; Vécsei, L; Dékány, I

    2014-11-01

    The interaction between kynurenic acid (KYNA) and two peptide fragments (ca. 30 residues) of Human Glutamate Receptor 201-300 (GluR1) using surface plasmon resonance (SPR) spectroscopy was investigated. Because of the medical interest in the neuroscience, GluR1 is one of the important subunits of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR). AMPARs are ionotoropic glutamate receptors, which are mediating fast synaptic transmission and are crucial for plasticity in the brain. On the other hand, KYNA has been suggested to have neuroprotective activity and it has been considered for apply in therapy in certain neurobiological disorders. In this article the adsorption of the GluR1201-230 and GluR1231-259 peptides were studied on gold biosensor chip. The peptides were chemically bonded onto the gold surface via thiol group of L-cysteine resulted in the formation of peptide monolayer on the SPR chip surface. Because the GluR1231-259 peptide does not contain L-cysteine the Val256 was replaced by Cys256. The cross sectional area and the surface orientation of the studied peptides were determined by SPR and theoretical calculations (LOMETS) as well. The binding capability of KYNA on the peptide monolayer was studied in the concentration range of 0.1-5.0 mM using 150 mM NaCl ionic strength at pH 7.4 (±0.02) in phosphate buffer solutions. In order to determine the binding enthalpy the experiments were carried out between +10°C and +40°C. The heat of adsorption was calculated by using adsorption isotherms at different surface loading of KYNA on the SPR chip.

  6. Modeling mercury porosimetry using statistical mechanics.

    PubMed

    Porcheron, F; Monson, P A; Thommes, M

    2004-07-20

    We consider mercury porosimetry from the perspective of the statistical thermodynamics of penetration of a nonwetting liquid into a porous material under an external pressure. We apply density functional theory to a lattice gas model of the system and use this to compute intrusion/extrusion curves. We focus on the specific example of a Vycor glass and show that essential features of mercury porosimetry experiments can be modeled in this way. The lattice model exhibits a symmetry that provides a direct relationship between intrusion/extrusion curves for a nonwetting fluid and adsorption/desorption isotherms for a wetting fluid. This relationship clarifies the status of methods that are used for transforming mercury intrusion/extrusion curves into gas adsorption/desorption isotherms. We also use Monte Carlo simulations to investigate the nature of the intrusion and extrusion processes.

  7. Oxidation of Mercury in Products of Coal Combustion

    SciTech Connect

    Peter Walsh; Giang Tong; Neeles Bhopatkar; Thomas Gale; George Blankenship; Conrad Ingram; Selasi Blavo Tesfamariam Mehreteab; Victor Banjoko; Yohannes Ghirmazion; Heng Ban; April Sibley

    2009-09-14

    Laboratory measurements of mercury oxidation during selective catalytic reduction (SCR) of nitric oxide, simulation of pilot-scale measurements of mercury oxidation and adsorption by unburned carbon and fly ash, and synthesis of new materials for simultaneous oxidation and adsorption of mercury, were performed in support of the development of technology for control of mercury emissions from coal-fired boilers and furnaces. Conversion of gas-phase mercury from the elemental state to water-soluble oxidized form (HgCl{sub 2}) enables removal of mercury during wet flue gas desulfurization. The increase in mercury oxidation in a monolithic V{sub 2}O{sub 5}-WO{sub 3}/TiO{sub 2} SCR catalyst with increasing HCl at low levels of HCl (< 10 ppmv) and decrease in mercury oxidation with increasing NH{sub 3}/NO ratio during SCR were consistent with results of previous work by others. The most significant finding of the present work was the inhibition of mercury oxidation in the presence of CO during SCR of NO at low levels of HCl. In the presence of 2 ppmv HCl, expected in combustion products from some Powder River Basin coals, an increase in CO from 0 to 50 ppmv reduced the extent of mercury oxidation from 24 {+-} 3 to 1 {+-} 4%. Further increase in CO to 100 ppmv completely suppressed mercury oxidation. In the presence of 11-12 ppmv HCl, increasing CO from 0 to {approx}120 ppmv reduced mercury oxidation from {approx}70% to 50%. Conversion of SO{sub 2} to sulfate also decreased with increasing NH{sub 3}/NO ratio, but the effects of HCl and CO in flue gas on SO{sub 2} oxidation were unclear. Oxidation and adsorption of mercury by unburned carbon and fly ash enables mercury removal in a particulate control device. A chemical kinetic mechanism consisting of nine homogeneous and heterogeneous reactions for mercury oxidation and removal was developed to interpret pilot-scale measurements of mercury oxidation and adsorption by unburned carbon and fly ash in experiments at pilot

  8. Mercury and autism: accelerating evidence?

    PubMed

    Mutter, Joachim; Naumann, Johannes; Schneider, Rainer; Walach, Harald; Haley, Boyd

    2005-10-01

    The causes of autism and neurodevelopmental disorders are unknown. Genetic and environmental risk factors seem to be involved. Because of an observed increase in autism in the last decades, which parallels cumulative mercury exposure, it was proposed that autism may be in part caused by mercury. We review the evidence for this proposal. Several epidemiological studies failed to find a correlation between mercury exposure through thimerosal, a preservative used in vaccines, and the risk of autism. Recently, it was found that autistic children had a higher mercury exposure during pregnancy due to maternal dental amalgam and thimerosal-containing immunoglobulin shots. It was hypothesized that children with autism have a decreased detoxification capacity due to genetic polymorphism. In vitro, mercury and thimerosal in levels found several days after vaccination inhibit methionine synthetase (MS) by 50%. Normal function of MS is crucial in biochemical steps necessary for brain development, attention and production of glutathione, an important antioxidative and detoxifying agent. Repetitive doses of thimerosal leads to neurobehavioral deteriorations in autoimmune susceptible mice, increased oxidative stress and decreased intracellular levels of glutathione in vitro. Subsequently, autistic children have significantly decreased level of reduced glutathione. Promising treatments of autism involve detoxification of mercury, and supplementation of deficient metabolites.

  9. Preparation of char from lotus seed biomass and the exploration of its dye removal capacity through batch and column adsorption studies.

    PubMed

    Nethaji, S; Sivasamy, A; Kumar, R Vimal; Mandal, A B

    2013-06-01

    Char was obtained from lotus seed biomass by a simple single-step acid treatment process. It was used as an adsorbent for the removal of malachite green dye (MG) from simulated dye bath effluent. The adsorbent was characterized for its surface morphology, surface functionalities, and zero point charge. Batch studies were carried out by varying the parameters such as initial aqueous pH, adsorbent dosage, adsorbent particle size, and initial adsorbate concentration. Langmuir and Freundlich isotherms were used to test the isotherm data and the Freundlich isotherm best fitted the data. Thermodynamic studies were carried out and the thermodynamic parameters such as ∆G, ∆H, and ∆S were evaluated. Adsorption kinetics was carried out and the data were tested with pseudofirst-order model, pseudosecond-order model, and intraparticle diffusion model. Adsorption of MG was not solely by intraparticle diffusion but film diffusion also played a major role. Continuous column experiments were also conducted using microcolumn and the spent adsorbent was regenerated using ethanol and was repeatedly used for three cycles in the column to determine the reusability of the regenerated adsorbent. The column data were modeled with the modeling equations such as Adam-Bohart model, Bed Depth Service Time (BDST) model, and Yoon-Nelson model for all the three cycles.

  10. Mercury removal from coal combustion flue gas by modified fly ash.

    PubMed

    Xu, Wenqing; Wang, Hairui; Zhu, Tingyu; Kuang, Junyan; Jing, Pengfei

    2013-02-01

    Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2, CuCl2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg0) into its oxidized form (Hg2+). Cu2+ and Fe3+ can also promote Hg0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2, CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.

  11. Mercury in mercury(II)-spiked soils is highly susceptible to plant bioaccumulation.

    PubMed

    Hlodák, Michal; Urík, Martin; Matúš, Peter; Kořenková, Lucia

    2016-01-01

    Heavy metal phytotoxicity assessments usually use soluble metal compounds in spiked soils to evaluate metal bioaccumulation, growth inhibition and adverse effects on physiological parameters. However, exampling mercury phytotoxicity for barley (Hordeum vulgare) this paper highlights unsuitability of this experimental approach. Mercury(II) in spiked soils is extremely bioavailable, and there experimentally determined bioaccumulation is significantly higher compared to reported mercury bioaccumulation efficiency from soils collected from mercury-polluted areas. Our results indicate this is not affected by soil sorption capacity, thus soil ageing and formation of more stable mercuric complexes with soil fractions is necessary for reasonable metal phytotoxicity assessments.

  12. Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers.

    PubMed

    Maksin, Danijela D; Nastasović, Aleksandra B; Milutinović-Nikolić, Aleksandra D; Suručić, Ljiljana T; Sandić, Zvjezdana P; Hercigonja, Radmila V; Onjia, Antonije E

    2012-03-30

    Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25-70°C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q(max), at pH 1.8 and 25°C was 143 mg g(-1) for PGME2-deta (sample with the highest amino group concentration) while at 70°C Q(max) reached the high value of 198 mg g(-1). Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta.

  13. JV Task 5 - Evaluation of Residual Oil Fly Ash As A Mercury Sorbent For Coal Combustion Flue Gas

    SciTech Connect

    Robert Patton

    2006-12-31

    The mercury adsorption capacity of a residual oil fly ash (ROFA) sample collected form Florida Power and Light Company's Port Everglades Power Plant was evaluated using a bituminous coal combustion flue gas simulator and fixed-bed testing protocol. A size-segregated (>38 {micro}g) fraction of ROFA was ground to a fine powder and brominated to potentially enhance mercury capture. The ROFA and brominated-ROFA were ineffective in capturing or oxidizing the Hg{sup 0} present in a simulated bituminous coal combustion flue gas. In contrast, a commercially available DARCO{reg_sign} FGD initially adsorbed Hg{sup 0} for about an hour and then catalyzed Hg{sup 0} oxidation to produce Hg{sup 2+}. Apparently, the unburned carbon in ROFA needs to be more rigorously activated in order for it to effectively capture and/or oxidize Hg{sup 0}.

  14. Potential hazards of brominated carbon sorbents for mercury emission control.

    PubMed

    Bisson, Teresa M; Xu, Zhenghe

    2015-02-17

    Mercury is a toxic air pollutant, emitted from the combustion of coal. Activated Carbon (AC) or other carbon sorbent (CS) injection into coal combustion flue gases can remove elemental mercury through an adsorption process. Recently, a brominated CS with biomass ash as the carbon source (Br-Ash) was developed as an alternative for costly AC-based sorbent for mercury capture. After mercury capture, these sorbents are disposed in landfill, and the stability of bromine and captured mercury is of paramount importance. The objective of this study is to determine the fate of mercury and bromine from Br-Ash and brominated AC after their service. Mercury and bromine leaching tests were conducted using the standard toxicity characteristic leaching procedure (TCLP). The mercury was found to be stable on both the Br-Ash and commercial brominated AC sorbents, while the bromine leached into the aqueous phase considerably. Mercury pulse injection tests on the sorbent material after leaching indicate that both sorbents retain significant mercury capture capability even after the majority of bromine was removed. Testing of the Br-Ash sorbent over a wider range of pH and liquid:solid ratios resulted in leaching of <5% of mercury adsorbed on the Br-Ash. XPS analysis indicated more organically bound Br and less metal-Br bonds after leaching.

  15. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal field, California, was measured at 150, 200, and 250 C as a function of steam pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption and desorption runs were made in order to investigate the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were made on the same rock samples. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there was no direct correlation between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The hysteresis decreased significantly at 250 C. The results indicate that multilayer adsorption, rather than capillary condensation, is the dominant water storage mechanism at high temperatures.

  16. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S; Holmes, Michael J; Pavlish, John Henry

    2013-08-20

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  17. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S.; Holmes, Michael J.; Pavlish, John Henry

    2014-09-02

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  18. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S.; Holmes, Michael J.; Pavlish, John H.

    2008-10-14

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  19. Sorbents for the oxidation and removal of mercury

    DOEpatents

    Olson, Edwin S [Grand Forks, ND; Holmes, Michael J [Thompson, ND; Pavlish, John H [East Grand Forks, MN

    2012-05-01

    A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.

  20. K4Nb6O17·4.5H2O: a novel dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III).

    PubMed

    Ma, Yuli; Liu, Xiaoqing; Li, Yang; Su, Yiguo; Chai, Zhanli; Wang, Xiaojing

    2014-08-30

    A series of orthorhombic phase K4Nb6O17·4.5H2O was synthesized via a hydrothermal approach. When presented in an acidic pH range, K4Nb6O17·4.5H2O showed a strong ability in quick reduction from Cr(VI) to Cr(III). The resulted Cr(III) ions were removed by an effective adsorption through simply adjusting the solution pH from strong acidity to near neutrality, owing to the sample's unique nano-sheet structure with a wide layer spacing. The Cr(III) ions adsorbed onto samples were released again for reusing by eluting with 1molL(-1) HCl solution, and K4Nb6O17·4.5H2O regenerated by immersing in a KOH solution. The reduction efficiency of Cr(VI) was still up to 98% after irradiation for 60min, and the removal efficiency of Cr(III) ions was as high as 83% even after five cycles. Therefore, K4Nb6O17·4.5H2O is clearly demonstrated to be an excellent dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III). The relevant materials reported herein might be found various environment-related applications.

  1. Mercury, elemental

    Integrated Risk Information System (IRIS)

    Mercury , elemental ; CASRN 7439 - 97 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  2. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  3. RECOVERY OF MERCURY FROM CONTAMINATED LIQUID WASTES

    SciTech Connect

    Robin M. Stewart

    1999-09-29

    magnetic field was evaluated. Field results indicated good removal of this mercury fraction from the Y-12 waters. In addition, this sorbent is easily regenerated by simply removing the magnetic field and flushing the columns with water. The fourth sorbent is still undergoing laboratory development, but results to date indicate exceptionally high mercury sorption capacity. The sorbent is capable of removing all forms of mercury typically present in natural and industrial waters, including Hg{sup 2+}, elemental mercury, methyl mercury, and colloidal mercury. The process possesses very fast kinetics, which allows for higher flow rates and smaller treatment units. These sorbent technologies, used in tandem or individually depending on the treatment needs, can provide DOE sites with a cost-effective method for reducing mercury concentrations to very low levels mandated by the regulatory community. In addition, the technologies do not generate significant amounts of secondary wastes for disposal. Furthermore, the need for improved water treatment technologies is not unique to the DOE. The new, stringent requirements on mercury concentrations impact other government agencies as well as the private sector. Some of the private-sector industries needing improved methods for removing mercury from water include mining, chloralkali production, chemical processing, and medical waste treatment. The next logical step is to deploy one or more of these sorbents at a contaminated DOE site or at a commercial facility needing improved mercury treatment technologies. A full-scale deployment is planned in fiscal year 2000.

  4. DFT study of Hg adsorption on M-substituted Pd(1 1 1) and PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Jiancheng; Yu, Huafeng; Geng, Lu; Liu, Jianwen; Han, Lina; Chang, Liping; Feng, Gang; Ling, Lixia

    2015-11-01

    The adsorption of Hgn (n = 1-3) on the Au-, Ag-, Cu-substituted Pd(1 1 1) surfaces as well as the PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces has been investigated using spin-polarized density functional theory calculations. It is found that M-substituted Pd(1 1 1) surfaces show as good Hg adsorption capacity as the perfect Pd(1 1 1) at low Hg coverage, while the Hg adsorption capacity is only slightly weakened at high Hg coverage. On the basis of stepwise adsorption energies analysis, it is concluded that M-substituted Pd(1 1 1) surfaces can contribute to the binding of Hg atom on the surfaces at high Hg coverage. The electronic properties of the second metal atoms are the main factor contributes to the Hg adsorption capacity. Gas phase Pd2 shows better Hg adsorption capacity than Pd2/γ-Al2O3, while PdM/γ-Al2O3 can adsorb Hg more efficiently than bare PdM clusters. It suggests that the γ-Al2O3 support can enhance the activity of PdM for Hg adsorption and reduces the activity of Pd2. It is also found that Pd is the main active composition responsible for the interaction of mercury with the surface for PdM/γ-Al2O3 sorbent. Taking Hg adsorption capacity and economic costs into account, Cu addition is a comparatively good candidate for Hg capture.

  5. Utility flue gas mercury control via sorbent injection

    SciTech Connect

    Chang, R.; Carey, T.; Hargrove, B.

    1996-12-31

    The potential for power plant mercury control under Title III of the 1990 Clean Air Act Amendments generated significant interest in assessing whether cost effective technologies are available for removing the mercury present in fossil-fired power plant flue gas. One promising approach is the direct injection of mercury sorbents such as activated carbon into flue gas. This approach has been shown to be effective for mercury control from municipal waste incinerators. However, tests conducted to date on utility fossil-fired boilers show that it is much more difficult to remove the trace species of mercury present in flue gas. EPRI is conducting research in sorbent mercury control including bench-scale evaluation of mercury sorbent activity and capacity with simulated flue gas, pilot testing under actual flue gas conditions, evaluation of sorbent regeneration and recycle options, and the development of novel sorbents. A theoretical model that predicts maximum mercury removals achievable with sorbent injection under different operating conditions is also being developed. This paper presents initial bench-scale and model results. The results to date show that very fine and large amounts of sorbents are needed for mercury control unless long residence times are available for sorbent-mercury contact. Also, sorbent activity and capacity are highly dependent on flue gas composition, temperature, mercury species, and sorbent properties. 10 refs., 4 figs., 2 tabs.

  6. Mercury's South Polar Region

    NASA Video Gallery

    This animation shows 89 wide-angle camera (WAC) images of Mercury’s south polar region acquired by the Mercury Dual Imaging System (MDIS) over one complete Mercury solar day (176 Earth days). Thi...

  7. Indicators: Sediment Mercury

    EPA Pesticide Factsheets

    Sediment mercury is mercury that has become embedded into the bottom substrates of aquatic ecosystems. Mercury is a common pollutant of aquatic ecosystems and it can have a substantial impact on both human and wildlife health.

  8. Adsorbents for capturing mercury in coal-fired boiler flue gas.

    PubMed

    Yang, Hongqun; Xu, Zhenghe; Fan, Maohong; Bland, Alan E; Judkins, Roddie R

    2007-07-19

    This paper reviews recent advances in the research and development of sorbents used to capture mercury from coal-fired utility boiler flue gas. Mercury emissions are the source of serious health concerns. Worldwide mercury emissions from human activities are estimated to be 1000 to 6000 t/annum. Mercury emissions from coal-fired power plants are believed to be the largest source of anthropogenic mercury emissions. Mercury emissions from coal-fired utility boilers vary in total amount and speciation, depending on coal types, boiler operating conditions, and configurations of air pollution control devices (APCDs). The APCDs, such as fabric filter (FF) bag house, electrostatic precipitator (ESP), and wet flue gas desulfurization (FGD), can remove some particulate-bound and oxidized forms of mercury. Elemental mercury often escapes from these devices. Activated carbon injection upstream of a particulate control device has been shown to have the best potential to remove both elemental and oxidized mercury from the flue gas. For this paper, NORIT FGD activated carbon was extensively studied for its mercury adsorption behavior. Results from bench-, pilot- and field-scale studies, mercury adsorption by coal chars, and a case of lignite-burned mercury control were reviewed. Studies of brominated carbon, sulfur-impregnated carbon and chloride-impregnated carbon were also reviewed. Carbon substitutes, such as calcium sorbents, petroleum coke, zeolites and fly ash were analyzed for their mercury-adsorption performance. At this time, brominated activated carbon appears to be the best-performing mercury sorbent. A non-injection regenerable sorbent technology is briefly introduced herein, and the issue of mercury leachability is briefly covered. Future research directions are suggested.

  9. Assessing sorbent injection mercury control effectiveness in flue gas streams

    USGS Publications Warehouse

    Carey, T.R.; Richardson, C.F.; Chang, R.; Meserole, F.B.; Rostam-Abadi, M.; Chen, S.

    2000-01-01

    One promising approach for removing mercury from coal-fired, utility flue gas involves the direct injection of mercury sorbents. Although this method has been effective at removing mercury in municipal waste incinerators, tests conducted to date on utility coal-fired boilers show that mercury removal is much more difficult in utility flue gas. EPRI is conducting research to investigate mercury removal using sorbents in this application. Bench-scale, pilot-scale, and field tests have been conducted to determine the ability of different sorbents to remove mercury in simulated and actual flue gas streams. This paper focuses on recent bench-scale and field test results evaluating the adsorption characteristics of activated carbon and fly ash and the use of these results to develop a predictive mercury removal model. Field tests with activated carbon show that adsorption characteristics measured in the lab agree reasonably well with characteristics measured in the field. However, more laboratory and field data will be needed to identify other gas phase components which may impact performance. This will allow laboratory tests to better simulate field conditions and provide improved estimates of sorbent performance for specific sites. In addition to activated carbon results, bench-scale and modeling results using fly ash are presented which suggest that certain fly ashes are capable of adsorbing mercury.

  10. New cellulose-lysine Schiff-base-based sensor-adsorbent for mercury ions.

    PubMed

    Kumari, Sapana; Chauhan, Ghanshyam S

    2014-04-23

    Mercury is a highly toxic environmental pollutant; thus, there is an urgent need to develop new materials for its simultaneous detection and removal from water. In the present study, new oxidized cellulose-based materials, including their Schiff bases, were synthesized and investigated as a sensor-adsorbent for simple, rapid, highly selective, and simultaneous detection and removal of mercury [Hg(II)] ions. Cellulose was extracted from the pine needles, etherified, oxidized, and modified to Schiff base by reaction with l-lysine. The well-characterized cellulose Schiff base materials were used as a sensor-adsorbent for Hg(II) from aqueous solution. Hg(II) sensing was analysed with naked-eye detection and fluorescence spectroscopy. Schiff base having a decyl chain, C10-O-cell-HC═N-Lys, was observed to be an efficient adsorbent with a very high maximum adsorption capacity of 258.75 mg g(-1). The data were analyzed on the basis of various kinetic and isotherm models, and pseudo-second-order kinetics and Langmuir isotherm were followed for Hg(II) adsorption.

  11. Mercury vapor release from broken compact fluorescent lamps and in situ capture by new nanomaterial sorbents.

    PubMed

    Johnson, Natalie C; Manchester, Shawn; Sarin, Love; Gao, Yuming; Kulaots, Indrek; Hurt, Robert H

    2008-08-01

    The projected increase in the use of compact fluorescent lamps (CFLs) motivates the development of methods to manage consumer exposure to mercury and its environmental release at the end of lamp life. This work characterizes the time-resolved release of mercury vapor from broken CFLs and from underlying substrates after removal of glass fragments to simulate cleanup. In new lamps, mercury vapor is released gradually in amounts that reach 1.3 mg or 30% of the total lamp inventory after four days. Similar time profiles but smaller amounts are released from spent lamps or from underlying substrates. Nanoscale formulations of S, Se, Cu, Ni, Zn, Ag, and WS2 are evaluated for capture of Hg vapor under these conditions and compared to conventional microscale formulations. Adsorption capacities range over 7 orders of magnitude, from 0.005 (Zn micropowder) to 188 000 microg/g (unstabilized nano-Se), depending on sorbent chemistry and particle size. Nanosynthesis offers clear advantages for most sorbent chemistries. Unstabilized nano-selenium in two forms (dry powder and impregnated cloth) was successfully used in a proof-of-principle test for the in situ, real-time suppression of Hg vapor escape following CFL fracture.

  12. Mercury Vapor Release from Broken Compact Fluorescent Lamps and In Situ Capture by New Nanomaterial Sorbents

    PubMed Central

    2008-01-01

    The projected increase in the use of compact fluorescent lamps (CFLs) motivates the development of methods to manage consumer exposure to mercury and its environmental release at the end of lamp life. This work characterizes the time-resolved release of mercury vapor from broken CFLs and from underlying substrates after removal of glass fragments to simulate cleanup. In new lamps, mercury vapor is released gradually in amounts that reach 1.3 mg or 30% of the total lamp inventory after four days. Similar time profiles but smaller amounts are released from spent lamps or from underlying substrates. Nanoscale formulations of S, Se, Cu, Ni, Zn, Ag, and WS2 are evaluated for capture of Hg vapor under these conditions and compared to conventional microscale formulations. Adsorption capacities range over 7 orders of magnitude, from 0.005 (Zn micropowder) to 188 000 μg/g (unstabilized nano-Se), depending on sorbent chemistry and particle size. Nanosynthesis offers clear advantages for most sorbent chemistries. Unstabilized nano-selenium in two forms (dry powder and impregnated cloth) was successfully used in a proof-of-principle test for the in situ, real-time suppression of Hg vapor escape following CFL fracture. PMID:18754507

  13. Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Shi, Zhan; Ma, Shengqian

    2014-11-01

    Highly effective and highly efficient decontamination of mercury from aqueous media remains a serious task for public health and ecosystem protection. Here we report that this task can be addressed by creating a mercury ‘nano-trap’ as illustrated by functionalizing a high surface area and robust porous organic polymer with a high density of strong mercury chelating groups. The resultant porous organic polymer-based mercury ‘nano-trap’ exhibits a record-high saturation mercury uptake capacity of over 1,000 mg g-1, and can effectively reduce the mercury(II) concentration from 10 p.p.m. to the extremely low level of smaller than 0.4 p.p.b. well below the acceptable limits in drinking water standards (2 p.p.b.), and can also efficiently remove >99.9% mercury(II) within a few minutes. Our work therefore presents a new benchmark for mercury adsorbent materials and provides a new perspective for removing mercury(II) and also other heavy metal ions from contaminated water for environmental remediation.

  14. Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution.

    PubMed

    Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Shi, Zhan; Ma, Shengqian

    2014-11-20

    Highly effective and highly efficient decontamination of mercury from aqueous media remains a serious task for public health and ecosystem protection. Here we report that this task can be addressed by creating a mercury 'nano-trap' as illustrated by functionalizing a high surface area and robust porous organic polymer with a high density of strong mercury chelating groups. The resultant porous organic polymer-based mercury 'nano-trap' exhibits a record-high saturation mercury uptake capacity of over 1,000 mg g(-1), and can effectively reduce the mercury(II) concentration from 10 p.p.m. to the extremely low level of smaller than 0.4 p.p.b. well below the acceptable limits in drinking water standards (2 p.p.b.), and can also efficiently remove >99.9% mercury(II) within a few minutes. Our work therefore presents a new benchmark for mercury adsorbent materials and provides a new perspective for removing mercury(II) and also other heavy metal ions from contaminated water for environmental remediation.

  15. Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.

    1999-01-01

    Among the major discoveries made by the Mariner 10 mission to the inner planets was the existence of an intrinsic magnetic field at Mercury with a dipole moment of approx. 300 nT R(sup 3, sub M). This magnetic field is sufficient to stand off the solar wind at an altitude of about 1 R(sub M) (i.e. approx. 2439 km). Hence, Mercury possesses a 'magnetosphere' from which the so]ar wind plasma is largely excluded and within which the motion of charged particles is controlled by the planetary magnetic field. Despite its small size relative to the magnetospheres of the other planets, a Mercury orbiter mission is a high priority for the space physics community. The primary reason for this great interest is that Mercury unlike all the other planets visited thus far, lacks a significant atmosphere; only a vestigial exosphere is present. This results in a unique situation where the magnetosphere interacts directly with the outer layer of the planetary crust (i.e. the regolith). At all of the other planets the topmost regions of their atmospheres become ionized by solar radiation to form ionospheres. These planetary ionospheres then couple to electrodynamically to their magnetospheres or, in the case of the weakly magnetized Venus and Mars, directly to the solar wind. This magnetosphere-ionosphere coupling is mediated largely through field-aligned currents (FACs) flowing along the magnetic field lines linking the magnetosphere and the high-latitude ionosphere. Mercury is unique in that it is expected that FACS will be very short lived due to the low electrical conductivity of the regolith. Furthermore, at the earth it has been shown that the outflow of neutral atmospheric species to great altitudes is an important source of magnetospheric plasma (following ionization) whose composition may influence subsequent magnetotail dynamics. However, the dominant source of plasma for most of the terrestrial magnetosphere is the 'leakage'of solar wind across the magnetopause and more

  16. Accumulation and oxidation of elemental mercury in tropical soils.

    PubMed

    Soares, Liliane Catone; Egreja Filho, Fernando Barboza; Linhares, Lucília Alves; Windmoller, Cláudia Carvalhinho; Yoshida, Maria Irene

    2015-09-01

    The role of chemical and mineralogical soil properties in the retention and oxidation of atmospheric mercury in tropical soils is discussed based on thermal desorption analysis. The retention of gaseous mercury by tropical soils varied greatly both quantitatively and qualitatively with soil type. The average natural mercury content of soils was 0.08 ± 0.06 μg g(-1) with a maximum of 0.215 ± 0.009 μg g(-1). After gaseous Hg(0) incubation experiments, mercury content of investigated soils ranged from 0.6 ± 0.2 to 735 ± 23 μg g(-1), with a mean value of 44 ± 146 μg g(-1). Comparatively, A horizon of almost all soil types adsorbed more mercury than B horizon from the same soil, which demonstrates the key role of organic matter in mercury adsorption. In addition to organic matter, pH and CEC also appear to be important soil characteristics for the adsorption of mercury. All thermograms showed Hg(2+) peaks, which were predominant in most of them, indicating that elemental mercury oxidized in tropical soils. After four months of incubation, the thermograms showed oxidation levels from 70% to 100%. As none of the samples presented only the Hg(0) peak, and the soils retained varying amounts of mercury despite exposure under the same incubation conditions, it became clear that oxidation occurred on soil surface. Organic matter seemed to play a key role in mercury oxidation through complexation/stabilization of the oxidized forms. The lower percentages of available mercury (extracted with KNO3) in A horizons when compared to B horizons support this idea.

  17. Mercury Control with Calcium-Based Sorbents and Oxidizing Agents

    SciTech Connect

    Thomas K. Gale

    2005-07-01

    This Final Report contains the test descriptions, results, analysis, correlations, theoretical descriptions, and model derivations produced from many different investigations performed on a project funded by the U.S. Department of Energy, to investigate calcium-based sorbents and injection of oxidizing agents for the removal of mercury. Among the technologies were (a) calcium-based sorbents in general, (b) oxidant-additive sorbents developed originally at the EPA, and (c) optimized calcium/carbon synergism for mercury-removal enhancement. In addition, (d) sodium-tetrasulfide injection was found to effectively capture both forms of mercury across baghouses and ESPs, and has since been demonstrated at a slipstream treating PRB coal. It has been shown that sodium-tetrasulfide had little impact on the foam index of PRB flyash, which may indicate that sodium-tetrasulfide injection could be used at power plants without affecting flyash sales. Another technology, (e) coal blending, was shown to be an effective means of increasing mercury removal, by optimizing the concentration of calcium and carbon in the flyash. In addition to the investigation and validation of multiple mercury-control technologies (a through e above), important fundamental mechanism governing mercury kinetics in flue gas were elucidated. For example, it was shown, for the range of chlorine and unburned-carbon (UBC) concentrations in coal-fired utilities, that chlorine has much less effect on mercury oxidation and removal than UBC in the flyash. Unburned carbon enhances mercury oxidation in the flue gas by reacting with HCl to form chlorinated-carbon sites, which then react with elemental mercury to form mercuric chloride, which subsequently desorbs back into the flue gas. Calcium was found to enhance mercury removal by stabilizing the oxidized mercury formed on carbon surfaces. Finally, a model was developed to describe these mercury adsorption, desorption, oxidation, and removal mechanisms, including

  18. Mathematical modeling of the integrated process of mercury bioremediation in the industrial bioreactor.

    PubMed

    Głuszcz, Paweł; Petera, Jerzy; Ledakowicz, Stanisław

    2011-03-01

    The mathematical model of the integrated process of mercury contaminated wastewater bioremediation in a fixed-bed industrial bioreactor is presented. An activated carbon packing in the bioreactor plays the role of an adsorbent for ionic mercury and at the same time of a carrier material for immobilization of mercury-reducing bacteria. The model includes three basic stages of the bioremediation process: mass transfer in the liquid phase, adsorption of mercury onto activated carbon and ionic mercury bioreduction to Hg(0) by immobilized microorganisms. Model calculations were verified using experimental data obtained during the process of industrial wastewater bioremediation in the bioreactor of 1 m³ volume. It was found that the presented model reflects the properties of the real system quite well. Numerical simulation of the bioremediation process confirmed the experimentally observed positive effect of the integration of ionic mercury adsorption and bioreduction in one apparatus.

  19. MERCURY RESEARCH STRATEGY.

    EPA Science Inventory

    The USEPA's ORD is pleased to announce the availability of its Mercury Research Strategy. This strategy guides ORD's mercury research program and covers the FY2001-2005 time frame. ORD will use it to prepare a multi-year mercury research implementation plan in 2001. The Mercury R...

  20. Mercury contamination extraction

    DOEpatents

    Fuhrmann, Mark; Heiser, John; Kalb, Paul

    2009-09-15

    Mercury is removed from contaminated waste by firstly applying a sulfur reagent to the waste. Mercury in the waste is then permitted to migrate to the reagent and is stabilized in a mercury sulfide compound. The stable compound may then be removed from the waste which itself remains in situ following mercury removal therefrom.

  1. LFCM (liquid-fed ceramic melter) processing characteristics of mercury

    SciTech Connect

    Goles, R.W.; Sevigny, G.J.; Andersen, C.M.

    1990-06-01

    An experimental-scale liquid-fed ceramic melter was used in a series of tests to evaluate the processing characteristics of mercury in simulated defense waste under various melter operating conditions. This solidification technology had no detectable capacity for incorporating mercury into its borosilicate, vitreous, product, and essentially all the mercury fed to the melter was lost to the off-gas system as gaseous effluent. An ejector venturi scrubber condensed and collected 97% of the mercury evolved from the melter. Chemically the condensed mercury effluent was composed entirely of chlorides, and except in a low-temperature test, mercury chlorides (Hg{sub 2}Cl{sub 2}) was the primary chloride formed. As a result, combined mercury accounted for most of the insoluble mass collected by the process quench scrubber. Although macroscopic quantities of elemental mercury were never observed in process secondary waste streams, finely divided and dispersed mercury that blackened all condensed Hg{sub 2}Cl{sub 2} residues was capable of saturating the quenched process exhaust with mercury vapor. However, the vapor pressure of mercury in the quenched melter exhaust was easily and predictably controlled with an off-gas stream chiller. 5 refs., 4 figs., 12 tabs.

  2. Volatilization and sorption of dissolved mercury by metallic iron of different particle sizes: implications for treatment of mercury contaminated water effluents.

    PubMed

    Vernon, Julianne D; Bonzongo, Jean-Claude J

    2014-07-15

    Batch experiments were conducted to investigate the interactions between metallic iron particles and mercury (Hg) dissolved in aqueous solutions. The effect of bulk zero valent iron (ZVI) particles was tested by use of (i) granular iron and (ii) iron particles with diameters in the nano-size range and referred to herein as nZVI. The results show that the interactions between Hg(n+) and Fe(0) are dominated by Hg volatilization and Hg adsorption; with Hg adsorption being the main pathway for Hg removal from solution. Hg adsorption kinetic studies using ZVI and nZVI resulted in higher rate constants (k) for nZVI when k values were expressed as a function of mass of iron used (day(-1)g(-1)). In contrast, ZVI showed higher rates of Hg removal from solution when k values were expressed as a function iron particles' specific surface area (gm(-2)day(-1)). Overall, nZVI particles had a higher maximum sorption capacity for Hg than ZVI, and appeared to be an efficient adsorbent for Hg dissolved in aqueous solutions.

  3. Mercury embrittlement of Cu-Al alloys under cyclic loading

    NASA Technical Reports Server (NTRS)

    Regan, T. M.; Stoloff, N. S.

    1977-01-01

    The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.

  4. Mercury Quick Facts: Health Effects of Mercury Exposure

    MedlinePlus

    Mercury Quick Facts Health Effects of Mercury Exposure What is Elemental Mercury? Elemental (metallic) mercury is the shiny, silver-gray metal found in thermometers, barometers, and thermostats and other ...

  5. Raw and Treated Rice Husks as Sorbents for Mercury Removal from Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Befani, Maria R.; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.; Quintero, César E.

    2014-05-01

    for further study: RH2, RHA3, RHA4, and RHA800. The batch adsorption kinetic experiments were performed at Co = 50 mg Hg(II)/L, pH 5, and values were taken periodically since the first 5 min until 480 h. The equilibrium was attained at 240 h for RHA3 and RHA4 and at 48 h for RH2 and RHA800. According to the kinetic data, the equilibrium adsorption capacities achieved were: 12 mg/g (RH2), 15 mg/g (RHA800), 27 mg/g (RHA3) and 61 mg/g (RHA4). Sorption kinetics was well described by the pseudo-second-order model. The mercury removal capacity was found to be in the following order: RHA4> RHA3> RHA300> RH3> RHA800> RH2> RH1. The pyrolysis of rice husk resulted in an increase of the specific surface area, which is very important for the removal of mercury. The sorption values achieved in the present study is lower compared with other mesoporous materials reported in literature. Nevertheless, the mercury sorption capacity values obtained are comparable with values found by other authors in similar conditions using rice husk and its ash.

  6. Aerobic Mercury-resistant bacteria alter Mercury speciation and retention in the Tagus Estuary (Portugal).

    PubMed

    Figueiredo, Neusa L; Canário, João; O'Driscoll, Nelson J; Duarte, Aida; Carvalho, Cristina

    2016-02-01

    Aerobic mercury-resistant bacteria were isolated from the sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and one natural reserve area (Alcochete) in order to test their capacity to transform mercury. Bacterial species were identified using 16S rRNA amplification and sequencing techniques and the results indicate the prevalence of Bacillus sp. Resistance patterns to mercurial compounds were established by the determination of minimal inhibitory concentrations. Representative Hg-resistant bacteria were further tested for transformation pathways (reduction, volatilization and methylation) in cultures containing mercury chloride. Bacterial Hg-methylation was carried out by Vibrio fluvialis, Bacillus megaterium and Serratia marcescens that transformed 2-8% of total mercury into methylmercury in 48h. In addition, most of the HgR bacterial isolates showed Hg(2+)-reduction andHg(0)-volatilization resulting 6-50% mercury loss from the culture media. In summary, the results obtained under controlled laboratory conditions indicate that aerobic Hg-resistant bacteria from the Tagus Estuary significantly affect both the methylation and reduction of mercury and may have a dual face by providing a pathway for pollution dispersion while forming methylmercury, which is highly toxic for living organisms.

  7. Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Wang, S. X.; Wu, Q. R.; Wang, F. Y.; Lin, C.-J.; Zhang, L. M.; Hui, M. L.; Hao, J. M.

    2015-11-01

    Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, municipal solid waste incinerators, and biomass burning. Mercury in coal, ores and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of gaseous elemental mercury (Hg0) to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g.,TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non

  8. Phosphate adsorption on lanthanum loaded biochar.

    PubMed

    Wang, Zhanghong; Shen, Dekui; Shen, Fei; Li, Tianyu

    2016-05-01

    To attain a low-cost and high-efficient phosphate adsorbent, lanthanum (La) loaded biochar (La-BC) prepared by a chemical precipitation method was developed. La-BC and its pristine biochar (CK-BC) were comparatively characterized using zeta potential, BET surface area, scanning electron microscopy/energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The adsorption ability and the mechanisms during adsorption process for the La-BC samples were also investigated. La loaded on the surface of biochar can be termed as La-composites (such as LaOOH, LaONO3 and La(OH)3), leading to the decrease of negative charge and surface area of biochar. La-BC exhibited the high adsorption capacity to phosphate compared to CK-BC. Adsorption isotherm and adsorption kinetic studies showed that the Langmuir isotherm and second order model could well describe the adsorption process of La-BC, indicating that the adsorption was dominated by a homogeneous and chemical process. The calculated maximum adsorption capacity was as high as 46.37 mg g(-1) (computed in P). Thermodynamic analysis revealed that the adsorption was spontaneous and endothermic. SEM, XRD, XPS and FT-IR analysis suggested that the multi-adsorption mechanisms including precipitation, ligand exchange and complexation interactions can be evidenced during the phosphate adsorption process by La-composites in La-BC.

  9. Metal chlorides loaded on activated carbon to capture elemental mercury.

    PubMed

    Shen, Zhemin; Ma, Jing; Mei, Zhijian; Zhang, Jianda

    2010-01-01

    Activated carbon (AC) was considered to be an effective sorbent to control mercury in combustion systems. However, its capture capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury (Hg0) capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC to remove gaseous mercury. X-ray diffractometer (XRD), thermogravimetric analyzer (TGA) and specific surface area by Brunauer-Emmett-Teller method (BET) analysis showed the main mechanisms: first, AC had an enormous surface area for loading enough MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl2 might be released from AC's porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg0 oxidization may accelerate both oxidation and halogenation of Hg0. The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect of valence variable metal and chlorine oxidation.

  10. Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of mercury in water and food samples employing cold vapor atomic absorption spectrometry.

    PubMed

    Roushani, Mahmoud; Abbasi, Shahryar; Khani, Hossein

    2015-09-01

    We describe a nanosized Hg(II)-imprinted polymer that was prepared from methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as cross-linker, 2,2'-azobisisobutyronitrile (AIBN) as radical initiator, 2, 2'-di pyrydyl amine as a specific ligand, and Hg (II) as the template ions by precipitation polymerization method in methanol as the progeny solvent. Batch adsorption experiments were carried out as a function of pH, Hg (II) imprinted polymer amount, adsorption and desorption time, volume, and concentration of eluent. The synthesized polymer particles were characterized physically and morphologically by using infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopic techniques. The maximum adsorption capacity of the ion-imprinted and non-imprinted sorbent was 27.96 and 7.89 mg g(-1), respectively. Under optimal conditions, the detection limit for mercury was 0.01 μg L(-1) and the relative standard deviation was 3.2 % (n = 6) at the 1.00 μg L(-1). The procedure was applied to determination of mercury in fish and water samples with satisfactory results.

  11. Application of a sorbent trap system to gas-phase elemental and oxidized mercury analysis.

    PubMed

    Zhang, Zishuo; Eom, Yujin; Lee, Michelle J; Lee, Tai Gyu

    2016-07-01

    A sorbent trap that utilizes activated carbon (AC) as the solid trapping medium is a new technology for measuring total mercury (Hg) emissions from combustion facilities. In this study, sorbent trap technology was further developed, improved and evaluated at the laboratory scale. AC was impregnated with 5% aqua regia to enhance its Hg adsorption capacity. Sorbent traps spiked with an Hg standard solution were found to be reproducibly prepared and highly stable. The effect of the Hg concentration on the spiking efficiency was further investigated. The adsorption of elemental and oxidized Hg by the sorbent trap was studied under various experimental conditions (temperature, flow rate and inlet Hg concentration). The Hg concentration of the flue gas effluent from the sorbent trap was measured. In addition, the concentration of Hg adsorbed on the AC was determined by digesting the used AC with an acid according to US EPA method 3052 and then analyzing it with cold vapor atomic absorption spectrometry. Furthermore, the gas-phase Hg emissions from a combustion source were measured using the sorbent trap according to US EPA method 30B. The results showed that the sorbent trap could be used for Hg concentrations between 10.0 and 40.0 μg m(-3) and flow rates between 0.5 and 1.0 lpm with adsorption efficiencies greater than 90%.

  12. EXAFS and XRD characterization of palladium sorbents for high temperature mercury capture from fuel gas.

    PubMed

    Poulston, Stephen; Hyde, Timothy I; Hamilton, Hugh; Mathon, Olivier; Prestipino, Carmelo; Sankar, Gopinathan; Smith, Andrew W J

    2010-01-14

    Removal of pollutants such as mercury at elevated temperatures provides improvements in the overall thermal efficiency during the process of coal gasification. The two high temperature sorbents studied were 5 wt% Pd/Al(2)O(3) and 5 wt% Pd/SiO(2): materials shown to have significantly different Hg adsorption capacities. A combination of XRD and EXAFS has been used to characterize the Pd-Hg alloy formed when these Pd-based sorbents were exposed to fuel gas (CO, CO(2), H(2)) containing Hg vapour at 204 degrees C. Significant differences were found in the nature of the alloy formed on the two sorbents following Hg exposure. The Pd/Al(2)O(3) sorbent produced a single homogeneous solid solution of Pd-Hg whilst the silica-supported Pd produced an alloy of varying composition.

  13. Global Trends in Mercury Management

    PubMed Central

    Choi, Kyunghee

    2012-01-01

    The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health. PMID:23230466

  14. Modeling Transport and Transformation of Dissolved and Sediment Associated Mercury in Rivers

    NASA Astrophysics Data System (ADS)

    Massoudieh, A.; Ginn, T. R.; Bombardelli, F. A.

    2005-12-01

    Mercury is a hazardous metal in the environment. In many cases, the presence of mercury in water bodies is in the form of a distinct, high-concentration-mercury layer in the bed sediments that is often buried but can be exposed due to erosion of the top layer. In this research, a one-dimensional flow and transport model representing the transport of mercury in the river is coupled with several one-dimensional models incorporating diffusive transport, transformation and sorption of mercury species in the bed sediments. Transport of dissolved and particle associated mercury in the water, and thus the effect of erosion and resuspension of particles on the transport process is taken into consideration. A set of one-dimensional reactive transport sub-models are utilized to model the release, adsorption, and burial of mercury species to the bed sediments. Also, the coupled transport and transformation of a wide variety of mercury species as well as biomass and organic matter which are effective in production of Methyl-Mercury are implemented into the model. Model parameters are obtained using available thermodynamics databases and by calibration of the one-dimensional reactive transport model to available column and batch study data. The model can be used for predicting transport of mercury and production of methyl-mercury, examining various remediation scenarios, and evaluating the effect of anthropological activities on resuspension or burial of mercury species in water systems after doing appropriate calibrations.

  15. New Jersey mercury regulations

    SciTech Connect

    Elias, D.F.; Corbin, W.E.

    1996-12-31

    Mercury, or quicksilver, and its major ore cinnabar (HgS) have been known for thousands of years. Health effects from mercury such as dementia were known as early as the late 19th century ({open_quotes}mad as a hatter{close_quotes}). In the 1960`s and 1970`s, reported levels of mercury in tuna reawakened public awareness of mercury pollution. In the 1970`s, major epidemics of acute mercury poisoning were reported in Japan and Iraq. These incidents highlighted the extreme health risks, such as kidney damage, birth defects, and death, associated with severe mercury poisoning. Fetuses and young children are particularly vulnerable since mercury poisoning can damage growing neural tissues. Recently, the perception of mercury as a dangerous pollutant has been on the rise. Advisories warning the public to avoid or reduce the consumption of freshwater fish caught in specific waterbodies due to mercury contamination have been issued in numerous states. The discovery of mercury in {open_quotes}pristine{close_quotes} lakes in the United States, Canada, and Scandinavia, remote from industry and any known mercury sources, has focused attention on atmospheric emissions of mercury as potential significant sources of mercury.

  16. Novel regenerable sorbent for mercury capture from flue gases of coal-fired power plant.

    PubMed

    Liu, Yan; Kelly, David J A; Yang, Hongqun; Lin, Christopher C H; Kuznicki, Steve M; Xu, Zhenghe

    2008-08-15

    A natural chabazite-based silver nanocomposite (AgMC) was synthesized to capture mercury from flue gases of coal-fired power plants. Silver nanoparticles were engineered on zeolite through ion-exchange of sodium ions with silver ions, followed by thermal annealing. Mercury sorption test using AgMC was performed at various temperatures by exposing it to either pulse injection of mercury or continuous mercury flow. A complete capture of mercury by AgMC was achieved up to a capture temperature of 250 degrees C. Nano silver particles were shown to be the main active component for mercury capture by amalgamation mechanism. Compared with activated carbon-based sorbents, the sorbent prepared in this study showed a much higher mercury capture capacity and upper temperature limit for mercury capture. More importantly, the mercury captured by the spent AgMC could be easily released for safe disposal and the sorbent regenerated by simple heating at 400 degrees C. Mercury capture tests performed in real flue gas environment showed a much higher level of mercury capture by AgMC than by other potential mercury sorbents tested. In our mercury capture tests, the AgMC exposed to real flue gases showed an increased mercury capture efficiency than the fresh AgMC.

  17. Minamata Convention on Mercury

    EPA Pesticide Factsheets

    On November 6, 2013 the United States signed the Minamata Convention on Mercury, a new multilateral environmental agreement that addresses specific human activities which are contributing to widespread mercury pollution

  18. Basic Information about Mercury

    MedlinePlus

    ... globe -- before it is deposited in soil or water. Mercury that remains in the air for prolonged periods of time and travels across continents is said to be in the "global cycle." One major source of mercury emissions outside of ...

  19. Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Wang, Shuxiao; Wu, Qingru; Wang, Fengyang; Lin, Che-Jen; Zhang, Leiming; Hui, Mulin; Yang, Mei; Su, Haitao; Hao, Jiming

    2016-02-01

    Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non-ferrous metal smelting, cement and

  20. Removal of Toxic Mercury from Petroleum Oil by Newly Synthesized Molecularly-Imprinted Polymer

    PubMed Central

    Khairi, Nor Ain Shahera; Yusof, Nor Azah; Abdullah, Abdul Halim; Mohammad, Faruq

    2015-01-01

    In recent years, molecularly-imprinted polymers (MIPs) have attracted the attention of several researchers due to their capability for molecular recognition, easiness of preparation, stability and cost-effective production. By taking advantage of these facts, Hg(II) imprinted and non-imprinted copolymers were prepared by polymerizing mercury nitrate stock solution (or without it) with methacrylic acid (MAA), 2-hydroxyl ethyl methacrylate (HEMA), methanol and ethylene glycol dimethacrylate (EGDMA) as the monomer, co-monomer solvent (porogen) and cross-linker, respectively. Thus, the formed Hg(II) imprinted polymer was characterized by using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Brunauer, Emmett and Teller (BET) and thermal gravimetric analysis (TGA). The separation and preconcentration characteristics of Hg(II) imprinted polymer were investigated by solid phase extraction (SPE) procedures, and an optimal pH of 7 was investigated as ideal. The specific surface area of the Hg(II) imprinted polymer was found to be 19.45 m2/g with a size range from 100 to 140 µm in diameter. The maximum adsorption capacity was observed to be 1.11 mg/g of Hg(II) imprinted beads with 87.54% removal of Hg(II) ions within the first 5 min. The results of the study therefore confirm that the Hg(II) imprinted polymer can be used multiple times without significantly losing its adsorption capacity. PMID:26006226

  1. Removal of toxic mercury from petroleum oil by newly synthesized molecularly-imprinted polymer.

    PubMed

    Khairi, Nor Ain Shahera; Yusof, Nor Azah; Abdullah, Abdul Halim; Mohammad, Faruq

    2015-05-08

    In recent years, molecularly-imprinted polymers (MIPs) have attracted the attention of several researchers due to their capability for molecular recognition, easiness of preparation, stability and cost-effective production. By taking advantage of these facts, Hg(II) imprinted and non-imprinted copolymers were prepared by polymerizing mercury nitrate stock solution (or without it) with methacrylic acid (MAA), 2-hydroxyl ethyl methacrylate (HEMA), methanol and ethylene glycol dimethacrylate (EGDMA) as the monomer, co-monomer solvent (porogen) and cross-linker, respectively. Thus, the formed Hg(II) imprinted polymer was characterized by using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Brunauer, Emmett and Teller (BET) and thermal gravimetric analysis (TGA). The separation and preconcentration characteristics of Hg(II) imprinted polymer were investigated by solid phase extraction (SPE) procedures, and an optimal pH of 7 was investigated as ideal. The specific surface area of the Hg(II) imprinted polymer was found to be 19.45 m2/g with a size range from 100 to 140 µm in diameter. The maximum adsorption capacity was observed to be 1.11 mg/g of Hg(II) imprinted beads with 87.54% removal of Hg(II) ions within the first 5 min. The results of the study therefore confirm that the Hg(II) imprinted polymer can be used multiple times without significantly losing its adsorption capacity.

  2. Mercury Surveillance Program

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Background on mercury exposure is presented including forms, sources, permissible exposure limits, and physiological effects. The purpose of the Mercury Surveillance Program at LeRC is outlined, and the specifics of the Medical Surveillance Program for Mercury Exposure at LeRC are discussed.

  3. Mercury in the environment

    NASA Technical Reports Server (NTRS)

    Fulkerson, W.; Lyon, W. S.; Shults, W. D.; Wallace, R. A.

    1972-01-01

    Problems in assessing mercury concentrations in environmental materials are discussed. Data for situations involving air, water, rocks, soils, sediments, sludges, fossil fuels, plants, animals, foods, and man are drawn together and briefly evaluated. Details are provided regarding the toxicity of mercury along with tentative standards and guidelines for mercury in air, drinking water, and food.

  4. Ancient Maya Mercury

    NASA Astrophysics Data System (ADS)

    Pendergast, David M.

    1982-08-01

    Discovery of mercury in an ancient Maya offering at Lamanai, Belize, has stimulated examination of possible sources of the material in the Maya area. Two zones of cinnabar and native mercury deposits can be defined in the Maya highlands, and the presence of the native metal suggests that the ancient Maya collected rather than extracted the mercury from ore.

  5. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. )

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  6. Multilayer adsorption on fractal surfaces.

    PubMed

    Vajda, Péter; Felinger, Attila

    2014-01-10

    Multilayer adsorption is often observed in liquid chromatography. The most frequently employed model for multilayer adsorption is the BET isotherm equation. In this study we introduce an interpretation of multilayer adsorption measured on liquid chromatographic stationary phases based on the fractal theory. The fractal BET isotherm model was successfully used to determine the apparent fractal dimension of the adsorbent surface. The nonlinear fitting of the fractal BET equation gives us the estimation of the adsorption equilibrium constants and the monolayer saturation capacity of the adsorbent as well. In our experiments, aniline and proline were used as test molecules on reversed phase and normal phase columns, respectively. Our results suggest an apparent fractal dimension 2.88-2.99 in the case of reversed phase adsorbents, in the contrast with a bare silica column with a fractal dimension of 2.54.

  7. Kinetics of Hg(II) adsorption and desorption in calcined mussel shells.

    PubMed

    Peña-Rodríguez, Susana; Fernández-Calviño, David; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Núñez-Delgado, Avelino; Fernández-Sanjurjo, María José; Alvarez-Rodríguez, Esperanza

    2010-08-15

    The potential use of calcined mussel shells to purify water contaminated with mercury was evaluated. The Hg(II) adsorption and desorption kinetics were studied in batch-type and stirred-flow chamber experiments. The adsorption/desorption experiments revealed some differences between the batches of shells used. The batch of shells that displayed the greatest capacity to adsorb Hg(II), via a highly irreversible reaction, also contained more Fe and Al than the other batches. The results of the stirred-flow chamber experiments indicated a high degree of irreversibility in the process of Hg(II) adsorption in the mussel shell, and that Hg(II) was rapidly retained. The results of these experiments also revealed that the efficiency of depuration differed depending on the length of time that the system was used: when the system was operated for 55 min, depurating 162 mL of inflowing water g(-1) mussel shell, a 90% reduction in the initial concentration of Hg(II) was obtained; use of the system for 90 min, depurating 265 mL water g(-1) mussel shell, produced a 75% reduction in the initial Hg(II), and use of the system for 162.5 min, depurating 487 mL of water g(-1) mussel shell, resulted in a 50% reduction in the initial Hg(II).

  8. Mercury removal from solution by superconducting magnetic separation with nanostructured magnetic adsorbents

    NASA Astrophysics Data System (ADS)

    Okamoto, T.; Tachibana, S.; Miura, O.; Takeuchi, M.

    2011-11-01

    Recently, mercury Hg concentration in human blood increases due to expanding the global mercury contamination. Excess mercury bioaccumulation poses a significant health risk. In order to decrease mercury concentration in the environment and human blood, we have developed two different kinds of nanostructured magnetic adsorbents for mercury to apply them to superconducting magnetic separation instead of conventional filtration. One is magnetic beads (MBs) which have nanosize magnetite particles in the core and a lot of SH radicals on the surface to adsorb Hg ions effectively. MBs were developed mainly to remove mercury from human blood. The maximum amount of the adsorption for MBs is 6.3 mg/g in the solution in less than a minute. Dithiothreitol can easily remove mercury adsorbed to MBs, hence MBs can be reusable. The other is nanostructured magnetic activated carbon (MAC) which is activated carbon with mesopores and nanosize magnetite. The maximum amount of the adsorption for MAC is 38.3 mg/g in the solution. By heat-treatment mercury can be easily removed from MAC. We have studied superconducting magnetic separation using each adsorbent for mercury removal from solution.

  9. Phytoremediation of Ionic and Methyl Mercury P

    SciTech Connect

    Meagher, Richard B.

    1999-06-01

    Our long-term goal is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic heavy metal pollutants as an environmentally friendly alternative to physical remediation methods. We have focused this phytoremediation research on soil and water-borne ionic and methylmercury. Mercury pollution is a serious world-wide problem affecting the health of human and wild-life populations. Methylmercury, produced by native bacteria at mercury-contaminated wetland sites, is a particularly serious problem due to its extreme toxicity and efficient biomagnification in the food chain. We engineered several plant species (e.g., Arabidopsis, tobacco, canola, yellow poplar, rice) to express the bacterial genes, merB and/or merA, under the control of plant regulatory sequences. These transgenic plants acquired remarkable properties for mercury remediation. (1) Transgenic plants expressing merB (organomercury lyase) extract methylmercury from their growth substrate and degrade it to less toxic ionic mercury. They grow on concentrations of methylmercury that kill normal plants and accumulate low levels of ionic mercury. (2) Transgenic plants expressing merA (mercuric ion reductase) extract and electrochemically reduce toxic, reactive ionic mercury to much less toxic and volatile metallic mercury. This metal transformation is driven by the powerful photosynthetic reducing capacity of higher plants that generates excess NADPH using solar energy. MerA plants grow vigorously on levels of ionic mercury that kill control plants. Plants expressing both merB and merA degrade high levels of methylmercury and volatilize metallic mercury. These properties were shown to be genetically stable for several generations in the two plant species examined. Our work demonstrates that native trees, shrubs, and grasses can be engineered to remediate the most abundant toxic mercury pollutants. Building on these data our working hypothesis for the next grant period is that

  10. [Chronic occupational metallic mercurialism].

    PubMed

    Faria, Marcília de Araújo Medrado

    2003-02-01

    This is a review on current knowledge of chronic occupational mercurialism syndrome. Major scientific studies and reviews on clinical manifestation and physiopathology of mercury poisoning were evaluated. The search was complemented using Medline and Lilacs data. Erethism or neuropsychological syndrome, characterized by irritability, personality change, loss of self-confidence, depression, delirium, insomnia, apathy, loss of memory, headaches, general pain, and tremors, is seen after exposure to metallic mercury. Hypertension, renal disturbances, allergies and immunological conditions are also common. Mercury is found in many different work processes: industries, gold mining, and dentistry. As prevention measures are not often adopted there is an increasing risk of mercury poisoning. The disease has been under diagnosed even though 16 clinical forms of mercury poisoning are described by Brazilian regulations. Clinical diagnosis is important, especially because abnormalities in the central nervous, renal and immunological systems can be detected using current medical technology, helping to develop the knowledge and control measures for mercurialism.

  11. Production of simple molecules on the surface of Mercury

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.

    1977-01-01

    Lunar sample studies have shown that solar-wind irradiation of the lunar surface has produced a variety of low-molecular-weight compounds. Analysis of the lunar soils has revealed the presence of H2, CH4, H2O, N2, CO, CO2, He, Ne and other components which are extralunar. Irradiation experiments on lunar materials and analogs have shown that solar-wind and solar-flare irradiation of the lunar surface produces selected low-molecular-weight components. Solar-wind irradiation of Mercury's surface should also produce a wide variety of low-molecular-weight species because of the increased solar flux, which results from Mercury being nearer the sun than the moon. The thermal regime of Mercury's surface would result in thermal evaporation of low-temperature components followed by 'cold-trapping' on the night-time side of the planet. Such desorption-adsorption processes assist chemical weathering of Mercury's regolith.

  12. Adsorption of acid dye onto organobentonite.

    PubMed

    Baskaralingam, P; Pulikesi, M; Elango, D; Ramamurthi, V; Sivanesan, S

    2006-02-06

    Removal of Acid Red 151 from aqueous solution at different dye concentrations, adsorbent doses and pH has been studied. The bentonite clay has been modified using cationic surfactants, which has been confirmed using XRD and FT-IR analyses. Experimental result has shown that the acidic pH favours the adsorption. The adsorption isotherms are described by means of Langmuir and Freundlich isotherms. The adsorption capacity has been found to be 357.14 and 416.66 mg g(-1) for the cetyldimethylbenzylammonium chloride-bentonite (CDBA-bent) and cetylpyridinium chloride-bentonite (CP-bent), respectively. Kinetic studies show that the adsorption followed second-order kinetics.

  13. Development of bamboo-derived sorbents for mercury removal in gas phase.

    PubMed

    Siddiqui, Naved; Don, Jarlen; Mondal, Kanchan; Mahajan, Ajay

    2011-01-01

    Activated carbon sorbents were synthesized from bamboo precursors by carbonization in an inert atmosphere followed by physiochemical activation with carbon dioxide and finally acidulation in hydrochloric acid. Bamboo strips with and without the epidermal tissue (bark) were used. The morphology and specific surface area changes due to the treatment were analysed. The adsorption characteristics of these sorbents after each stage of treatment were also analysed and the data were correlated to the changes in the physical characteristics of the sorbents. Kinetic studies were conducted on these samples. The adsorption equilibrium and kinetics of elemental mercury adsorption on these carbons were evaluated at room temperature. Elemental mercury uptake at different sorbent loading and initial elemental mercury concentrations were examined. The adsorption rate constants and the mass transfer constants were estimated for the sorbents prepared under different conditions. Adsorption isotherms of the elemental mercury on these activated carbons were determined and correlated with Langmuir and Freundlich adsorption isotherm equations. It was found that the overall process was mass transfer controlled and that the adsorption equilibrium could be described by a linear isotherm for the concentrations used in this study.

  14. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals.

  15. Adsorption of crude oil on anhydrous and hydrophobized vermiculite.

    PubMed

    da Silva, Umberto G; de F Melo, Marcus A; da Silva, Adaílton F; de Farias, Robson F

    2003-04-15

    This publication reports the adsorption of crude oil on vermiculite samples, expanded and hydrophobized with carnauba (Copernícia Cerífera) wax. The adsorption studies were performed by using columns filled with the vermiculite matrices and by dispersion of the vermiculite samples in an oil-water (50 ppm of oil) emulsion. The hydrate vermiculite exhibits a very low adsorption capacity against crude oil. On the other hand, anhydrous (expanded) and hydrophobized matrices show a high adsorption capacity. The 10% hydrophobized matrix show a 50% increased adsorption capacity, in comparison with the expanded one. For adsorption performed in the water-oil emulsion, saturation of the solid hydrophobized matrix is achieved after 60 min. The hydrophobized samples exhibit adsorption factors in the 0.7-1.0 range.

  16. In vitro adsorption of tilidine HCl by activated charcoal.

    PubMed

    Cordonnier, J A; Van den Heede, M A; Heyndrickx, A M

    In vitro studies were carried out in order to determine the adsorption of tilidine HCl, a narcotic analgesic, by activated charcoal (max. adsorption capacity 185.5 mg/g of charcoal). The path of the adsorption isotherms at pH 1.2 and 7.5 suggests that the in vivo adsorption of tilidine HCl may be increased when the drug passes from the stomach to the intestine, unless the intestinal content exerts a displacing effect. Nevertheless, the adsorption was dependent on the quantity of activated charcoal used, becoming more complete when the quantity of activated charcoal was increased. The effects of additives on the adsorption capacity of activated charcoal were also investigated in vitro. Ethanol, sorbitol and sucrose significantly reduced drug adsorption, while cacao powder, milk and starch had no effect on tilidine adsorption. At an acid pH, Federa Activated Charcoal significantly adsorbed more drug than either Norit A or Activated Charcoal Merck.

  17. [Removal Characteristics of Elemental Mercury by Mn-Ce/molecular Sieve].

    PubMed

    Tan, Zeng-qiang; Niu, Guo-ping; Chen, Xiao-wen; An, Zhen

    2015-06-01

    The impregnation method was used to support molecular sieve with active manganese and cerium components to obtain a composite molecular sieve catalyst. The mercury removal performance of the catalyst was studied with a bench-scale setup. XPS analysis was used to characterize the sample before and after the modification in order to study the changes in the active components of the catalyst prepared. The results showed that the catalyst carrying manganese and cerium components had higher oxidation ability of elemental mercury in the temperature range of 300 degrees C - 450 degrees C, especially at 450 degrees C, the oxidation efficiency of elemental mercury was kept above 80%. The catalyst had more functional groups that were conducive to the oxidation of elemental mercury, and the mercury removal mainly depended on the chemical adsorption. The SO2 and NO in flue gas could inhibit the oxidation of elemental mercury to certain extent.

  18. CRYOGENIC ADSORPTION OF HYDROGEN ISOTOPES OVER NANO-STRUCTURED MATERIALS

    SciTech Connect

    Xiao, S.; Heung, L.

    2010-10-07

    Porous materials such as zeolites, activated carbon, silica gels, alumina and a number of industrial catalysts are compared and ranked for hydrogen and deuterium adsorption at liquid nitrogen temperature. All samples show higher D{sub 2} adsorption than that of H{sub 2}, in which a HY sample has the greatest isotopic effect while 13X has the highest hydrogen uptake capacity. Material's moisture content has significant impact to its hydrogen uptake. A material without adequate drying could result in complete loss of its adsorption capacity. Even though some materials present higher H{sub 2} adsorption capacity at full pressure, their adsorption at low vapor pressure may not be as good as others. Adsorption capacity in a dynamic system is much less than in a static system. A sharp desorption is also expected in case of temperature upset.

  19. Mercury Report-Children's exposure to elemental mercury

    MedlinePlus

    ... PDF - 781KB] En Español [PDF - 6.6MB] What did ATSDR find? For children, most elemental mercury exposures ... that exposed children to elemental mercury. The report did not include a review of mercury exposures from ...

  20. Mercury Calibration System

    SciTech Connect

    John Schabron; Eric Kalberer; Joseph Rovani; Mark Sanderson; Ryan Boysen; William Schuster

    2009-03-11

    U.S. Environmental Protection Agency (EPA) Performance Specification 12 in the Clean Air Mercury Rule (CAMR) states that a mercury CEM must be calibrated with National Institute for Standards and Technology (NIST)-traceable standards. In early 2009, a NIST traceable standard for elemental mercury CEM calibration still does not exist. Despite the vacature of CAMR by a Federal appeals court in early 2008, a NIST traceable standard is still needed for whatever regulation is implemented in the future. Thermo Fisher is a major vendor providing complete integrated mercury continuous emissions monitoring (CEM) systems to the industry. WRI is participating with EPA, EPRI, NIST, and Thermo Fisher towards the development of the criteria that will be used in the traceability protocols to be issued by EPA. An initial draft of an elemental mercury calibration traceability protocol was distributed for comment to the participating research groups and vendors on a limited basis in early May 2007. In August 2007, EPA issued an interim traceability protocol for elemental mercury calibrators. Various working drafts of the new interim traceability protocols were distributed in late 2008 and early 2009 to participants in the Mercury Standards Working Committee project. The protocols include sections on qualification and certification. The qualification section describes in general terms tests that must be conducted by the calibrator vendors to demonstrate that their calibration equipment meets the minimum requirements to be established by EPA for use in CAMR monitoring. Variables to be examined include linearity, ambient temperature, back pressure, ambient pressure, line voltage, and effects of shipping. None of the procedures were described in detail in the draft interim documents; however they describe what EPA would like to eventually develop. WRI is providing the data and results to EPA for use in developing revised experimental procedures and realistic acceptance criteria based on

  1. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

  2. Mercury: The World Closest to the Sun.

    ERIC Educational Resources Information Center

    Cordell, Bruce M.

    1984-01-01

    Discusses various topics related to the geology of Mercury including the origin of Mercury's magnetism, Mercury's motions, volcanism, scarps, and Mercury's violent birth and early life. Includes a table comparing Mercury's orbital and physical data to that of earth's. (JN)

  3. Formation of nanocolloidal metacinnabar in mercury-DOM-sulfide systems

    USGS Publications Warehouse

    Gerbig, C.A.; Kim, C.S.; Stegemeier, J.P.; Ryan, J.N.; Aiken, G.R.

    2011-01-01

    Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., <4 nmol Hg (mg DOM)-1) by combining solid phase extraction using C18 resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 ??M total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ?? 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 ??). In the presence of sulfide, mercury showed greater affinity for the C18 resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury-sulfur bonds with a longer interatomic distance (2.51-2.53 ??) similar to the mercury-sulfur bond distance in metacinnabar (2.53 ??) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg -1) mercury was coordinated by 2.3 ?? 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these

  4. Synthesis and characterization of LTA nanozeolite using barley husk silica: Mercury removal from standard and real solutions

    SciTech Connect

    Azizi, Seyed Naser; Dehnavi, Ahmad Roozbehani; Joorabdoozha, Amir

    2013-05-15

    Highlights: ► Silica extraction from barley husk with high purity for the synthesis of A nanozeolite. ► Free template A nanozeolite synthesized via new source of silica at low temperature. ► Optimization of SiO{sub 2}/Al{sub 2}O{sub 3}, Na{sub 2}O/SiO{sub 2} ratios, temperature and time of the synthesis. ► Utilizing of synthesized A nanozeolite for mercury removal from aqueous solutions. ► Mercury removal at optimized pH, contact time and adsorbent dose from real solution. - Abstract: In this study, synthesized Lined Type A (LTA) nanozeolite from barley husk silica (BHS) was used for mercury removal from standard and real aqueous solutions. The BHS in amorphous phase with 80% purity was extracted from barley husk ash (BHA), and used effectively as a new source of silica for the synthesis of NaA nanozeolite. The NaA nanocrystal in pure phase has been synthesized at low temperature, without adding any organic additives. The effects of heating time, reaction temperature, SiO{sub 2}/Al{sub 2}O{sub 3}, and Na{sub 2}O/SiO{sub 2} mole ratios on the crystallization of NaA nanozeolite were studied. The adsorption capacity of mercury (II) was studied as a function of pH, contact time, and amount of adsorbent. The crystallization of NaA nanozeolite from BHS was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET), and FTIR techniques. Moreover, concentration of Hg{sup 2+} ions in the aqueous solutions was analyzed by hydride generation atomic absorption spectroscopy method (HG-AAS). The standard and real samples analysis showed that NaA nanozeolite is capable of Hg{sup 2+} ions removal from the aqueous solutions. Efficiency of mercury (II) adsorption from real solutions onto the nano-sized NaA zeolite was 98%.

  5. Process for low mercury coal

    DOEpatents

    Merriam, N.W.; Grimes, R.W.; Tweed, R.E.

    1995-04-04

    A process is described for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal. 4 figures.

  6. Process for low mercury coal

    DOEpatents

    Merriam, Norman W.; Grimes, R. William; Tweed, Robert E.

    1995-01-01

    A process for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal.

  7. Adsorption of phenolic compound by aged-refuse.

    PubMed

    Xiaoli, Chai; Youcai, Zhao

    2006-09-01

    The adsorption of phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol by aged-refuse has been studied. Adsorption isotherms have been determined for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol and the data fits well to the Freundlich equation. The chlorinated phenols are absorbed more strongly than the phenol and the adsorption capacity has an oblivious relationship with the numbers and the position of chlorine subsistent. The experiment data suggests that both the partition function and the chemical adsorption involve in the adsorption process. Pseudo-first-order and pseudo-second-order model were applied to investigate the kinetics of the adsorption and the results show that it fit the pseudo-second-order model. More than one step involves in the adsorption process and the overall rate of the adsorption process appears to be controlled by the chemical reaction. The thermodynamic analysis indicates that the adsorption is spontaneous and endothermic.

  8. Effective removal of mercury(II) ions from chlor-alkali industrial wastewater using 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite.

    PubMed

    Anirudhan, T S; Shainy, F

    2015-10-15

    A novel adsorbent, 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite [P(MB-IA)-g-MNCC] was synthesized for adsorbing mercury(II) [Hg(II)] ions selectively from aqueous solutions. Fourier transforms infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric studies were performed to characterize the adsorbent. The optimum pH for Hg(II) adsorption was found to be 8.0, and the adsorption attained equilibrium within 60 min. The kinetic data were found to follow pseudo-second-order which assumes the ion exchange followed by complexation mechanism. The temperature dependence indicates an exothermic process. The well agreement of equilibrium data with Freundlich adsorption model confirms the multilayer coverage of Hg(II) onto P(MB-IA)-g-MNCC. The maximum adsorption capacity was found to be 240.0 mg/g. Complete removal of Hg(II) from aqueous solution was possible with an adsorbent dosage of 2.0 g/L. Spent adsorbent was effectively degenerated with 0.1M HCl. The present investigation shows that P(MB-IA)g-MNCC is a promising adsorbent for the removal and recovery of Hg(II) ions from aqueous solutions.

  9. Mercury removal using ground and calcined mussel shell.

    PubMed

    Peña-Rodríguez, Susana; Bermúdez-Couso, Alipio; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Fernández-Sanjurjo, María J; Alvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino

    2013-12-01

    We determined mercury retention on calcined and ground mussel shell, in presence and absence of phosphate, using batch and stirred flow chamber experiments. In batch experiments the calcined shell exhibited higher Hg adsorption, with good fitting to Freundlich equation (R2: 0.925-0.978); the presence of phosphate increased Hg adsorption; mercury desorption was 13% or lower, diminishing up to 2% under the presence of phosphates. In stirred flow chamber experiments calcined shell retained more Hg than ground shells (6300 vs. 4000-5200 micromol/kg); Hg retention increased an additional 40% on calcined shell and up to an additional 70% on ground shells when phosphates were present; mercury desorption was quite similar in all shell types (20%-34%), increasing up to 49%-60% in ground shells when phosphates were present. The higher Hg adsorption on calcined shell would be related to its calcite and dolomite concentrations; mercury-phosphate interactions would cause the increase in Hg retention when phosphates are present. Data on Hg desorption suggest that Hg retention was not easily reversible after batch experiments, increasing in the stirred flow chamber due to convective flow. Calcined and ground mussel shells could be recycled removing Hg from water, with the presence of phosphates in solution improving efficacy.

  10. Enhanced sorption of mercury from compact fluorescent bulbs and contaminated water streams using functionalized multiwalled carbon nanotubes.

    PubMed

    Gupta, Avinash; Vidyarthi, S R; Sankararamakrishnan, Nalini

    2014-06-15

    Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg(2+) as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90 min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S>CNT-I>CNT-OX>CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams.

  11. Comparative evaluation of adsorption kinetics of diclofenac and isoproturon by activated carbon.

    PubMed

    Torrellas, Silvia A; Rodriguez, Araceli R; Escudero, Gabriel O; Martín, José María G; Rodriguez, Juan G

    2015-01-01

    Adsorption mechanism of diclofenac and isoproturon onto activated carbon has been proposed using Langmuir and Freundlich isotherms. Adsorption capacity and optimum adsorption isotherms were predicted by nonlinear regression method. Different kinetic equations, pseudo-first-order, pseudo-second-order, intraparticle diffusion model and Bangham kinetic model, were applied to study the adsorption kinetics of emerging contaminants on activated carbon in two aqueous matrices.

  12. Thallium Mercury Laser Development

    DTIC Science & Technology

    1981-01-01

    THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu and D. W. Feldman FINAL REPORT (PHASE III) (Period between Feb. 1, 1980 and Jan. 31, 1981) 0 Contract No...Pittsburgh, Pennsylvania 15235 Approved for public release;IDistribution Unlimited 1/i;THALLIUM MERCURY LASER DEVELOPMENT * , , IS C. S./Liu tRD. W /eldman...9 ’ t4 THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu and D. W. Feldman Westinghouse R&D Center Pittsburgh, Pennsylvania 15235 1

  13. Substorms on Mercury?

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Ness, N. F.; Yeates, C. M.

    1974-01-01

    Qualitative similarities between some of the variations in the Mercury encounter data and variations in the corresponding regions of the earth's magnetosphere during substorms are pointed out. The Mariner 10 data on Mercury show a strong interaction between the solar wind and the plant similar to a scaled down version of that for the earth's magnetosphere. Some of the features observed in the night side Mercury magnetosphere suggest time dependent processes occurring there.

  14. Thief process for the removal of mercury from flue gas

    DOEpatents

    Pennline, Henry W.; Granite, Evan J.; Freeman, Mark C.; Hargis, Richard A.; O'Dowd, William J.

    2003-02-18

    A system and method for removing mercury from the flue gas of a coal-fired power plant is described. Mercury removal is by adsorption onto a thermally activated sorbent produced in-situ at the power plant. To obtain the thermally activated sorbent, a lance (thief) is inserted into a location within the combustion zone of the combustion chamber and extracts a mixture of semi-combusted coal and gas. The semi-combusted coal has adsorptive properties suitable for the removal of elemental and oxidized mercury. The mixture of semi-combusted coal and gas is separated into a stream of gas and semi-combusted coal that has been converted to a stream of thermally activated sorbent. The separated stream of gas is recycled to the combustion chamber. The thermally activated sorbent is injected into the duct work of the power plant at a location downstream from the exit port of the combustion chamber. Mercury within the flue gas contacts and adsorbs onto the thermally activated sorbent. The sorbent-mercury combination is removed from the plant by a particulate collection system.

  15. Peru Mercury Inventory 2006

    USGS Publications Warehouse

    Brooks, William E.; Sandoval, Esteban; Yepez, Miguel A.; Howard, Howell

    2007-01-01

    In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has long been mined and used in South America for artisanal gold mining and imported for chlor-alkali production, dental amalgam, and other uses. The U.S. Geological Survey (USGS) provides information on domestic and international mercury production, trade, prices, sources, and recycling in its annual Minerals Yearbook mercury chapter. Therefore, in response to UNEP-Chemicals, the USGS, in collaboration with the Economic Section of the U.S. Embassy, Lima, has herein compiled data on Peru's exports, imports, and byproduct production of mercury. Peru was selected for this inventory because it has a 2000-year history of mercury production and use, and continues today as an important source of mercury for the global market, as a byproduct from its gold mines. Peru is a regional distributor of imported mercury and user of mercury for artisanal gold mining and chlor-alkali production. Peruvian customs data showed that 22 metric tons (t) of byproduct mercury was exported to the United States in 2006. Transshipped mercury was exported to Brazil (1 t), Colombia (1 t), and Guyana (1 t). Mercury was imported from the United States (54 t), Spain (19 t), and Kyrgyzstan (8 t) in 2006 and was used for artisanal gold mining, chlor-alkali production, dental amalgam, or transshipment to other countries in the region. Site visits and interviews provided information on the use and disposition of mercury for artisanal gold mining and other uses. Peru also imports mercury-containing batteries, electronics and computers, fluorescent lamps, and thermometers. In 2006, Peru imported approximately 1,900 t of a wide variety of fluorescent lamps; however, the mercury contained in these lamps, a minimum of approximately 76 kilograms (kg), and in

  16. The Canadian Clean Air Regulatory Agenda Mercury Science Program.

    PubMed

    Morrison, Heather A

    2011-10-01

    The Clean Air Regulatory Agenda (CARA) Mercury Science Program was developed to provide scientific information to support regulatory activities and accountability pertaining to atmospheric emissions of mercury in Canada. The first phase of the science program, entitled "Setting-the-Baseline", sought to achieve the following: identify key indicators of the state-of-the-Canadian environment with respect to the transport, fate and effects of mercury; define these indicators; and, understand the processes that relate these indicators to anthropogenic emissions of mercury. To achieve these outcomes, a consultative process was used to identify the scientific needs of the agenda for mercury; understand Canada's scientific capacity; and, develop a plan to fulfill these scientific needs. The science plan that emerged from this process was structured around the themes of atmospheric monitoring, landscape-based risk assessment, ecological risk assessment, ecosystem modeling, and trends. Implementation of the science plan necessitated a multi-disciplinary and extensively partnered program. To date, the CARA Mercury Science Program is producing coordinated science at the national-scale that aims to directly assess the effectiveness of the CARA for mercury and for many of Canada's other mercury-related policies.

  17. Experimental evaluation of sorbents for the capture of mercury in flue gases

    SciTech Connect

    Livengood, C.D.; Huang, H.S.; Wu, J.M.

    1994-06-01

    The results and conclusions to date from the Argonne research program on air toxics (mercury) control can be summarized as follows: (1) Mercury emissions from coal-fired combustors are generally in the range of 10--70 {mu}g/m{sup 3} and are highly variable. (2) Existing FGC technologies are only partially effective in controlling mercury emissions. (3) Lime hydrates, either regular or high-surface-area, are not effective in removing mercury. (4) Mercury removals are enhanced by the addition of activated carbon. (5) Mercury removals with activated carbon decrease with increasing temperature, larger particle size, and decreasing mercury concentration in the gas. (6) Chemical pretreatment (with sulfur or CaCl{sub 2}) can greatly increase the removal capacity of activated carbon.

  18. Mercury distribution in contaminated surface sediments from four estuaries, Khuzestan shore, north part of Persian Gulf.

    PubMed

    Sarasiab, Abdolah Raeisi; Hosseini, Mehdi; Mirsalari, Zohreh

    2014-11-01

    The distribution of mercury in surface sediment from four estuaries along the Khuzestan shore, north part of Persian Gulf, was measured. The concentration of mercury varied among sampling stations (p < 0.05). The concentrations of mercury in all estuaries were from 0.01 to 2.16 µg g(-1). Relatively high mercury concentrations were observed in sediments from Musa estuary. The percentage of mercury associated with different fractions in the sediment from all stations were in the order of residual (70.4 %) > organic matter (16.6 %) > easily and exchangeable (2.2 %) > acid reduction (0.8 %). I geo values calculated for mercury (1.5) showed higher values in Musa estuary than in the other stations. The bioavailability of mercury in sediments could be controlled by physicochemical factors such as pH, oxidation and reduction potential, organic carbon content and cation exchange capacity.

  19. Regenerable sorbents for mercury capture in simulated coal combustion flue gas.

    PubMed

    Rodríguez-Pérez, Jorge; López-Antón, M Antonia; Díaz-Somoano, Mercedes; García, Roberto; Martínez-Tarazona, M Rosa

    2013-09-15

    This work demonstrates that regenerable sorbents containing nano-particles of gold dispersed on an activated carbon are efficient and long-life materials for capturing mercury species from coal combustion flue gases. These sorbents can be used in such a way that the high investment entailed in their preparation will be compensated for by the recovery of all valuable materials. The characteristics of the support and dispersion of gold in the carbon surface influence the efficiency and lifetime of the sorbents. The main factor that determines the retention of mercury and the regeneration of the sorbent is the presence of reactive gases that enhance mercury retention capacity. The capture of mercury is a consequence of two mechanisms: (i) the retention of elemental mercury by amalgamation with gold and (ii) the retention of oxidized mercury on the activated carbon support. These sorbents were specifically designed for retaining the mercury remaining in gas phase after the desulfurization units in coal power plants.

  20. Functionalized SBA-15 materials for bilirubin adsorption

    NASA Astrophysics Data System (ADS)

    Tang, Tao; Zhao, Yanling; Xu, Yao; Wu, Dong; Xu, Jun; Deng, Feng

    2011-05-01

    To investigate the driving force for bilirubin adsorption on mesoporous materials, a comparative study was carried out between pure siliceous SBA-15 and three functionalized SBA-15 mesoporous materials: CH 3-SBA-15 (MS), NH 2-SBA-15 (AS), and CH 3/NH 2-SBA-15 (AMS) that were synthesized by one-pot method. The obtained materials exhibited large surface areas (553-810 m 2/g) and pore size (6.6-7.1 nm) demonstrated by XRD and N 2-ad/desorption analysis. The SEM images showed that the materials had similar fiberlike morphology. The functionalization extent was calculated according to 29Si MAS NMR spectra and it was close to the designed value (10%). The synthesized mesoporous materials were used as bilirubin adsorbents and showed higher bilirubin adsorption capacities than the commercial active carbon. The adsorption capacities of amine functionalized samples AMS and AS were larger than those of pure siliceous SBA-15 and MS, indicating that electrostatic interaction was the dominant driving force for bilirubin adsorption on mesoporous materials. Increasing the ionic strength of bilirubin solution by adding NaCl would decrease the bilirubin adsorption capacity of mesoporous material, which further demonstrated that the electrostatic interaction was the dominant driving force for bilirubin adsorption. In addition, the hydrophobic interaction provided by methyl groups could promote the bilirubin adsorption.

  1. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

    SciTech Connect

    Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

    2013-10-15

    Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

  2. Fly Ash and Mercury Oxidation/Chlorination Reactions

    SciTech Connect

    Sukh Sidhu; Patanjali Varanasi

    2008-12-31

    a diffusion tube as the source of Hg0(g). All experiments were conducted using 4% O2 in nitrogen mix as a reaction gas, and other reactants (HCl, H2O and SO2, NO2, Br2) were added as required. The fixed bed reactor was operated over a temperature range of 200 to 400 C. In each experiment, the reactor effluent was analyzed using the modified Ontario-Hydro method. After each experiment, fly ash particles were also analyzed for mercury. The results show that the ability of fly ash to adsorb and/or oxidize mercury is primarily dependent on its carbon, iron and calcium content. There can be either one or more than one key component at a particular temperature and flue gas condition. Surface area played a secondary role in effecting the mercury transformations when compared to the concentration of the key component in the fly ash. Amount of carbon and surface area played a key important role in the adsorption of mercury. Increased concentration of gases in the flue gas other than oxygen and nitrogen caused decreased the amount of mercury adsorbed on carbon surface. Mercury adsorption by iron oxide primarily depended on the crystalline structure of iron oxide. {alpha}-Iron oxide had no effect on mercury adsorption or oxidation under most of the flue gas conditions, but ?-iron oxide adsorbed mercury under most of the flue gas conditions. Bromine is a very good oxidizing agent for mercury. But in the presence of calcium oxide containing fly ashes, all the oxidized mercury would be reduced to elemental form. Among the catalysts, it was observed that presence of free lattice chlorine in the catalyst was very important for the oxidation of mercury. But instead of using the catalyst alone, using it along with carbon may better serve the purpose by providing the adsorption surface for mercury and also some extra surface area for the reaction to occur (especially for fly ashes with low surface area).

  3. Carbon dioxide adsorption in graphene sheets

    NASA Astrophysics Data System (ADS)

    Mishra, Ashish Kumar; Ramaprabhu, Sundara

    2011-09-01

    Control over the CO2 emission via automobiles and industrial exhaust in atmosphere, is one of the major concerns to render environmental friendly milieu. Adsorption can be considered to be one of the more promising methods, offering potential energy savings compared to absorbent systems. Different carbon nanostructures (activated carbon and carbon nanotubes) have attracted attention as CO2 adsorbents due to their unique surface morphology. In the present work, we have demonstrated the CO2 adsorption capacity of graphene, prepared via hydrogen induced exfoliation of graphitic oxide at moderate temperatures. The CO2 adsorption study was performed using high pressure Sieverts apparatus and capacity was calculated by gas equation using van der Waals corrections. Physical adsorption of CO2 molecules in graphene was confirmed by FTIR study. Synthesis of graphene sheets via hydrogen exfoliation is possible at large scale and lower cost and higher adsorption capacity of as prepared graphene compared to other carbon nanostructures suggests its possible use as CO2 adsorbent for industrial application. Maximum adsorption capacity of 21.6 mmole/g was observed at 11 bar pressure and room temperature (25 °C).

  4. Modeling Mercury in Proteins

    SciTech Connect

    Smith, Jeremy C; Parks, Jerry M

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively non-toxic, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. Here we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.

  5. Parametric study of a silica gel-water adsorption refrigeration cycle -- The influence of thermal capacitance and heat exchanger UA-values on cooling capacity, power density, and COP

    SciTech Connect

    Boelman, E.C.; Saha, B.B.; Kashiwagi, Takao

    1997-12-31

    The influence of heat exchanger UA-values (adsorber/desorber, evaporator, and condenser) is investigated for an adsorption chiller, with consideration given to the thermal capacitance of the adsorber/desorber by means of a lumped-parameter cycle simulation model developed by the authors and co-workers for the single-stage silica gel-water adsorption chiller. The closed-cycle-type chiller, for use in air conditioning, is driven by low-grade waste heat (85 C [185 F]) and cooled by water at 31 C (88 F) and operates on relatively short cycle times (420 seconds adsorption/desorption; 30 second adsorber/desorber sensible cooling and heating). The results showed cycle performance to be considerably affected by the thermal capacitance and UA-value of the adsorber/desorber, which is attributed to the severe sensible cooling/heating requirements resulting from batched cycle operation. The model is also sensitive to the evaporator UA-value--but to a lesser extent. The condenser UA-value is the least sensitive parameter due to the working pair adsorption behavior in the temperature range defined for desorption and condensation.

  6. Adsorption of carbon black using carboxymethyl chitosan in deinking process

    NASA Astrophysics Data System (ADS)

    Muryeti, Budimulyani, Estuti; Sinurat, Ellya

    2017-03-01

    The study about synthesis, characterization, and application carboxymethyl chitosan as adsorbent in deinking process was conducted. Adsorption of carbon black onto carboxymethyl chitosan has been investigated in a batch system. This research was conducted to obtain the adsorption capacity of carboxymethyl chitosan. The experiments were carried out to study the effect of carbon black concentration, contact time and dosage of carboxymethyl chitosan to the adsorption capacity of carboxymethyl chitosan. The optimum condition of carbon black adsorption was achieved at contact time of 60 min and weight doses of 1.0 g. The adsorption capacity of carboxymethyl chitosan was 14.34 mg/g and the adsorption effectivity was 70.54%. The result indicates that carboxymethyl chitosan could be used as adsorbent of carbon black in deinking process.

  7. [Adsorption dynamics and breakthrough characteristics based on the fluidization condition].

    PubMed

    Wang, Jun; Wang, Yao; Huang, Xing; Yuan, Yi-Long; Chen, Rui-Hui; Zhou, Hang; Zhou, Dan-Dan

    2014-02-01

    Few studies on the adsorption dynamics and breakthrough characteristics based on the fluidization condition have been reported. In a fluidized bed adsorption reactor with phenol as the adsorbate and granular activated carbon as the adsorbent, the adsorption efficiency, adsorption dynamic characteristics, adsorption breakthrough curves and adsorption capacities were studied and compared with those of a fixed bed operated under the same conditions. The results showed that the adsorption efficiencies exceeded 93% in 5 min in both the fluidized conditions and fixed conditions at the superficial velocities of 8 mm x s(-1) and 13 mm x s(-1). Meanwhile, the above adsorption reactions fitted to Pseudo-second-order with linear correlation coefficients greater than 0.999. The adsorption capacity of fluidized conditions was 8.77 mg x g(-1) and 24.70 mg x g(-1) at the superficial velocities of 6 mm x s(-1) and 8 mm x s(-1). Generally, the fluidized bed reactor showed a higher adsorption efficiency and greater adsorption capacity than the fixed bed reactor.

  8. Mercury and Pregnancy

    MedlinePlus

    ... made when mercury in the air gets into water. The mercury in the air comes from natural sources (such as volcanoes) and man-made sources (such as burning coal and other pollution). You can get methylmercury in your body by ...

  9. Atmospheric Deposition of Mercury

    EPA Science Inventory

    With the advent of the industrial era, the amount of mercury entering the global environment increased dramatically. Releases of mercury in its elemental form from gold mines and chlor-alkali plants, as sulfides such as mercaptans and agricultural chemicals, and as volatile emiss...

  10. Mercury in the environment

    SciTech Connect

    Idaho National Laboratory - Mike Abbott

    2008-08-06

    Abbott works for Idaho National Laboratory as an environmental scientist. Using state-of-thescienceequipment, he continuously samples the air, looking for mercury. In turn, he'll analyzethis long-term data and try to figure out the mercury's point of or

  11. Dynamic duo captures mercury

    SciTech Connect

    Senior, C.; Adams, B.

    2006-02-15

    There is strong evidence that the combination of wet flue gas desulphurisation (FGD) scrubbers and selective catalytic reduction (SCR) can prove a viable and formidable combination for knocking out mercury. This article analyzes the capabilities and limitations of the SCR-FGD combination for mercury compliance, including applicability to different types of coal and issues with scrubber by-products. 3 figs.

  12. Mercury in the environment

    ScienceCinema

    Idaho National Laboratory - Mike Abbott

    2016-07-12

    Abbott works for Idaho National Laboratory as an environmental scientist. Using state-of-thescienceequipment, he continuously samples the air, looking for mercury. In turn, he'll analyzethis long-term data and try to figure out the mercury's point of or

  13. Mercury: the forgotten planet.

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.

    1997-11-01

    Mercury is the neglected child of the planetary system. Only one spacecraft has every ventured near it, whereas scores have probed the moon, Venus and Mars. The scant facts available show this strange, blazingly hot planet is full of surprises: its anomalous density and magnetic field suggest that Mercury may be where to seek clues to the origin of the solar system.

  14. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  15. Mercury concentrations in estuarine sediments, Lavaca and Matagorda bays, Texas, 1992

    USGS Publications Warehouse

    Brown, David S.; Snyder, Grant L.; Taylor, R. Lynn

    1998-01-01

    U.S. Environmental Protection Agency Method 7471 (Cold Vapor Atomic Absorption) was an acceptable analytical method for determining the total mercury concentrations in the Lavaca-Matagorda Bays estuarine sediment samples. Measurement of additional trace metals would aid in the characterization of total mercury concentrations and in the identification of concentrator/collector relations that are principally responsible for the adsorption of mercurous compounds to particulates in the bottom sediments.

  16. Getting rid of mercury

    SciTech Connect

    Reisch, M.S.

    2008-11-24

    Anticipating a US rule on mercury removal from coal flue gas, technology providers jockey for position. By 2013, if the federal rule imposing regulation of mercury emissions which have begun or are about to begin in 20 eastern states goes nationwide, mercury control will be big business. For the near term, utilities are adopting activated carbon to control mercury emissions. McIlvaine Co. projects the US market for activated carbon will jump from 10 million lb in 2010 to 350 million by 2013. Norit and Calgon Carbon are already increasing production of activated carbon (mainly from coal) and ADA Environmental Solutions (ADA-ES) is building a new plant. Albermarle is developing a process to treat activated carbon with bromine; Corning has developed a sulfur impregnated activated carbon filtration brick. New catalysts are being developed to improve the oxidation of mercury for removal from flue gas. 2 photos.

  17. Mercury poisoning in wildlife

    USGS Publications Warehouse

    Heinz, G.H.; Fairbrother, Anne; Locke, Louis N.; Hoff, Gerald L.

    1996-01-01

    Mercury is an intriguing contaminant because it has complex chemical properties, a wide range of harmful effects, and an infinite persistence in the environment. Die-offs of wildlife due to mercury have occurred in many countries, especially before mercury seed dressings were banned. Today, most mercury problems are associated with aquatic environments. Methylmercury, the most toxic chemical form, attacks many organ systems, but damage to the central nervous system is most severe. Harmful wet-weight concentrations of mercury, as methylmercury, in the tissues of adult birds and mammals range from about 8-30 ppm in the brain, 20-60 ppm in liver, 20-60 ppm in kidney, and 15-30 ppm in muscle. Young animals may be more sensitive.

  18. COMPETITIVE ADSORPTION OF VOCS AND BOM: THE ROLE OF MOLECULAR OXYGEN

    EPA Science Inventory

    In this study, the presence of background organic matter (BOM) was seen to reduce the adsorptive capacity of carbon for chloroform, chlorobenzene, and dibromochloropropane. Adsorption of these compounds was further reduced under oxic conditions. This additional reduction in cap...

  19. Getting Mercury out of Schools.

    ERIC Educational Resources Information Center

    1999

    This guide was prepared while working with many Massachusetts schools to remove items that contain mercury and to find suitable alternatives. It contains fact sheets on: mercury in science laboratories and classrooms, mercury in school buildings and maintenance areas, mercury in the medical office and in medical technology classrooms in vocational…

  20. Adsorption of halogenated aliphatic contaminants by graphene nanomaterials.

    PubMed

    Zhou, Yang; Apul, Onur Guven; Karanfil, Tanju

    2015-08-01

    In this study, adsorption of ten environmentally halogenated aliphatic synthetic organic compounds (SOCs) by a pristine graphene nanosheet (GNS) and a reduced graphene oxide (rGO) was examined, and their adsorption behaviors were compared with those of a single-walled carbon nanotube (SWCNT) and a granular activated carbon (GAC). In addition, the impacts of background water components (i.e., natural organic matter (NOM), ionic strength (IS) and pH) on the SOC adsorption behavior were investigated. The results indicated HD3000 and SWCNT with higher microporous volumes exhibited higher adsorption capacities for the selected aliphatic SOCs than graphenes, demonstrating microporosity of carbonaceous adsorbents played an important role in the adsorption. Analysis of adsorption isotherms demonstrated that hydrophobic interactions were the dominant contributor to the adsorption of aliphatic SOCs by graphenes. However, π-π electron donor-acceptor and van der Waals interactions are likely the additional mechanisms contributing to the adsorption of aliphatic SOCs on graphenes. Among the three background solution components examined, NOM showed the most influential effect on adsorption of the selected aliphatic SOCs, while pH and ionic strength had a negligible effects. The NOM competition on aliphatic adsorption was less pronounced on graphenes than SWCNT. Overall, in terms of adsorption capacities, graphenes tested in this study did not exhibit a major advantage over SWCNT and GAC for the adsorption of aliphatic SOCs.

  1. Fluorocarbon Adsorption in Hierarchical Porous Frameworks

    SciTech Connect

    Motkuri, Radha K.; Annapureddy, Harsha V.; Vijayakumar, M.; Schaef, Herbert T.; Martin, P F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-09

    The adsorption behavior of a series of fluorocarbon derivatives was examined on a set of microporous metal organic framework (MOF) sorbents and another set of hierarchical mesoporous MOFs. The microporous M-DOBDC (M = Ni, Co) showed a saturation uptake capacity for R12 of over 4 mmol/g at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous MOF MIL-101 showed an exceptionally high uptake capacity reaching over 14 mmol/g at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption were found to generally correlate with the polarizability of the refrigerant with R12 > R22 > R13 > R14 > methane. These results suggest the possibility of exploiting MOFs for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling and refrigeration applications.

  2. Competitive adsorption of heavy metals onto sesame straw biochar in aqueous solutions.

    PubMed

    Park, Jong-Hwan; Ok, Yong Sik; Kim, Seong-Heon; Cho, Ju-Sik; Heo, Jong-Soo; Delaune, Ronald D; Seo, Dong-Cheol

    2016-01-01

    Objective of this research was to evaluate adsorption of heavy metals in mono and multimetal forms onto sesame straw biochar (SSB). Competitive sorption of metals by SSB has never been reported previously. The maximum adsorption capacities (mgg(-1)) of metals by SSB were in the order of Pb (102)≫Cd (86)≫Cr (65)>Cu (55)≫Zn (34) in the monometal adsorption isotherm and Pb (88)≫Cu (40)≫Cr (21)>Zn (7)⩾Cd (5) in the multimetal adsorption isotherm. Based on data obtained from the distribution coefficients, Freundlich and Langmuir adsorption models, and three-dimensional simulation, multimetal adsorption behaviors differed from monometal adsorption due to competition. Especially, during multimetal adsorption, Cd was easily exchanged and substituted by other metals. Further competitive adsorption studies are necessary in order to accurately estimate the heavy metal adsorption capacity of biochar in natural environments.

  3. Detoxification of mercury pollutant leached from spent fluorescent lamps using bacterial strains.

    PubMed

    Al-Ghouti, Mohammad A; Abuqaoud, Reem H; Abu-Dieyeh, Mohammed H

    2016-03-01

    The spent fluorescent lamps (SFLs) are being classified as a hazardous waste due to having mercury as one of its main components. Mercury is considered the second most toxic heavy metal (arsenic is the first) with harmful effects on animal nervous system as it causes different neurological disorders. In this research, the mercury from phosphor powder was leached, then bioremediated using bacterial strains isolated from Qatari environment. Leaching of mercury was carried out with nitric and hydrochloric acid solutions using two approaches: leaching at ambient conditions and microwave-assisted leaching. The results obtained from this research showed that microwave-assisted leaching method was significantly better in leaching mercury than the acid leaching where the mercury leaching efficiency reached 76.4%. For mercury bio-uptake, twenty bacterial strains (previously isolated and purified from petroleum oil contaminated soils) were sub-cultured on Luria Bertani (LB) plates with mercury chloride to check the bacterial tolerance to mercury. Seven of these twenty strains showed a degree of tolerance to mercury. The bio-uptake capacities of the promising strains were investigated using the mercury leached from the fluorescent lamps. Three of the strains (Enterobacter helveticus, Citrobacter amalonaticus, and Cronobacter muytjensii) showed bio-uptake efficiency ranged from 28.8% to 63.6%.

  4. Control of mercury emissions from stationary coal combustion sources in China: Current status and recommendations.

    PubMed

    Hu, Yuanan; Cheng, Hefa

    2016-11-01

    Coal burning in power plants and industrial boilers is the largest combustion source of mercury emissions in China. Together, power plants and industrial boilers emit around 250 tonnes of mercury each year, or around half of atmospheric mercury emissions from anthropogenic sources in the country. Power plants in China are generally equipped with multi-pollutant control technologies, which offer the co-benefit of mercury removal, while mercury-specific control technologies have been installed in some facilities. In contrast, most industrial boilers have only basic or no flue gas cleaning. A combination of measures, including energy conservation, coal switching and blending, reducing the mercury contents of coals through washing, combustion controls, and flue gas cleaning, can be used to reduce mercury emissions from these stationary combustion sources. More stringent emission standards for the major air pollutants from coal-fired power plants and industrial boiler, along with standards for the previously unregulated mercury, were implemented recently, which is expected to bring significant reduction in their mercury emissions through the necessary upgrades of multi-pollutant and mercury-specific control technologies. Meanwhile, strong monitoring capacity and strict enforcement are necessary to ensure that the combustion sources operate in compliance with the new emission standards and achieve significant reduction in the emissions of mercury and other air pollutants.

  5. Leaching of mercury from seal carcasses into Antarctic soils.

    PubMed

    Zvěřina, Ondřej; Coufalík, Pavel; Brat, Kristián; Červenka, Rostislav; Kuta, Jan; Mikeš, Ondřej; Komárek, Josef

    2017-01-01

    More than 400 seal mummies and skeletons are now mapped in the northern part of James Ross Island, Antarctica. Decomposing carcasses represent a rare source of both organic matter and associated elements for the soil. Owing to their high trophic position, seals are known to carry a significant mercury body burden. This work focuses on the extent of the mercury input from seal carcasses and shows that such carcasses represent locally significant sources of mercury and methylmercury for the environment. Mercury contents in soil samples from the surrounding areas were determined using a single-purpose AAS mercury analyzer. For the determination of methylmercury, an ultra-sensitive isotopic dilution HPLC-ICP-MS technique was used. In the soils lying directly under seal carcasses, mercury contents were higher, with levels reaching almost 40 μg/kg dry weight of which methylmercury formed up to 2.8 % of the total. The spatial distribution implies rather slow vertical transport to the lower soil layers instead of a horizontal spread. For comparison, the background level of mercury in soils of the investigated area was found to be 8 μg/kg dry weight, with methylmercury accounting for less than 0.1 %. Apart from the direct mercury input, an enhanced level of nutrients in the vicinity of carcasses enables the growth of lichens and mosses with accumulative ability with respect to metals. The enhanced capacity of soil to retain mercury is also anticipated due to the high content of total organic carbon (from 1.6 to 7.5 %). According to the results, seal remains represent a clear source of mercury in the observed area.

  6. Kinetic and thermodynamic studies of sulforaphane adsorption on macroporous resin.

    PubMed

    Yuanfeng, Wu; Lei, Zhang; Jianwei, Mao; Shiwang, Liu; Jun, Huang; Yuru, You; Lehe, Mei

    2016-08-15

    The adsorption equilibrium, kinetic and thermodynamic of sulforaphane (SF) adsorption onto macroporous resin in aqueous phase were studied. The SP850 resin was screened as the appropriate resin for SF purification. From the equilibrium studies, the Redlich-Peterson model was found to be the best for description of the adsorption behavior of SF onto SP850 resin, followed by the Freundlich model and the Langmuir model. Batch equilibrium experiments demonstrated that, in the examined temperature range, the equilibrium adsorption capacity of SP850 resin decreased with increasing adsorption temperature. Thermodynamics studies indicated that the adsorption of SF was a physical, exothermic, and spontaneous process. The adsorption kinetics revealed that the pseudo-second-order kinetic model was suitable to characterize the kinetics of adsorption of SF onto SP850. Finally, the intra-particle diffusion model demonstrated that SF diffused quickly into macropores, and that diffusion slowed down in the meso- and micropores.

  7. Competitive adsorption of VOCcs and BOM: Oxic and anoxic environments

    SciTech Connect

    Sorial, G.A.; Papadimas, S.P.; Suidan, M.T.; Speth, T.F.

    1994-01-01

    The effect of the presence of molecular oxygen on the adsorption of volatile organic compounds (VOCs) in distilled Milli-Q water and in water supplemented with background organic matter (BOM) is evaluated. Experiments are conducted under conditions where molecular oxygen is present in the test environment (oxic adsorption), and where oxygen is absent from the test environment (anoxic adsorption). Adsorption isotherms for tetrachloroethylene (PCE) and trichloroethylene (TCE) in Milli-Q water showed no impact of the presence of oxygen on their adsorption behavior, while adsorption isotherms for cis-1,2-dichloroethylene (DCE) showed higher capacities under toxic conditions. The Ideal Adsorbed Solution Theory (IAST) successfully predicted the VOCs anoxic adsorption isotherms in BOM. However, the IAST model did not predict the VOCs oxic adsorption isotherms in BOM.

  8. Adsorption of thorium from aqueous solutions by perlite.

    PubMed

    Talip, Z; Eral, M; Hiçsönmez, U

    2009-02-01

    The use of expanded perlite for the adsorption of thorium from aqueous solution by batch technique is presented. The effects of particle size, pH of the solution, initial thorium concentration, shaking time, V/m ratio and temperature were determined. It was found that the adsorption capacity increases by the increase in the pH of the suspensions. The rate of thorium adsorption on expanded perlite was observed to be fast in the first hour of the reaction time. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models and the adsorption experiments conducted at 30 +/- 1 degrees C showed that the adsorption isotherms correlated well with the Langmuir model. From the adsorption data, thermodynamic parameters such as DeltaG(o), DeltaH(o) and DeltaS(o) were calculated as a function of temperature.

  9. Assessing The Impact Of Mercury Contamination To Lake Balkyldak In Kazakhstan

    EPA Science Inventory

    Adjacent to Lake Balkyldak in Kazakhstan, there is a large wastewater holding pond from a former mercury cell chloralkali plant which contains high levels of mercury-contamination. The holding pond capacity is 74 million m3 with a water-surface area of 18 km2

  10. Factors affecting drug adsorption on beta zeolites.

    PubMed

    Pasti, Luisa; Sarti, Elena; Cavazzini, Alberto; Marchetti, Nicola; Dondi, Francesco; Martucci, Annalisa

    2013-05-01

    The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO2/Al2O3 ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X-ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity.

  11. Demonstration of Mer-Cure Technology for Enhanced Mercury Control

    SciTech Connect

    John Marion; Dave O'Neill; Kevin Taugher; Shin Kang; Mark Johnson; Gerald Pargac; Jane Luedecke; Randy Gardiner; Mike Silvertooth; Jim Hicks; Carl Edberg; Ray Cournoyer; Stanley Bohdanowicz; Ken Peterson; Kurt Johnson; Steve Benson; Richard Schulz; Don McCollor; Mike Wuitshick

    2008-06-01

    Alstom Power Inc. has completed a DOE/NETL-sponsored program (under DOE Cooperative Agreement No. De-FC26-07NT42776) to demonstrate Mer-Cure{trademark}, one of Alstom's mercury control technologies for coal-fired boilers. The Mer-Cure{trademark}system utilizes a small amount of Mer-Clean{trademark} sorbent that is injected into the flue gas stream for oxidation and adsorption of gaseous mercury. Mer-Clean{trademark} sorbents are carbon-based and prepared with chemical additives that promote oxidation and capture of mercury. The Mer-Cure{trademark} system is unique in that the sorbent is injected into an environment where the mercury capture kinetics is accelerated. The full-scale demonstration program originally included test campaigns at two host sites: LCRA's 480-MW{sub e} Fayette Unit No.3 and Reliant Energy's 190-MW{sub e} Shawville Unit No.3. The only demonstration tests actually done were the short-term tests at LCRA due to budget constraints. This report gives a summary of the demonstration testing at Fayette Unit No.3. The goals for this Mercury Round 3 program, established by DOE/NETL under the original solicitation, were to reduce the uncontrolled mercury emissions by 90% at a cost significantly less than 50% of the previous target of $60,000/lb mercury removed. The results indicated that Mer-Cure{trademark} technology could achieve mercury removal of 90% based on uncontrolled stack emissions. The estimated costs for 90% mercury control, at a sorbent cost of $0.75 to $2.00/lb respectively, were $13,400 to $18,700/lb Hg removed. In summary, the results from demonstration testing show that the goals established by DOE/NETL were met during this test program. The goal of 90% mercury reduction was achieved. Estimated mercury removal costs were 69-78% lower than the benchmark of $60,000/lb mercury removed, significantly less than 50% of the baseline removal cost.

  12. Formation of nanocolloidal metacinnabar in mercury-DOM-sulfide systems

    USGS Publications Warehouse

    Gerbig, Chase A.; Kim, Christopher S.; Stegemeier, John P.; Ryan, Joseph N.; Aiken, George R.

    2011-01-01

    Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., -1) by combining solid phase extraction using C18 resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 μM total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ± 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 Å). In the presence of sulfide, mercury showed greater affinity for the C18 resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury–sulfur bonds with a longer interatomic distance (2.51–2.53 Å) similar to the mercury–sulfur bond distance in metacinnabar (2.53 Å) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg-1) mercury was coordinated by 2.3 ± 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to

  13. Fibrous polymer-grafted chitosan/clay composite beads as a carrier for immobilization of papain and its usability for mercury elimination.

    PubMed

    Metin, Ayşegül Ülkü; Alver, Erol

    2016-07-01

    Papain, which is an industrially important enzyme, has been immobilized on fibrous polymer-modified composite beads, namely poly(methacrylic acid)-grafted chitosan/clay. Characterization studies have been done using FTIR and SEM analysis. Operating parameters such as pH and initial concentration of papain have been varied to obtain the finest papain immobilized polymer-modified composite beads. The immobilization capacity of composite beads has been determined as 34.47 ± 1.18 (n = 3) mg/g. The proteolytic activity of immobilized papain was operated using bovine serum albumin (BSA) and maximum velocity (V max) and Michaelis-Menten constant (Km) values of the free and immobilized enzymes were determined using Lineweaver-Burk and Eadie-Hofstee equations. Usability of papain immobilized polymer-modified composite beads as adsorbents for the elimination of mercury was investigated. The maximum removal capacity of PIPMC beads has been found to be 4.88 ± 0.21 mg Hg/g when the initial metal concentration and weight of polymer-modified composite beads were 50 mg/L and 0.04 g at pH 7, respectively. Mercury removal performance of the papain immobilized polymer-modified composite beads was investigated in conjunction with Cu (II), Zn (II) and Cd (II) ions. The mercury adsorption capacity of papain immobilized polymer-modified composite beads was a slight reduction from 1.15 to 0.89 mg/g in presence of multiple metal salts.

  14. Poultry manure as raw material for mercury adsorbents in gas applications

    SciTech Connect

    Klasson, K.T.; Lima, I.M.; Boihem, L.L.

    2009-09-30

    The quantity of poultry manure generated each year is large, and technologies that take advantage of the material should be explored. At the same time, increased emphasis on the reduction of mercury emissions from coal-fired electric power plants has resulted in environmental regulations that may, in the future, require application of activated carbons as mercury sorbents. The sorbents could be injected into the flue gas stream, where they could adsorb the mercury. The sorbents (now containing mercury) would be removed via filtration or other means from the flue gas. Our preliminary work has demonstrated that activated carbon made from poultry manure can adsorb mercury from air with good efficiency. In laboratory experiments, an activated carbon made from turkey cake manure removed the majority of elemental mercury from a hot air stream. Other activated carbons made from chicken and turkey litter manure were also efficient. In general, unwashed activated carbons made from poultry manure were more efficient in removing mercury than their acid-washed counterparts. The results suggest that the adsorption of mercury was mainly due to chemisorption on the surface of the carbon. Other potential uses for the activated carbons are the removal of mercury from air and natural gas.

  15. Mercury in the ecosystem

    SciTech Connect

    Mitra, S.

    1986-01-01

    This treatise on the environmental dispersion of mercury emphasizes the importance of ''mercury-consciousness'' in the present-day world, where rapidly expanding metallurgical, chemical, and other industrial developments are causing widespread contamination of the atmosphere, soil, and water by this metal and its toxic organic derivatives. Concepts concerning the mechanism of mercury dispersion and methyl-mercury formation in the physico-biological ecosystem are discussed in detail and a substantial body of data on the degree and nature of the mercury contamination of various plants, fish, and land animals by industrial and urban effluents is presented. Various analytical methods for the estimation of mercury in inorganic and organic samples are presented. These serve as a ready guide to the selection of the correct method for analyzing environmental samples. This book is reference work in mercury-related studies. It is written to influence industrial policies of governments in their formulation of control measures to avoid the recurrence of human tragedies such as the well-known Minamata case in Japan, and the lesser known cases in Iraq, Pakistan, and Guatamala.

  16. Mercury Metadata Toolset

    SciTech Connect

    2009-09-08

    Mercury is a federated metadata harvesting, search and retrieval tool based on both open source software and software developed at Oak Ridge National Laboratory. It was originally developed for NASA, and the Mercury development consortium now includes funding from NASA, USGS, and DOE. A major new version of Mercury (version 3.0) was developed during 2007 and released in early 2008. This Mercury 3.0 version provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS delivery of search results, and ready customization to meet the needs of the multiple projects which use Mercury. For the end users, Mercury provides a single portal to very quickly search for data and information contained in disparate data management systems. It collects metadata and key data from contributing project servers distributed around the world and builds a centralized index. The Mercury search interfaces then allow the users to perform simple, fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data.

  17. Mercury's Dynamic Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  18. Catalysts for oxidation of mercury in flue gas

    DOEpatents

    Granite, Evan J.; Pennline, Henry W.

    2010-08-17

    Two new classes of catalysts for the removal of heavy metal contaminants, especially mercury (Hg) from effluent gases. Both of these classes of catalysts are excellent absorbers of HCl and Cl.sub.2 present in effluent gases. This adsorption of oxidizing agents aids in the oxidation of heavy metal contaminants. The catalysts remove mercury by oxidizing the Hg into mercury (II) moieties. For one class of catalysts, the active component is selected from the group consisting of iridium (Ir) and iridum-platinum (Ir/Pt) alloys. The Ir and Ir/Pt alloy catalysts are especially corrosion resistant. For the other class of catalyst, the active component is partially combusted coal or "Thief" carbon impregnated with Cl.sub.2. Untreated Thief carbon catalyst can be self-activating in the presence of effluent gas streams. The Thief carbon catalyst is disposable by means of capture from the effluent gas stream in a particulate collection device (PCD).

  19. Inorganic: the other mercury.

    PubMed

    Risher, John F; De Rosa, Christopher T

    2007-11-01

    There is a broad array of mercury species to which humans may be exposed. While exposure to methylmercury through fish consumption is widely recognized, the public is less aware of the sources and potential toxicity of inorganic forms of mercury. Some oral and laboratory thermometers, barometers, small batteries, thermostats, gas pressure regulators, light switches, dental amalgam fillings, cosmetic products, medications, cultural/religious practices, and gold mining all represent potential sources of exposure to inorganic forms of mercury. The route of exposure, the extent of absorption, the pharmacokinetics, and the effects all vary with the specific form of mercury and the magnitude and duration of exposure. If exposure is suspected, a number of tissue analyses can be conducted to confirm exposure or to determine whether an exposure might reasonably be expected to be biologically significant. By contrast with determination of exposure to methylmercury, for which hair and blood are credible indicators, urine is the preferred biological medium for the determination of exposure to inorganic mercury, including elemental mercury, with blood normally being of value only if exposure is ongoing. Although treatments are available to help rid the body of mercury in cases of extreme exposure, prevention of exposure will make such treatments unnecessary. Knowing the sources of mercury and avoiding unnecessary exposure are the prudent ways of preventing mercury intoxication. When exposure occurs, it should be kept in mind that not all unwanted exposures will result in adverse health consequences. In all cases, elimination of the source of exposure should be the first priority of public health officials.

  20. Methylene blue adsorption by algal biomass based materials: biosorbents characterization and process behaviour.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2007-08-17

    Dead algal biomass is a natural material that serves as a basis for developing a new family of sorbent materials potentially suitable for many industrial applications. In this work an algal industrial waste from agar extraction process, algae Gelidium and a composite material obtained by immobilization of the algal waste with polyacrylonitrile (PAN) were physical characterized and used as biosorbents for dyes removal using methylene blue as model. The apparent and real densities and the porosity of biosorbents particles were determined by mercury porosimetry and helium picnometry. The methylene blue adsorption in the liquid phase was the method chosen to calculate the specific surface area of biosorbent particles as it seems to reproduce better the surface area accessible to metal ions in the biosorption process than the N2 adsorption-desorption dry method. The porous texture of the biosorbents particles was also studied. Equilibrium isotherms are well described by the Langmuir equation, giving maximum uptake capacities of 171, 104 and 74 mg g(-1), respectively for algae, algal waste and composite material. Kinetic experiments at different initial methylene blue concentrations were performed to evaluate the equilibrium time and the importance of the driving force to overcome mass transfer resistances. The pseudo-first-order and pseudo-second-order kinetic models adequately describe the kinetic data. The biosorbents used in this work proved to be promising materials for removing methylene blue from aqueous solutions.

  1. Thallium Mercury Laser Development.

    DTIC Science & Technology

    1980-04-17

    AD-A9 840 WESTINGHOUSE RESEARCH AND DEVELOPMENT CENTER PITTSBU--ETC F/A 20/5 THALLIUM MERCURY LASER DEVELOPMENT .(U) APR 80 C S LIU, D W FELDMAN, J L...PACK NO001I78-C-0131 lIlrt A nEQE-WOTFX-R NL THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu, D. W. Feldman and J. L. Pack FINAL REPORT (PHASE II...PERIOD COVERED Thallium Mercury Laser Development -T- Final Report (Phase II) Feb. 1, 1979 to Jan. 31, 1980 77a. w-atF. -REPORT NUMBER _,___C2-OTEX

  2. Global change and mercury

    USGS Publications Warehouse

    Krabbenhoft, David P.; Sunderland, Elsie M.

    2013-01-01

    More than 140 nations recently agreed to a legally binding treaty on reductions in human uses and releases of mercury that will be signed in October of this year. This follows the 2011 rule in the United States that for the first time regulates mercury emissions from electricity-generating utilities. Several decades of scientific research preceded these important regulations. However, the impacts of global change on environmental mercury concentrations and human exposures remain a major uncertainty affecting the potential effectiveness of regulatory activities.

  3. Removal of mercury from powder river basin coal by low-temperature thermal treatment

    SciTech Connect

    Merriam, N.W.

    1993-07-01

    This report describes work conducted at Western Research Institute (WRI) to remove mercury from Powder River Basin (PRB) coal as part of the research performed under Task 2.1, Development and Optimization of a Process for the Production of a Premium Solid Fuel from Western US Coals, of the 1993 Annual Project Plan. In the tests minus 16 mesh PRB coal was fed to a bench-scale fluidized-bed reactor where it was heated by contact with carbon dioxide fluidizing gas. A side stream of the gas from the reactor was passed through traps containing activated carbon where mercury driven from the coal was collected. The feed coal (which contains about 0.062 milligrams of mercury/kilogram of coal), the fines elutriated from the reactor, the activated carbon, and the condensed water from the reactor were analyzed for mercury. The solid products were analyzed using cold vapor atomic adsorption spectroscopy (ASTM D3684) while the water was analyzed using US Environmental Protection Agency (EPA) Method 245.1 which is based upon reduction of mercury to elemental form followed by adsorption at a wave length of 253.7 nanometers. The results of these tests show that about 70 to 80 wt % of the mercury is removed from the coal when the temperature is raised from about 300{degree}F (149{degree}C) to about 550{degree}F (288{degree}C). The remaining 20 wt % of the mercury remains in the char at temperatures up to about 1100{degree}F (593{degree}C). About 0.5 wt % of the mercury in the feed coal is condensed with water recovered from the coal. Nearly all of the mercury driven from the coal remains in the gas stream. Fines elutriated from the reactor contain about the same concentration of mercury as the feed coal.

  4. Mercury content in mushroom species in the Cordoba area

    SciTech Connect

    Zurera, G.; Rincon, F.; Arcos, F.; Pozo-Lora, R.

    1986-05-01

    Numerous investigations have established that fish is the food which shows the highest levels of mercury, thus being the most hazardous for humans. Recently much research has been carried out in several places of Europe on the high capacity of mushrooms to accumulate heavy metals. It has been noticed that the various species differ in their tendency to accumulate heavy metals. Two genera in which mercury accumulation was very marked are Agaricus and Lycoperdon. It is suggested that members of the genus Agaricus could be used as indicator organisms in the study of mercury pollution. The object of the present paper is to provide data on the levels of mercury contents in mushroom species collected in the Cordoba area (Spain).

  5. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, M.W.; George, W.A.

    1991-06-18

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figures.

  6. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1988-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  7. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1989-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  8. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, M.W.; George, W.A.

    1989-11-07

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figs.

  9. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1991-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  10. Polychelated cryogels: hemoglobin adsorption from human blood.

    PubMed

    Erol, Kadir

    2017-02-01

    The separation and purification methods are extremely important for the hemoglobin (Hb) which is a crucial biomolecule. The adsorption technique is popular among these methods and the cryogels have been used quite much due to their macropores and interconnected flow channels. In this study, the Hb adsorption onto the Cu(II) immobilized poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), poly(HEMA-GMA)-Cu(II), cryogels was investigated under different conditions (pH, interaction time, initial Hb concentration, temperature and ionic strength) to optimize adsorption conditions. The swelling test, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), surface area (BET), elemental and ICP-OES analysis were performed for the characterization of cryogels. Polyethyleneimine (PEI) molecule was used as a Cu(II)-chelating ligand. The Hb adsorption capacity of cryogels was determined as 193.8 mg Hb/g cryogel. The isolation of Hb from human blood was also studied under optimum adsorption conditions determined and the Hb (124.5 mg/g cryogel) was isolated. The adsorption model was investigated in the light of Langmuir and Freundlich adsorption isotherm models and it was determined to be more appropriate to the Langmuir adsorption isotherm model.

  11. Phosphoryl functionalized mesoporous silica for uranium adsorption

    NASA Astrophysics Data System (ADS)

    Xue, Guo; Yurun, Feng; Li, Ma; Dezhi, Gao; Jie, Jing; Jincheng, Yu; Haibin, Sun; Hongyu, Gong; Yujun, Zhang

    2017-04-01

    Phosphoryl functionalized mesoporous silica (TBP-SBA-15) was synthesized by modified mesoporous silica with γ-amino propyl triethoxy silane and tributyl phosphate. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), thermo-gravimetric/differential thermalanalyzer (TG/DTA), N2 adsorption-desorption (BET) and Fourier transform infrared spectroscopy (FT-IR) techniques. Results showed that TBP-SBA-15 had large surface areas with ordered channel structure. Moreover, the effects of adsorption time, sorbent dose, solution pH, initial uranium concentration and temperature on the uranium adsorption behaviors were investigated. TBP-SBA-15 showed a high uranium adsorption capacity in a broad range of pH values. The U(VI) adsorption rate of TBP-SBA-15 was fast and nearly achieved completion in 10 min with the sorbent dose of 1 g/L. The U(VI) adsorption of TBP-SBA-15 followed the pseudo-second-order kinetic model and Freundlich isotherm model, indicating that the process was belonged to chemical adsorption. Furthermore, the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) confirmed that the adsorption process was endothermic and spontaneous.

  12. Mercury cycling in terrestrial watersheds

    USGS Publications Warehouse

    Shanley, James B.; Bishop, Kevin; Banks, Michael S.

    2012-01-01

    This chapter discusses mercury cycling in the terrestrial landscape, including inputs from the atmosphere, accumulation in soils and vegetation, outputs in streamflow and volatilization, and effects of land disturbance. Mercury mobility in the terrestrial landscape is strongly controlled by organic matter. About 90% of the atmospheric mercury input is retained in vegetation and organic matter in soils, causing a buildup of legacy mercury. Some mercury is volatilized back to the atmosphere, but most export of mercury from watersheds occurs by streamflow. Stream mercury export is episodic, in association with dissolved and particulate organic carbon, as stormflow and snowmelt flush organic-rich shallow soil horizons. The terrestrial landscape is thus a major source of mercury to downstream aquatic environments, where mercury is methylated and enters the aquatic food web. With ample organic matter and sulfur, methylmercury forms in uplands as well—in wetlands, riparian zones, and other anoxic sites. Watershed features (topography, land cover type, and soil drainage class) are often more important than atmospheric mercury deposition in controlling the amount of stream mercury and methylmercury export. While reductions in atmospheric mercury deposition may rapidly benefit lakes, the terrestrial landscape will respond only over decades, because of the large stock and slow turnover of legacy mercury. We conclude with a discussion of future scenarios and the challenge of managing terrestrial mercury.

  13. The Study of Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, Louise M.; Bedini, Peter D.

    2010-01-01

    When the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft enters orbit about Mercury in March 2011 it will begin a new phase in an age-old scientific study of the innermost planet. Despite being visible to the unaided eye, Mercury's proximity to the Sun makes it extremely difficult to observe from Earth. Nonetheless, over the centuries man has pursued a quest to understand the elusive planet, and has teased out information about its motions in the sky, its relation to the other planets, and its physical characteristics. A great leap was made in our understanding of Mercury when the Mariner 10 spacecraft flew past it three times in the mid-1970s, providing a rich set of close-up observations. Now, three decades later, The MESSENGER spacecraft has also visited the planet three times, and is poised to add significantly to the study with a year-long orbital observation campaign.

  14. ULF Waves at Mercury

    NASA Astrophysics Data System (ADS)

    Kim, E.-H.; Boardsen, S. A.; Johnson, J. R.; Slavin, J. A.

    2016-02-01

    This chapter provides a brief overview of the observed characteristics of ultra-low-frequency (ULF) waves at Mercury. It shows how field-aligned propagating ULF waves at Mercury can be generated by externally driven fast compressional waves (FWs) via mode conversion at the ion-ion hybrid resonance. Then, the chapter reviews the interpretation that the strong magnetic compressional waves near and its harmonics observed with 20 of Mercury's magnetic equator could be the ion Bernstein wave (IBW) mode. A recent statistical study of ULF waves at Mercury based on MESSENGER data reported the occurrence and polarization of the detected waves. The chapter further introduces the field line resonance and the electromagnetic ion Bernstein waves to explain such waves, and shows that both theories can partially explain the observations.

  15. Field Demonstration of Enhanced Sorbent Injection for Mercury Control

    SciTech Connect

    Shin Kang; Robert Schrecengost

    2009-01-07

    Alstom Power Inc. has conducted a DOE/NETL-sponsored program (under DOE Cooperative Agreement No. DE-FC26-04NT42306) to demonstrate Mer-Cure{trademark}, one of Alstom's mercury control technologies for coal-fired boilers. Mer-Cure{trademark} utilizes a small amount of Mer-Clean{trademark} sorbent that is injected into the flue gas stream for oxidation and adsorption of gaseous mercury. Mer-Clean{trademark} sorbents are carbon-based and prepared with chemical additives that promote oxidation and capture of mercury. Mer-Cure{trademark} is unique in that the sorbent is injected into an environment where the mercury capture kinetics is accelerated. This full-scale demonstration program was comprised of three seven-week long test campaigns at three host sites including PacifiCorp's 240-MW{sub e} Dave Johnston Unit No.3 burning a Powder River Basin (PRB) coal, Basin Electric's 220-MW{sub e} Leland Olds Unit No.1 burning a North Dakota lignite, and Reliant Energy's 170-MW{sub e} Portland Unit No.1 burning an Eastern bituminous coal. All three boilers are equipped with electrostatic precipitators. The goals for this Round 2 program, established by DOE/NETL under the original solicitation, were to reduce the uncontrolled mercury emissions by 50 to 70% at a cost 25 to 50% lower than the previous target of $60,000/lb mercury removed. The results for all three host sites indicated that Mer-Cure{trademark} technology could achieve mercury removal of 90%. The estimated mercury removal costs were 25-92% lower than the benchmark of $60,000/lb mercury removed. The estimated costs for control, at sorbent cost of $1.25 to $2.00/lb respectively, are as follows: (1) Dave Johnston Unit No.3--$2,650 to $4,328/lb Hg removed (92.8% less than $60k/lb); (2) Leland Olds Unit No.1--$8,680 to $13,860/lb Hg removed (76.7% less than $60k/lb); and (3) Portland Unit No.1--$28,540 to $45,065/lb Hg removed (24.9% less than $60k/lb). In summary, the results from demonstration testing at all three host

  16. Ecosystem conceptual model- Mercury

    USGS Publications Warehouse

    Alpers, Charles N.; Eagles-Smith, Collin A.; Foe, Chris; Klasing, Susan; Marvin-DiPasquale, Mark C.; Slotton, Darell G.; Windham-Myers, Lisamarie

    2008-01-01

    Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the mercury contamination occurs in sediments stored in the riverbeds, floodplains, and the Bay- Delta, where scouring of Gold-Rush-era sediment represents an ongoing source.Conversion of inorganic mercury to toxic methylmercury occurs in anaerobic environments including some wetlands. Wetland restoration managers must be cognizant of potential effects on mercury cycling so that the problem is not exacerbated. Recent research suggests that wettingdrying cycles can contribute to mercury methylation. For example, high marshes (inundated only during the highest tides for several days per month) tend to have higher methylmercury concentrations in water, sediment, and biota compared with low marshes, which do not dry out completely during the tidal cycle. Seasonally inundated flood plains are another environment experiencing wetting and drying where methylmercury concentrations are typically elevated. Stream restoration efforts using gravel injection or other reworking of coarse sediment in most watersheds of the Central Valley involve tailings from historical gold mining that are likely to contain elevated mercury in associated fines. Habitat restoration projects, particularly those involving wetlands, may cause increases in methylmercury exposure in the watershed. This possibility should be evaluated.The DRERIP

  17. Effects of HCl and SO{sub 2} concentration on mercury removal by activated carbon sorbents in coal-derived flue gas

    SciTech Connect

    Ryota Ochiai; M. Azhar Uddin; Eiji Sasaoka; Shengji Wu

    2009-09-15

    The effect of the presence of HCl and SO{sub 2} in the simulated coal combustion flue gas on the Hg{sup 0} removal by a commercial activated carbon (coconut shell AC) was investigated in a laboratory-scale fixed-bed reactor in a temperature range of 80-200{sup o}C. The characteristics (thermal stability) of the mercury species formed on the sorbents under various adsorption conditions were investigated by the temperature-programmed decomposition desorption (TPDD) technique. It was found that the presence of HCl and SO{sub 2} in the flue gas affected the mercury removal efficiency of the sorbents as well as the characteristics of the mercury adsorption species. The mercury removal rate of AC increased with the HCl concentration in the flue gas. In the presence of HCl and the absence of SO{sub 2} during Hg{sup 0} adsorption by AC, a single Hg{sup 0} desorption peak at around 300{sup o}C was observed in the TPDD spectra and intensity of this peak increased with the HCl concentration during mercury adsorption. The peak at around 300{sup o}C may be derived from the decomposition and desorption of mercury chloride species. The presence of SO{sub 2} during mercury adsorption had an adverse effect on the mercury removal by AC in the presence of HCl. In the presence of both HCl and SO{sub 2} during Hg{sup 0} adsorption by AC, the major TPDD peak temperatures changed drastically depending upon the concentration of HCl and SO{sub 2} in flue gas during Hg{sup 0} adsorption. 16 refs., 7 figs.

  18. Mercury CEM Calibration

    SciTech Connect

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  19. To Mercury dynamics

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.; Ferrandiz, J. M.

    Present significance of the study of rotation of Mercury considered as a core-mantle system arises from planned Mercury missions. New high accurate data on Mercury's structure and its physical fields are expected from BepiColombo mission (Anselmi et al., 2001). Investigation of resonant rotation of Mercury, begun by Colombo G. (1966), will play here main part. New approaches to the study of Mercury dynamics and the construction of analytical theory of its resonant rotation are suggested. Within these approaches Mercury is considered as a system of two non-spherical interacting bodies: a core and a mantle. The mantle of Mercury is considered as non-spherical, rigid (or elastic) layer. Inner shell is a liquid core, which occupies a large ellipsoidal cavity of Mercury. This Mercury system moves in the gravitational field of the Sun in resonant traslatory-rotary regime of the resonance 3:2. We take into account only the second harmonic of the force function of the Sun and Mercury. For the study of Mercury rotation we have been used specially designed canonical equations of motion in Andoyer and Poincare variables (Barkin, Ferrandiz, 2001), more convenient for the application of mentioned methods. Approximate observational and some theoretical evaluations of the two main coefficients of Mercury gravitational field J_2 and C22 are known. From observational data of Mariner-10 mission were obtained some first evaluations of these coefficients: J_2 =(8± 6)\\cdot 10-5(Esposito et al., 1977); J_2 =(6± 2)\\cdot 10-5and C22 =(1.0± 0.5)\\cdot 10-5(Anderson et al., 1987). Some theoretical evaluation of ratio of these coefficients has been obtained on the base of study of periodic motions of the system of two non-spherical gravitating bodies (Barkin, 1976). Corresponding values of coefficients consist: J_2 =8\\cdot 10-5and C22 =0.33\\cdot 10-5. We have no data about non-sphericity of inner core of Mercury. Planned missions to Mercury (BepiColombo and Messenger) promise to

  20. Method and apparatus for monitoring mercury emissions

    DOEpatents

    Durham, Michael D.; Schlager, Richard J.; Sappey, Andrew D.; Sagan, Francis J.; Marmaro, Roger W.; Wilson, Kevin G.

    1997-01-01

    A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber.

  1. Method and apparatus for monitoring mercury emissions

    DOEpatents

    Durham, M.D.; Schlager, R.J.; Sappey, A.D.; Sagan, F.J.; Marmaro, R.W.; Wilson, K.G.

    1997-10-21

    A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber. 15 figs.

  2. Mercury exposure and public health.

    PubMed

    Clifton, Jack C

    2007-04-01

    Mercury is a metal that is a liquid at room temperature. Mercury has a long and interesting history deriving from its use in medicine and industry, with the resultant toxicity produced. In high enough doses, all forms of mercury can produce toxicity. The most devastating tragedies related to mercury toxicity in recent history include Minamata Bay and Niagata, Japan in the 1950s, and Iraq in the 1970s. More recent mercury toxicity issues include the extreme toxicity of the dimethylmercury compound noted in 1998, the possible toxicity related to dental amalgams, and the disproved relationship between vaccines and autism related to the presence of the mercury-containing preservative, thimerosal.