The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Ping'an Peng - One of the best experts on this subject based on the ideXlab platform.
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Enhanced molybdenum(VI) removal using sulfide-modified nanoscale zerovalent Iron: Kinetics and influencing factors
Water science and technology : a journal of the International Association on Water Pollution Research, 2020Co-Authors: Jianjun Lian, Yin Zhong, Weilin Huang, M. Yang, Huiliang Wang, Bo Chen, Ping'an PengAbstract:The overall goal of this study is to investigate the effect of sulfidated nanoscale zerovalent Iron (S-nZVI) on the removal of hexavalent molybdate (MoO42-) under different aquatic chemistry conditions. Surface analysis suggests that Mo(VI) is removed mainly by adsorption and co-precipitation onto the surface of S-nZVI and a small amount of Mo(VI) can be reduced to Mo(V) species. The results of batch tests show that Mo(VI) removal by S-nZVI are well described with the pseudo-second-order adsorption model. The removal rate increases with a decrease in solution pH (4.0-9.0) and is significantly affected by the S/Fe ratio of S-nZVI, with the optimal S/Fe ratio being 0.5. The presence of anions WO42- or CrO42- can reduce the Mo(VI) removal, which is likely because they compete for adsorption sites on the solid surfaces. The divalent cations Ni2+, Cu2+ and Co2+ also inhibit the removal of Mo(VI) whereas Zn2+, Ca2+ and Mg2+ enhance it. After being aged for 35 d in water, S-nZVI still exhibits high reactivity towards Mo(VI) removal (57.39%). The study demonstrates that S-nZVI can be used as an envIronmentally friendly material for effectively removing Mo(VI) from contaminated water.
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Abiotic transformation of hexabromocyclododecane by sulfidated nanoscale zerovalent Iron: Kinetics, mechanism and influencing factors
Water research, 2017Co-Authors: Xifen Zhu, Yin Zhong, Weilin Huang, Ping'an PengAbstract:Recent studies showed that sulfidated nanoscale zerovalent Iron (S-nZVI) is a better reducing agent than nanoscale zerovalen Iron (nZVI) alone for reductive dechlorination of several organic solvents such as trichloroethylene (TCE) due to the catalytic role of Iron sulfide (FeS). We measured the rates of transformation of hexabromocyclododecane (HBCD) by S-nZVI and compared them to those by FeS, nZVI, and reduced sulfur species. The results showed that: i) HBCD (20 mg L-1) was almost completely transformed by S-nZVI (0.5 g L-1) within 12 h; ii) the reaction with β-HBCD was much faster than with α- and γ-HBCD, suggesting the diastereoisomeric selectivity for the reaction by S-nZVI; and iii) the reaction with S-nZVI was 1.4-9.3 times faster than with FeS, S2- and nZVI, respectively. The study further showed that the HBCD reaction by S-nZVI was likely endothermic, with the optimal solution pH of 5.0, and could be slowed in the presence of Ca2+, Mg2+, NO3-, HCO3- and Cl-, and by increasing ionic strength, solvent content and initial HBCD concentration, or decreasing the S-nZVI dosage. GC-MS analysis showed that tetrabromocyclododecene and dibromocyclododecadiene were the products. XPS spectra indicated that both Fe(II) and S(-II) on the S-nZVI surface were oxidized during the reaction, suggesting that FeS might act as both catalyst and reactant. The study not only demonstrated the superiority of S-nZVI over other well-known reactive reagents, but also provided insight to the mechanisms of the reaction.
Jiri Petrak - One of the best experts on this subject based on the ideXlab platform.
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Iron transport in K562 cells: a kinetic study using native gel electrophoresis and 59Fe autoradiography
Biochimica et biophysica acta, 1998Co-Authors: Daniel Vyoral, Jiri PetrakAbstract:Abstract The exact mechanisms of Iron transport from endosomes to the target Iron containing cellular proteins are currently unknown. To investigate this problem, we used the gradient gel electrophoresis and the sensitive detection of 59 Fe by autoradiography to detect separate cellular Iron compounds and their Iron Kinetics. Cells of human leukemic line K562 were labeled with [ 59 Fe]transferrin for 30–600 s and cellular Iron compounds in cell lysates were analyzed by native electrophoretic separation followed by 59 Fe autoradiography. Starting with the first 30 s of Iron uptake, Iron was detectable in a large membrane bound protein complex (Band I) and in ferritin. Significant amounts of Iron were also found in labile Iron compound(s) with the molecular weight larger than 5000 as judged by ultrafiltration. Iron Kinetics in these compartments was studied. Band I was the only compound with the kinetic properties of an intermediate. Transferrin, transferrin receptor and additional proteins of the approximate molecular weights of 130 000, 66 000 and 49 000 were found to be present in Band I. The labile Iron compounds and ferritin behaved kinetically as end products. No evidence for low molecular weight transport intermediates was found. These results suggest that intracellular Iron transport is highly compartmentalized, that Iron released from endosomal transferrin passes to its cellular targets in a direct contact with the endosomal membrane complex assigned as Band I. The nature of the labile Iron pool and its susceptibility to Iron chelation is discussed.
Weilin Huang - One of the best experts on this subject based on the ideXlab platform.
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Enhanced molybdenum(VI) removal using sulfide-modified nanoscale zerovalent Iron: Kinetics and influencing factors
Water science and technology : a journal of the International Association on Water Pollution Research, 2020Co-Authors: Jianjun Lian, Yin Zhong, Weilin Huang, M. Yang, Huiliang Wang, Bo Chen, Ping'an PengAbstract:The overall goal of this study is to investigate the effect of sulfidated nanoscale zerovalent Iron (S-nZVI) on the removal of hexavalent molybdate (MoO42-) under different aquatic chemistry conditions. Surface analysis suggests that Mo(VI) is removed mainly by adsorption and co-precipitation onto the surface of S-nZVI and a small amount of Mo(VI) can be reduced to Mo(V) species. The results of batch tests show that Mo(VI) removal by S-nZVI are well described with the pseudo-second-order adsorption model. The removal rate increases with a decrease in solution pH (4.0-9.0) and is significantly affected by the S/Fe ratio of S-nZVI, with the optimal S/Fe ratio being 0.5. The presence of anions WO42- or CrO42- can reduce the Mo(VI) removal, which is likely because they compete for adsorption sites on the solid surfaces. The divalent cations Ni2+, Cu2+ and Co2+ also inhibit the removal of Mo(VI) whereas Zn2+, Ca2+ and Mg2+ enhance it. After being aged for 35 d in water, S-nZVI still exhibits high reactivity towards Mo(VI) removal (57.39%). The study demonstrates that S-nZVI can be used as an envIronmentally friendly material for effectively removing Mo(VI) from contaminated water.
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Abiotic transformation of hexabromocyclododecane by sulfidated nanoscale zerovalent Iron: Kinetics, mechanism and influencing factors
Water research, 2017Co-Authors: Xifen Zhu, Yin Zhong, Weilin Huang, Ping'an PengAbstract:Recent studies showed that sulfidated nanoscale zerovalent Iron (S-nZVI) is a better reducing agent than nanoscale zerovalen Iron (nZVI) alone for reductive dechlorination of several organic solvents such as trichloroethylene (TCE) due to the catalytic role of Iron sulfide (FeS). We measured the rates of transformation of hexabromocyclododecane (HBCD) by S-nZVI and compared them to those by FeS, nZVI, and reduced sulfur species. The results showed that: i) HBCD (20 mg L-1) was almost completely transformed by S-nZVI (0.5 g L-1) within 12 h; ii) the reaction with β-HBCD was much faster than with α- and γ-HBCD, suggesting the diastereoisomeric selectivity for the reaction by S-nZVI; and iii) the reaction with S-nZVI was 1.4-9.3 times faster than with FeS, S2- and nZVI, respectively. The study further showed that the HBCD reaction by S-nZVI was likely endothermic, with the optimal solution pH of 5.0, and could be slowed in the presence of Ca2+, Mg2+, NO3-, HCO3- and Cl-, and by increasing ionic strength, solvent content and initial HBCD concentration, or decreasing the S-nZVI dosage. GC-MS analysis showed that tetrabromocyclododecene and dibromocyclododecadiene were the products. XPS spectra indicated that both Fe(II) and S(-II) on the S-nZVI surface were oxidized during the reaction, suggesting that FeS might act as both catalyst and reactant. The study not only demonstrated the superiority of S-nZVI over other well-known reactive reagents, but also provided insight to the mechanisms of the reaction.
Yin Zhong - One of the best experts on this subject based on the ideXlab platform.
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Enhanced molybdenum(VI) removal using sulfide-modified nanoscale zerovalent Iron: Kinetics and influencing factors
Water science and technology : a journal of the International Association on Water Pollution Research, 2020Co-Authors: Jianjun Lian, Yin Zhong, Weilin Huang, M. Yang, Huiliang Wang, Bo Chen, Ping'an PengAbstract:The overall goal of this study is to investigate the effect of sulfidated nanoscale zerovalent Iron (S-nZVI) on the removal of hexavalent molybdate (MoO42-) under different aquatic chemistry conditions. Surface analysis suggests that Mo(VI) is removed mainly by adsorption and co-precipitation onto the surface of S-nZVI and a small amount of Mo(VI) can be reduced to Mo(V) species. The results of batch tests show that Mo(VI) removal by S-nZVI are well described with the pseudo-second-order adsorption model. The removal rate increases with a decrease in solution pH (4.0-9.0) and is significantly affected by the S/Fe ratio of S-nZVI, with the optimal S/Fe ratio being 0.5. The presence of anions WO42- or CrO42- can reduce the Mo(VI) removal, which is likely because they compete for adsorption sites on the solid surfaces. The divalent cations Ni2+, Cu2+ and Co2+ also inhibit the removal of Mo(VI) whereas Zn2+, Ca2+ and Mg2+ enhance it. After being aged for 35 d in water, S-nZVI still exhibits high reactivity towards Mo(VI) removal (57.39%). The study demonstrates that S-nZVI can be used as an envIronmentally friendly material for effectively removing Mo(VI) from contaminated water.
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Abiotic transformation of hexabromocyclododecane by sulfidated nanoscale zerovalent Iron: Kinetics, mechanism and influencing factors
Water research, 2017Co-Authors: Xifen Zhu, Yin Zhong, Weilin Huang, Ping'an PengAbstract:Recent studies showed that sulfidated nanoscale zerovalent Iron (S-nZVI) is a better reducing agent than nanoscale zerovalen Iron (nZVI) alone for reductive dechlorination of several organic solvents such as trichloroethylene (TCE) due to the catalytic role of Iron sulfide (FeS). We measured the rates of transformation of hexabromocyclododecane (HBCD) by S-nZVI and compared them to those by FeS, nZVI, and reduced sulfur species. The results showed that: i) HBCD (20 mg L-1) was almost completely transformed by S-nZVI (0.5 g L-1) within 12 h; ii) the reaction with β-HBCD was much faster than with α- and γ-HBCD, suggesting the diastereoisomeric selectivity for the reaction by S-nZVI; and iii) the reaction with S-nZVI was 1.4-9.3 times faster than with FeS, S2- and nZVI, respectively. The study further showed that the HBCD reaction by S-nZVI was likely endothermic, with the optimal solution pH of 5.0, and could be slowed in the presence of Ca2+, Mg2+, NO3-, HCO3- and Cl-, and by increasing ionic strength, solvent content and initial HBCD concentration, or decreasing the S-nZVI dosage. GC-MS analysis showed that tetrabromocyclododecene and dibromocyclododecadiene were the products. XPS spectra indicated that both Fe(II) and S(-II) on the S-nZVI surface were oxidized during the reaction, suggesting that FeS might act as both catalyst and reactant. The study not only demonstrated the superiority of S-nZVI over other well-known reactive reagents, but also provided insight to the mechanisms of the reaction.
Gordon C C Yang - One of the best experts on this subject based on the ideXlab platform.
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chemical reduction of nitrate by nanosized Iron Kinetics and pathways
Water Research, 2005Co-Authors: Gordon C C YangAbstract:Abstract This study was conducted to investigate chemical reduction of nitrate by nanoscale zero-valent Iron (ZVI) in aqueous solution and related Kinetics and pathways. In the last decade, employment of micro-scale ZVI has gained its popularity in nitrate reduction. To further study chemical reduction of nitrate, nanosized Iron was synthesized and tested in this work. It has a size in the range of 50–80 nm and a BET surface area of 37.83 m2 g−1. Chemical reduction of nitrate by nanosized Iron under various pHs was carried out in batch experiments. Experimental results suggest that nitrate reduction by nanosized ZVI primarily is an acid-driven surface-mediated process. A stronger acidic condition is more favorable for nitrate reduction. Results of the Kinetics study have indicated that a higher initial concentration of nitrate would yield a greater reaction rate constant. Additional test results also showed that the reduction rate of nitrate increased as the dose of nanosized ZVI increased. In all tests, reaction rate equations developed do not obey the first- or pseudo-first-order reaction Kinetics with respect to the nitrate concentration. Based on the research findings obtained, two possible reaction pathways for nitrate reduction by nanoscale Iron particles have been proposed in this work.
