A crystalline polyferric sulfate(PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area(SSA), and adsorptive efficacy...A crystalline polyferric sulfate(PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area(SSA), and adsorptive efficacy of the adsorbent to As(Ⅲ) were characterized by scanning electron microscope(SEM) and transmission electron microscopy(TEM) images, X-ray diffraction(XRD) patterns, Fourier-transform infrared(FTIR) spectra, BET SSA analyses, and adsorption experiments. The adsorbent showed a near-spherical aggregate structure and had good crystallinity. A significant amount of α-goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased SSA of the adsorbent. The stability region of ferric compounds in the process was drawn and applied to analyze the iron behavior during the synthesis. The adsorption of As(Ⅲ) in high As(Ⅲ)-containing solutions fitted the Langmuir isotherm model adequately. The absorbent with co-precipitation of α-goethite showed good adsorbability for As(Ⅲ) and good filtering performance in the high As(Ⅲ)-containing solution of 10–100 mg/L under acidic, neutral, and alkaline conditions(pH 2.09–9.01). After the adsorption process, the stability of the residues bearing As(Ⅲ) was evaluated by toxic characteristic leaching procedure(TCLP) tests. The results indicated that the residues were extremely stable, and the concentrations of arsenic in the leaching solutions were less than 0.01 mg/L.展开更多
Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with ...Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide,resulting in enhanced removal efficiency.The experiment was conducted under various conditions:concentration,dosage,pH,agitation,and temperature.Material characterizations such as Brunauer Emmett Teller,X-ray diffraction,scanning electron microscopy,and Fourier transform infrared spectroscopy were implied to understand adsorption mechanisms.The Langmuir model revealed optimal concentrations for As(V)=500μg/L at pH-5 and As(III)=200μg/L at pH-7,resulting in 95%and 93%adsorption efficiencies,respectively.Maximum adsorption capacities“qm”were found to be 1266.943μg/g for As(V)and 1080.241μg/g for As(III).Freundlich model demonstrated favorable adsorption by indicating“n>1”such as As(V)=2.542 and As(III)=2.707;similarly,the speciation factor“RL<1”for both species as As(V)=0.1 and As(III)=0.5,respectively.The kinetic study presented a pseudo-second-order model as best fitted,indicating throughout chemisorption processes for removing As(V)and As(III).Furthermore,incorporating calcium carbonate presented a significant leap in the removal efficiency,indicating As(V)from 95%to 98%and As(III)from 93%to 96%,respectively.Our findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination,underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.展开更多
Arsenopyrite is one of the most important primary arsenic mineral. It is easily oxi-dized under hypergene conditions to release Fe, As, S and other elements. Of the released elements, dissolved arsenic is an extremely...Arsenopyrite is one of the most important primary arsenic mineral. It is easily oxi-dized under hypergene conditions to release Fe, As, S and other elements. Of the released elements, dissolved arsenic is an extremely toxic element. It is of particular importance to study arsenopyrite and the conversion of As species for environmental protection. This paper deals with the stability of arsenopyrite and As(III) in acidic Fe2(SO4)3 and FeCl3 solutions with the concentrations within the range of 10-2—10-5 mol·kg-1. Experimental researches revealed the following points: (1) under the conditions of the experiment arsenopyrite is unstable and its oxi-dation extent tends to increase with increasing Fe3+ concentration and reaction temperature and decreasing pH; (2) arsenic released during the oxidation of arsenopyrite is dominated by hydrous oxides of As(III); (3) in the FeCl3 solution the oxidation rate of arsenopyrite and As(III) toward As(V) is faster than in the Fe2(SO4)3; and (4) the stability of As(III) tends to increase with de-creasing oxidant concentration and reaction temperature, but to decrease with increasing Cl- concentration and illuminance.展开更多
Oxidation of Mn (Ⅱ) or As(Ⅲ) by molecular oxygen is slow at pH<9,while they can be catalytically oxidized in the presence of oxide minerals and then removed from contaminated water.However,the reaction mechanisms...Oxidation of Mn (Ⅱ) or As(Ⅲ) by molecular oxygen is slow at pH<9,while they can be catalytically oxidized in the presence of oxide minerals and then removed from contaminated water.However,the reaction mechanisms on simultaneous oxidation of Mn(Ⅱ) and As (Ⅲ)on oxide mineral surface and their accompanied removal efficiency remain unclear.This study compared Mn (Ⅱ) oxidation on four common metal oxides (γ-Al_(2)O_(3),CuO,α-Fe2O_(3)and ZnO) and investigated the simultaneous oxidation and removal of Mn (Ⅱ) and As (Ⅲ) through batch experiments and spectroscopic analyses.Among the tested oxides,CuO and α-Fe2O_(3)possess greater catalytic activity toward Mn (Ⅱ) oxidation.Oxidation and removal kinetics of Mn (Ⅱ) and As (Ⅲ) on CuO indicate that O_(2)is the terminal electron acceptor for Mn (Ⅱ) and As (Ⅲ) oxidation on CuO,and Mn (Ⅱ) acts as an electron shuttle to promote As (Ⅲ) oxidation and removal.The main oxidized product of Mn (Ⅱ) on CuO is high-valent MnO_(x)species.This newly formed Mn (Ⅲ) or Mn (IV) phases promote As (Ⅲ) oxidation on CuO at circumneutral pH 8 and is reduced to Mn (Ⅱ),which may be then released into solution.This study provides new insights into metal oxide-catalyzed oxidation of pollutants Mn (Ⅱ) and As (Ⅲ) and suggests that CuO should be considered as an efficient material to remediate Mn (Ⅱ) and As(Ⅲ)contamination.展开更多
Arsenite(As(III))as the most toxic and mobile form is the dominant arsenic(As)species in flooded paddy fields,resulting in higher accumulation of As in paddy rice than other terrestrial crops.Mitigation of As toxicity...Arsenite(As(III))as the most toxic and mobile form is the dominant arsenic(As)species in flooded paddy fields,resulting in higher accumulation of As in paddy rice than other terrestrial crops.Mitigation of As toxicity to rice plant is an important way to safeguard food production and safety.In the current study,As(III)-oxidizing bacteria Pseudomonas sp.strain SMS11 was inoculated with rice plants to accelerate conversion of As(III)into lower toxic arsenate(As(V)).Meanwhile,additional phosphate was supplemented to restrict As(V)uptake by the rice plants.Growth of rice plant was significantly inhibited under As(III)stress.The inhibition was alleviated by the introduction of additional P and SMS11.Arsenic speciation showed that additional P restricted As accumulation in the rice roots via competing common uptake pathways,while inoculation with SMS11 limited As translocation from root to shoot.Ionomic profiling revealed specific characteristics of the rice tissue samples from different treatment groups.Compared to the roots,ionomes of the rice shoots were more sensitive to environmental perturbations.Both extraneous P and As(III)-oxidizing bacteria SMS11 could alleviate As(III)stress to the rice plants through promoting growth and regulating ionome homeostasis.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51574285)
文摘A crystalline polyferric sulfate(PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area(SSA), and adsorptive efficacy of the adsorbent to As(Ⅲ) were characterized by scanning electron microscope(SEM) and transmission electron microscopy(TEM) images, X-ray diffraction(XRD) patterns, Fourier-transform infrared(FTIR) spectra, BET SSA analyses, and adsorption experiments. The adsorbent showed a near-spherical aggregate structure and had good crystallinity. A significant amount of α-goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased SSA of the adsorbent. The stability region of ferric compounds in the process was drawn and applied to analyze the iron behavior during the synthesis. The adsorption of As(Ⅲ) in high As(Ⅲ)-containing solutions fitted the Langmuir isotherm model adequately. The absorbent with co-precipitation of α-goethite showed good adsorbability for As(Ⅲ) and good filtering performance in the high As(Ⅲ)-containing solution of 10–100 mg/L under acidic, neutral, and alkaline conditions(pH 2.09–9.01). After the adsorption process, the stability of the residues bearing As(Ⅲ) was evaluated by toxic characteristic leaching procedure(TCLP) tests. The results indicated that the residues were extremely stable, and the concentrations of arsenic in the leaching solutions were less than 0.01 mg/L.
基金funded by the National Natural Science Foundation of China(Nos.42177078 and 42020104005).
文摘Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas media.Additionally,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide,resulting in enhanced removal efficiency.The experiment was conducted under various conditions:concentration,dosage,pH,agitation,and temperature.Material characterizations such as Brunauer Emmett Teller,X-ray diffraction,scanning electron microscopy,and Fourier transform infrared spectroscopy were implied to understand adsorption mechanisms.The Langmuir model revealed optimal concentrations for As(V)=500μg/L at pH-5 and As(III)=200μg/L at pH-7,resulting in 95%and 93%adsorption efficiencies,respectively.Maximum adsorption capacities“qm”were found to be 1266.943μg/g for As(V)and 1080.241μg/g for As(III).Freundlich model demonstrated favorable adsorption by indicating“n>1”such as As(V)=2.542 and As(III)=2.707;similarly,the speciation factor“RL<1”for both species as As(V)=0.1 and As(III)=0.5,respectively.The kinetic study presented a pseudo-second-order model as best fitted,indicating throughout chemisorption processes for removing As(V)and As(III).Furthermore,incorporating calcium carbonate presented a significant leap in the removal efficiency,indicating As(V)from 95%to 98%and As(III)from 93%to 96%,respectively.Our findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination,underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.
基金This work was part of the research project"On the influence of geological environment on the development of economy and sustained development"under the Sino-Canadian Cooperative Program(SULCP).Prof.Gammons offered great help with the establishment of this project.This project was financially supported jointly by the National Natural Science Foundation of China(Grant No.49773202)the Key Laboratory of Ore Deposit Geochemistry,the Institute of Geochemistry,the Chinese Academy of Sciences.
文摘Arsenopyrite is one of the most important primary arsenic mineral. It is easily oxi-dized under hypergene conditions to release Fe, As, S and other elements. Of the released elements, dissolved arsenic is an extremely toxic element. It is of particular importance to study arsenopyrite and the conversion of As species for environmental protection. This paper deals with the stability of arsenopyrite and As(III) in acidic Fe2(SO4)3 and FeCl3 solutions with the concentrations within the range of 10-2—10-5 mol·kg-1. Experimental researches revealed the following points: (1) under the conditions of the experiment arsenopyrite is unstable and its oxi-dation extent tends to increase with increasing Fe3+ concentration and reaction temperature and decreasing pH; (2) arsenic released during the oxidation of arsenopyrite is dominated by hydrous oxides of As(III); (3) in the FeCl3 solution the oxidation rate of arsenopyrite and As(III) toward As(V) is faster than in the Fe2(SO4)3; and (4) the stability of As(III) tends to increase with de-creasing oxidant concentration and reaction temperature, but to decrease with increasing Cl- concentration and illuminance.
基金supported by the National Natural Science Foundation of China (Nos. 42030709, 42167031)the National Key Research and Development Program of China (No. 2017YFD0200201)Y.T. acknowledges support by the U.S. National Science Foundation (NSF) under Grant No. 2108688。
文摘Oxidation of Mn (Ⅱ) or As(Ⅲ) by molecular oxygen is slow at pH<9,while they can be catalytically oxidized in the presence of oxide minerals and then removed from contaminated water.However,the reaction mechanisms on simultaneous oxidation of Mn(Ⅱ) and As (Ⅲ)on oxide mineral surface and their accompanied removal efficiency remain unclear.This study compared Mn (Ⅱ) oxidation on four common metal oxides (γ-Al_(2)O_(3),CuO,α-Fe2O_(3)and ZnO) and investigated the simultaneous oxidation and removal of Mn (Ⅱ) and As (Ⅲ) through batch experiments and spectroscopic analyses.Among the tested oxides,CuO and α-Fe2O_(3)possess greater catalytic activity toward Mn (Ⅱ) oxidation.Oxidation and removal kinetics of Mn (Ⅱ) and As (Ⅲ) on CuO indicate that O_(2)is the terminal electron acceptor for Mn (Ⅱ) and As (Ⅲ) oxidation on CuO,and Mn (Ⅱ) acts as an electron shuttle to promote As (Ⅲ) oxidation and removal.The main oxidized product of Mn (Ⅱ) on CuO is high-valent MnO_(x)species.This newly formed Mn (Ⅲ) or Mn (IV) phases promote As (Ⅲ) oxidation on CuO at circumneutral pH 8 and is reduced to Mn (Ⅱ),which may be then released into solution.This study provides new insights into metal oxide-catalyzed oxidation of pollutants Mn (Ⅱ) and As (Ⅲ) and suggests that CuO should be considered as an efficient material to remediate Mn (Ⅱ) and As(Ⅲ)contamination.
基金This work was supported by the National Natural Science Foundation of China(No.41977351)the Natural Science Foundation of Hunan Province,China(No.2020JJ4698).
文摘Arsenite(As(III))as the most toxic and mobile form is the dominant arsenic(As)species in flooded paddy fields,resulting in higher accumulation of As in paddy rice than other terrestrial crops.Mitigation of As toxicity to rice plant is an important way to safeguard food production and safety.In the current study,As(III)-oxidizing bacteria Pseudomonas sp.strain SMS11 was inoculated with rice plants to accelerate conversion of As(III)into lower toxic arsenate(As(V)).Meanwhile,additional phosphate was supplemented to restrict As(V)uptake by the rice plants.Growth of rice plant was significantly inhibited under As(III)stress.The inhibition was alleviated by the introduction of additional P and SMS11.Arsenic speciation showed that additional P restricted As accumulation in the rice roots via competing common uptake pathways,while inoculation with SMS11 limited As translocation from root to shoot.Ionomic profiling revealed specific characteristics of the rice tissue samples from different treatment groups.Compared to the roots,ionomes of the rice shoots were more sensitive to environmental perturbations.Both extraneous P and As(III)-oxidizing bacteria SMS11 could alleviate As(III)stress to the rice plants through promoting growth and regulating ionome homeostasis.
