Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the...Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the formation of uranyl arsenate minerals have remained largely elusive.Herein,the formation pathway of the non-charged UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 complex was investigated to elucidate the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral(where n represents the stoichiometric number of H_(2)O),a representative uranyl arsenate mineral.Based on the combination experiments of U(VI)and As(V),our findings underscore the sig-nificant dependence of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 formation on solution pH(4.0–10.0).Density functional theory(DFT)calculations reveal a two-step reaction involving two distinct pathways(Pathway 1 and Pathway 2)for the formation of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O,and the intermediate was confirmed by in situ Raman and fluorescence spec-troscopy.Specifically,the hydroxyl‑connected uranyl(UO_(2)OH^(+))reacts with the protonated arsenate(H_(2)AsO_(4)^(-))species to form the intermediate UO_(2)HAsO4·H_(2)O(Pathway 1)or UO_(2)OH–H2AsO4(Pathway 2)with a U/As ratio of 1:1.Meanwhile,all the transition states also were obtained and the energy barrier suggested that the UO_(2)(H_(2)AsO_(4))_(2)·2H_(2)O0 formed by Pathway 1 is thermodynamically favored over Pathway 2,and may serve as the primary fundamental structural unit or precursor for the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral phase.Altogether,this study contributes to advancing the understanding of the formation of uranyl arsenate min-erals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.展开更多
Excessive phosphorus and arsenic in water bodies not only destroy ecosystems but also pose a serious threat to human health.In this study,a series of Al-doped modified metal-organic frameworks(Zr-Al-MOF)were prepared ...Excessive phosphorus and arsenic in water bodies not only destroy ecosystems but also pose a serious threat to human health.In this study,a series of Al-doped modified metal-organic frameworks(Zr-Al-MOF)were prepared by solvothermal method,which achieved efficient removal of phosphate and arsenate in water.Due to the use of inexpensive Al salts,the material has a lower cost and is more economical.The molar ratio of metal salts,adsorption time,solution pH,initial concentration,temperature and coexisting anions were studied,and it was found that when the molar ratio of Zr:Al was 2,Zr-Al-MOF had the best adsorption performance for phosphate and arsenate,and the maximum adsorption capacity was 93.04 mg P/g and 173.83 mg As/g,respectively.It traps phosphate and arsenate at a fast reaction rate and can be recycled repeatedly.In addition,0.15 g/L of 2Zr-Al-MOF can effectively reduce the phosphate and arsenate content in the contaminated spring water samples of Yangzonghai Lake to the standard range of drinking water,which further confirms the application potential of 2Zr-Al-MOF.By FT-IR and XPS analysis,it was found that the adsorption mechanism was ligand exchange,electrostatic attraction and hydrogen bond formation.The theoretical calculation shows that the adsorption energy is negative,which indicates that 2Zr-Al-MOF is attractive to phosphate and arsenate,and the adsorption state is stable.The results show that 2Zr-Al-MOF is an effective phosphate and arsenate adsorbent and has broad application prospects in eutrophication water treatment.展开更多
Arsenic （As） is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide. Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in fres...Arsenic （As） is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide. Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in freshwater aquatic systems. Arsenic metabolism processes of this alga through arsenate reduction and sequent store and efflux were investigated. When supplied with 10 μmol/L arsenate, arsenic speciation analysis showed that arsenite concentration increased from 5.7 to 15.7 mg/kg dry weight during a 7-day period, accounting for 18%–24% of the total As in alga. When treated with different levels of arsenate （10, 20, 30, 40, 50 μmol/L） for 7 days, the arsenite concentration increased with increasing external arsenate concentrations, the proportion of arsenite was up to 23%–28% of the total As in alga. In efflux experiments, both arsenate and arsenite could be found in the efflux solutions. Additionally, the efflux of arsenate was more than that of arsenite. Furthermore, two arsenate reductase genes of C. reinhardtii （CrACR2s） were cloned and expressed in Escherichia coli strain WC3110 （？arsC） for the first time. The abilities of both CrACR2s genes to complement the arsenate- sensitive strain were examined. CrACR2.1 restored arsenate resistance at 0.8 mmol/L. However, CrACR2.2 showed much less ability to complement. The gene products were demonstrated to reduce arsenate to arsenite in vivo. In agreement with the complementation results, CrACR2.1 showed higher reduction ability than CrACR2.2, when treated with 0.4 mmol/L arsenate for 16 hr incubation.展开更多
Many investigations suggest that dissimilatory arsenate-respiring prokaryotes(DARPs)play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental ...Many investigations suggest that dissimilatory arsenate-respiring prokaryotes(DARPs)play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental Mn(Ⅱ)affects the DARPs-mediated reductive mobilization of arsenic.To resolve this issue,we collected soil samples from a realgar tailingsaffected area.We found that there were diverse arsenate-respiratory reductase(arr)genes in the soils.The microbial communities had high arsenate-respiring activity,and were able to efficiently stimulate the reductive mobilization of As.Compared to the microcosms without Mn(Ⅱ),addition of 10 mmol/L Mn(Ⅱ)to the microcosms led to 23.99%-251.79%increases in the microbial mobilization of As,and led to 133.3%-239.2%increases in the abundances of arr genes.We further isolated a new cultivable DARP,Bacillus sp.F11,from the arseniccontaminated soils.It completely reduced 1 mmol/L As(V)in 5 days under the optimal reaction conditions.We further found that it was able to efficiently catalyze the reductive mobilization and release of As from the solid phase;the addition of 2 mmol/L Mn(Ⅱ)led to 98.49%-248.78%increases in the F11 cells-mediated reductive mobilization of As,and70.6%-104.4%increases in the arr gene abundances.These data suggest that environmental Mn(Ⅱ)markedly increased the DARPs-mediated reductive mobilization of As in arseniccontaminated soils.This work provided a new insight into the close association between the biogeochemical cycles of arsenic and manganese.展开更多
The removal of arsenic from water and wastewater is obligatory. Resin is one of the most effective adsorbents for the removal of arsenic. In order to improve the adsorption capacity of resin, a new cerium-loaded catio...The removal of arsenic from water and wastewater is obligatory. Resin is one of the most effective adsorbents for the removal of arsenic. In order to improve the adsorption capacity of resin, a new cerium-loaded cation exchange resin arsenic adsorbent was prepared by impregnating cerium into the cation exchange resin. Batch adsorption experiments under various conditions, such as time, temperature, pH and with coexisting ions were carried out to evaluate the adsorption characteristics of cerium-loaded resin in the removal of As（V） and As（III） from aqueous solutions. The results showed that the adsorption kinetics of As（V） and As（III） obeyed a pseudo second-order kinetic model and the adsorption rate constants were 0.3159 and 0.5215 g.mg-1-min-1, respectively. The adsorption of As（V） followed the Freundlich adsorption isotherm model and the adsorption isotherm data for As（III） fitted well to the Langmuir equation model. The adsorption capacities were 1.0278 mg/g for As（V） and 2.5297 mg/g for As（Ill）. Both the adsorption of As（V） and As（Ill） were found to be pH sensitive and the optimum pH was found to be 5-6. Except for the phosphate ion, the coexisting anionics, such as nitrate, chlorate, sulphate and carbonate, showed no remarkable effect on As（V） and As（ill） adsorption. The desorption and regeneration study showed that the adsorption capacity of Ce-loaded resin for As（V） and As（Ill） could be restored to 97.80% and 69.61%, respectively, using 0.5 moFL sodium hydroxide solution.展开更多
The mesoporous Cu/Mg/Fe layered double hydroxide（Cu/Mg/Fe-LDH） with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions.The Cu/Mg/Fe-LDH was characterized by Fourier t...The mesoporous Cu/Mg/Fe layered double hydroxide（Cu/Mg/Fe-LDH） with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions.The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry,X-ray diffraction crystallography,scanning electron microscopy,X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller.Effects of various physico-chemical parameters such as pH,adsorbent dosage,contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated.Results showed that it was efficient for the removal of arsenate,and the removal efficiency of arsenate increased with the increment of the adsorbent dosage,while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11.The adsorption isotherms can be well described by the Langmuir model with R 2 〉 0.99.Its adsorption kinetics followed the pseudo second-order kinetic model.Coexisting ions such as HPO42-,CO32-,SO42and NO3could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH.The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process.It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of 〈 10 μg/L under the experimental conditions,and makes it a potential material for the decontamination of arsenate polluted water.展开更多
Chromium and/or arsenate removal by Fe（Ⅱ） as a function of pH, Fe（Ⅱ） dosage and initial Cr（Ⅵ）/As（Ⅴ） ratio were examined in batch tests. The presence of arsenate reduced the removal efficiency of chromium b...Chromium and/or arsenate removal by Fe（Ⅱ） as a function of pH, Fe（Ⅱ） dosage and initial Cr（Ⅵ）/As（Ⅴ） ratio were examined in batch tests. The presence of arsenate reduced the removal efficiency of chromium by Fe（Ⅱ）, while the presence of chromate significantly increased the removal efficiency of arsenate by Fe（Ⅱ） at pH 6-8, In the absence of arsenate, chromium removal by Fe（Ⅱ） increased to a maximum with increasing pH from 4 to 7 and then decreased with a further increase in pH. The increment in Fe（Ⅱ） dosage resulted in an improvement in chromium removal and the improvement was more remarkable under alkaline conditions than that under acidic conditions. Chromium removal by Fe（Ⅱ） was reduced to a larger extent under neutral and alkaline conditions than that under acidic conditions due to the presence of 10 μtmol/L arsenate. The presence of 20 μmol/L arsenate slightly improved chromium removal by Fe（Ⅱ） at pH 3.9-5,8, but had detrimental effects at pH 6.7-9.8. Arsenate removal was improved significantly at pH 4-9 due to the presence of 10μmol/L chromate at Fe（Ⅱ） dosages of 20-60 μmol/L. Elevating the chromate concentration from 10 to 20μmol/L resulted in a further improvement in arsenate removal at pH 4.0-4.6 when Fe（Ⅱ） was dosed at 30-60 μmol/L.展开更多
Objective To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor(ODF)mRNA and osteoprotegerin(OPG)mRNA.Methods Osteoblasts were obtained by enz...Objective To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor(ODF)mRNA and osteoprotegerin(OPG)mRNA.Methods Osteoblasts were obtained by enzymatic isolation from newborn SD rats.A factorial experiment was performed.Osteoblasts were exposed to NaF(0.5 mmolF/L,4 molF/L)and Na3AsH2(12.5μmolAs/L and 200μmolAs/L)separately or F plus As and cultured for 48 h.The gene expression of osteoblastic ODF and OPG was observed by RT-PCR.Results The expression ofODF mRNA increased in F0.5,F4 groups compared with control group and two groups of F0.As200,F,As200 compared with As200 group,and decreased significantly in groups of F4As12.5,F0.5As200,and F4As200.The expression of OPG rnRNA decreased in groups of F4,As200,F4As12.5,F0.5As200,and F4As200.Conclusion The joint effect of fluoride and arsenate on the gene expression of ODF is antagonistic,while the combined effect on the gene expression of OPG is synergistic.F4,F4As12.5,and F0.5As200 promote bone resorption of rat osteoclasts,whereas F0.5As12.5 inhibits osteolytic effect of rat osteoclasts.展开更多
The fate of arsenic in natural environments is influenced by adsorption onto metal(hydr)oxides.The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids.Recently,some studies ...The fate of arsenic in natural environments is influenced by adsorption onto metal(hydr)oxides.The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids.Recently,some studies reported that there existed competitive adsorption between arsenate and citrate on goethite.Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution,hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another.The results showed that at the arsenate concentrations used in this study(0.006-0.27 mmol/L),citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH.In comparison,citrate adsorption was inhibited at acidic pH,but enhanced at alkaline pH by arsenate.This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid.These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites,but the cooperation between the two species at the watergoethite interface as well.展开更多
Presented here is the influence of membrane pore size and dissolved organic matters on the diffusion coefficient（D） of aqueous arsenate, investigated by the diffusion cell method for the first time. The p H-dependen...Presented here is the influence of membrane pore size and dissolved organic matters on the diffusion coefficient（D） of aqueous arsenate, investigated by the diffusion cell method for the first time. The p H-dependent diffusion coefficient of arsenate was determined and compared with values from previous studies; the coefficient was found to decrease with increasing p H, showing the validity of our novel diffusion cell method. The D value increased dramatically as a function of membrane pore size at small pore sizes, and then increased slowly at pore sizes larger than 2.0 μm. Using the Exp Assoc model, the maximum D value was determined to be 11.2565 × 10^-6cm^2/sec. The presence of dissolved organic matters led to a dramatic increase of the D of arsenate, which could be attributed to electrostatic effects and ionic effects of salts. These results improve the understanding of the diffusion behavior of arsenate, especially the important role of various environmental parameters in the study and prediction of the migration of arsenate in aquatic water systems.展开更多
The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of ...The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of sodium arsenate in the slag and flue gas phases were approximately 30%and 70%,respectively.The addition of sodium arsenate depolymerized the fayalite structure and changed it from a crystalline state to an amorphous state.The fayalite structural changes indicated that the[AsO_(4)]tetrahedron in sodium arsenate combined with the[SiO_(4)]tetrahedron and[FeO_(4)]tetrahedron through bridging oxygen to form a silicate glass structure.The TCLP test results of the samples before and after the high temperature reaction of fayalite and sodium arsenate showed that after high temperature reaction,fayalite could effectively reduce the leaching toxicity of sodium arsenate,reducing the leaching concentration of arsenic from 3025.52 to 12.8 mg/L before and after reaction,respectively.展开更多
Little information is available on influences of the conversion of dissolved organic phosphorus(DOP) to inorganic phosphorus(IP) on algal growth and subsequent behaviors of arsenate(As(V)) in Microcystis aeruginosa(M....Little information is available on influences of the conversion of dissolved organic phosphorus(DOP) to inorganic phosphorus(IP) on algal growth and subsequent behaviors of arsenate(As(V)) in Microcystis aeruginosa(M. aeruginosa). In this study, the influences factors on the conversion of three typical DOP types including adenosine-5-triphosphate disodium salt(ATP), β-glycerophosphate sodium(βP) and D-glucose-6-phosphate disodium salt(GP)were investigated under different extracellular polymeric secretions(EPS) ratios from M.aeruginosa, and As(V) levels. Thus, algal growth, As(V) biotransformation and microcystins(MCs) release of M. aeruginosa were explored in the different converted DOP conditions compared with IP. Results showed that the three DOP to IP without EPS addition became in favor of algal growth during their conversion. Compared with IP, M. aeruginosa growth was thus facilitated in the three converted DOP conditions, subsequently resulting in potential algal bloom particularly at arsenic(As) contaminated water environment. Additionally, DOP after conversion could inhibit As accumulation in M. aeruginosa, thus intracellular As accumulation was lower in the converted DOP conditions than that in IP condition. As(V) biotransformation and MCs release in M. aeruginosa was impacted by different converted DOP with their different types. Specifically, DMA concentrations in media and As(III) ratios in algal cells were promoted in converted βP condition, indicating that the observed dissolved organic compositions from βP conversion could enhance As(V) reduction in M. aeruginosa and then accelerate DMA release. The obtained findings can provide better understanding of cyanobacteria blooms and As biotransformation in different DOP as the main phosphorus source.展开更多
FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated...FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated.The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5,milling time of 2 h,ball-to-material mass ratio of 15:1 and milling with stainless steel ball.Then,the composites were characterized by XRD,SEM,FTIR,etc.The physicochemical properties of FeS2/Fe mixture change dramatically,which is responsible for its excellent performance.Finally,the stabilization process of FAS was optimized.When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min,the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.展开更多
Insights from the adverse effect of humic acid （HA） on arsenate removal with hydrous ferric oxide （HFO） coprecipitation can further our understanding of the fate of As（V） in water treatment process. The motivati...Insights from the adverse effect of humic acid （HA） on arsenate removal with hydrous ferric oxide （HFO） coprecipitation can further our understanding of the fate of As（V） in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As（V） on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering （SERS）, extended X-ray absorption fine structure （EXAFS） spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared （ATR-FTIR） measurement, and charge distribution multisite complexation （CD- MUSIC） modeling. The As（V） removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As（V） mass concentration. The SERS analysis excluded the HA-As（V） complex formation. The EXAFS results indicate that As（V） formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26--3.31 ,~. The in situ ATR-FTIR measurements show that As（V） replaces surface hydroxyl groups and forms inner- sphere complex. High concentrations of HA may physically block the surface sites and inhibit the As（V） access. The adsorption of As（V） and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As（V） and HA reasonably well.展开更多
The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） wa...The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） was added, N and P in the medium showed effective regulation on arsenic（As） metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration（4–20 mg/L） significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid（DMA）, the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell.However, As（V） uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment,resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As（V） transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As（V） biotransformation processes.展开更多
The treatment of microglial BV-2 cells with sodium arsenate（As（V）：0.1-400 μmol/L — 48 hr）induces a dose-dependent response.The neurotoxic effects of high concentrations of As（V）（100,200 and 400 μmol/L） are...The treatment of microglial BV-2 cells with sodium arsenate（As（V）：0.1-400 μmol/L — 48 hr）induces a dose-dependent response.The neurotoxic effects of high concentrations of As（V）（100,200 and 400 μmol/L） are characterized by increased levels of mitochondrial complexesⅠ,Ⅱ,and Ⅳ followed by increased superoxide anion generation.Moreover,As（V） triggers an apoptotic mode of cell death,demonstrated by an apoptotic SubG1 peak,associated with an alteration of plasma membrane integrity.There is also a decrease in transmembrane mitochondrial potential and mitochondrial adenosine triphosphate ATP.It is therefore tempting to speculate that As（V） triggers mitochondrial dysfunction,which may lead to defective oxidative phosphorylation subsequently causing mitochondrial oxidative damage,which in turn induces an apoptotic mode of cell death.展开更多
Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic(As),which may simultaneously result in the release of As and affect the oxidation process of pyrite.However,the oxidation and elect...Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic(As),which may simultaneously result in the release of As and affect the oxidation process of pyrite.However,the oxidation and electrochemical behaviors of As on the oxidation reactivity of pyrites are still not clear.In this study,pyrite was prepared by a hydrothermal method and applied to study the oxidation mechanism between pyrite and aqueous arsenate.Analyses of X-ray diffraction,X-ray photoelectron spectroscopy,and scanning electron microscopy demonstrate that the as-prepared sample is an octahedron-like pyrite with high purity and crystallinity.The interaction between As(V)and pyrite as well as the electrochemical behaviors of pyrite oxidation in the presence of aqueous arsenate were investigated under acidic conditions by an ion analysis method,cyclic voltammetry(CV),Tafel,and electrochemical impedance spectroscopy(EIS).The results of the chemical reaction indicate that electrons are transferred from S 22-to dissolved oxygen with the formation of SO 42-in the initial As(V)concentration range of 0–0.3 mmol/L.In the initial As(V)concentration range of 0.4–1.2 mmol/L,electrons are transferred from S 22-to As(V)with the formation of elemental S 0 and As(III).The CV,the Tafel plot and EIS analyses indicate that aqueous arsenate in an electrolyte promotes oxidation reactivity and passivation of the pyrite electrode.Moreover,the electron transfer rate increases with increasing aqueous arsenate concentration in the electrolyte.展开更多
In this study, a commercial cube-shaped open-celled cellulose sponge adsorbent was modified by in-situ co-precipitation of superparamagnetic iron oxide nanoparticles(SPION) and used to remove As(V) from aqueous soluti...In this study, a commercial cube-shaped open-celled cellulose sponge adsorbent was modified by in-situ co-precipitation of superparamagnetic iron oxide nanoparticles(SPION) and used to remove As(V) from aqueous solutions. Fe K-edge X-ray absorption spectroscopy(XAS) and TEM identified maghemite as the main iron phase of the SPION nanoparticles with an average size 13 nm. Batch adsorption experiments at 800 mg/L showed a 63% increase of adsorption capacity when loading 2.6 wt.% mass fraction of SPION in the cube-sponge.Experimental determination of the adsorption thermodynamic parameters indicated that the As(V) adsorption on the composite material is a spontaneous and exothermic process.As K-edge XAS results confirmed that the adsorption enhancement on the composite can be attributed to the nanoparticles loaded. In addition, adsorbed As(V) did not get reduced to more toxic As(Ⅲ) and formed a binuclear corner-sharing complex with SPION. The advantageous cube-shape of the sponge-loaded SPION composite together with its high affinity and good adsorption capacity for As(V), good regeneration capability and the enhanceddiffusion attributed to its open-celled structure make this adsorbent a good candidate for industrial applications.展开更多
The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-...The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-O-Sb, Sb-OH and Sb-O-Sb in Raman spectra of AAAc(1 : 1) at 100 - 1 000 cm-1. The solution of AAAc(1 : 1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexabasic acid with dissociation constants of k1 = 3.62 × 10-2 , k2 = 3.05 × 10-3 , k3 = 6. 43 × 10-6 , k4 = 9. 78 × 10-8 ,k5 = 1.32 × 10-11 , k6 =3.87 × 10-12. AAAc(1 : 1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analyture of AsO ( OH )2-OH-Sb ( OH )4-O-Sb ( OH )4-OH-AsO ( OH )2 or As ( OH )3-O-Sb(OH)4-O-Sb(OH)4-O-As(OH)3 (isomerism) through experimental determination and geometry optimization.展开更多
This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsena...This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U20A20267 and 22376223)Hunan Provincial Natural Science Foundation(No.2023JJ0065).
文摘Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the formation of uranyl arsenate minerals have remained largely elusive.Herein,the formation pathway of the non-charged UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 complex was investigated to elucidate the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral(where n represents the stoichiometric number of H_(2)O),a representative uranyl arsenate mineral.Based on the combination experiments of U(VI)and As(V),our findings underscore the sig-nificant dependence of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 formation on solution pH(4.0–10.0).Density functional theory(DFT)calculations reveal a two-step reaction involving two distinct pathways(Pathway 1 and Pathway 2)for the formation of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O,and the intermediate was confirmed by in situ Raman and fluorescence spec-troscopy.Specifically,the hydroxyl‑connected uranyl(UO_(2)OH^(+))reacts with the protonated arsenate(H_(2)AsO_(4)^(-))species to form the intermediate UO_(2)HAsO4·H_(2)O(Pathway 1)or UO_(2)OH–H2AsO4(Pathway 2)with a U/As ratio of 1:1.Meanwhile,all the transition states also were obtained and the energy barrier suggested that the UO_(2)(H_(2)AsO_(4))_(2)·2H_(2)O0 formed by Pathway 1 is thermodynamically favored over Pathway 2,and may serve as the primary fundamental structural unit or precursor for the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral phase.Altogether,this study contributes to advancing the understanding of the formation of uranyl arsenate min-erals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.
基金supported by the NSFC-Yunnan Joint Fund(No.U2102210)the National Natural Science Foundation of China(No.22168044)+1 种基金Yunnan Provincial Department of Science and Technology(No.202201BF070001-013)the Research Innovation Fund for Graduate Students of Yunnan University(No.KC-23234004).
文摘Excessive phosphorus and arsenic in water bodies not only destroy ecosystems but also pose a serious threat to human health.In this study,a series of Al-doped modified metal-organic frameworks(Zr-Al-MOF)were prepared by solvothermal method,which achieved efficient removal of phosphate and arsenate in water.Due to the use of inexpensive Al salts,the material has a lower cost and is more economical.The molar ratio of metal salts,adsorption time,solution pH,initial concentration,temperature and coexisting anions were studied,and it was found that when the molar ratio of Zr:Al was 2,Zr-Al-MOF had the best adsorption performance for phosphate and arsenate,and the maximum adsorption capacity was 93.04 mg P/g and 173.83 mg As/g,respectively.It traps phosphate and arsenate at a fast reaction rate and can be recycled repeatedly.In addition,0.15 g/L of 2Zr-Al-MOF can effectively reduce the phosphate and arsenate content in the contaminated spring water samples of Yangzonghai Lake to the standard range of drinking water,which further confirms the application potential of 2Zr-Al-MOF.By FT-IR and XPS analysis,it was found that the adsorption mechanism was ligand exchange,electrostatic attraction and hydrogen bond formation.The theoretical calculation shows that the adsorption energy is negative,which indicates that 2Zr-Al-MOF is attractive to phosphate and arsenate,and the adsorption state is stable.The results show that 2Zr-Al-MOF is an effective phosphate and arsenate adsorbent and has broad application prospects in eutrophication water treatment.
基金supported by the National Natural Sci- ence Foundation of China (No. 40973058, 21077100)the Doctor Foundation of Shandong Province (No. BS2009HZ024)
文摘Arsenic （As） is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide. Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in freshwater aquatic systems. Arsenic metabolism processes of this alga through arsenate reduction and sequent store and efflux were investigated. When supplied with 10 μmol/L arsenate, arsenic speciation analysis showed that arsenite concentration increased from 5.7 to 15.7 mg/kg dry weight during a 7-day period, accounting for 18%–24% of the total As in alga. When treated with different levels of arsenate （10, 20, 30, 40, 50 μmol/L） for 7 days, the arsenite concentration increased with increasing external arsenate concentrations, the proportion of arsenite was up to 23%–28% of the total As in alga. In efflux experiments, both arsenate and arsenite could be found in the efflux solutions. Additionally, the efflux of arsenate was more than that of arsenite. Furthermore, two arsenate reductase genes of C. reinhardtii （CrACR2s） were cloned and expressed in Escherichia coli strain WC3110 （？arsC） for the first time. The abilities of both CrACR2s genes to complement the arsenate- sensitive strain were examined. CrACR2.1 restored arsenate resistance at 0.8 mmol/L. However, CrACR2.2 showed much less ability to complement. The gene products were demonstrated to reduce arsenate to arsenite in vivo. In agreement with the complementation results, CrACR2.1 showed higher reduction ability than CrACR2.2, when treated with 0.4 mmol/L arsenate for 16 hr incubation.
基金supported by the General Programs(No.41472219)the Foundations for Innovative Research Groups(No.41521001)from the National Natural Science Foundation of China。
文摘Many investigations suggest that dissimilatory arsenate-respiring prokaryotes(DARPs)play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental Mn(Ⅱ)affects the DARPs-mediated reductive mobilization of arsenic.To resolve this issue,we collected soil samples from a realgar tailingsaffected area.We found that there were diverse arsenate-respiratory reductase(arr)genes in the soils.The microbial communities had high arsenate-respiring activity,and were able to efficiently stimulate the reductive mobilization of As.Compared to the microcosms without Mn(Ⅱ),addition of 10 mmol/L Mn(Ⅱ)to the microcosms led to 23.99%-251.79%increases in the microbial mobilization of As,and led to 133.3%-239.2%increases in the abundances of arr genes.We further isolated a new cultivable DARP,Bacillus sp.F11,from the arseniccontaminated soils.It completely reduced 1 mmol/L As(V)in 5 days under the optimal reaction conditions.We further found that it was able to efficiently catalyze the reductive mobilization and release of As from the solid phase;the addition of 2 mmol/L Mn(Ⅱ)led to 98.49%-248.78%increases in the F11 cells-mediated reductive mobilization of As,and70.6%-104.4%increases in the arr gene abundances.These data suggest that environmental Mn(Ⅱ)markedly increased the DARPs-mediated reductive mobilization of As in arseniccontaminated soils.This work provided a new insight into the close association between the biogeochemical cycles of arsenic and manganese.
基金National Natural Science Foundation of China(21077048)the Analysis and Testing Foundation of Kunming University of Science and Technology(2010177)
文摘The removal of arsenic from water and wastewater is obligatory. Resin is one of the most effective adsorbents for the removal of arsenic. In order to improve the adsorption capacity of resin, a new cerium-loaded cation exchange resin arsenic adsorbent was prepared by impregnating cerium into the cation exchange resin. Batch adsorption experiments under various conditions, such as time, temperature, pH and with coexisting ions were carried out to evaluate the adsorption characteristics of cerium-loaded resin in the removal of As（V） and As（III） from aqueous solutions. The results showed that the adsorption kinetics of As（V） and As（III） obeyed a pseudo second-order kinetic model and the adsorption rate constants were 0.3159 and 0.5215 g.mg-1-min-1, respectively. The adsorption of As（V） followed the Freundlich adsorption isotherm model and the adsorption isotherm data for As（III） fitted well to the Langmuir equation model. The adsorption capacities were 1.0278 mg/g for As（V） and 2.5297 mg/g for As（Ill）. Both the adsorption of As（V） and As（Ill） were found to be pH sensitive and the optimum pH was found to be 5-6. Except for the phosphate ion, the coexisting anionics, such as nitrate, chlorate, sulphate and carbonate, showed no remarkable effect on As（V） and As（ill） adsorption. The desorption and regeneration study showed that the adsorption capacity of Ce-loaded resin for As（V） and As（Ill） could be restored to 97.80% and 69.61%, respectively, using 0.5 moFL sodium hydroxide solution.
基金supported by the National Natural Science Foundation of China (No. 41072173)the National High Technology Research and Development Program(863) of China (No. 2009AA062905)
文摘The mesoporous Cu/Mg/Fe layered double hydroxide（Cu/Mg/Fe-LDH） with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions.The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry,X-ray diffraction crystallography,scanning electron microscopy,X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller.Effects of various physico-chemical parameters such as pH,adsorbent dosage,contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated.Results showed that it was efficient for the removal of arsenate,and the removal efficiency of arsenate increased with the increment of the adsorbent dosage,while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11.The adsorption isotherms can be well described by the Langmuir model with R 2 〉 0.99.Its adsorption kinetics followed the pseudo second-order kinetic model.Coexisting ions such as HPO42-,CO32-,SO42and NO3could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH.The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process.It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of 〈 10 μg/L under the experimental conditions,and makes it a potential material for the decontamination of arsenate polluted water.
基金supported by the National Natural Science Foundation of China (No. 50908060,50821002)the Ph.D Program Foundation of Ministry of Education of China for New Faculty (No. 200802131053)
文摘Chromium and/or arsenate removal by Fe（Ⅱ） as a function of pH, Fe（Ⅱ） dosage and initial Cr（Ⅵ）/As（Ⅴ） ratio were examined in batch tests. The presence of arsenate reduced the removal efficiency of chromium by Fe（Ⅱ）, while the presence of chromate significantly increased the removal efficiency of arsenate by Fe（Ⅱ） at pH 6-8, In the absence of arsenate, chromium removal by Fe（Ⅱ） increased to a maximum with increasing pH from 4 to 7 and then decreased with a further increase in pH. The increment in Fe（Ⅱ） dosage resulted in an improvement in chromium removal and the improvement was more remarkable under alkaline conditions than that under acidic conditions. Chromium removal by Fe（Ⅱ） was reduced to a larger extent under neutral and alkaline conditions than that under acidic conditions due to the presence of 10 μtmol/L arsenate. The presence of 20 μmol/L arsenate slightly improved chromium removal by Fe（Ⅱ） at pH 3.9-5,8, but had detrimental effects at pH 6.7-9.8. Arsenate removal was improved significantly at pH 4-9 due to the presence of 10μmol/L chromate at Fe（Ⅱ） dosages of 20-60 μmol/L. Elevating the chromate concentration from 10 to 20μmol/L resulted in a further improvement in arsenate removal at pH 4.0-4.6 when Fe（Ⅱ） was dosed at 30-60 μmol/L.
文摘Objective To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor(ODF)mRNA and osteoprotegerin(OPG)mRNA.Methods Osteoblasts were obtained by enzymatic isolation from newborn SD rats.A factorial experiment was performed.Osteoblasts were exposed to NaF(0.5 mmolF/L,4 molF/L)and Na3AsH2(12.5μmolAs/L and 200μmolAs/L)separately or F plus As and cultured for 48 h.The gene expression of osteoblastic ODF and OPG was observed by RT-PCR.Results The expression ofODF mRNA increased in F0.5,F4 groups compared with control group and two groups of F0.As200,F,As200 compared with As200 group,and decreased significantly in groups of F4As12.5,F0.5As200,and F4As200.The expression of OPG rnRNA decreased in groups of F4,As200,F4As12.5,F0.5As200,and F4As200.Conclusion The joint effect of fluoride and arsenate on the gene expression of ODF is antagonistic,while the combined effect on the gene expression of OPG is synergistic.F4,F4As12.5,and F0.5As200 promote bone resorption of rat osteoclasts,whereas F0.5As12.5 inhibits osteolytic effect of rat osteoclasts.
基金supported by the National Natural Science Foundation of China(No.40673079,40773076).
文摘The fate of arsenic in natural environments is influenced by adsorption onto metal(hydr)oxides.The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids.Recently,some studies reported that there existed competitive adsorption between arsenate and citrate on goethite.Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution,hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another.The results showed that at the arsenate concentrations used in this study(0.006-0.27 mmol/L),citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH.In comparison,citrate adsorption was inhibited at acidic pH,but enhanced at alkaline pH by arsenate.This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid.These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites,but the cooperation between the two species at the watergoethite interface as well.
基金supported by the National Natural Science Foundation of China(Nos.41530643,41273133)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB14020203)
文摘Presented here is the influence of membrane pore size and dissolved organic matters on the diffusion coefficient（D） of aqueous arsenate, investigated by the diffusion cell method for the first time. The p H-dependent diffusion coefficient of arsenate was determined and compared with values from previous studies; the coefficient was found to decrease with increasing p H, showing the validity of our novel diffusion cell method. The D value increased dramatically as a function of membrane pore size at small pore sizes, and then increased slowly at pore sizes larger than 2.0 μm. Using the Exp Assoc model, the maximum D value was determined to be 11.2565 × 10^-6cm^2/sec. The presence of dissolved organic matters led to a dramatic increase of the D of arsenate, which could be attributed to electrostatic effects and ionic effects of salts. These results improve the understanding of the diffusion behavior of arsenate, especially the important role of various environmental parameters in the study and prediction of the migration of arsenate in aquatic water systems.
基金the financial supports from the National Natural Science Foundation of China(No.51634010)National Key R&D Program of China(No.2018YFC1900300).
文摘The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of sodium arsenate in the slag and flue gas phases were approximately 30%and 70%,respectively.The addition of sodium arsenate depolymerized the fayalite structure and changed it from a crystalline state to an amorphous state.The fayalite structural changes indicated that the[AsO_(4)]tetrahedron in sodium arsenate combined with the[SiO_(4)]tetrahedron and[FeO_(4)]tetrahedron through bridging oxygen to form a silicate glass structure.The TCLP test results of the samples before and after the high temperature reaction of fayalite and sodium arsenate showed that after high temperature reaction,fayalite could effectively reduce the leaching toxicity of sodium arsenate,reducing the leaching concentration of arsenic from 3025.52 to 12.8 mg/L before and after reaction,respectively.
基金supported by the National Nature Science Foundation of China (Nos. 42177384 and 41976150)the Nature Science Foundation of Fujian Province (No. 2020J01804)the Program for New Century Excellent Talents in Fujian Province University。
文摘Little information is available on influences of the conversion of dissolved organic phosphorus(DOP) to inorganic phosphorus(IP) on algal growth and subsequent behaviors of arsenate(As(V)) in Microcystis aeruginosa(M. aeruginosa). In this study, the influences factors on the conversion of three typical DOP types including adenosine-5-triphosphate disodium salt(ATP), β-glycerophosphate sodium(βP) and D-glucose-6-phosphate disodium salt(GP)were investigated under different extracellular polymeric secretions(EPS) ratios from M.aeruginosa, and As(V) levels. Thus, algal growth, As(V) biotransformation and microcystins(MCs) release of M. aeruginosa were explored in the different converted DOP conditions compared with IP. Results showed that the three DOP to IP without EPS addition became in favor of algal growth during their conversion. Compared with IP, M. aeruginosa growth was thus facilitated in the three converted DOP conditions, subsequently resulting in potential algal bloom particularly at arsenic(As) contaminated water environment. Additionally, DOP after conversion could inhibit As accumulation in M. aeruginosa, thus intracellular As accumulation was lower in the converted DOP conditions than that in IP condition. As(V) biotransformation and MCs release in M. aeruginosa was impacted by different converted DOP with their different types. Specifically, DMA concentrations in media and As(III) ratios in algal cells were promoted in converted βP condition, indicating that the observed dissolved organic compositions from βP conversion could enhance As(V) reduction in M. aeruginosa and then accelerate DMA release. The obtained findings can provide better understanding of cyanobacteria blooms and As biotransformation in different DOP as the main phosphorus source.
基金Projects(2018YFC1900305,2018YFC1903301)supported by the National Key R&D Program of ChinaProject(51825403)supported by the National Natural Science Foundation for Distinguished Young Scholars of China+1 种基金Project(51634010)supported by the National Natural Science Foundation of ChinaProject(2017RS3010)supported by the Science and Technology Program of Hunan Province,China
文摘FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated.The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5,milling time of 2 h,ball-to-material mass ratio of 15:1 and milling with stainless steel ball.Then,the composites were characterized by XRD,SEM,FTIR,etc.The physicochemical properties of FeS2/Fe mixture change dramatically,which is responsible for its excellent performance.Finally,the stabilization process of FAS was optimized.When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min,the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.
基金supported by the National Natural Science Foundation of China (No. 41373123, 41023005, 21321004)Research Center for EcoEnvironmental Sciences, Chinese Academy of Sciences (No. YSW2013A01)
文摘Insights from the adverse effect of humic acid （HA） on arsenate removal with hydrous ferric oxide （HFO） coprecipitation can further our understanding of the fate of As（V） in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As（V） on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering （SERS）, extended X-ray absorption fine structure （EXAFS） spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared （ATR-FTIR） measurement, and charge distribution multisite complexation （CD- MUSIC） modeling. The As（V） removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As（V） mass concentration. The SERS analysis excluded the HA-As（V） complex formation. The EXAFS results indicate that As（V） formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26--3.31 ,~. The in situ ATR-FTIR measurements show that As（V） replaces surface hydroxyl groups and forms inner- sphere complex. High concentrations of HA may physically block the surface sites and inhibit the As（V） access. The adsorption of As（V） and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As（V） and HA reasonably well.
基金supported by the National Nature Science Foundation of China (Nos. 21277136 and 21577138)
文摘The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） was added, N and P in the medium showed effective regulation on arsenic（As） metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration（4–20 mg/L） significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid（DMA）, the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell.However, As（V） uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment,resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As（V） transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As（V） biotransformation processes.
基金supported by grants from the University of Bourgogne(Dijon,France)the University of Monastir(Monastir,Tunisia)
文摘The treatment of microglial BV-2 cells with sodium arsenate（As（V）：0.1-400 μmol/L — 48 hr）induces a dose-dependent response.The neurotoxic effects of high concentrations of As（V）（100,200 and 400 μmol/L） are characterized by increased levels of mitochondrial complexesⅠ,Ⅱ,and Ⅳ followed by increased superoxide anion generation.Moreover,As（V） triggers an apoptotic mode of cell death,demonstrated by an apoptotic SubG1 peak,associated with an alteration of plasma membrane integrity.There is also a decrease in transmembrane mitochondrial potential and mitochondrial adenosine triphosphate ATP.It is therefore tempting to speculate that As（V） triggers mitochondrial dysfunction,which may lead to defective oxidative phosphorylation subsequently causing mitochondrial oxidative damage,which in turn induces an apoptotic mode of cell death.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFC0211500)the National Natural Science Foundation of China (Nos. 51878449+1 种基金 21806121 51508384)
文摘Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic(As),which may simultaneously result in the release of As and affect the oxidation process of pyrite.However,the oxidation and electrochemical behaviors of As on the oxidation reactivity of pyrites are still not clear.In this study,pyrite was prepared by a hydrothermal method and applied to study the oxidation mechanism between pyrite and aqueous arsenate.Analyses of X-ray diffraction,X-ray photoelectron spectroscopy,and scanning electron microscopy demonstrate that the as-prepared sample is an octahedron-like pyrite with high purity and crystallinity.The interaction between As(V)and pyrite as well as the electrochemical behaviors of pyrite oxidation in the presence of aqueous arsenate were investigated under acidic conditions by an ion analysis method,cyclic voltammetry(CV),Tafel,and electrochemical impedance spectroscopy(EIS).The results of the chemical reaction indicate that electrons are transferred from S 22-to dissolved oxygen with the formation of SO 42-in the initial As(V)concentration range of 0–0.3 mmol/L.In the initial As(V)concentration range of 0.4–1.2 mmol/L,electrons are transferred from S 22-to As(V)with the formation of elemental S 0 and As(III).The CV,the Tafel plot and EIS analyses indicate that aqueous arsenate in an electrolyte promotes oxidation reactivity and passivation of the pyrite electrode.Moreover,the electron transfer rate increases with increasing aqueous arsenate concentration in the electrolyte.
基金financially supported by the MINECO ministry of Spain (No. CTM2015–65414-C2–1-R)the Innovation Found for Competitiveness of the Chilean Economic Development Agency (CORFO, No. es 13CEI2–21839)+1 种基金the China scholarship council for the fellowship (No. 201708110179)funding support from the European Union’s Horizon 2020 research and innovation program under the Marie Sk?odowska-Curie grant agreement (No. 665919)。
文摘In this study, a commercial cube-shaped open-celled cellulose sponge adsorbent was modified by in-situ co-precipitation of superparamagnetic iron oxide nanoparticles(SPION) and used to remove As(V) from aqueous solutions. Fe K-edge X-ray absorption spectroscopy(XAS) and TEM identified maghemite as the main iron phase of the SPION nanoparticles with an average size 13 nm. Batch adsorption experiments at 800 mg/L showed a 63% increase of adsorption capacity when loading 2.6 wt.% mass fraction of SPION in the cube-sponge.Experimental determination of the adsorption thermodynamic parameters indicated that the As(V) adsorption on the composite material is a spontaneous and exothermic process.As K-edge XAS results confirmed that the adsorption enhancement on the composite can be attributed to the nanoparticles loaded. In addition, adsorbed As(V) did not get reduced to more toxic As(Ⅲ) and formed a binuclear corner-sharing complex with SPION. The advantageous cube-shape of the sponge-loaded SPION composite together with its high affinity and good adsorption capacity for As(V), good regeneration capability and the enhanceddiffusion attributed to its open-celled structure make this adsorbent a good candidate for industrial applications.
基金Project(50274075) supported by the National Natural Science Foundation of China
文摘The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-O-Sb, Sb-OH and Sb-O-Sb in Raman spectra of AAAc(1 : 1) at 100 - 1 000 cm-1. The solution of AAAc(1 : 1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexabasic acid with dissociation constants of k1 = 3.62 × 10-2 , k2 = 3.05 × 10-3 , k3 = 6. 43 × 10-6 , k4 = 9. 78 × 10-8 ,k5 = 1.32 × 10-11 , k6 =3.87 × 10-12. AAAc(1 : 1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analyture of AsO ( OH )2-OH-Sb ( OH )4-O-Sb ( OH )4-OH-AsO ( OH )2 or As ( OH )3-O-Sb(OH)4-O-Sb(OH)4-O-As(OH)3 (isomerism) through experimental determination and geometry optimization.
文摘This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.
