WATER RESEARCH
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2024
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IF 11.4
Fangyuan Meng,Hui Tong,Chunhua Feng,Ziyuan Huang,Pan Wu,Jimei Zhou,Jian Hua,Fei Wu,Chengshuai Liu
Magnetite is a reductive Fe(II)-bearing mineral, and its reduction property is considered important for degradation of contaminants in groundwater and anaerobic subsurface environments. However, the redox condition of subsurface environments frequently changes from anaerobic to aerobic owing to natural and anthropogenic disturbances, generating reactive oxygen species (ROS) from the interaction between Fe(II)-bearing minerals and O 2 . Despite this, the mechanism of ROS generation induced by magnetite under aerobic conditions is poorly understood, which may play a crucial role in As(III) oxidation. Herein, we found that magnetite could activate O 2 and induce the oxidative transformation of As(III) under aerobic conditions. As(III) oxidation was attributed to the ROS generated via structural Fe(II) within the magnetite octahedra oxygenation. The electron paramagnetic resonance and quenching tests confirmed that O 2 •− , H 2 O 2 , and •OH were produced by magnetite. Moreover, density function theory calculations combined with experiments demonstrated that O 2 •− was initially formed via single electron transfer from the structural Fe(II) to the adsorbed O 2 ; O 2 •− was then converted to •OH and H 2 O 2 via a series of free radical reactions. Among them, O 2 •− and H 2 O 2 were the primary ROS responsible for As(III) oxidation, accounting for approximately 52 % and 19 % of As(III) oxidation. Notably, As(III) oxidation mainly occurred on the magnetite surface, and As was immobilized further within the magnetite structure. This study provides solid evidence regarding the role of magnetite in determining the fate and transformation of As in redox-fluctuating subsurface environments.
研究领域:
环境科学
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地球化学
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DOI
PubMed
高影响因子
Scientific Reports
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2017
·Vol. 7
·期 1
·1-11
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IF 4.259
Tian Zeyuan,Feng Yong,Guan Yiyi,Shao Binbin,Zhang Yalei,Wu Deli
Freshly prepared carbonate structural Fe(II) (CSF) was used to immobilize As(III) and As(V) in wastewater under oxic and anoxic conditions. Dissolved oxygen was found to exert opposite effects on these two arsenic species. The sorption density of As(III) was higher under oxic conditions, whereas that of As(V) was higher under anoxic conditions. X-ray diffraction and infrared spectroscopic analyses indicated that crystalline parasymplesite (Fe(II) 3 (AsO 4 ) 2 ·8H 2 O) was formed when As(V) was removed under anoxic conditions, while an amorphous Fe-As-containing precipitate was formed when As(III) was removed under oxic conditions. The distribution of arsenic and iron between the solution and sediments suggested that the oxidation of structural Fe(II) promoted coprecipitation process and inhibited surface complexation. X-ray photoelectron spectroscopic analyses revealed that more As(III) was oxidized under oxic condition, which contributed to a higher sorption capacity for As(III). The formation of parasymplesite through surface complexation/precipitation was proposed to be more effective for the removal of As(V) by CSF, while As(III) was more efficiently removed through coprecipitation. Together, the results suggest that CSF may be an effective material for sequestering both As(III) and As(V). In addition, attention should be paid to the dissolved oxygen content when remediating different arsenic species.
研究领域:
环境科学
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化学
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DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2016
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IF 5.31
Binbin Shao,Yufan Chen,Deli Wu,Chaomeng Dai,Yalei Zhang
Structural Fe(II/III) hydroxides on the shell of nano-zerovalent iron (nZVI) are reactive sites for As(III) adsorption. Well-controlled structural Fe(II) hydroxides (SFH) is prepared to serve for As(III) removal in present study. With oxygen As(III) removal by SFH occurred efficiently but the removal efficiency was greatly reduced under anoxic conditions. The mineral transformation from SFH to lepidocrocite probably contributed to the robust removal efficiency of As(III). It is found that Cu(II), Cr(VI) and NO 2 − in aqueous solution could act as oxidants and promote the mineral transformation of SFH. A more efficient As(III) removal was therefore observed without oxygen. The removal efficiency decreased in the order O 2 /SFH ≈ Cu(II)/SFH > Cr(VI)/SFH ≈ NO 2 − /SFH at near neutral pH. The removal efficiency was less dependent on the initial pH for O 2 /SFH and Cu(II)/SFH systems than Cr(VI)/SFH and NO 2 − /SFH systems. Distribution of As on solid phases was able to describe the removal mechanism of As(III), and the results showed that the mineral transformation promoted the precipitation process and inhibited outer-sphere complexation, thus leading to enhanced As removal. With Cu(II), Cr(VI) and NO 2 − , the generation of oxidants from SFH transformation drove As(III) oxidation, and contributed to total As removal.
研究领域:
环境科学
·
化学
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DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2016
·
IF 2.76
Binbin Shao,Yiyi Guan,Zeyuan Tian,Xiaohong Guan,Deli Wu
Structural Fe(II) Hydroxide (SFH) was used to remove As(III) and As(V) from aerated synthetic wastewater with initially 30 mg/L As at neutral pH values. Batch experiments were performed to investigate the influence of O 2 , pH and coexisting HPO 4 2⿿ on As removal by 0.5 g (Fe)/L SFH. The results suggested that removal efficiency for As(III) and As(V) were ⿼60% and ⿼50% under anoxic conditions at initial pH 7.0 and 9.0, respectively. However, the efficiency increased to over 90% for both As(III) and As(V) under oxic conditions. The in situ mineral transformation of SFH to newly formed Fe(II/III) and FeOOH was responsible for the robust removal. As(III) removal was nearly unaffected by HPO 4 2⿿ (1.0 mM), while obviously inhibition was observed in the case of As(V). The microstructure of fresh and reacted SFH was characterized by FTIR and XPS and these results indicate that As was removed via inner-sphere complexation and precipitation. XPS studies showed that As(III) was converted to As(V) after 2 h of reaction in the pH range of 7.0⿿9.0, which is attributable to enhanced formation of Fe(IV) by the Fenton reaction during mineral transformation. In practice, results of this study suggest that aeration is advantageous to significantly enhancement of As(III) oxidation and removal with highly reactive SFH.
研究领域:
环境科学
·
水处理工程
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DOI
高影响因子
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