Knowledge Management System Of Guangzhou Institute of Geochemistry，CAS
Chang, Pei1; Zhu, Xiangyu1; Xian, Haiyang2; Zhu, Jianxi2 ; He, Hongping2; Teng, H. Henry1
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| Kinetics, stoichiometry, and mechanism of arsenopyrite-water interaction under anoxic conditions | |
| Source Publication | GEOCHIMICA ET COSMOCHIMICA ACTA
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| ISSN | 0016-7037 |
| 2023-12-15 | |
| Volume | 363Pages:68-76 |
| DOI | 10.1016/j.gca.2023.10.030 |
| Language | 英语 |
| WOS Research Area | Geochemistry & Geophysics |
| Abstract | Arsenopyrite dissolution is an important source of arsenic's environmental occurrence and is well-studied under oxidative conditions. However, little is known of anoxic leaching of arsenopyrite by water, though it is probably one of the dominant abiotic processes controlling arsenic mobility in oxygen-limited environments such as groundwaters and paddy fields. The present study attempts to probe the mechanism of arsenopyrite-water interaction in anoxic environment through examining the pH dependence of dissolution kinetics and stoichiometry, as well as speciation changes both on the surface and in solution. Batch and flow-through experiments were first carried out to measure dissolution rates and the results showed alkaline pH mildly encourages As release. Furthermore, the dissolution was found to be near stoichiometric with respect to As and S but not with Fe/As or Fe/S, and the non-stoichiometry exhibited a negative dependence on pH. Combining speciation ana-lyses that revealed the presence of H2O2, SO42- and S2O32- in solutions and a positive correlation of surface species Fe(III)-O, S(-II), and As(I), As(III), As(V), and As(-III) to solution pH, we interpreted the anoxic dissolution behavior of arsenopyrite through a mechanism that combines surface complexation and interfacial redox reactions. The kinetic measurements came to be concerning as data indicates arsenopyrite dissolution in anoxic environment can lead to water having arsenic concentrations above the 10 ppb WHO guideline value in one day at the experimental conditions. The observed H2O2 production indicated the dissolution is associated with or initiated by electron transfer despite the anoxic condition, further suggesting that a more comprehensive theory other than surface complexation model may be needed to better understand the geochemical behavior of As and possibly S in the context of sulfide mineral-water interactions. |
| Keyword | Arsenic Release Arsenopyrite Anoxic Dissolution Surface Complexation Kinetics and Stoichiometry Electron Transfer |
| WOS ID | WOS:001128452400001 |
| Indexed By | SCI |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.gig.ac.cn/handle/344008/76061 |
| Collection | 中国科学院矿物学与成矿学重点实验室 |
| Corresponding Author | Zhu, Xiangyu |
| Affiliation | 1.Tianjin Univ, Sch Earth Syst Sci, Tianjin 300072, Peoples R China 2.Chinese Acad Sci, Guangzhou Inst Geochem, CAS Key Lab Mineral & Metallogeny, Guangdong Prov Key Lab Mineral Phys & Mat, Guangzhou 510640, Peoples R China |
| Recommended Citation GB/T 7714 | Chang, Pei,Zhu, Xiangyu,Xian, Haiyang,et al. Kinetics, stoichiometry, and mechanism of arsenopyrite-water interaction under anoxic conditions[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2023,363:68-76. |
| APA | Chang, Pei,Zhu, Xiangyu,Xian, Haiyang,Zhu, Jianxi,He, Hongping,&Teng, H. Henry.(2023).Kinetics, stoichiometry, and mechanism of arsenopyrite-water interaction under anoxic conditions.GEOCHIMICA ET COSMOCHIMICA ACTA,363,68-76. |
| MLA | Chang, Pei,et al."Kinetics, stoichiometry, and mechanism of arsenopyrite-water interaction under anoxic conditions".GEOCHIMICA ET COSMOCHIMICA ACTA 363(2023):68-76. |
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