草酸钙钝化砷黄铁矿生物氧化同时促进砷固定的机制  

Mechanisms by which calcium oxalate passivates arsenopyrite bio-oxidation and promotes arsenic immobilization

作　　者：陈红瑞 张多瑞 李骞[1] 张雁[1] CHEN Hongrui;ZHANG Duorui;LI Qian;ZHANG Yan(School of Minerals Processing and Bioengineering,Central South University,Changsha 410083)

机构地区：[1]中南大学资源加工与生物工程学院,长沙410083

出　　处：《环境科学学报》2023年第5期430-440,共11页Acta Scientiae Circumstantiae

基　　金：湖南科技厅重点研发项目(No.2022NK2057,2020SK2125)。

摘　　要：含砷硫化矿(ABSMs)的暴露溶解是导致矿区周边水域和土壤中砷含量超标的重要原因之一.嗜酸铁硫氧化微生物、氧气和水的接触会显著加速ABSMs的氧化和砷的释放.选择砷黄铁矿(FeAsS,最典型的ABSMs)为研究对象,探究了草酸钙(COM)对典型嗜酸菌Sulfobacillus thermosulfidooxidans生物氧化砷黄铁矿的钝化效应.结果表明,COM介导FeAsS生物氧化过程中产生的无定型纳米颗粒会致密包裹在细菌和矿物表面,抑制了细菌在矿物表面的吸附、Fe(II)的生物氧化和Fe3+对矿物的直接催化作用,最终钝化了FeAsS的溶解和砷的释放.在初始pH=2.0、COM添加量(以Ca^(2+)浓度计)分别为0.25、0.5和1 g·L^(-1)条件下生物氧化10 d后,As浓度由不含COM氧化体系的3.73 g·L^(-1)分别降低至2.89、2.03和1.47 g·L^(-1).同时,COM的添加不仅明显抑制了黄钾铁矾的形成和累积,还使矿物表面砷的氧化受阻.COM浓度越高,表观钝化效应越强.在酸性条件下,被纳米颗粒粘附包裹后的细菌有利于砷的固定.The exposure and dissolution of arsenic(As)-bearing sulfide minerals(ABSMs)is one of the most important inducements for the As contamination in the waters and soils around sulfide mining areas.The contact of ABSMs with acidophilic Fe/S-oxidizing bacteria,oxygen,and water can significantly accelerate ABSMs oxidation and As release.This study investigated the passivation effect of calcium oxalate monohydrate(COM)on the bio-oxidation of arsenopyrite(one of the most typical ABSMs)by the typical acidophilic bacterium Sulfobacillus thermosulfidooxidans;The results showed that the amorphous nanoparticles formed from FeAsS bio-oxidation mediated by COM were tightly wrapped on the surface of bacteria and minerals,which inhibited the adsorption of bacteria onto the mineral surface,the bio-oxidation of Fe(II),and the attack of Fe3+on FeAsS,and finally passivates FeAsS.Consequently,FeAsS dissolution and As release were passivated.After 10 days of bio-oxidation at initial pH=2.0 and COM addition(calculated by Ca^(2+)concentration)of 0.25,0.5,and 1 g·L^(-1),soluble As concentration decreased from 3.73 g·L^(-1) in the assay without COM to 2.89,2.03,and 1.47 g·L^(-1),respectively.Meanwhile,the presence of COM not only inhibited the formation and accumulation of jarosite,but also hindered the oxidation of As on the mineral surface.The higher the concentration of COM,the stronger the apparent passivation effect was observed.Under acidic condition,the bacteria cells tightly wrapped by the nanoparticles were favored for the immobilization of arsenic released from arsenopyrite oxidation.

关 键 词：砷 砷黄铁矿 草酸钙 生物氧化 钝化 固定 

分 类 号：X131[环境科学与工程—环境科学]