一硫代砷酸盐在介质上的吸附特征及机制  

Characteristics and Mechanism of Monothioarsenate Adsorption on Sand,Sediment,and Goethite

作　　者：廖丹雪 单慧媚 彭三曦 潘敖然 黄健[1] 陈辉 赵超然 LIAO Dan-xue;SHAN Hui-mei;PENG San-xi;PAN Ao-ran;HUANG Jian;CHENG Hui;ZHAO Chao-ran(College of Environmental Science and Engineering,Guilin University of Technology,Guilin 541004,China;College of Earth Sciences,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学环境科学与工程学院,桂林541004 [2]桂林理工大学地球科学学院,桂林541004

出　　处：《环境科学》2020年第1期284-292,共9页Environmental Science

基　　金：国家自然科学基金项目(41877194,41502232);广西自然科学基金项目(2017GXNSFAA198096)

摘　　要：在实验室条件下合成纯度> 99%的MTA,开展不同pH和固液比条件下MTA在细砂、土壤沉积物和针铁矿这3种介质上的吸附实验,分析其吸附特征和作用机制.结果发现:①MTA质量浓度分别在0. 14~23. 59、0. 19~41. 27和0. 27~32. 02mg·L-1范围时,其在细砂、土壤沉积物和针铁矿的最大平衡吸附量(Qm)分别为21. 54、277. 98和2 607. 42 mg·kg-1.值得注意的是,当MTA在3种介质上达到吸附平衡后,溶液中部分MTA开始转化形成亚砷酸盐和砷酸盐.②随着pH的增加(4~10),MTA在细砂上的平衡吸附量(Qe)逐渐减少,在土壤沉积物和针铁矿上的Qe先减少后增加;随着固液比的增加,MTA在3种介质上的Qe均呈现出逐渐减小趋势.③XRD、SEM和BET测试结果揭示出3种介质吸附MTA的主要控制因素不同,分别是细砂的低孔容特征、土壤沉积物的高结晶程度以及针铁矿上大量的羟基官能团(-OH).Batch experiments were conducted to investigate the adsorption characteristics and mechanism of monothioarsenate( MTA)( > 99%) on sand,soil sediment,and goethite under different pH and solid-liquid ratio conditions. Results showed the following.① When MTA ranged from 0. 14 to 23. 59,0. 19 to 41. 27,and 0. 27 to 32. 02 mg·L-1 in solutions,its maximum equilibrium adsorption capacity( Qm) in sand,soil sediment,and goethite was 21. 54,277. 98,and 2 607. 42 mg·kg-1,respectively. After its adsorption reached equilibrium,a small amount of the MTA in the solutions transformed into arsenite and arsenate. ② As pH increased from 4 to 10,the equilibrium adsorption capacity( Qe) of MTA on sand decreased gradually,whereas Qe first decreased and then increased for soil sediment and goethite. As the solid-liquid ratio increased,the Qe of MTA in the three media gradually decreased.③ X-ray powder diffraction( XRD),scanning electron microscope( SEM),and BET results further showed that the major factors controlling MTA adsorption on the three media included the low pore volume of sand,the high degree of crystallization of the soil sediment,and the large number of hydroxyl functional groups( -OH) on goethite.

关 键 词：一硫代砷酸盐(MTA) 土壤沉积物 针铁矿 吸附动力学 等温吸附 作用机制 

分 类 号：X131[环境科学与工程—环境科学]