硝酸盐对土壤吸附一硫代砷的影响特征及机理  

Characteristics and mechanism of nitrate on adsorption of monothioarsenate in soil

作　　者：石谦 单慧媚 刘吉刚 李哲映 张进贤 SHI Qian;SHAN Hui-mei;LIU Ji-gang;LI Zhe-ying;ZHANG Jin-xian(Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology,Collaborative Innovation Center for Water Pollution Control and Water Security in Karst Areas,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学,广西环境污染控制理论与技术重点实验室,岩溶地区水污染控制与用水安全保障协同创新中心,广西桂林541004

出　　处：《中国环境科学》2023年第9期4750-4759,共10页China Environmental Science

基　　金：国家自然科学基金资助项目(42167026,41877194);广西自然科学青年基金资助项目(2022GXNSFBA035600)。

摘　　要：设计并开展批实验,分析不同浓度NO_(3)^(-)(0~50mg/L)影响下MTA与土壤的相互作用特征,结合XRD、SEM-EDS、XPS等表征测试进一步揭示影响机理.结果发现:(1)土壤对MTA的平衡吸附量(Qe)随着反应体系中NO_(3)^(-)浓度的增加而逐渐增大,当NO_(3)^(-)浓度从0增加至50mg/L时,Qe从27.73mg/kg增加至32.95mg/kg,SEM-EDS测试结果发现随着NO_(3)^(-)初始浓度的增加,反应后土壤表面的砷含量有所增加.证实NO_(3)^(-)的存在能够促进土壤对MTA的固定,且NO_(3)^(-)浓度越高土壤对MTA的固定作用增强.(2)添加NO_(3)^(-)的土壤-MTA反应体系中,反应后溶液中NO_(3)^(-)含量出现不同程度的减小,同时检测到NH4+的生成,而土壤中有含砷、氮的铝氧化物和铁氧化物生成.分析认为:MTA主要被土壤中的铁和铝氧化物吸附,当存在NO_(3)^(-)时,伴随着溶液中NO_(3)^(-)部分发生还原转化成NH_(4)^(+),土壤表面的Fe(Ⅱ)氧化成Fe(Ⅲ)(氢)氧化物,从而促进了MTA的吸附.In this study,batch experiments were carried out to investigate the effects of NO_(3)^(-)(0~50mg/L)addition on monothioarsenate(MTA)adsorption by natural soil.Characterization analysis of XRD,SEM-EDS,XPS,etc.was conducted to further identify the mechanisms.Results showed that:(1)the equilibrium adsorption capacity of MTA on soil(Qe)gradually increased with the increase of NO_(3)^(-)concentrations.Specifically,when the NO_(3)^(-)concentration increased from 0to 50mg/L,Qe increased from 27.73mg/kg to 32.95mg/kg,respectively.Besides,SEM-EDS results showed that after the reaction,the As content of the soil increased slightly with the increasing concentrations of NO_(3)^(-)in the reaction system.These findings indicated that the presence of NO_(3)^(-)can promote the adsorption of MTA on soil,and higher concentrations of NO_(3)^(-)lead to more MTA adsorbed by soil.(2)After MTA adsorption,the NO_(3)^(-)content in the solution decreased to various degrees and NH_(4)^(+)was detected in the MTA-soil-NO_(3)^(-)system,meanwhile aluminum oxides and iron oxides containing arsenic and nitrogen were formed on the surface of soil.This was attributed to the fact that MTA was mainly adsorbed by iron and aluminum oxides in soil.When NO_(3)^(-)was present in the reaction system,accompanied by NO_(3)^(-)partially reduction to NH_(4)^(+),Fe(II)was oxidized to Fe(III)(hydrogen)oxide on the soil surface,which helped improve the MTA adsorption.

关 键 词：一硫代砷 土壤 硝酸盐 作用机理 形态分布 

分 类 号：X131.3[环境科学与工程—环境科学]