摘要
通过设计批实验和表征分析,探究不同浓度的磷酸盐影响下,一硫代砷酸盐(MTA)在土壤上的吸附特征和机理.结果发现,Elovich动力学模型和Langmuir等温吸附模型可较好地拟合MTA在土壤中的吸附过程,相关系数R^(2)分别为0.983和0.994,表明土壤吸附MTA发生在局部位置,吸附过程主要以非均相扩散为主,拟合所得最大单层吸附量为254.214mg/kg.MTA与磷酸盐共存时,随着溶液中磷酸盐初始浓度的增大,土壤对MTA的平衡吸附量逐渐下降,对磷酸盐的吸附量逐渐增大;SEM-EDS结果表明无论是否添加磷酸盐,反应后的土壤表面都能检测到少量As,但添加磷酸盐条件下土壤表面的As含量则相对较低,证实磷酸盐的存在降低了土壤对MTA的吸附;XRD结果表明MTA能与土壤中的铁铝矿物发生络合反应生成内球络合物-[2Al(H_(2)AsO_(4))_(3)]、≡Al_(2)O_(2)AsO(SH)和-[2Fe(H_(2)AsO_(4))_(3)],而磷酸盐会与土壤表面的羟基形成内球络合物,导致土壤对MTA的吸附能力减弱.
In this study,batch experiments and characterization analysis were conducted to explore the characteristics and mechanism of MTA adsorption on soil by adding different concentrations of phosphate.Results showed that:the Elovich kinetic model and Langmuir isothermal adsorption model can better fit the adsorption process of MTA on soil,indicating that the adsorption process of MTA was mainly affected by the diffusion of pore size.The maximum adsorption capacity of MTA on soil was 254.214mg/kg.With the increase of the initial concentrations of adding phosphate in the solution,the equilibrium adsorption capacity of MTA on soil gradually decreases,and that of phosphate gradually increases.SEM-EDS results showed that a small amount of As was detected on the surface of soil whether adding phosphate or not.In the system with phosphate addition,the soil showed a relatively low content of As,confirming that the presence of phosphate can reduce the adsorption of MTA on soil.In addition,XRD results showed that MTA can form endosphere complexes of-[2Al(H_(2)AsO_(4))_(3)],≡Al_(2)O_(2)AsO(SH)and-[2Fe(H_(2)AsO_(4))_(3)]with Fe-Al minerals in soil samples,and phosphate can form endosphere complexes with hydroxyl groups on the surface of soil,weakening the adsorption of MTA.
作者
张进贤
单慧媚
廖丹雪
彭三曦
杜海玲
刘允全
石谦
ZHANG Jin-xian;SHAN Hui-mei;LIAO Dan-xue;PENG San-xi;DU Hai-ling;LIU Yun-quan;SHI Qian(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;College of Ecological and Environmental Protection,Guangxi Ecological Engineering Vocational and Technical College,Liuzhou 545003,China;College of Earth Sciences,Guilin University of Technology,Guilin 541004,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2022年第8期3849-3857,共9页
China Environmental Science
基金
国家自然科学基金资助项目(41877194,42062015,42167026),广西自然科学基金资助项目(桂科AD19110024,桂科AD19110062)。
关键词
一硫代砷
土壤
吸附
磷酸盐
monothiosarsenate
soil
adsorption
phosphate
