镉砷在针铁矿界面共吸附的相互作用机制  

Cadmium and Arsenic Interactions During Co-adsorption onto Goethite

作　　者：苏子贤 刘赛红 管玉峰 陶亮 SU Zi-xian;LIU Sai-hong;GUAN Yu-feng;TAO Liang(School of Environmental Science,South China Normal University,Guangzhou 510006,China;Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management,National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China,Institute of Eco-environmental and Soil Sciences,Guangdong Academy of Sciences,Guangzhou 510650,China;Huangpu Technology Center of Guangzhou Municipal Ecological Environment Bureau,Guangzhou 510530,China)

机构地区：[1]华南师范大学环境学院,广州510006 [2]广东省科学院生态环境与土壤研究所,华南土壤污染控制与修复国家地方联合工程研究中心,广东省农业环境综合治理重点实验室,广州510650 [3]广州市生态环境局黄埔技术中心,广州510530

出　　处：《环境科学》2023年第7期3970-3977,共8页Environmental Science

基　　金：国家自然科学基金项目(41877038,42077016);广东省“珠江人才计划”本土创新科研团队项目(2017BT01Z176);广东省科研事业单位重点领域研发计划项目(2020B1111530001)。

摘　　要：通过吸附动力学和吸附热力学结合表面物理化学表征等手段,研究了As(Ⅴ)和Cd(Ⅱ)在针铁矿界面上的相互作用过程,解析了As(Ⅴ)和Cd(Ⅱ)在针铁矿界面共吸附过程中形成三元络合物的形态.结果表明:(1)As(Ⅴ)和Cd(Ⅱ)在针铁矿界面的吸附过程均符合准二级动力学模型,吸附以化学吸附为主;(2)As(Ⅴ)在针铁矿界面吸附均以内圈吸附为主,具有单层吸附的典型特征,Cd(Ⅱ)在针铁矿界面单吸附过程与As(Ⅴ)类似,而添加了As(Ⅴ)的共吸附过程则出现了外圈吸附,呈现多层吸附的典型特征;(3)As(Ⅴ)和Cd(Ⅱ)共存时可通过静电作用以及形成三元络合物的方式相互促进对方在针铁矿界面上的吸附;(4)通过对比各种表征结果,推导As(Ⅴ)和Cd(Ⅱ)在针铁矿上共吸附过程中生成了“Fe-As-Cd”形式的三元络合物.研究结果进一步丰富了对土壤-氧化铁界面重金属元素微化学相互作用过程的理解.Cadmium(Cd)and arsenic(As)are commonly co-adsorbed onto iron oxides in the soil environment,especially in south China.This study aimed to elucidate the regulatory mechanisms in determining the As(Ⅴ)-Cd(Ⅱ)interactions on a goethite interface after excluding pH interference.At pH 6.0,the results obtained illustrated that As(Ⅴ)and Cd(Ⅱ)adsorbed onto goethite obeyed the pseudo-second-order kinetic model,and the adsorption processes were mainly chemical adsorption.Furthermore,As(Ⅴ)adsorbed onto goethite were mainly inner ring adsorption and monolayer adsorption both in the single adsorption process and in co-adsorption processes with Cd(Ⅱ).For comparison,Cd(Ⅱ)adsorbed onto goethite also demonstrated inner ring adsorption and monolayer adsorption during single adsorption,and As(Ⅴ)-Cd(Ⅱ)co-adsorption were transformed to outer ring adsorption and multilayer adsorption processes.Through analysis by Zeta potential,X-ray diffraction,and X-ray photoelectron spectroscopy,electrostatic adsorption and formation of ternary complexes(Fe-As-Cd)were proven to be the critical mechanisms in determining the interactions between As(Ⅴ)and Cd(Ⅱ)during their co-adsorption processes.The results obtained in this study should help us to further understand the micro-chemical interaction processes of heavy metals on the soil environment.

关 键 词：镉(CD) 砷(As) 共吸附 针铁矿 三元络合物 

分 类 号：X13[环境科学与工程—环境科学]