聚硫代酰胺修饰活性炭对Au(Ⅲ)的选择性吸附效果与机制  

Selective Adsorption of Au(Ⅲ)by Activated Carbon Supported Polythioamides and Adsorption Mechanism

作　　者：赵文金 张顺 安晓强 兰华春 刘会娟 曲久辉 ZHAO Wen-jin;ZHANG Shun;AN Xiao-qiang;LAN Hua-chun;LIU Hui-juan;QU Jiu-hui(Center for Water and Ecology,School of Environment,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学环境学院水质与水生态研究中心,北京100084

出　　处：《环境科学》2022年第3期1521-1528,共8页Environmental Science

基　　金：国家自然科学基金项目(51978373)。

摘　　要：通过在活性炭(AC)上原位合成聚硫代酰胺(PTA),成功制备了一种聚硫代酰胺修饰的活性炭基吸附材料(AC-PTA),研究其对废水中三价金[Au(Ⅲ)]的选择性吸附效果及机制.结果表明,AC-PTA在较宽的pH范围(<5.0)内对多金属离子共存溶液中的Au(Ⅲ)表现出优异的选择性吸附性能,Au(Ⅲ)的剩余浓度小于0.1 mg·L^(-1),其它金属离子几乎未被吸附;在pH 2~3时对Au(Ⅲ)的吸附效果最好;对Au(Ⅲ)的选择性吸附动力学过程符合伪二级动力学模型(R^(2)=0.9853),热力学过程符合Langmuir吸附等温线模型(R^(2)=0.9936),吸附容量最高可达2018 mg·g^(-1).AC-PTA对Au(Ⅲ)优异的选择性吸附性能主要归因于AC-PTA表面官能团—■NH—与Au(Ⅲ)的配位作用、带正电的AC-PTA与Au(Ⅲ)络合态阴离子之间的静电吸附作用以及AC对Au(Ⅲ)的直接还原作用.最后将吸附后的AC-PTA在空气条件下1000℃灼烧4 h,得到质量分数为90.0%的固态金,实现了金的高效回收,为实际废水中低浓度Au(Ⅲ)的选择性吸附与回收提供了技术支撑.By using in-situ synthesis of polythioamide(PTA)on activated carbon(AC),a polythioamide-modified activated carbon-based adsorbent(AC-PTA)was successfully prepared and used to study the selective adsorption effect and mechanism of Au(Ⅲ)in wastewater.The results showed that AC-PTA exhibited excellent selective adsorption to Au(Ⅲ)in the coexisting solution of multiple metal ions in a wide pH range(<5.0).The adsorption effect for Au(Ⅲ)was the best at a pH of 2 and 3;the concentration of residue Au(Ⅲ)was less than 0.1 mg·L^(-1),whereas other metals were barely adsorbed.The selective adsorption process for Au(Ⅲ)conformed to the pseudo-second kinetic model(R^(2)=0.9853),the thermodynamic process conformed to the Langmuir isotherm process(R^(2)=0.9936),and adsorption capacity was up to 2018 mg·g^(-1).Such advantages were mainly attributed to the coordination interaction between the—■NH—functional groups on the AC-PTA surface and Au(Ⅲ),the electrostatic adsorption between the positive AC-PTA and negative Au(Ⅲ)complex anions,and the direct reduction of Au(Ⅲ)by AC.The successful recovery of gold was finally realized by burning the adsorbed AC-PTA at 1000℃for 4 hours under air conditions,and solid gold with a mass fraction higher than 90.0%was obtained.This study provided the possibility for selective adsorption and recovery of low concentration Au(Ⅲ)from actual wastewater.

关 键 词：聚硫代酰胺修饰活性炭 金(Au) 吸附 选择性 吸附机制 

分 类 号：X703[环境科学与工程—环境工程]