铬渣堆周边土壤对Cr(Ⅵ)的吸附动力学和热力学研究  

Study on Kinetics and Thermodynamics of Cr(Ⅵ) Adsorption on Soils in Vicinity of Chromium-slag Dumping Site

作　　者：李银[1] 胡羽成 刘瑜[1] 

机构地区：[1]天津市水利科学研究院,天津300061 [2]天津市海河管理处,天津300141

出　　处：《环境科学与技术》2016年第9期71-76,124,共7页Environmental Science & Technology

基　　金：天津市水务局科技计划项目(KY2014-03)

摘　　要：结合天津某铬渣堆周边地区的污染情况和地质状况,选取该区域有代表性的3种土壤(黏土、粉质黏土、粉土)作为研究对象,研究了其对Cr(Ⅵ)的吸附动力学和热力学。结果表明:3种土壤对Cr(Ⅵ)的吸附在120 min时达到吸附平衡,符合拟二级动力学方程,相关系数达到0.99以上,吸附等温模型符合Freundlich模型,且吸附能力由大到小的顺序依次为黏土、粉质黏土、粉土。土壤对Cr(Ⅵ)的吸附量随温度的升高而增加。土壤的吸附自由能△G~θ<0、吸附焓变△H~θ>0,表明Cr(Ⅵ)在土壤中的吸附是自发的吸热过程;吸附熵变△S~θ>0,表明吸附是焓推动作用;△G~θ在-0.020 7^-1.352 2 k J/mol间,说明土壤对Cr(Ⅵ)的吸附以物理吸附为主、物理吸附和化学吸附共存的吸附过程。According to the pollution status and local geological condition in the vicinity of a chromium-slag dumping site in Tianjin, where three kinds of representative soil （clay, silty clay and silt） were selected to study Cr（Ⅵ） adsorption to the soils in regard to adsorption kinetics and thermodynamics. Results of the study revealed that the adsorption equilibrium attained at 120 min and the adsorption behavior fit in with the pseudo-second-order kinetics equation, the correlation coefficient being greater than 0.99; the adsorption isothermal model conformed with the Freundlich model, and among others, the adsorption capacity of clay was the strongest, followed by silty clay and silt. In general, the capacity of Cr（Ⅵ） adsorption increases with the rise of temperature. Moreover, the adsorption free energy △Gθ〈0, the adsorption enthalpy change △Hθ〉0, which implied that the Cr（Ⅵ） adsorption was a spontaneous endothermic process; on the other hand, the fact that adsorption entropy change △Sθ〉0 indicated that Cr（Ⅵ） adsorption was driven by enthalpy. AGo ranged from -0.0207 to -1.352 2 kJ/mol, which suggested that the adsorption process could be interpreted by both physical and chemical adsorption, mainly by physical adsorption.

关 键 词：铬渣堆 Cr(Ⅵ) 黏土 粉质黏土 粉土 吸附动力学 吸附热力学 

分 类 号：X53[环境科学与工程—环境工程]