掺杂MnO2土壤对多种雌激素化合物的吸附热力学特征及机理  

Thermodynamic Characteristics and Mechanisms of Estrogen Hormones Adsorption on Soil Doped with MnO_2

作　　者：李鱼[1] 张琛[1] 刘建林[1] 李小朋[1] 王夏娇[1] 

机构地区：[1]华北电力大学资源与环境研究院区域能源系统优化教育部重点实验室,北京102206

出　　处：《高等学校化学学报》2013年第3期634-640,共7页Chemical Journal of Chinese Universities

基　　金：国家“九七三”计划项目(批准号:2004CB3418501)资助

摘　　要：通过析因实验设计优化了掺杂MnO2土壤对雌酮(E1)、雌二醇(E2)、17α-乙炔基雌二醇(EE2)、雌三醇(E3)和双酚A(BPA)等多种雌激素化合物的吸附条件,采用Langmuir吸附等温式和Gibbs方程考察了掺杂MnO2土壤吸附雌激素化合物的热力学规律和吸附过程的热力学性质,并利用傅里叶变换红外光谱对吸附机理进行了探讨,同时利用液相色谱-质谱联用技术对土壤中多种雌激素化合物的主要降解产物进行了定性分析.结果表明,雌激素化合物浓度和MnO2掺杂比例对雌激素化合物在掺杂MnO2土壤中的吸附量起显著的正效应,土壤质量对雌激素的吸附起负效应,土壤-水吸附体系的pH值对E2的吸附量起正效应而对E3起负效应.Langmuir吸附等温式能够描述雌激素在掺杂MnO2土壤中的热力学吸附行为(R2>0.99),吸附过程中雌激素化合物的ΔG均为负值,绝对值均小于40 kJ/mol,说明土壤吸附雌激素化合物为自发的物理吸附过程;掺杂MnO2土壤对雌激素的吸附既存在物理吸附作用,也存在化学降解作用.雌激素化合物的降解主要由于土壤中的有机碳增强了MnO2的导电性能,说明MnO2可以作为土壤固定化剂,能够有效地防止雌激素化合物因解吸作用而形成的'二次污染'.Adsorption conditions of multiple estrogen compounds on soil doped MnO2 were optimized by factorial experiment design.The thermodynamic characteristics and thermodynamic properties in the course of estrogen hormones adsorption on soil doped MnO2 were investigated by Langmuir adsorption isotherm and Gibbs equation.Finally,the adsorption mechanism of multiple estrogen compounds on soil doped MnO2 was explored by Fourier transform infrared spectroscopy and liquid chromatography-mass spectrometry technology,and the main degradation products were analyzed.The experiment results showed that estrogen concentration and MnO2 had significant positive effects on adsorption capacity of estrogen compounds on soil doped MnO2,and the amount of soil had negative effect.The pH value had positive effect on the adsorption capacity of E2 but negative effect on E3 adsorption.The adsorption behavior of estrogen compounds on soil doped MnO2 could be described by Langmuir adsorption isotherm（R20.99）.All the calculated ΔG values of estrogen hormones in the course of adsorption were negative,and their absolute values were less than 40 kJ/mol.It demonstrated that the adsorption of the estrogen hormones on soil is a spontaneous physical adsorption process.The adsorption of estrogen hormones on soil doped MnO2 both had physical adsorption and chemical degradation.The degradation reaction was improved which was probably resulted from the enhancement of conductive property of MnO2 through organic carbons in soil.Therefore,MnO2 can be used as a stabilization agent for the soil,which could effectively prevent secondary pollution of estrogen hormones caused by desorption.

关 键 词：土壤 雌激素化合物 二氧化锰 热力学吸附 固定化作用 

分 类 号：O647.3[理学—物理化学] X132[理学—化学]