以十六烷基三甲基溴化铵(CTMAB)制备的有机膨润土为代表,设置有机膨润土中CTMAB的负载量为1.0倍的阳离子交换量(CEC),测试了其吸附酚类、胺类、硝基类等25种有机物的有机碳标化的吸附系数(Koc)值.在此基础上,运用多元线性回归方法得到了有机膨润土吸附有机物的多元线性溶剂化能关系(LSER)模型,以明确各种作用因素对有机膨润土吸附性能的相对贡献.结果表明,有机膨润土吸附有机物的多元LSER模型为:logKoc=1.886E-0.625S+0.525A-2.223B+2.332V+0.427,表明在该有机膨润土-水吸附体系中,过剩摩尔折射率(E)、氢键酸(A)和生成孔穴(V)作用对有机物在有机膨润土上的吸附为正贡献,而偶极(S)和氢键碱(B)作用为负贡献,这与土壤有机质-水吸附体系中各作用项的贡献相同,说明有机膨润土与土壤有机质有相似的吸附特征.以上5种作用对有机膨润土吸附25种有机物的贡献分别为:e×E(43%~93%),s×S(-48%~-13%),a×A(0~24%),b×B(-75%~-11%),v×V(62%~115%),其中,生成孔穴作用对吸附过程起主导作用.
In this paper,cetyltrimethylammonium bromide(CTMAB) modified organobentonite was selected as the representative of organobentonites.The cetyltrimethylammonium bromide loading amount was equal to 1.0 CEC.Values of the organic-carbon-based partition coefficient(Koc) for 25 organic compounds(including phenols,amines,nitro,etc.) on this organobentonite were calculated.The linear solvation energy relationship model for the organic compounds adsorption by organobentonites was obtained by multilinear regression analysis to clarify the role of various factors on the adsorption of organobentonites.The results show that LSER equation could be described as logKoc=0.427+1.886E-0.625S+0.525A-2.223B+2.332V,which shows that the excess molar refraction term(e×E),hydrogen-bond acidity term(a×A) and cavity formation term(v×V) play a positive role in the sorption of organic compounds from water to organobentonites,while the polarity and polarizability term(s×S) and hydrogen-bond basicity term(b×B) play a negative role.This is in accordance with the sorption of organic compounds from water to soil organic matter(SOM),and it indicates that the sorptive characteristics of organobentonite have similarity to those of SOM.The overall contributions of the five terms to the sorption of the 25 organic compounds on organobentonites were calculated as:e×E(43%~93%),s×S(-48%~-13%),a×A(0~24%),b×B(-75%~-11%),v×V(62%~115%).The cavity formation term plays a dominant role in the sorption process.