不同土壤有机质组分对憎水有机物的吸附机理研究

Sorption mechanism of hydrophobic organic contaminants by soil organic matter fractions

采用完全混合一步平衡反应实验方法,选择菲、萘、三氯苯和二甲苯作为憎水有机物(HOCs)的探针,研究了它们在土壤及其中的胡敏酸、胡敏素等有机质组分中的等温平衡吸附行为,探讨了非线性吸附的机制。结果表明,HOCs在水与土壤体系中表现为非线性吸附,其非线性的吸附行为主要受到土壤有机质(SOMs)的控制。SOMs具有高度不均匀的性质,HOCs表现出非线性吸附行为是其在不同的SOMs相扩散转移以及在相对聚结的胡敏素和“黑炭”的表面吸附的结果。

Phenanthrene, naphthalene, 1,3,5 trichlorobenzene and o xylene are selected as solute probes of the hydrophobic organic contaminants (HOCs). Completely mixed batch sorption experiments are conducted to study the sorption equilibriums on soil and its humic acid and humin fractions, and to have an insight into the mechanisms of nonlinearity sorption. The Freundlich isotherm model is used to fit the sorption data, and all of the isotherms are nonlinear (n=0.634～ 0.986 < 1). The soil organic matters (SOMs) in Chelsea soil are high heterogeneous, in which humic acid, humin and black carbon are existed. The results show that the nonlinear sorption of HOCs in soil is primarily regulated by SOMs. The sorption nonlinearity of HOCs is likely to be caused by the transfer of HOCs from one domain of SOMs to another and the adsorption on the surface of humin and black carbon.