Experimental And QSPR Study On Soil Sorption Properties Of Phthalic Acid Esters

Phthalate esters (PAEs) are a series of organic compound which are widely used all over the world. It has been reported that PAEs were distributed all over the world and frequently detected in air, water, soil and food. Moreover, many researches show that PAEs have estrogenic effects on animals and human, i.e. they can interfere with the endocrine system and procreation ability. Therefore, the environmental behaviors of PAEs become a hot area of research.This work studies the sorption behaviors of phthalic acid esters (PAEs) on soil by batch equilibration experiments and quantitative structure property relationship (QSPR) methodology, the main contents and corresponding conclusions are as follows:(1) The effects of soil type, dissolved organic matter and pH on the sorption of four PAEs (DMP, DEP, DAP, DBP) are investigated. The results indicate that all the sorption isotherms of four PAEs can be fitted by the Freundlich model.(2) For the three soils:Nanchang Honggutan soil, Nanjing Qixia soil and Jiaxing Huzhou soil, the sorption behavior PAEs are different. The order of sorption capacity of three soils is Jiaxing Huzhou> Nanjing Qixia> Nanchang Honggutan. This order is same with their organic carbon content. For Nanchang Honggutan soil and Nanjing Qixia soil, the n values are close to lwhich suggested that the sorption is linear, for Jiaxing Huzhou soil, the n values are in the range of1.11to1.22, indicating non-linearity of PAEs sorption in this soil.(3) With regard to the influence of pH, a negative correlation between pH values and the sorption capacities was found for four PAEs, the maximum sorption occurred at pH4.0. In the experimental pH range, the biggest reduction in Kf values appeared when pH increased from5.0to8.5(from acidity conditions to alkalinity conditions). In addition, the pH can’t affect the linearity of sorption behavior.(4) The effect of DOM on PAEs sorption may be more complicated. The sorption of four PAEs is promoted by low concentrations of DOM, the extent of promotion increases at the beginning and then decreases with the increasing of DOM, when reaches a certain concentration, the sorption of four PAEs is inhibited by DOM.(5) The organic carbon content normalized sorption coefficients (logKoc) of17PAEs on three soils were measured, and then two QSPR models were developed with13theoretical parameters to get reliable logKoc predictions. The leave-one-out cross validation (CV-LOO) and F value indicated that the internal predictive power of two models was satisfactory.