水溶性有机物对菲的表观溶解度和正辛醇/水分配系数的影响

以农业上常用有机物料绿肥、猪粪和污泥作为水溶性有机物(DOM)的提取材料,以菲(Phe)作为多环芳烃(PAHs)的代表,通过摇瓶法研究了不同来源的DOM对菲在水中的表观溶解度和正辛醇/水分配系数的影响.结果表明,菲在超纯水中的溶解近似一级反应动力学过程.超纯水体系中添加了DOM后,菲溶解的平衡时间相对滞后,但却明显增加了菲的表观溶解度.当DOM浓度为150 mg·L-1(以DOC计)时,在含Tween-80、猪粪DOM、污泥DOM和绿肥DOM的体系中菲的表观溶解度分别是纯水体系的20.39、2.082、1.838和1.549倍.菲的表观溶解度随着外加DOM浓度的增加而增大,它们之间存在着明显的线性关系.回归直线的斜率可以用来表征DOM对菲的增溶效果,本试验4种体系中DOM的增溶效果大小依次为表面活性剂Tween-80＞猪粪DOM＞污泥DOM＞绿肥DOM.同时,DOM可降低菲的正辛醇/水溶液分配系数,各体系中logKow值的高低顺序与增溶效果的顺序恰好相反.研究结果显示,DOM的存在可明显地改变PAHs在水相中的溶解度和正辛醇/水溶液分配系数.

Effect of dissolved organic matter (DOM) on the apparent water solubility and the n-octanol/water partition coefficient of phenanthrene

Batch experiments with a shake-flask method were carried out to investigate effect of dissolved organic matter (DOM) derived from green manure, pig manure, and sewage sludge on the apparent aqueous solubility, and the n-octanol/water partition coefficient of phenanthrene (Phe). The results showed that the dissolution of Phe in pure water could be described by simple first-order kinetics. The equilibrium time of Phe dissolved in water was lagged and Phe apparent solubility increased due to the addition of DOM. The apparent water solubility of Phe in the presence of 150 mg·L^-1 could increased by 20.39 folds for Tween-80, and 2.08, 1.84 or 1.55 folds for DOM from pig manure, sewage sludge and green manure, respectively. Furthermore, the solubility of Phe increased with the increase of DOM concentration with a good positive linear correlation (R₂>0.95). The solubilizing sequence among DOM was Tween-80>pig manure DOM>sewage sludge DOM>green manure DOM. The addition of DOM in water also could decrease the n-octanol/water partition coefficient. The decrease sequence among DOM was in contrast to the order mentioned above. it was concluded that DOM can alter significantly the physicochemical properties of PAHs in water incorporated with DOM.