溶解性有机质对黑炭吸附和解吸苯并[a]芘的影响

Effect of Dissolved Organic Matter on Sorption and Desorption of Benzo[a]pyrene on Black Carbon

通过静态吸附实验,研究了3种不同类型的溶解性有机质(L-苯丙氨酸、蛋白胨和柠檬酸)对苯并[a]芘(BaP)在黑炭表面吸附解吸的影响。结果表明,3种溶解性有机质的存在均会增加BaP在黑炭表面吸附的非线性程度。L-苯丙氨酸和蛋白胨的存在均可以抑制BaP在黑炭表面的吸附,同时促进了BaP的解吸,这主要取决于L-苯丙氨酸和蛋白胨对BaP的增溶作用。但是由于BaP可以分配到黑炭表面吸附态的蛋白胨中,在相同添加浓度下,L-苯丙氨酸对BaP吸附的抑制作用更强。与L-苯丙氨酸和蛋白胨相反,柠檬酸的存在增加了BaP在黑炭表面的吸附并减小了吸附过程的可逆性,这主要是由于吸附在黑炭表面的柠檬酸对BaP的吸附作用。当柠檬酸的浓度从0mg·L-1增加到50和100mg·L-1时,BaP的吸附能力参数Kd值(在ce=100μg·L-1下)分别从119 268mL·g-1升高到134 877和180 639mL·g-1,解吸滞后指数H分别从0.44减小到0.41和0.39。本研究为预测多环芳烃在溶解性有机质污染的环境中的分布特征和最终归趋提供了理论依据。

Sorption and desorption of benzo[a]pyrene （BaP） on black carbon （BC） ex- tracted from sediment were studied in the presence of three types of dissolved organic matter （DOM）, including L-phenylalanine, peptone and citric acid, to examine the role of DOM in sorption and desorption. Nonlinearity of the sorption isotherms of BaP in- creased in the presence of DOM. The presence duced the sorption capacity and desorption hy PHE in L-phenylalanine and peptone solution. of L-phenylalanine and peptone both re steresis because of the Compared to peptone, solubilization of L-phenylalaninecan inhibit BaP sorption more strongly at the same concentration, due to the distribution of BaP to the absorbed peptone on BC surface. Unlike L-phenylalanine and peptone, cit- ric acid enhanced the sorption capacity and irreversibility of BaP on BC mainly due to the strong sorption of citric acid on BC surface. When the critic acid concentration increased from 0 to 50 and 100 mg · L-1 , the sorption capacity parameter Ka value （at ce = 100 μg · L-1） increased from 119 268 mL · g-1 to 134 877 and 180 639 mL · g-1, respectively, and the hysteresis index H value decreased from 0.44 to 0.41 and 0.39. Our finding can provide more information for predicting the distribution and fate of PAH in the DOM polluted environment.