典型PPCPs在河流沉积物中的吸附特性

Experimental and modeling study of sorption characteristics of selected PPCPs onto river sediments

选取了咖啡因、氯霉素、卡马西平、磺胺甲噁唑和三氯生等5种PPCPs,在实验室条件下,近似模拟了自然河流的水/沉积物界面,应用中心复合实验设计,考察了温度、pH值、有机质含量和流速对PPCPs吸附比例的影响;利用多元回归方程拟合实验数据得到PPCPs吸附模型,并利用独立数据对模型进行验证,以建立适用于自然河流的PPCPs吸附模型.实验结果表明,咖啡因和卡马西平的吸附过程是放热反应,而磺胺甲噁唑、氯霉素和三氯生的吸附为吸热反应;pH值的升高对磺胺甲噁唑和三氯生的吸附能力产生抑制,但能促进咖啡因吸附,而对氯霉素和卡马西平的影响不大;有机质含量、流速和初始浓度对5种PPCPs的吸附比例变化趋势影响一致,随着各因素浓度或速度升高,PPCPs的吸附比例均随之增大,但影响程度有所不同.另外,吸附模型结果表明,5种PPCPs的吸附比例拟合值与实测值相关系数均达到0.8以上;独立数据验证结果表明,拟合值与实测值相关系数均达到0.8以上;因此,多元回归方程能较好地拟合环境因素与PPCPs吸附之间的关系,同时,在所考察的环境因素浓度范围内,多元回归方程较好地预测了PPCPs在自然河流沉积物中的吸附行为.

A water/sediment interface was roughly simulated in laboratory, and a central composite design was applied to investigate the influence of temperature, pH, organic content, and velocity on the sorption proprotion of five selected PPCPs (caffeine, chloramphenicol, carbamazepine, sulfamethoxazole and triclosan). Based on the experimental data, multiple regression equations were fitted and calibrated to establish favorable sorption models for PPCPs in the river systems. The results showed that the sorption process of caffeine and carbamazepine were exothermic reaction, and the sorption of sulfamethoxazole, chloramphenicol and triclosan were endothermic reaction. The increase of pH inhibited the sorption capacity of sulfamethoxazole and triclosan, but it could promote the sorption of caffeine, while it had little effect on the sorption of chloramphenicol and carbamazepine. The organic content, velocity and initial concentration had consistent effect on the sorption ratio of PPCPs. With the increase of the values of the factors, the sorption ratio of the five PPCPs increased with different degrees. The fitting and calibration results showed that the correlation coefficients between fitted and measured values of PPCPs sorption proportions were both above 0.8. Therefore, within the ranges of concentration of the investigated factors, the multiple regression equations were able to reasonably model and predict the sorption of PPCPs onto rivers sediment.