有机粘土矿物对水中低浓度菲的吸附性能和机理

Adsorption of phenanthrene on organic clays

分别选用十六烷三甲基溴化铵(HDTMA-Br)、四甲基溴化铵(TMA-Br)、聚乙二醇(PEG)表面活性剂改性天然粘土矿物,研究其对水中低浓度多环芳烃类难降解有机物菲的吸附性能和机理,并讨论了有机粘土的用量对吸附菲的性能的影响,验证了有机粘土矿物吸附菲后的稳定性。3种有机粘土矿物对菲的吸附等温线均呈中凹型,表现为分配系数(Kp)逐渐增大,表明吸附是分配作用和溶剂化效应共同作用的结果。根据Kp及土样有机碳含量(foc)所得的经有机碳归一化的分配系数(Koc)基本为常数,远远高于天然土壤/沉积物的Koc。在相同实验条件下,3种有机粘土矿物中HDTMA改性粘土矿物对菲的吸附性能最强,PEG改性粘土矿物次之,TMA改性粘土矿物最差。

Three organic clay samples were prepared by mixing a small quantity of natural clay with surfactant solutions of hexadecyltrimethylammonium bromide （HDTMA-Br）, tetramethylammonium bromide （TMA-Br） and polyethylene glycol 400 （PEG 400）. Series of adsorption isotherm experiments were performed to determine the capacity of organic clays for polycyclic aromatic hydrocarbon （PAH） phenanthrene. The dish shape isotherm curves suggested that adsorption of phenanthrene resulted from both partition and solvent effect. The organic content normalized clay samples had the same distribution coefficient （Koc value）. The HDTMA-modified clay had the highest capacity, followed by the PEG-modified clay and then TMA-modified clay. Less than 5% of adsorbed PAH was released after multiple washing.