Sorption of phenanthrene on the complexes of kaolinite and different organic component

Sorption of hydrophobic organic chemicals by various components influences their behavior and fate in environment. In the natural environment, mineral components, organic matter and microorganism didn＇t exist alone. They combined or reacted one another and formed the mineral-humic, mineral-microorganic and mineral- humic- microorganic complexes. A clear understanding of the sorption of organic chemicals by the complexes of mineral and humic acid and/or microorganism will help to determine their sorptive mechanisms in environment. In this paper, the sorption patterns of phenanthrene on the complexes of kaolinite and different organic component （humic acid and microorganism） have been carried on. The results show that the combination of HA and kaolinite not only changed the structure of HA, but also modified the surface chemistry of clay mineral. Interaction between HA and kaolinite is presumably ascribable to coulombic interactions and ligand exchange between the -COOH groups of HA and OH groups at the kaolinite surface. During the sorption on mineral surface, aliphatic fractions of HA were preferentially sored by kaolinite while aromatic fractions were left in the solution. More linear isotherms and higher Koc values were observed for kaolinite-HA complex in comparison of the pure HA. The sorption capacity of kaolinite-HA complex increased with increasing ionic strength and pH, and showed more nonlinear character. Kaolinite, microorganism and kaolinite-microorganism complex can all sorb phenanthrene, but the sorption capacity significantly differed. Bacterial cell sorbed more phenanthrene than kaolinite. The biofllm coating of kaolinite affected its sorption to phenanthrene. Kaolinite with biolfilm coating sorbed more phenanthrene than that without biofilm coating. The sorption capacity of kaolinite-microorganism complex decreased with increasing ionic strength and decreasing pH, but showed more nonlinear character. Both HA and microorganism can alter the nature of kaolinite sorbing phenanthrene respectively.

Sorption of phenanthrene on the complexes of kaolinite and different organic component