Sorption Of Lindane On Multi-solid Material Coexisting Systems In Natural Aquatic System

Organochlorine pesticides, as a typical representative of the persistent organicpollutants, have been one of the hot research fields of environmental science for itshigh toxicity, bioaccumulation, nonbiodegradable characteristics. Natural water is acomplex ecosystem. Apart from the aqueous phase, solid phase materials, whichinclude biofilms, suspended particles and sediments, is a necessary part of the naturalwater. Sorption is supposed to be the key step in the further migration andtransformation of pollutants in the environment. These three solid phases play adecisive role to a large extent in the migration, transformation and fate of manycontaminants in the natural environment.In this dissertation, sorption characteristics of the lindane on the biofilms,suspended particles and surface sediments and their major components gathered fromthe same natural water were studied simultaneously; the differences of kinetics andthermodynamics of the lindane sorption on these solid materials were comparativelyanalyzed; the relations between components and structures of these solid materialsand the sorption characteristics were discussed; and the possible sorption mecha nismswere analyzed. Meanwhile, the effects of typical heavy metals, As(Ⅴ) and Cr(Ⅵ) onthe lindane sorption on these solid materials were examined; Furthermore, thesorption characteristics of the lindane on these solid materials in multiphasecoexisting system were studied in this dissertation. It was shown that the data ofsorption kinetics fit the pseudo second-order model and the correlation coefficient R2was above0.99. The order of initial sorption rate of these solid materials from big tosmall was as follow: surface sediments> suspended particles> biofilms. Biofilms onthe sorption isotherm of the lindane in line with the linear assignment model showed agood linear relationship. Sediments and suspended particulate matter sorptionisotherms with the Freundlich model, as opposed to the biofilm, the sorptionisotherms showed a stronger nonlinear. The order of initial sorption capacity of thesesolid materials from big to small was as follow: Biofilms> suspended particles>surface sediments, and their TOC content of the same size. The restrain competition of solid materials sorption of lindane became weaker with the increase of initialconcentration of lindane in multiphase coexisting system. Simulating naturalenvironmental conditions, the coexistence of heavy metals As (Ⅴ) and Cr (Ⅵ) couldcause the inhibition of the sorption capacity of the solid materials.