Study On Adsorption/Desorption Of Toxic Organic Pollutants On Soil

Adsorption and desorption process has received considerable attention asone of the most important processes affecting the mobility, degradation andbiological activity of pollutants in the environment. Thus, the study of thebehavior of adsorption/desorption of organic pollutants on soil becomesparticularly important in risk assessment, controlling pollution and developingremediation strategies. Based on the determination of adsorption/desorptionamounts of organic pollutants on soil by a method of soil column liquidchromatography(SCLC) with stepwise adsorption/desorption, this paper presentsthe quick determination of soil organic carbon adsorption coefficient,irreversible adsorption and the influence of surfactant on adsorption /desorption oforganic pollutants on soil, etc.Based on the determination methods for adsorption amount on soil by usingSCLC with frontal curve and by batch equilibrium method with multipleadsorption/desorption cycles, adsorption/desorption isotherms were determinedby a new method of soil column liquid chromatography with stepwiseadsorption/desorption. Adsorption isotherms of diuron, naphthalene, tebuconazole,azinphos-methyl, phenol,atrazine and prometyn were determined by the developedmethod. Adsorption/desorption of experimental samples fit well with Freundlichisotherm equation. Their correlation coefficients were approximately 0.99. Theexperimental results were in consistant with the values reported in literature.Compared with other methods, this method has the advantages of simplicity,rapidity and accuracy . Atrazine, diuron, azinphos-methyl and prometyn were chosen as models toinvestigate the irreversible adsorption of pesticides on soil by the method of SCLCwith stepwise adsorption/desorption. The results showed that adsorptioncoefficients of atrazine,diuron, azinphos-methyl and prometyn on the 3# Europeanreference soil were obviously different from those on Kaldenkirchen soil. However,the amount of soil organic carbon had less effect on irreversible adsorption amount.Irreversible adsorption amounts of different compounds on the same soil weredifferent. Temperature affected the irreversible adsorption amount of the pesticideon soil. The effects of surfactant sodium dodecylbenzene sulfonate(SDBS) on theadsorption/desorption and irreversible adsorption behavior of diuron on soil wereinvestigated. The results showed that the presence of surfactant can reduce theadsorption coefficient and irreversible adsorption amount of diuron on soil. Withthe increase of surfactant concentration, both the adsorption coefficients of organicpollutants on soil and irreversible adsorption amounts fluctuated. Furthermore,the possible mechanism of the interaction of surfactant affectingadsorption/desorption behavior of organic pollutants on soil is discussed.