The Study On Adsorption And Desorption Of Lead On Black Soil

With the rapid development of technology and industry, soil lead pollution problems have become increasingly prominent. Soil colloids is the most important part of the soil. Therefore, the study of adsorption and desorption of lead onto soil colloids is extremely important. Black soil sample was collected and three kinds of particle size colloids (5-10,2-5 and 1-2 μm) were extracted. The adsorption kinetics and isothermal adsorption experiments of lead onto black soil were study by batch test, at different temperature and differernt pH. The experimental data were fitted by quasi-one Lagranian dynamics equation, quasi-two Lagranian dynamics equation, diffusion model, Langmuir, Freundlich and Dubinin-Redushkevich(D-R). The desorption kinetics of lead were study by batch test, and the experimental data were fitted by a kinetic equation and two kinetic equation. The effect of eluent concentration and pH on Pb2+ desorption was researched by batch test.Results indicated that black soil colloids had higher capacity of adsorbing Pb2+. The adsorption process of Pb2+ on the different particle sized colloids could be divided into two stages. The adsorption capacities of Pb2+ on the colloids were in decreasing order with particle sizes. The saturated adsorption capacities of Pb2+ on the colloids increased with the increase of pH, temperatur. The colloidal adsorption kinetics characteristics of Pb2+ on the different particle sized colloids are in good agreement with quasi-two Lagrangian dynamics equation, which demonstrated that that the adsorption process was dominated by chemical adsorption. Under the condition of different temperature, the sorption of Pb2+ on the colloids was fitted with Freundlich model and D-R modal. Sorption capacity of Pb2+ on the colloids would decrease with the increase of colloid size. Under the different pH of solution, the sorption equilibrium of Pb2+ on the black soil colloids of different sizes was better fitted with Freundlich model. Sorption capacity of Pb2+ on the colloids increased with the increase of solution pH. The sorption of Pb2+ on the colloids could be defined as chemical sorption.Saporin and Rhamnolipid have the ability to remove lead. The optimal conditions of the removal of lead by saporin at concentraton of 5%, pH 5.0. The optimal conditions of the removal of lead by rhamnolipid at concentraton of 3%, pH 6.0.