Study on Zn and Cd Colloid-affected Adsorption in Three Different Soils

Heavy metal ions of zinc,cadmium and colloid were used through the batch experiment to study the single and competitive adsorption behavior of zinc and cadmium in three soils different in texture and the effects of the colloid on the adsorption amounts.The Langmuir equation and Freundlich equation were used to fit the experiment data.The results indicated that the adsorption amounts of zinc and cadmium in soils increased with the increasing equilibrium concentration;the sequence of the adsorption amounts of three soils was sandy loam silty loam loamy sand;the adsorption amounts of the two ions in the competitive experiment were less than those in single system;the colloid increased the adsorption amounts of zinc but decreased the adsorption amounts of cadmium.In this paper,Freundlich equation was more accurately than the Langmuir equation in describing adsorption behavior of two heavy metals.