Experimental study on adsorption of PbCl2 and CdCl2 on kaolin modified by leachates from municipal solid waste incineration power plant

Abstract

Six kinds of waste liquids produced in the treatment process of leachate in a waste incineration plant were used to improve the adsorption effect of raw kaolin on heavy metal chloride. The capture performances of these modified kaolin on PbCl₂ and CdCl₂ vapor were investigated in a two-stage fixed bed combustor. The results indicated that the adsorption effects of raw kaolin on PbCl₂ and CdCl₂ were improved in some experimental groups, main effective component was Na⁺ in the leachate, but the influences did not change regularly with the increase in the concentration of Na ⁺ introduced into kaolin. The adsorbents formed by modifying 10 g kaolin with 21.25 ml leachate 2 were the best adsorbents for PbCl₂ and CdCl₂. The capture efficiencies of PbCl₂ and CdCl₂ can reach 95% and 63.88%, with the increase of 36% and 53%, respectively. Using leachate as modifying agent had the same effect as directly using Na⁺. Adsorptions of PbCl₂ and CdCl₂ were still mainly chemical adsorptions. After adsorption of PbCl₂, the modified kaolin not only generated PbA1₂Si₂O₈, but also produced other chemical compounds. The adsorption of CdCl₂ by modified kaolin did not generate CdAl₂Si₂O₈, but other chemical reactions occurred to generate CdAl₂O₄ and Pb₈Cd (Si₂O₇)₃.

Keywords: Heavy metal capture; Incineration; Kaolin; Leachate; Modification.