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

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.