Experiment and mechanism study on enrichment of heavy metals during MSW pyrolysis by modified kaolin

Experiment and mechanism studies on the enrichment of Pb, Cd, Zn, As, and Cr by modified kaolin were investigated during MSW (municipal solid waste) pyrolysis at 450 similar to 650 degrees C. The results showed that yAlOK(micro- and nano-gamma Al2O3 by hydrothermal method modified kaolin) was relatively selective for the solid phase enrichment of Cr and As, while CaHPK (CaHPO4 impregnated modified kaolinite) was more advantageous for the adsorption of Pb and Zn, which might be related to the thermal stability of gamma Al2O3 and the thermal conversion of CaHPO4. Compared with the original kaolin, the adsorption and retention capacity of gamma AlOK for As was improved by 20 similar to 30%. Moreover, the retention rate of modified kaolin for Cd decreased from 66.75 to 30.30% at 450 650 degrees C, and the effect of temperature on the volatilization of Cd was always greater than the active components on the surface of modified kaolin. In the fluidized bed experiment, the physical mixing of different modified kaolin achieves complementary advantages on the retention capacity of heavy metals. In addition, the AE between Ca2P2O7 and PbCl2 is smaller than that of gamma Al2O3 at 500 similar to 650 degrees C, i.e., their electron transfer induction is stronger, and therefore more favorable for electron transfer and stable chemical bond formation.

Automated summary

The enrichment of Pb, Cd, Zn, As, and Cr by modified kaolin during MSW pyrolysis was investigated. Different modified kaolin showed selective adsorption for different heavy metals, and the thermal stability and active components of modified kaolin played important roles in the enrichment of heavy metals. The physical mixing of different modified kaolin achieved complementary advantages on the retention capacity of heavy metals.