Characteristics of Molten Salt Gasification of Waste PVC

Abstract

Molten salt oxidation is a robust thermal process with the inherent capability to catalytically oxidize the organic compounds while retaining the inorganic ingredients in salt bath. In the present study, molten salt gasification was used for the disposal of waste PVC. The characteristics of molten salt gasification of PVC under different temperatures and air equivalence ratios (ERs) on the gasification characteristics, chlorine retention efficiency, PCDD/F generation, and the distribution of heavy metals such as Cu, Pb, and Zn were investigated. The results showed that increasing the temperature and ER could effectively enhance the yield of gasification gas and carbon conversion efficiency. The highest gasification efficiency of 41.2% was achieved at 750 °C and ER = 0.4, with a gas yield of 0.442 Nm3/kg PVC. Molten carbonates showed an absorption and retention efficiency of more than 99.5% for chlorine under all conditions. Increasing temperature resulted in a significant reduction in the generation of PCDD/F. At 750 °C, the PCDD/F generation was less than 19 pg/g PVC with an I-TEQ of less than 1.4 pg/g PVC, and the ER had a minor effect on PCDD/F. During the molten salt gasification process, most of the heavy metals, such as Cu, Pb, and Zn, were retained in the salt bath.