Cohydrothermal carbonization of waste polyvinyl chloride and wood chip for dechlorination

Abstract

The co-hydrothermal carbonization (Co-HTC) of polyvinyl chloride (PVC) film and wood chip (WC) was conducted at 200-260oC in an autoclave filled in air or nitrogen for the chemical recycling of wastes with dechlorination of PVC. Effects of the Co-HTC temperature and the oxidation reaction during the Co-HTC on the decomposition behaviors were investigated. The percentage decomposition in nitrogen atmosphere increased with increasing the reaction temperature and reached 76.1% at 260oC. The percentage decompositions in nitrogen were several percent higher than those in air. The synergistic effect of PVC and WC for the decomposition was observed at 220oC in N2. When the Co-HTC was performed in air, decomposition was suppressed, indicating the increase in hydrochar yield. The dechlorination yield was determined from the Cl content in the recovered PVC after the Co-HTC reaction. Under nitrogen atmosphere conditions, the dechlorination yield increased slightly with increasing the temperature. At a carbonization temperature of 260oC, the dechlorination yield of PVC was about 40%.