Role of acidic hydrochar on dechlorination of waste PVC in high temperature hydrothermal treatment and fuel properties enhancement of solid residues

In this study, the chlorine mitigation from waste polyvinyl chloride (WPVC) during high temperature cohydrothermal treatment (co-HTT) and the properties of the generated solid products were assessed. WPVC was co-fed with acidic hydrochar (AHC), which was produced via hydrothermal carbonization of pineapple waste in the presence of citric acid water solution. High temperature co-HTT experiments were performed at 300-350 degrees C, 0.25-4 h of reaction time, and 0-20 wt% AHC loading. Co-HTT solid products (co-HTT_SP) were characterized via proximate analysis, ultimate analyses, combustion analysis, and ash analysis. The results show that the addition of 5% AHC enhances the dechlorination efficiency (DE) of WPVC from 89.35% to 97.66% at 325 degrees C and 0.5 h. The highest DE, reaching 99.46%, was achieved at 350 degrees C and 1 h in the presence of 5 wt% AHC. Furthermore, loading 5% AHC improved the higher heat value (HHV) of the solid products from 23.09 to 31.25 MJ/kg at 325 degrees C and 0.5 h. The maximum HHV (34.77 MJ/kg) of a solid product was achieved at 350 degrees C, 4 h, in the presence of 5 wt% of AHC. The co-HTT solids shown low slagging indices, fouling indices, alkali indices, and medium chlorine contents. These findings support the viability of WPVC conversion into clean solid fuel via co-HTT.

Automated summary

This study assessed the chlorine mitigation and properties of solid products generated from waste polyvinyl chloride (WPVC) under high temperature cohydrothermal treatment (co-HTT). The results showed that the addition of 5% acidic hydrochar (AHC) increased the dechlorination efficiency (DE) of WPVC from 89.35% to 97.66% at 325 degrees C and 0.5 h. The highest DE of 99.46% was achieved at 350 degrees C and 1 h with 5 wt% AHC. Furthermore, loading 5% AHC improved the higher heat value (HHV) of the solid products from 23.09 to 31.25 MJ/kg at 325 degrees C and 0.5 h. The maximum HHV (34.77 MJ/kg) of a solid product was achieved at 350 degrees C, 4 h, with 5 wt% AHC. The co-HTT solids showed low slagging indices, fouling indices, alkali indices, and medium chlorine contents, supporting the viability of WPVC conversion into clean solid fuel via co-HTT.