Co-hydrothermal carbonization of cotton textile waste and polyvinyl chloride waste for the production of solid fuel: Interaction mechanisms and combustion behaviors

Abstract In this study, to recover energy from cotton textile waste (CTW) and polyvinyl chloride waste (PVCW), the co-hydrothermal carbonization (co-HTC) of two types of feedstocks in different mixing ratios and under hydrothermal temperature was conducted to obtain the hydrochars for the exploration of alternative solid fuel. The Py-GC/MS analysis showed that the distribution of pyrolysis products hydrochars was changed, which were mainly composed of benzene and its derivatives, indicating that the co-HTC process could improve the interaction to obtain highly aromatic hydrochars. The results confirmed that the interaction effects existed during the co-HTC, and the potential conversion mechanism of hydrochars during co-HTC was proposed. HCl produced from PVCW during dechlorination promoted the hydrothermal conversion of CTW, and in turn, the surface functionality of CTW-derived hydrochars particles improved the substitution of C-Cl bond on the polymer skeleton in PVCW and further promoted the hydrothermal conversion and dechlorination effect of PVCW. As expected, the higher heating values, fuel ratio, and dechlorination efficiency reached 30.65 MJ/kg, 0.68, and 90.79% respectively. The TG-DTG analysis displayed that the co-HTC improved the ignition temperature and burnout temperatures which showed better combustion reactivity of hydrochars. Overall, the co-HTC of CTW and PVCW could be regarded as a promising renewable energy production strategy.