(629a) Utilization of Process Liquid from Hydrothermal Carbonization to Enhance Dehalogenation of Waste PVC

The United States generates more than 42 million metric tons of waste plastic waste every year. One of the main portions of waste plastic waste is waste polyvinyl chloride (PVC), which is a halogenated plastic. The rising awareness of the potential difficulties created by waste PVC plastics necessitates the development of a reliable method for treating them in a safe and ecologically friendly way, without the release of chlorinated organic compounds. Dehalogenation of waste PVC by hydrothermal treatment is a potential technology for creating a non-toxic and nearly completely closed system for waste PVC treatment. At subcritical conditions, water reacts with PVC, releasing chloride from the solid. According to several research, acids are often used to accelerate hydrothermal processes. In this work, the acidic process liquid of hydrothermal carbonization (HTC) of orange peel was employed to enhance the dehalogenation of PVC during hydrothermal liquefaction. The HTC was performed at 260 °C, and 1 h to produce the acidic process liquid with a pH of 4.2. On the other hand, HTL experiments were performed using a Hast-C Parr batch reactor at 300-350 °C, and 0.25-4 h. The results indicated that HTC process liquid improves HTL conversion with a maximum value of 3.2 wt%. The maximum HTL conversion was 50.1 %, which was achieved at 350 °C and 1 h. Moreover, HTL crude contains low chloride and significantly more carbon and hydrogen, resulting in a significantly greater heating value. Finally, the results indicated that the dehalogenation efficiency is high, which demonstrates HTL can significantly remove chlorine from PVC and move it into the aqueous phase. It means that there is an appropriate potential for upcycling PVC to clean solid fuel using HTL.