Co-treatment of plastics with subcritical water for valuable chemical and clean solid fuel production

Plastic nylon 66, ethylene-vinyl acetate (EVA) and polyvinyl chloride (PVC) were treated in subcritical water to produce value-added liquid chemicals and clean solid fuels. A synergistic effect was found in the co-treatment of PVC and the other two plastic polymers. Nylon 66 was totally decomposed to water-soluble oligomers with the reaction at 330 °C for 45 min. The same condition was required for the complete hydrolysis of EVA to produce acetic acid and deacetylated solid fuel. The activation energy for nylon 66 and EVA hydrolysis were 99.30 and 146.46 kJ/mol, respectively. However, a relatively low temperature (250 °C) was adequate for PVC dechlorination (efficiency >80%). The hydrochloric acid released from PVC worked as the acidic catalyst, which significantly accelerated the hydrolysis of nylon 66 and EVA, consequently more moderate reaction conditions (250 °C for 60 min) are required. Co-treatment of PVC with other polymers by subcritical water showed a great perspective.