Supercritical Solvents Treatment of Waste Plastic from Waste Electric and Electronic Equipment (WEEE)

摘要

Waste plastic containing organobromine from waste electric and electronic equipment (WEEE) was subjected to supercritical solvents (methanol, acetone, isopropanol, water) treatments so as to understand the decomposing properties of polymers and flame retardants in the process. The results showed that 400°C was suitable for oil recycling because the conversion rate increased sharply between 350 to 400°C and decreased over 400°C caused by coking except water. Acetone was not suitable for this process though it had the highest conversion rate which was ascribed to the solubility of plastic in the reagent. The highest oil yield was 60.0% which was obtained in supercritical isopropanol at 400°C after 60min treatment, while methanol and water had the highest oil yield of 47% and 40.7% at 420 , respectively. From GC/MS results, it was found °C that the oil mainly consisted of phenol, chlorinated phenol, brominated phenol, and alkylphenol, which mainly came from the degradation of flame retardant below 350. However, benzene and other benzene derivates, °C coming from the degradation of plastic, accounted for large proportion of the products when the temperature was over 400. Under supercritical water t °C reatment, 96.8% of the bromine atoms were transferred into aqueous phase, and over 92.2% of the bromine existed in oil as inorganic bromine when organic solvents were used at 400. °C