Alcoholysis of Waste Polycarbonate Plastic by Methanol into Bisphenol A under Mild Conditions
Polycarbonate (PC) is a widely utilized engineering plastic, but its accumulation in waste streams poses environmental and health risks due to the leaching of toxic bisphenol A (BPA). This study presents a catalyst-free methanolysis route for the chemical recycling of waste PC into BPA under mild conditions. At 160 °C, complete depolymerization of PC (100.0% conversion) was achieved with a high BPA yield of 95.0% without any catalyst or auxiliary solvent. A scaled-up experiment with 10 g PC demonstrated a facile separation process, recovering BPA with over 85.0% yield. The method proved effective for various commercial PC grades and mixed plastics, including ABS-PC blends, as well as other polyesters such as polylactic acid, polyglycolic acid, and polyethylene terephthalate. Based on SEM and GPC analyses, a probable alcoholysis depolymerization mechanism was proposed, involving initial swelling and gradual breakdown of PC into soluble macromolecules with broad molecular weight distribution, ultimately yielding BPA. This work offers a facile, green, and efficient approach for the alcoholysis recovery of polyester plastics, addressing both environmental concerns and sustainable resource utilization.