Task-specific ionic liquids and ultrasound irradiation: a successful strategy to drive the alcoholysis of polycarbonate†

Abstract

The release of plastics into the environment is a pressing issue of the modern society, and the identification of strategies for their recycling is a challenge in chemical research. This work analyses the possibility of combining the efficiency of task-specific ionic liquids (TSILs) with the effect of ultrasound irradiation (US) to perform the alcoholysis of polycarbonate (BPA-PC). Aliphatic cations were combined with environmentally friendly basic anions to obtain TSILs able to perform the process at room temperature. Different operational parameters were optimized. The process performance was evaluated using a holistic approach to green chemistry, and the best catalysts were tested for their cytotoxicity toward two different normal cell lines, namely, the mammary epithelium (HB2) and retinal pigment epithelium (hTERT-RPE-1) cell lines. The collected data demonstrated that the best catalyst performed the process at 30 °C with an irradiation time of 90 minutes, offering conversion and yield values higher than 80%. Interestingly, it could be used to process post-consumer samples, like a digital CD and a BPA-PC sheet, providing results comparable to the ones obtained using pristine BPA-PC and bisphenol A with good purity. Furthermore, the proposed protocol could be scaled up without a drop in performance.