Photocatalytic conversion of polylactic acid waste to ethyl acetate in alkaline solution under mild conditions

Abstract

The growing accumulation of plastic waste, especially biodegradable polylactic acid (PLA), demands sustainable valorization strategies beyond conventional disposal methods. Direct photoreforming of solid PLA into valuable chemicals presents a promising solution. Herein, a visible-light-driven CdS-TiO2-Ag nanorods were synthesized via a multi-step hydrothermal and deposition approach. Comprehensive characterization revealed a well-defined CdS-TiO2-Ag architecture with enhanced visible-light absorption and improved charge separation/transfer kinetics. The optimized catalyst demonstrated exceptional performance, achieving rapid solid PLA digestion rate (92.3% in 5 h) and high ethyl acetate yield (21.11 mmol gcat.⁻¹ after 20 h) under optimized conditions. Kinetic studies identified a multi-stage pathway involving initial solid breakdown into soluble intermediates (e.g., lactic acid) followed by efficient liquid-phase conversion to ethyl acetate.Mechanistic insights suggest charge transfer-driven bond scission and intermediate transformation, with carbon analysis revealing partial mineralization and gaseous byproduct formation. The catalyst exhibited excellent reusability and structural stability. This work advances plastic waste management by demonstrating an efficient route for converting solid PLA into a valuable chemical commodity, highlighting the potential of rationally designed photocatalysts for sustainable resource utilization.