Converging waste streams: dual valorization of azeotropic effluents and bioplastic solids

The efficient valorization of industrial wastewater and plastic solid waste constitutes a major challenge in sustainable chemical manufacturing. This study presents an integrated strategy that concurrently tackles the separation of dioxane–ethanol–water ternary azeotropes and the upcycling of polylactic acid (PLA) waste. By employing potassium carbonate (K₂CO₃) as a bifunctional agent, we combine salting-out separation and base-catalyzed alcoholysis into a single process. K₂CO₃ not only facilitates phase separation, achieving >99 % recovery of both dioxane and ethanol with a residual water content below 0.67 wt%, but also catalyzes the depolymerization of PLA within the organic-rich phase. The dehydrated extract serves as a reactive medium, efficiently converting PLA into ethyl lactate with a yield of 65.18 %. This approach establishes a novel reactive azeotrope-breaking pathway. The resulting ethyl lactate and dioxane can be separated via fractional distillation without requiring external solvents or further purification. This integrated methodology transforms two challenging waste streams, namely azeotropic solvent effluents and PLA plastics, into value-added products through a consolidated and solvent-minimized process. Our work provides a blueprint for coupling separation science with catalytic valorization in waste-intensive industries.