A sustainable waste plastic valorisation: conversion of discarded polyurethane into an active micro-cleaner using a DES system

Abstract

Discarded or waste plastic in the environment can alter the health of habitats and natural processes, severely impacting ecosystems, food production capabilities, people's livelihoods, and social well-being. Plastics constitute a major material group with a global production of approximately 368 million metric tons per year. Among them, polyurethane (PU) is a flexible substance with a wide range of applications in daily life and offers adaptability, toughness, and affordability resulting in a rapidly increasing demand worldwide. In contrast, recycling of PU is still limited, and more research and development are needed to improve the efficiency and effectiveness of PU recycling and upcycling. Herein, we demonstrated a sustainable and eco-friendly conversion of waste PU into useful active micro-cleaners via a deep eutectic solvent (DES) assisted solvothermal process. In this process, a greener solvent system containing choline chloride and ferric chloride which acts as a solvent and catalyses PU foam to form valuable carbonaceous products under solvothermal conditions was established. The prepared PU-derived carbon (PUC) was characterized using suitable analytical techniques to understand its physicochemical properties and used for the adsorption of a variety of contaminants such as malachite green, methylene blue, and a pharmaceutical ciprofloxacin molecule. Furthermore, PUC successfully acted as a Fenton-like catalyst and exhibited an excellent recyclability efficiency (>80%) even after the 5^th cycle which shows the potential of the material in sustainable wastewater treatment.