Synthesis of Plastic Char from Plastic Waste Doped with Fe/Ca for Peroxymonosulfate Activation and Bisphenol a Degradation

Abstract

Traditional plastic waste disposal methods, such as landfills and incineration, not only occupy a large amount of land but also release harmful substances that directly threaten the ecological environment. Using plastic waste to prepare carbon-based materials for the activation of persulfate is a promising method for simultaneously removing organic pollutants from water and achieving the resource utilization of plastic waste. Herein, polyethylene, polypropylene, polymethyl methacrylate and polyethylene terephthalate were pyrolyzed to prepare char doped with Fe and Ca. It demonstrated effective removal of bisphenol A from dilute solutions. The adsorption process followed the pseudo-second-order kinetics and with the Freundlich isotherm, indicating a multi-phase, multi-layer adsorption process. The char activated peroxymonosulfate to remove 94.1% of bisphenol A within 10 minutes. Any Cl-, NO3-, HCO3- or dissolved organic matter present inhibited bisphenol A removal. Quenching experiments and electron paramagnetic resonance measurements indicated that the active species degrading bisphenol A were SO4-·, ·OH, ·O2- and 1O2. Fe(II), Fe(III) and C=O functional group in the catalyst accelerated electron transfer during the activation process. Moreover, the toxicity of the degradation intermediates decreased during the process. Pyrolyzing mixed plastic waste also produced a char which exhibited outstanding degradation performance. That suggests a feasible approach for recycling plastic waste while effectively and rapidly removing organic pollutants from water.

Keywords: Plastic waste, Doped char, Peroxymonosulfate activation, degradation, Bisphenol A