Accelerated degradation of polyvinyl alcohol via a novel and cost effective heterogeneous system based on Na2S2O8 activated by Fe complex functionalized waste PAN fiber and visible LED irradiation

To realize the low cost and highly effective removal of PVA from wastewater, waste polyacrylonitrile (PAN) fiber was modified and reacted with Fe3+ ions to fabricate the amidoximated PAN fiber Fe complex (Fe-AO-PAN), which then was characterized and employed to activate Na2S2O8 for PVA degradation. Fe-AO-PAN was found to effectively activate Na2S2O8 in the dark, and LED visible irradiation enhanced its activation effect on Na2S2O8, thus accelerating the PVA degradation. Increasing irradiation or high Fe content of Fe-AO-PAN could significantly promote the PVA degradation. Fe-AO-PAN also showed better activation performance for Na2S2O8 in a wide pH range. Electron Spin Resonance (ESR) studies suggested that hydroxyl radicals were the main reactive oxygen species generated in Na2S2O8/Fe-AO-PAN system, which was primarily responsible for PVA degradation. By increasing LED visible irradiation, Na2S2O8/Fe-AO-PAN system exhibited the similar degradation and de-toxicity efficiency of PVA solution to H2O2/Fe-AO-PAN system with high pressure Hg lamp irradiation. These findings presented a novel method of waste control by waste in environmental remediation.