Visible-Light Photocatalytic Degradation of Water-Soluble Polyvinyl Alcohol in Aqueous Solution by Cu2oTio2 : Optimization of Conditions, Mechanisms and Toxicity Analysis

Polyvinyl alcohol (PVA), a water-soluble synthetic polymer, is one of the most widely distributed exotic particles in nature. It can cause serious environmental pollution but is often overlooked due to inherent invisibility. To achieve efficient degradation of polyvinyl alcohol (PVA) in wastewater, Cu2O@TiO2 was prepared by modifying titanium dioxide with cuprous oxide, which was then characterized for visible photocatalytic degradation of PVA. The degradation can be significantly promoted by increasing the proportion of cuprous oxide or being put under alkaline conditions. The radical trapping experiments and electron spin resonance (ESR) studies showed that superoxide radicals were mainly responsible for the degradation in the reaction system., which exhibited 98% PVA solution degradation efficiency as well as 58.7% PVA mineralization efficiency. During the degradation, the PVA was decomposed from long-chain macromolecules to produce ethanol, as well as small molecular substances containing aldehyde, ketone, carboxylic acid and other groups. Although the intermediate products are less toxic, there are still some toxic hazards