From the accelerated production of •OH radicals to the crosslinking of polyvinyl alcohol: The role of free radicals initiated by persulfates

Persulfates are the concerned oxidants in the advanced oxidation processes recently. Besides, persulfates with higher concentrations can initiate the free radical crosslinking of the polymeric chain, which is considered as one of the solutions for the pollution control of soluble polymers. In this study, the combination of free radical crosslinking and oxidation initiated by a thermally activated persulfate system was used to simultaneously remove polyvinyl alcohol (PVA) and the coexisting organic pollutants, i.e. dyes. Especially, the catalyst-like function of PVA could accelerate the production of center dot OH radicals via the elimination of -OH groups. It can promote the crosslinking itself and facilitate the degradation of coexisting pollutants. Given initial COD and PVA concentrations of 14406.0 mg/L and 8063.2 mg/L, respectively, a maximum of 93.6 % COD and 98.4 % PVA was removed under the optimal conditions. Meanwhile, the PVA with high concentration did not have negative effects on the degradation of coexisting pollutants.