Insight into the mechanism of CuO activated persulfate with the assistance of bicarbonate for removing organic pollutants

CuO can activate persulfate (PS) via radical and non-radical ways for organic pollutants removal, while bicarbonate can suppress the leaching of Cu. However, the key parameter affecting the performance of bicarbonate-CuO-PS is still unclear. Hence, in this work, four CuO samples were synthesized by different methods and used to activate PS in the presence of bicarbonate for removing different organic pollutants in water. The correlation between the surface properties of CuO and the activation efficiency of PS by different pathways was studied. The key reactive species for pollutants degradation were identified. The result indicates that the bicarbonate-CuO-PS process is effective not only for degradation but also for mineralization of organic pollutants. Activated PS generated via the non-radical pathway should be the dominant reactive species for pollutants removal . The Cu 2+ with more electron deficiency should be the active site for the generation of activated PS. Synthesis of CuO with high percentage of the aforementioned Cu 2+ and/or large surface area should be an effective way to promote the formation of activated PS. In addition, a novel method was developed to estimate the amount of activated PS, which is useful for investigating non-radical activation of PS. The finding of this work provides a possible way for enhancing the non-radical activation of PS with CuO, thus improving the performance of bicarbonate-CuO-PS.