Activation of peroxymonosulfate by MgCoAl layered double hydroxide: Potential enhancement effects of catalyst morphology and coexisting anions

The morphology and specific surface area of layered double hydroxide (LDH) are of great significance for optimizing the application of LDH in sewage treatment. Herein, we present a study of the relation between the catalytic property and the morphology of LDH via activating peroxymonosulfate (PMS) for degradation of organic pollutants. The results demonstrated that LDH nanoscrolls possessed a superior performance for methylene blue (MB) degradation, which achieved almost 100% removal in 40 min and the calculated apparent rate constant was about 2.1, 4.5 and 11.5 times higher than that of LDH nanosheets, Co2+ and Co3O4, respectively. According to the results of X-ray photoelectrons spectroscopy (XPS) and electron paramagnetic resonance (EPR), 1O2 was confirmed to play a dominant role in the MB degradation, where the redox cycle of Co3+/Co2+ provided the impetus for the reaction. Moreover, the pH and ion tolerance abilities of LDH nanoscrolls in PMS activating process were determined as well. Remarkably, CO32− and H2PO4− could even promote the generation of •OH and 1O2 to facilitate the progress of reaction. Overall, these findings in the study may provide more opportunities in the preparation of high-efficiency catalysts and give insight into the accelerated degradation of refractory contaminants with surrounding anions.