Heterogeneous activation of peroxymonosulfate by LaCo1-xCuxO3 perovskites for degradation of organic pollutants

Recently cobalt-based heterogeneous catalysts have been widely investigated for peroxymonosulfate (PMS) activation in sulfate radical-based advanced oxidation processes. However, the improvement of the catalytic performance for PMS activation remains to be a challenge. As the limiting step, the rapid transformation of CoII/CoIII redox pairs is crucial for PMS activation. Perovskites attract increasing attention due to their controllable oxidation state of B-site metal and formation of oxygen vacancies, which accelerates the cycle of redox pairs. LaCo1-xMxO3 (M = Cu, Fe and Mn) perovskites as heterogeneous catalysts of PMS were synthesized for the degradation of phenol. The results showed that LaCo0.4Cu0.6O3 exhibited the highest catalytic activity. The pseudo first-order kinetic constant of phenol degradation on LaCo0.4Cu0.6O3 is 0.302 min-1, being about 5 times as high as Co2+ with same molar concentration of cobalt in LaCo0.4Cu0.6O3. XPS analysis confirmed that substitution of copper could promote the cycle of CoII/CoIII, thus enhance the catalytic efficiency for PMS activation. The facilitated cycle of CoII/CoIII played a crucial role in the generation of sulfate radicals, hydroxyl radicals and singlet oxygen. And sulfate radical was the primary radical responsible for pollutants degradation. The results provide insights into constructing novel perovskite catalysts for the removal of organic pollutants in water.