Catalytic ozonation with biogenic Fe-Mn-Co oxides: Biosynthesis protocol and catalytic performance

Metal oxides, as a popular group of ozonation catalyst, are usually synthesized with physiochemical protocols involving hazardous materials and extreme conditions. In this study, a biological method was studied with manganese oxidizing bacteria Pseudomonas sp. to synthesize multi-metal oxides consisting of iron, manganese, and cobalt (Bio-FeMnCoOx) to catalyze ozonation for the first time. It was found that the dosage of cobalt, the cultivation time, and the polishing methods could significantly impact the catalytic activities of degrading benzotriazole as a model. The second-order degrading kinetic constant with optimized Bio-FeMnCoOx was 4.8 times that with the physiochemically synthesized peer. The activity of Bio-FeMnCoOx was compared with other reported catalysts in terms of Rct value. The quenching tests and EPR spectra indicated the participation of hydroxyl radicals, superoxide radicals, and singlet oxygen. The study demonstrates the great potential of biosynthesis as a green protocol for preparing metal oxides to efficiently catalyze ozonation.