Efficient removal of organic and bacterial pollutants by Ag-La₀.₈Ca₀.₂Fe₀.₉₄O₃-δ perovskite via catalytic peroxymonosulfate activation

Abstract

Removal of toxic organics and bacterial disinfection are important tasks in wastewater treatment. Most heavy metal-based catalysts for degradation of aqueous organic pollutants in heterogeneous Fenton-like processes suffer from the toxicity of leached metals. The present work reports environmentally benign systems for both degradation of organics and bacterial disinfection. Calcium substituted LaFeO(3-δ) perovskite was demonstrated as an efficient catalyst to activate peroxymonosulfate (PMS) for degradation of phenol, methylene blue and rhodamine 6 G. Compared to LaFeO(3-δ) and nanocrystal Fe(3)O(4), the lattice oxygen vacancies in B-site cation-deficient perovskite of La(0.8)Ca(0.2)Fe(0.94)O(3-δ) (LaCaFeO(3-δ)) particles renders this material a greatly improved catalytic performance. Electron paramagnetic resonance (EPR) suggested that both sulfate (SO(4)•–) and hydroxyl radicals (•OH) played critical roles in the advanced oxidation processes. Moreover, silver doped perovskite (Ag-LaCaFeO(3-δ))/PMS successfully inhibited the growth of waterborne pathogen Escherichia coli and Methicillin-resistant Staphylococcus aureus (MRSA) at a lower dose than silver ions, proving a synergetic effect between free radicals and Ag⁺ in killing the bacteria. Therefore, Ag-LaCaFeO(3-δ)/PMS would be promising for practical wastewater treatment.