Activation of peroxymonosulfate by a novel stratiform Co-MOF as catalyst for degradation of dyes in water

Cobalt-based metal-organic frameworks (MOFs) have been used as catalysts to remove macromolecular organic pollutants from wastewater. In this work, a novel type of cobalt-based MOF, CUST-593, was synthesized from cobalt nitrate hexahydrate (Co(NO3)2•6H2O), 2,2-bipyridine (BIPY), and 4,4ˊ,4ˊˊ-nitrilotrisbenzoic acid (NTB) using solvothermal method. The catalytic properties of CUST-593 for degrading dyes in water were then investigated. CUST-593, with the chemical formula {Co(NTB)(BIPY)(H2O)•0.5H2O•0.1DMA}, exhibited excellent catalytic activity in degrading dyes such as methyl orange (MO) and rhodamine B (RhB) in aqueous solutions. CUST-593 has a multi-layered structure, connected by carboxylate hydrogen bonds, which is beneficial to improving its water stability. Synthetic test results showed that CUST-593 effectively attacked dyes by primarily generating sulfate radicals (SO4•−) and a portion of hydroxyl radicals (•OH). Under the testing conditions, MO removal efficiency reached approximately 95%. Moreover, CUST-593 exhibited remarkable cycling catalytic properties, broad pH range applicability, and long-term effectiveness. A mechanism for the degradation of dyes by CUST-593 was proposed. The experimental findings in this study collectively support the conclusion that CUST-593 serves as a green and environmentally friendly catalyst for the degradation of dyes in polluted water.