Improving azo dyes degradation by CoFe2O4-activated peroxymonosulfate: Performance, degradation mechanism, and ecotoxicity assessment

Abstract

Development of an effective catalyst is essential to eliminate the risks to ecological environment and human health caused by the accumulation of azo dyes in environmental water. Herein, the cobalt ferrite (CoFe2O4) nanoparticles (NPs), facilely prepared by a one-pot hydrothermal procedure, were developed for peroxymonosulfate (PMS) activation towards Congo red (CR) degradations. The key experimental parameters were comprehensively investigated to optimize the degradation performance for CR in CoFe2O4/PMS system. Under optimal conditions, the CoFe2O4 NPs exhibited an excellent capability for PMS activation to degrade CR with the degradation efficiency of nearly 100 % in a wide range of pH values (3.0–9.0). The electron paramagnetic resonance (EPR) and quenching experiments confirmed that the entire CR degradation process was dominantly by the non-radical (1O2) and surface-bound SO4·−and ·OH. CoFe2O4 NPs displayed the remarkable stability and reusability, with degradation efficiency of 85.5 % even after six recycles. The possible degradation pathway in CR degradation process was proposed, and the qualitative analysis and ecotoxicity of the degradation intermediates were investigated. This work provided a facile and green strategy to prepare a prospective catalyst for the efficient removal of azo dyes by PMS activation.