Facile synthesis of NaA zeolite supported Co2Fe1 for highly efficient degradation of Acid Orange 7 by activation of peroxymonosulfate

Abstract

Abstract The development of heterogeneous Co-based catalysts with an effective combination mode of Co/Fe and supporter, a facile synthetic method, and a low treatment costs is an important environment challenge for azo dyes degradation by peroxymonosulfate (PMS) activation. In this study, NaA zeolite supported CoxFey with various molar ratio of Fe/Si and Co/Fe was synthesized by a facile hydrothermal process, and used to activate PMS for Acid Orange 7 (AO7) degradation. NaA zeolite supported Co2Fe1 with the Fe/Si molar ratio of 1:10 showed superior catalytic performance compared with other NaA zeolite supported CoxFey. In a system containing 0.6 g/L catalysts, 4 mM PMS, pH 5 and T = 30℃, 95.8% AO7 and 79.1% COD conversion could be achieved at 20 and 60 min, respectively, and the first order kinetic rate constant reached 0.14795 min− 1. Moreover, NaA zeolite supported Co2Fe1/PMS system exhibited excellent catalytic effect in a wide pH range of 3–9. Temperature had an obvious effect on AO7 degradation, and the activation energy was 31.36 kJ/mol. HCO3− demonstrated an obvious depression on AO7 degradation, while Cl−, SO42− and H2PO4− had a relatively poor impact. Quenching experiments showed that both sulfate radicals (SO4•-) and hydroxyl radicals (·OH) were generated in the PMS reaction system, and the (SO4•-) was the dominant active radical. During 3 cycles experiments, an acceptable AO7 conversion ratio (91.8%) within 30 min was arrived, suggesting the good stability of NaA zeolite supported Co2Fe1.