Synergistic activation of peroxymonosulfate by nickel-cobalt hexacyanoferrate derived hybrid metal oxides for efficient sulfamethoxazole degradation

The development of a heterogeneous catalyst for efficient activation of peroxymonosulfate (PMS) is still highly desired in metal-based advanced oxidation processes. In this study, nickel-cobalt-iron hybrid oxides (NiCoFe-HO) catalyst was fabricated via direct thermal decomposition of nickel-cobalt hexacyanoferrate to activate PMS for sulfamethoxazole (SMX) degradation. NiCoFe-HO presented a much greater catalytic performance in SMX degradation with PMS under neutral pH (k = 0.079 min-1). The degradation rate of SMX with NiCoFe-HO was 2.3 and 3.0 times higher than that with nickel-iron hybrid oxides and cobalt-iron hybrid oxides, respectively. The synergistic effect among Ni, Co and Fe was experimentally verified to elucidate the superior catalytic activity. Sulfate radical and singlet oxygen were identified as the predominant reactive species in the current oxidation process. SMX degradation efficiency was gradually enhanced with the increase of catalyst dosage, PMS dosage and temperature but decreased with the increase of pH. In addition, NiCoFe-HO showed good stability and reusability. This study extends the design of hybrid metal oxides as efficient heterogeneous catalysts for PMS activation.