Magnetic mesoporous FeCo₂O₄–Fe₃O₄ microrods as novel peroxymonosulfate activators for effective metronidazole degradation

Abstract

BACKGROUND: Metronidazole (MNZ) is a highly typical representative antibiotic widely occurring in wastewaters. Its release poses potential threats to the environment and human health. Advanced oxidation processes based on heterogeneous catalysis are promising technologies for organic matter removal. In this study, a new type of magnetic mesoporous FeCo 2 O 4-Fe 3 O 4 microrods was prepared and evaluated as catalyst to activate peroxymonosulfate (PMS) for metronidazole (MNZ) degradation. RESULTS: The effects of catalyst dosage, PMS concentration, and pH on MNZ degradation were investigated. A 96.8% removal of MNZ (100 mg L −1) was attained in the FeCo 2 O 4-Fe 3 O 4 /PMS under the optimum conditions of 4 mM PMS, 0.4 g L −1 FeCo 2 O 4-Fe 3 O 4 loading, pH 7 and 60 min reaction time. The hydroxyl radicals (•OH) and sulfate radicals (SO 4 •−) were identified as the primary reactive species attributed to MNZ removal. The plausible mechanism of the catalytic degradation was proposed and assumed to be related to the Co/Fe species that exerted the synergistic effect during reactions. FeCo 2 O 4-Fe 3 O 4 showed excellent reusability and stability, which was testified by the successive degradation experiments. More importantly, FeCo 2 O 4-Fe 3 O 4 exhibited general applicability in eliminating various antibiotics, including ciprofloxacin, 2,4-dichlorophenol, ofloxacin, and tetracycline. The efficiencies of which were 78.8%, 77.1%, 81.3%, and 60.7%, respectively, under identical reaction conditions as MNZ. CONCLUSION: This study proved that mesoporous FeCo 2 O 4-Fe 3 O 4 microrods are efficient PMS activators and provided a novel strategy for developing FeCo 2 O 4-based catalysts for the removal of organic pollutants from water.

Advances in Electrochemical and Catalytic Performance of Nanostructured FeCo2O4 and Its Composites

“…Various oxidants such as hydrogen peroxide (H 2 O 2 ), ozone (O 3 ), peroxymono sulphate (PMS) and persulfate (PS) are activated via heat, UV irradiation, ultrasound, alkaline medium and transition metals, to produce these reactive radicals. [114] SO 4 *À is considered as more efficient oxidising species due to its higher standard redox potential (2.5-3.1 V) than OH * (1.8-2.7 V) and stability in aqueous medium at wide range of pH. Furthermore, SO 4 *À exhibits superior selectivity, a relatively long half-life, and higher effectiveness for decomposing contaminants at neutral pH.…”

“…In addition, the 'nano'-sized spinel oxide further improves the photocatalytic activity by increasing the surface area of photocatalyst and decreased reunion of charge carriers. Hence, Nusrat et al [124] studied the photocatalytic activity of nano-crystalline, mixed transition metal oxides ( [114] (c) The possible mechanism for ATZ (Atrazine) degradation in the 30%-FeCo 2 O 4 /Rectorite composite/PMS system. (d) Degradation of ATZ (Atrazine) in different reaction systems.…”

“…[117] Adapted/ reproduced with permissions from Ref. [114]. Copyright 2020 John Wiley and Sons, Ref.…”

“…(e) Effect of initial pH on removal of 2, 4-DCP [117]. Adapted/ reproduced with permissions from Ref [114]…”

Advanced Oxidation Processes Based on Sulfate Radicals for Wastewater Treatment: Research Trends

“…SR-AOPs have been used in the treatment of different WW to degrade organic pollutants, including pharmaceuticals [58][59][60][61][62], herbicides [33,37], dyes [39] and a number of additives used in the manufacture of plastics [32,55]. Likewise, they have been used for the disinfection of WW with the presence of Escherichia coli and Enterococcus faecalis [8,36].…”