The use of attapulgite (ATP)-based materials for adsorption of pollutants from water and wastewater has received growing attention. However, recovering ATP-based adsorbents remains a challenge. In this study, a magnetic adsorbent ATP/CoFe2O4with high tannic acid (TA) adsorptive capacity was fabricated via a facile co-precipitation approach and was well characterized. The loaded CoFe2O4particles were embedded into the adsorbent surfaces to allow magnetic separability. For this material, its TA adsorption kinetics, isotherm behavior, and magnetic separation efficiency are reported. The developed magnetic composites had rapid sorption kinetics of 3 h, high sorption capacity of 109.36 mg/g, and good magnetic separation efficiency of 80%. The used ATP/CoFe2O4was successfully regenerated by NaOH and reused five times without a substantial reduction in TA removal and magnetic performance. Intermolecular hydrogen bonding formation and surface complexation were identified as the sorption mechanisms of TA by ATP/CoFe2O4.Keywords:attapulgite;adsorption;CoFe2O4magnetic nanoparticle;tannic acid
CoFe 2 O 4 magnetic nanoparticles (CoFe 2 O 4 MNPs) were used as heterogeneous catalysts to activate peroxymonosulfate (PMS) for moxifloxacin (MOX) removal in this study. The impacts of initial pH, PMS, catalyst dosage, coexisting ions, and natural organic matter (NOM) were investigated, and the possible degradation pathways of MOX were proposed. The results indicated that efficient degradation of MOX (99.8%) could be achieved in the CoFe 2 O 4 /PMS system with the optimum reaction condition (initial pH = 9, CoFe 2 O 4 dosage = 100 mg/L, PMS dosage = 0.25 mM, reaction time = 30 min, and MOX concentration = 5 mg/L). The rule of MOX degradation followed the pseudo-first order kinetic reaction equation ( k obs = 0.194 min −1 ). According to the results of radical scavenging experiments, the contribution of HO• on MOX removal was negligible, and SO 4 •− played a dominant role in MOX degradation. Five probable MOX degradation pathways were proposed based on the identified fifteen degradation intermediates, including defluorination, decarboxylation, decyclopropyl reaction, transformation of quinolone moieties, oxidation, and cleavage of nitrogen-containing heterocycle. The existence of 5 mM Cl - , HCO 3 − , and HA posed stronger negative effects on MOX removal. However, the MOX removal efficiency increased with H 2 PO 4 - concentration in the first 15 min. The removal efficiency of MOX decreased significantly in the CoFe 2 O 4 /PMS system when the catalyst was reused five times. These research conclusions could provide useful information for the practical application of CoFe 2 O 4 /PMS system in wastewater treatment of antibiotics.
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