Separation and Purification Technology, Vol.212, 536-544, 2019
Nanoscaled magnetic CuFe2O4 as an activator of peroxymonosulfate for the degradation of antibiotics norfloxacin
In this study, a magnetically separable nanoscale CuFe2O4 synthesized by co-precipitation-calcination method was employed as a heterogeneous catalyst to activate peroxymonosulfate (PMS) for the generation of powerful oxidizing sulfate radical (SO4 center dot-). The degradation of the fluoroquinolone antibiotics norfloxacin (NOR) in aqueous solution by CuFe2O4/PMS system was examined. The effect of experimental parameters, including initial pH, oxidant and NOR concentrations, catalyst dose, and water matrices on NOR removal was systematically investigated. The evolution of inorganic ions (e.g., NO3-, F-, and NH4+) and low molecular weight organic acids (e.g., formic acid, lactic acid, acetic acid, and oxalic acid) during NOR degradation was monitored by using ion chromatography. Experimental results showed that NOR degradation was in accordance with the pseudo first-order reaction kinetics. At pH = 7, more than 90% of 25 mu M NOR was removed in 120 min by using 200 mg L-1 CuFe2O4 to activate 0.5 mM PMS. Free radical quenching experiments revealed the dominant role of SO4 center dot- in oxidizing NOR in CuFe2O4/PMS system. TOC test indicated that > 64% of initial carbon content was removed in 12 h; meanwhile an increasing buildup of carboxylic acids was observed and contributed to 32.9% of initial carbon content in 12h, suggesting that they were the predominant end products before completely mineralization. The XRD profile of the catalyst before and after the reaction was characterized. It was found that the structure and properties of the catalyst kept stable, and the recovered catalyst exhibited good performance during the reusability test. The result therefore suggested that CuFe2O4/PMS is a promising alternative as a possible application for treatment of water polluted by norfloxacin antibiotics.