Dual promoted ciprofloxacin degradation by Fe0/PS system with ascorbic acid and pre-magnetization

As a widely used and hard-to-degrade pharmaceuticals and personal care product (PPCP), ciprofloxacin (CIP) was frequently found in water environment and the detected concentration was gradually increased. Although zero-valent iron (ZVI) has been shown to be effective in destroying refractory organic pollutants, the practical application and sustained catalytic performance is not satisfactory. Herein, introduction of ascorbic acid (AA) and employment of pre-magnetized Fe0 was achieved to maintain a high-concentration of Fe2+ during persulfate (PS) activation. Pre-Fe0/PS/AA system presented the best performance for CIP degradation, achieving almost complete elimination of 5 mg/L CIP within 40 min in the reaction conditions of 0.2 g/L pre-Fe0，0.05 mM AA and 0.2 mM PS. The CIP degradation retarded as excess pre-Fe0 and AA were added, therefore, the optimum dosages of pre-Fe0 and AA were determined to be 0.2 g/L and 0.05 mM, respectively. The CIP degradation gradually decreased as the initial pH increased from 3.05 to 11.03. The presence of Cl-, HCO3-, Al3+, Cu2+ and humic acid significantly influenced the performance of CIP removal, while Zn2+, Mg2+, Mn2+, and NO3- slightly affected the CIP degradation. Combined with the results of HPLC analysis and previous literature, several possible degradation pathways of CIP were proposed.