Zero-valent iron/activated carbon microelectrolysis to activate peroxydisulfate for efficient degradation of chlortetracycline in aqueous solution.

Tetracycline antibiotics are widely used in human and veterinary medicine; however, their gradual increase in the aquatic environment poses a serious threat to human health and ecosystems. The reactivity of peroxydisulfate (PDS) in the degradation of chlortetracycline (CTC) in aqueous solution using a zero-valent iron/activated carbon (AC) microelectrolysis method (Fe-AC/PDS) was investigated by batch experiments. The results showed that the effects of different systems were as follows: Fe-AC/PDS > Fe/PDS > AC/PDS > Fe-AC > AC > Fe > PDS. In the Fe-AC/PDS system, the degradation efficiency of CTC could reach 88% under the following optimal experimental conditions: Fe dose of 0.4 g L, PDS dose of 2 g L, pH of 3 and initial CTC concentration of 50 mg L. The presence of Cl, HCO and HPO inhibited the degradation of CTC, while humic acid accelerated the degradation rate of CTC. The mineralization of CTC was evaluated from the TOC, with a value of 31.44% in 7 h. Free radical identification experiments showed that SO ˙ and O ˙ were involved in the degradation of CTC. The iron and carbon materials had good reusability, and the degradation rate of CTC was still approximately 70% after four cycles. Finally, the possible mechanism for the degradation of CTC by the Fe-AC/PDS systems was discussed. Based on the above conclusions, Fe-AC microelectrolysis is a new heterogeneous catalytic method for green and efficient activation of PDS and demonstrates potential applicability in the treatment of wastewater.