Degradation of tetracycline by activated peroxodisulfate using a sulfur-modified iron-based material

Abstract

The activation of persulfate by an iron-based catalyst presents a promising approach for the degradation of antibiotics; however, the activation efficiency remains a challenge. Herein, a sulfur-modified iron-based catalyst (S–Fe) by co-precipitation of sodium thiosulfate and ferrous sulfate in a molar ratio of 1:2 was prepared and the efficacy of the S–Fe/PDS system for the removal of tetracycline (TCH) was studied, where a higher removal efficiency was observed compared to the Fe/PDS system. Moreover, the effects of TCH concentration, PDS concentration, initial pH, and catalyst dosage on TCH removal were evaluated, and the highest efficiency was about 92.6% within a 30 min reaction time using a catalyst dosage of 1.0 g/L, a PDS dosage of 2.0 g/L, and a solution pH value of 7. The products and degradation pathways of TCH were analyzed by LC–MS. The free-radical-quenching experiments revealed that both SO4− • and •OH radicals contributed to the degradation of TCH in the S–Fe/PDS system, with the former playing a more significant role. The S–Fe catalyst also showed good stability and reusability for the removal of organic pollutants. Our findings suggest that the modification of an iron-based catalyst offers an effective approach to activate persulfate for removal of tetracycline antibiotics. HIGHLIGHTS The sulfur-modified iron-based catalyst (S–Fe) was prepared.; Both SO4− • and •OH radicals played the role in the degradation of TCH in the S–Fe/PDS system.; The S–Fe catalyst showed high catalytic activity and reusability for the removal of organic pollutants.;

Keywords

• free radical
• iron-based material
• peroxodisulfate
• tetracycline