Synthesis of Fe0/Fe3O4@porous carbon through a facile heat treatment of iron-containing candle soots for peroxymonosulfate activation and efficient degradation of sulfamethoxazole

Developing highly efficient, reusable, non-toxic and low-cost catalysts is of great importance for persulfate-based advanced oxidation processes (AOPs). In this work, ferrocene was mixed into paraffin to prepare a candle, and the iron-containing candle soots were collected and heated at 500 degrees C similar to 900 degrees C under N-2 atmosphere for 1 h to prepare magnetically recyclable Fe-0/Fe3O4@porous carbon (Fe-0/Fe3O4@PC) catalysts. The Fe-0/Fe3O4@PC-700 obtained after pyrolysis at 700 degrees C exhibited the best catalytic activity for sulfamethoxazole (SMX) degradation. 10 mg/L SMX could be completely degraded within 10 min by 0.2 g/L of Fe-0/Fe3O4@PC-700 and 0.5 mM PMS at pH 5.0. The carbon shell effectively inhibited the Fe leaching of Fe-0/Fe3O4@PC-700, and 99.73% of Fe was retained after five consecutive cycles. In the Fe-0/Fe3O4@PC-700/PMS system, SMX was degraded through the sulfate radical (SO4 center dot(-)), hydroxyl radical (center dot OH), superoxide radical (O-2 center dot(-)) dominated radical pathway, and the singlet oxygen (O-1(2)) dominated non-radical pathway. The coexisting inorganic ions and natural organic matters (NOM) in actual water inhibited the degradation of SMX. Finally, four possible degradation pathways were proposed based on the degradation intermediates of SMX. This work provides a facile heat treatment of iron-containing candle soots strategy to prepare the metal@carbon catalysts for PMS-based AOP.

Automated summary

The study focuses on developing efficient and reusable Fe-based catalysts for persulfate-based advanced oxidation processes. The iron-containing candle soots were utilized to prepare magnetically recyclable Fe-0/Fe3O4@porous carbon catalysts with high catalytic activity for sulfamethoxazole degradation. The system demonstrated rapid degradation of the target pollutant, magnetically recyclable properties, and good stability for multiple cycles.