Realizing the reuse of dye wastewater through Fe2O3 modified loofah biochar activated peroxymonosulfate

In this study, iron ion-loaded biochar catalysts were synthesized via a hydrothermal method and utilized for the degradation of reactive dye wastewater. The degradation reached 97.80 % using a 0.25 g/L iron oxide-doped loofah sponge biochar (Fe 2 O 3 @LSC) catalyst, with a 3 g/L peroxymonosulfate (PMS) mixture reacting for 60 min at 25 °C and an initial pH of 7. The dye degradation rate with the addition of sodium chloride (NaCl) was 1.78 times higher than that without the anion. However, the difference in the final dye degradation was not significant. The addition of sodium sulfate (Na 2 SO 4 ) inhibited dye degradation, resulting in degradations of less than 85 %. Experimental results confirm that dye degradation is attributable to the combined action of hydroxyl radicals (·OH), sulfate radicals (SO 4 •– ), and singlet oxygen ( 1 O 2 ). After recycling the Fe 2 O 3 @LSC catalyst four times, the dye degradation still reached 97 % by extending the treatment time, demonstrating the recyclability of catalyst. Compared to conventional dyeing, the use of treated dyeing wastewater for dyeing resulted in an increase in the dyeing percentage of reactive dyes by 2.23 % to 9.21 %. The study demonstrates the feasibility of using a treatment agent for rapid processing and recycling of reactive dye wastewater, offering valuable insights. • The obtained loofah sponge-derived biochar could effectively activate PMS. • SO 4 •− and 1 O 2 played a dominant role in the degradation of reactive dyes. • Sustainable reactive dyeing with the recycled dyeing wastewater was realized.