Degradation of dye wastewater by peroxymonosulfate activated with CuO-modified loofah biochar

Purpose This study aims to develop a copper oxide (CuO)-modified loofah biochar catalyst (CuO@LSC) for the activation of peroxymonosulfate (PMS), enabling the efficient degradation of C.I. Reactive Red 218 (RR218) in dye wastewater. Design/methodology/approach The study systematically examined the influence of various factors on the degradation of RR218, including initial pH, PMS concentration, CuO@LSC catalyst concentration, reaction temperature and the type and concentration of ionic species. Furthermore, the degradation mechanism of RR218 via free radical pathways was thoroughly investigated. Findings Under the conditions of 0.125 g/L CuO@LSC catalyst, 0.25 g/L PMS, at 25°C, and an initial pH of 9, a reaction time of 30 min achieved a degradation of up to 98.20%. Despite a 4.18-fold slowdown in dye degradation with sodium chloride (NaCl), the final degradation efficiency still reached 98%. In contrast, the addition of sodium sulfate (Na 2 SO 4 ) inhibited dye degradation, resulting in a degradation of less than 90%. Furthermore, the experimental results confirmed that dye degradation occurs due to the combined action of sulfate radicals (SO 4 •− ), singlet oxygen ( 1 O 2 ) and hydroxyl radicals (·OH). Originality/value This study successfully achieved the rapid treatment of dye wastewater, offering valuable insights for its recycling and reuse.