Enhanced degradation and recycling of reactive dye wastewater using cobalt loaded MXene catalysts

Cobalt-based catalysts were synthesized using the molten metal salt method and applied for the degradation of reactive dyeing wastewater. The results demonstrated a degradation of 97.1% for the C.I. Reactive Red 195 solution under the following conditions: 1.0 g/L of Co@MXene, 3 g/L of peroxymonosulfate (PMS), treated at 25 °C for 36 min with initial pH of 7. After adding 20 g/L of NaCl, the dye degradation rate increased to 5.57 times compared to the original rate 0.0894 min⁻¹, but the difference in final degradation was not significant. The enhanced degradation was attributed to the combined action of hydroxyl radicals (OH•), sulfate radicals (SO₄•⁻), and singlet oxygen (¹O₂). Notably, the Co@MXene catalyst maintained a high dye degradation percentage of 93.5% even after being recycled ten times. The treated dye residue can be recycled for dyeing cotton fabrics with reactive dyes. This study achieves rapid treatment of dye wastewater with wide applicability and provides valuable insights into dye wastewater treatment and environmental remediation.