Zero-valent copper catalysts derived from composite hydrogels efficiently activate persulfate for the degradation of chlorophenols

Transition metal/carbon composite catalysts can effectively activate persulfate (PMS) to degrade organic pollutants. In the present study, a simple pyrolysis technique was used to effectively transform a composite hydrogel adsorbent loaded with Cu (Ⅱ) into a zerovalent copper/carbon composite catalyst (C-Cu), which efficiently activated PMS and rapidly degraded 2,4-dichlorophenol (2,4-DCP). Under conditions of pH=5, a C-Cu dosage of 5 mg, and PMS concentration of 0.20 g/L, 2,4-DCP (0.1 mmol/L) was completely removed within 5 minutes, with a reaction kinetic constant as high as 3.4342 min^-1, which was 3 orders of magnitude higher than those of reported metal oxides. In compliance with the Integrated Wastewater Discharge Standard (GB 8978—1996) Grade I, C-Cu could stably operate for 81.3 hours in a dynamic column reactor. Under the coexistence conditions of pH=5-9, conventional inorganic salts, and natural organic matter, the degradation of 2,4-DCP in the C-Cu/PMS system was not significantly inhibited, demonstrating good environmental tolerance. Moreover, the C-Cu/PMS system showed superior removal performance for various chlorophenol pollutants. Quenching experiments of active species and EPR results consistently indicated that zerovalent copper acts as the active site for PMS activation, generating a large amount of ¹O₂ and ·O₂^-. LC-MS analysis results suggested that 2,4-DCP underwent processes such as dechlorination and ring-opening to achieve degradation and mineralization.