Chloride-enhanced oxidation of organic contaminants by Cu(II)-catalyzed Fenton-like reaction at neutral pH

[Display omitted] •The Cu(II)-catalyzed Fenton-like reaction was accelerated in the presence of Cl−.•The Cu(II)/H2O2/Cl− system was optimized at neutral pH.•Cu(III)-chloro complexes were suggested as major reactive oxidants.•The Cu(II)/H2O2/Cl− system can be a useful approach to treat saline wastewater. The Cu(II)-catalyzed Fenton-like reaction was found to be significantly accelerated in the presence of chloride ion (i.e., the Cu(II)/H2O2/Cl− system), enhancing the oxidative degradation of organic contaminants at neutral pH. The degradation of carbamazepine (a select target contaminant) by the Cu(II)/H2O2 system using 1μM Cu(II) and 10mM H2O2 was accelerated by 28-fold in the presence of 10,000mg/L Cl− at pH 7. The observed rate of carbamazepine degradation generally increased with increasing doses of Cu(II), H2O2, and Cl−, and exhibited an optimal value at around pH 7.5. Various other organic contaminants such as propranolol, phenol, acetaminophen, 4-chlorophenol, benzoic acid, and caffeine were also effectively degraded by the Cu(II)/H2O2/Cl− system. Experiments using oxidant probe compounds and electron paramagnetic spectroscopy suggested that cupryl (Cu(III)) species are the major reactive oxidants responsible for the degradation of these organic contaminants. The enhanced kinetics was further confirmed in natural seawater.