Multiple reinforcement of chloride ion on oxidizing acetaminophen with zero-valent copper particles: In-site formation and catalysis of hydrogen peroxide

Zero-valent copper particles (Cu0) used to degrade pollutant due to its in-site generation and activation of hydrogen peroxide (H2O2), while the disproportionation of Cu+ limited the efficacy. In this study, spiking chloride ion (Cl−) into zero-valent copper (Cu0) system (Cl−/Cu0 system) enhanced greatly acetaminophen degradation. The addition of Cl− not only reduced the dismutation reaction of Cu+, but also helped the comproportionation reaction of Cu0 and Cu2+, leading to much generation of Cu+ and H2O2. Hydroxyl radical (OH) and reactive chlorine species were identified as the dominant reactive oxidants in the Cl−/Cu0 system with its contribution ratio of degrading acetaminophen being respectively 73.4 % and 23.8 %. In the Cl−/Cu0 system, Cu+ was released by H+ corrosion from Cu0, and then Cu+ coupled with Cl− forming Cu-Cl complexes; Meanwhile, the reaction of O2 and the species of Cu+ (e. g. Cu-Cl complexes and Cu+) produced H2O2 and, then the species of Cu+ catalyzed H2O2 to form OH; Thereinto, partial OH was shifted by Cl− to reactive chlorine species. Except for fulvic acid, coexisting substrates such as sulphate, nitrate and phosphate ions had no obvious inhibition impact on oxidizing acetaminophen in the Cl−/Cu0 system. Furthermore, the Cl−/Cu0 system presented a good removal rate of acetaminophen in three actual water samples. Moreover, three kinds of dyes and painkillers was removed over 78 % in the Cl−/Cu0 system. The residual total dissolved copper was under II-level of environmental quality standards for surface water in China by alkali precipitation and filtration after reaction. Therefore, the study provided a new idea to enhance Cu0 for the purification of pollutants.