Efficient degradation of refractory organic contaminants by zero-valent copper/hydroxylamine/peroxymonosulfate process

Degradation of naproxen, bisphenol S and ibuprofen in a hydroxylamine enhanced zero-valent copper (Cu⁰) catalyzed peroxymonosulfate system was investigated for the first time. We found that hydroxylamine addition accelerated the reduction of Cu²⁺ to Cu⁺ as well as the corrosion of Cu⁰, and environmental friendly gas nitrogen was the main product of hydroxylamine. Additionally, hydroxyl radical and sulfate radical were identified to be the dominant reaction species by competitive experiments. The degradation of naproxen, bisphenol S and ibuprofen kept highly efficient in the pH range of 3.0–7.0 in Cu⁰/hydroxylamine/peroxymonosulfate process, with their degradation products identified by HPLC-MS, which showed that Cu⁰/hydroxylamine/peroxymonosulfate system could be an alternative to remove non-steroidal antiinflammatory drugs or plasticizers in wastewater. Furthermore, the effects of Cu⁰, hydroxylamine and peroxymonosulfate dosage were studied and optimized by a BBD based response surface model. This study provided a method to solve the disadvantages of Cu⁰/peroxymonosulfate systems, and gave a promising method to enhance the efficiencies of ZVMs activated system such as iron, cobalt and copper.