A novel photoelectro-peroxone process for the degradation and mineralization of substituted benzenes in water

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 286; pp. 239 - 248
• Main Authors: Frangos, Phivos, Wang, Huijiao, Shen, Wenhua, Yu, Gang, Deng, Shubo, Huang, Jun, Wang, Bin, Wang, Yujue
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2016
• Subjects: Advanced oxidation; Electrolysis; Ozone; Photoelectrocatalytic ozonation; Ultraviolet; Ozone; Advanced oxidation; Electrolysis; Ultraviolet; Photoelectrocatalytic ozonation
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2015.10.096

[Display omitted] •A novel photoelectro-peroxone (PEP) process was developed by coupling ozonation, UV photolysis, and electrolysis processes.•H2O2 is electro-generated from O2 in sparged O2 and O3 gas mixture (ozonizer effluent).•The in-situ generated H2O2 then undergoes UV-induced photolysis or reacts with O3 to yield OH.•The PEP process can produce more OH than UV/O3 and electro-peroxone (EP) processes.•PEP mineralizes substituted benzenes much more rapidly and energy-efficiently than UV/O3 and EP processes. A novel photoelectro-peroxone (PEP) process was developed by combining conventional ozonation, UV irradiation, and electrolysis process to treat substituted benzene (nitrobenzene, chlorobenzene, and benzaldehyde) solutions. The PEP process involves electrochemically generating H2O2 from O2 in the sparged ozone generator effluent (O2 and O3 gas mixture) at a carbon-based cathode. The in-situ generated H2O2 then undergoes UV-induced photolysis and reacts with the sparged O3 to yield OH, which can rapidly and non-selectively oxidize most organic pollutants. Thanks to the enhanced OH production, the PEP process considerably increased the pseudo-first order rate constants for the degradation of the three substituted benzenes to ∼4.7–8.4 times of the simple linear combination of the individual ozonation, UV, and electrolysis processes. In addition, the PEP process was capable of removing 98% total organic carbon (TOC) from the substituted benzene solution in 15min with a specific energy consumption (SEC) of 0.66kWh (gTOCremoved)−1. In comparison, UV/O3 and electro-peroxone (EP, i.e., ozonation in combination with electro-generation of H2O2) processes took ∼90min to remove the same amount of TOC with SEC of 3.56 and 1.07kWh (gTOCremoved)−1, respectively. Furthermore, the presence of Fe2+/Fe3+ did not negatively affect TOC removal by the PEP process, whereas it decreased the efficiency of the EP process considerably. The results indicate that the PEP process can significantly improve the kinetics and energy efficiency for substituted benzene mineralization compared with conventional ozonation, UV photolysis, electrolysis, and their combined processes (UV/O3 and EP) that have been previously investigated, and may thus offer a highly effective and energy-efficient alternative for wastewater treatment.