Photocatalytic degradation of ibuprofen over BiOCl nanosheets with identification of intermediates

• Published in: Journal of hazardous materials Vol. 358; pp. 1 - 9
• Main Authors: Arthur, Robert B., Bonin, Jesse L., Ardill, Luke P., Rourk, Ellery J., Patterson, Howard H., Stemmler, Elizabeth A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.09.2018
• Subjects: BiOCl; bismuth; Bismuth - chemistry; carboxylic acids; Catalysis; Chromatography, Liquid; high performance liquid chromatography; Ibuprofen; Ibuprofen - chemistry; LC-MS/MS; Light; nanosheets; Nanostructures - chemistry; Nanostructures - radiation effects; persistent organic pollutants; Photocatalysis; photocatalysts; Photolysis; Tandem Mass Spectrometry; Water Pollutants, Chemical - chemistry; Water Purification - methods; LC-MS/MS; BiOCl; Photocatalysis; Ibuprofen
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.06.018

•BiOCl photocatalytic degradation of ibuprofen was investigated by HPLC-DAD and LC-MS/MS.•Two primary products, 4-isobutylacetophenone and 1-(4-isobutyl)phenylethanol, were identified.•Secondary product formation was determined to originate from 4-isobutylacetophenone.•Enhanced ibuprofen removal by BiOCl prevents formation of hydroxylated side products. Photocatalysis directed at the removal of persistent organic pollutants, including pharmaceuticals, has been the subject of intense recent research. Bismuth oxychloride (BiOCl) has emerged as a potential alternative to traditional photocatalysts and has shown competitive removal efficiencies. However, pathways responsible for BiOCl photodegradation have not been well characterized. The present work is the first to determine, using LC-MS/MS analysis, the pathways by which BiOCl removes ibuprofen (IBP) from water. HPLC-DAD and LC-MS/MS analyses show that BiOCl converts IBP to two primary photochemical products, 4-isobutylacetophenone (IBAP) and 1-(4-isobutylphenyl)ethanol (IBPE). The reactivity for BiOCl is attributed to interactions of the carboxylic acid group of IBP with holes in the valence band. Hydroxylated-IBP was not detected in BiOCl photocatalytic degradation experiments which would be expected in a process driven by the formation and reactivity of reactive oxygen species. These data were used to formulate a photocatalytic degradation pathway for IBP and highlight the importance of studying both primary and secondary degradation reactions for photocatalytic studies.