Peroxymonosulfate decomposition by homogeneous and heterogeneous Co: Kinetics and application for the degradation of acetaminophen

• Published in: Journal of environmental sciences (China) Vol. 93; pp. 30 - 40
• Main Authors: Rodríguez-Narvaez, Oscar M., Rajapaksha, Ruwini D., Ranasinghe, Mahinda I., Bai, Xuelian, Peralta-Hernández, Juan Manuel, Bandala, Erick R.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-07-2020
• Subjects: Acetaminophen; Co3O4; Fenton-like reaction; OH production; PMS decomposition; OH production; Fenton-like reaction; PMS decomposition; Acetaminophen; Co3O4; CoO
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2020.03.002

Peroxymonosulfate (PMS) decomposition, hydroxyl radical (•OH) generation, and acetaminophen (ACT) degradation by the Co/PMS system using homogeneous (dissolved cobalt) and heterogeneous (suspended Co3O4) cobalt were assessed. For the homogeneous process, >99% PMS decomposition was observed and 10 mmol/L of •OH generation was produced using 5 mmol/L of PMS and different dissolved cobalt concentrations after 30 min. A dissolved cobalt concentration of 0.2 mmol/L was used to achieve >99% ACT degradation using the homogeneous process. For the heterogeneous process, 60% PMS decomposition and negligible •OH generation were observed for 5 mmol/L of the initial PMS concentration using 0.1 and 0.2 g/L of Co3O4. Degradation of ACT greater than 80% was achieved for all experimental runs using 5 mmol/L of the initial PMS concentration independently of the initial Co3O4 load used. For the heterogeneous process, the best experimental conditions for ACT degradation were found to be 3 mmol/L of PMS and 0.2 g/L of Co3O4, for which >99% ACT degradation was achieved after 10 min. Because negligible •OH was produced by the Co3O4/PMS process, a second-order kinetic model was proposed for sulfur-based free radical production to allow fair comparison between homogeneous and heterogeneous processes. Using the kinetic data and the reaction by-products identified, a mechanistic pathway for ACT degradation is suggested.
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