The Degradation of Aqueous Oxytetracycline by an O[sub.3]/CaO[sub.2] System in the Presence of HCO[sub.3][sup.−]: Performance, Mechanism, Degradation Pathways, and Toxicity Evaluation

• Published in: Molecules (Basel, Switzerland) Switzerland), 2024-01, Vol.29 (3)
• Main Authors: Li, Zedian, Xiang, Liangrui, Pan, Shijia, Zhu, Dahai, Li, Shen, Guo, He
• Format: Article
• Language: English
• Subjects: Ethylenediaminetetraacetic acid; Lime; Nonprescription drugs; Oxytetracycline
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29030659

This research constructed a novel O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] system to degrade antibiotic oxytetracycline (OTC) in water. The results indicated that CaO[sub.2] and HCO[sub.3] [sup.−] addition could promote OTC degradation in an O[sub.3] system. There is an optimal dosage of CaO[sub.2] (0.05 g/L) and HCO[sub.3] [sup.−] (2.25 mmol/L) that promotes OTC degradation. After 30 min of treatment, approximately 91.5% of the OTC molecules were eliminated in the O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] system. A higher O[sub.3] concentration, alkaline condition, and lower OTC concentration were conducive to OTC decomposition. Active substances including ·OH, [sup.1]O[sub.2], ·O[sub.2] [sup.−], and ·HCO[sub.3] [sup.−] play certain roles in OTC degradation. The production of ·OH followed the order: O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] > O[sub.3]/CaO[sub.2] > O[sub.3]. Compared to the sole O[sub.3] system, TOC and COD were easier to remove in the O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] system. Based on DFT and LC-MS, active species dominant in the degradation pathways of OTC were proposed. Then, an evaluation of the toxic changes in intermediates during OTC degradation was carried out. The feasibility of O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] for the treatment of other substances, such as bisphenol A, tetracycline, and actual wastewater, was investigated. Finally, the energy efficiency of the O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] system was calculated and compared with other mainstream processes of OTC degradation. The O[sub.3]/CaO[sub.2]/HCO[sub.3] [sup.−] system may be considered as an efficient and economical approach for antibiotic destruction.