WO3/Ag/ZnO S-scheme heterostructure thin film spinning disc photoreactor for intensified photodegradation of cephalexin antibiotic. (November 2022)

• Record Type: Journal Article
• Authors: Zamani, S.; Rahimi, M.R.; Ghaedi, M.; Dashtian, K.
• Is Part Of: Chemosphere. Volume 307:Part 3(2022)
• Publication Date: 2022-11
• Subjects: Cephalexin -- Photocatalytic degradation -- Spinning disc reactor -- Visible-light-driven -- S-scheme ZnO/Ag/WO3; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.135812
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The presence of antibiotics in wastes and drinking water has led to serious environmental and health concerns, further necessitating the development of an advanced sustainable strategy to eliminate antibiotics from aquatic media. In this context, the present research reports the successful fabrication of a spinning disc photoreactor (SDPR) supported ZnO/Ag/WO3 S-scheme visible-light-driven thin-film photocatalyst to study the degradation of cephalexin (CPX) as a target pollutant under blue light irradiation. The optical, electrochemical and physicochemical characterization of the as-prepared thin-film samples were carried out by XRD, top-view FE-SEM, EDS-mapping, UV–Vis-DRS, contact angle, EIS, transient photocurrent, mott Schottky and AFM techniques. The rod shape morphology of the samples with moderate surface roughness, desirable hydrophobicity, low bandgap and remarkable band structure alignment confirmed the applicability of as-prepared thin-film with an average photon flux of 1.94 × 10 −4 -8.61 × 10 −5 E's m −2 s −1 . The use of a rotating catalytic disc impressively declined the photon propagation distance, decremented the probability of light absorption by the solution, and intensified the mass transfer rate. The maximum throughputs of 98.8% efficiencies for CPX degradation were achieved at a rotational speed of 180 rpm, the solution flow rate of 1.0 L min −1, the light intensity of 11 mW cm −2, and initial CPX concentration of 40 mg L −1, illumination time of 80 min, and pH of 6. Damkohler number ( Da) value was found to be 1.23 × 10 −2 at the optimum conditions, indicating the negligibility of the external mass transfer resistance in the SDPR. The photocatalytic mechanism was elucidated for finding the most operative radical species, suggesting the crucial role of · O2 − in photodegradation of CPX and a drastic improvement of the charge separation by S-scheme heterostructure and facilitation by Ag mediator. Findings indicated that the developed reusable and robust SDPR benefited from an s-scheme photocatalyst can be a promising technology for degradation of the organic compounds. Graphical abstract: Image 1 Highlights: An innovative SDPR was fabricated for photocatalytic degradation of CPX under visible blue LED light. The catalyst film of WO3 /Ag/ZnO was immobilized on a ceramic disc substrate using the spray pyrolysis technique. The synthesized catalyst thin film exhibited high stability and appropriate after six cycles. The SDPR is superior and robust technology for disposal of CPX from wastewater treatment.