Efficient Removal of Methylene Blue and Ciprofloxacin from Aqueous Solution Using Flower-like, Nanostructured ZnO Coating under UV Irradiation

• Published in: Nanomaterials (Basel, Switzerland) Vol. 12; no. 13; p. 2193
• Main Authors: Tiron, Vasile, Ciolan, Mihai Alexandru, Bulai, Georgiana, Mihalache, Gabriela, Lipsa, Florin Daniel, Jijie, Roxana
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 26.06.2022; MDPI
• Subjects: Antibiotics; Aqueous solutions; Bacteria; Biodegradation; Catalytic activity; Chemical properties; Ciprofloxacin; Coating processes; Coatings; Contaminants; Coupled modes; Direct current; Dyes; Electron microscopy; flower-like architectures; Flowers; Gram-negative bacteria; Gram-positive bacteria; Irradiation; Methods; Methylene blue; Morphology; Nanorods; Nanostructure; Nanostructured materials; Nanotechnology; Oxidation; Photocatalysis; Photodegradation; Photoluminescence; Photons; Plasma; Pollutant removal; Spectroscopy; Synthesis; Thermionic Vacuum Arc; Thin films; Ultraviolet radiation; Zinc oxide; Zinc oxides; zinc-oxide coating; Romania
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano12132193

Flower-like ZnO architectures assembled with many nanorods were successfully synthesized through Thermionic Vacuum Arc, operated both in direct current (DC-TVA) and a pulsed mode (PTVA), and coupled with annealing in an oxygen atmosphere. The prepared coatings were analysed by scanning-electron microscopy with energy-dispersive X-ray-spectroscopy (SEM-EDX), X-ray-diffraction (XRD), and photoluminescence (PL) measurements. By simply modifying the TVA operation mode, the morphology and uniformity of ZnO nanorods can be tuned. The photocatalytic performance of synthesized nanostructured ZnO coatings was measured by the degradation of methylene-blue (MB) dye and ciprofloxacin (Cipro) antibiotic. The ZnO (PTVA) showed enhancing results regarding the photodegradation of target contaminants. About 96% of MB molecules were removed within 60 min of UV irradiation, with a rate constant of 0.058 min−1, which is almost nine times higher than the value of ZnO (DC-TVA). As well, ZnO (PTVA) presented superior photocatalytic activity towards the decomposition of Cipro, after 240 min of irradiation, yielding 96% degradation efficiency. Moreover, the agar-well diffusion assay performance against both Gram-positive and Gram-negative bacteria confirms the degradation of antibiotic molecules by the UV/ZnO (PTVA) approach, without the formation of secondary hazardous products during the photocatalysis process. Repeated cyclic usage of coatings revealed excellent reusability and operational stability.