Photodegradation, Anti-bacterial and Self-cleaning Analysis of Surface Modified Zinc Oxide and its Composites for Environmental Remediation
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Date
2025-01
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Avinashilingam
Abstract
Globalization and industrial expansion have increased environmental pollution. Discharge of untreated dye effluents into the waterways disrupts marine ecosystem and also poses considerable risks to human health. Developing nanomaterials as absorbents is an effective alternative for removing the organic and inorganic contaminants, and also an alternative treatment for microbial disinfection. Increased surface area of the nanoparticle facilitates generation of more hydroxyl radicals which participate actively in dye degradation, but they often lead to particle aggregation, which is a significant challenge. Hence, can be reduced using suitable surface modifiers for the photocatalytic nanomaterials. In this work environmentally stable, reusable photocatalytic material was synthesized for reducing environmental degradation. Nanomaterials of ZnO, ZnO/PEG and various combinations of silane (MTMS, MTES, VTMS and VTES) were synthesized by sol-gel technique. The semiconducting metal oxide and its surface modified nanocomposites were tested for their structural, morphological, optical, antibacterial activity, and photocatalytic degradation efficiency with UV and visible light exposure. Photodegradation analysis was done for Methylene blue, Malachite green and textile dye wastewater. ZnO/PEG/VTMS exhibited better degradation efficiency than all other composites due to its reduced crystallite size and PL intensity. The composite exhibited high stability and was found to be reusable even after five cyclic degradation of textile dye wastewater. Hence, this particular sample works as an efficient photocatalyst for dye effluent treatment. All the composites exhibited better antibacterial activity against the bacterial pathogens (Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa) than the control (Teicoplanin) used. Enhanced bacterial inhibition to gram positive bacteria than gram negative bacteria were noted. Optically transparent hydrophobic thin films were fabricated using sol-gel based spin coating technique for different silane-PEG combinations. The hydrophobic films with water repellent behavior demonstrated better self-cleaning activity. Stearic acid was deposited on ZnO/PEG/Silane film and its degradation upon UV irradiation was analyzed using FTIR and water contact angle analysis. Upon exposure to UV light, reduction in the hydrophobic behavior of the surface was observed due to photo-induced catalysis, confirming degradation of stearic acid. Among all composite films, ZnO/PEG/VTMS exhibited better degradation of stearic acid. Therefore, the composites aids in reducing environmental degradation.
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Physics