Evaluation of the Photocatalytic Behavior of Visible-Light-Active BaTiO3-Based Coatings Fabricated on Titanium Substrate

نوع: Type: Thesis

مقطع: Segment: masters

عنوان: Title: Evaluation of the Photocatalytic Behavior of Visible-Light-Active BaTiO3-Based Coatings Fabricated on Titanium Substrate

ارائه دهنده: Provider: setareh bahadori

اساتید راهنما: Supervisors: Dr Minoo Karbasi

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr Mohsen Sheilhi and Dr Hamid Esfehani

زمان و تاریخ ارائه: Time and date of presentation: 2026

مکان ارائه: Place of presentation: سالن کنفرانس

چکیده: Abstract: Abstract: The development of visible-light-active photocatalytic coatings for the removal of persistent pharmaceutical pollutants from wastewater has attracted considerable attention in the fields of surface engineering and materials science. The aim of this study was to design, fabricate, and evaluate the photocatalytic performance of barium titanate coatings produced on Ti substrates by plasma electrolytic oxidation (PEO) for the degradation of tetracycline under visible-light irradiation. First, the effects of key processing parameters, including the applied voltage (250, 300, and 350 V) and the concentration of the barium hydroxide precursor in the electrolyte (10, 20, and 30 g/L), on the visual appearance, current–voltage behavior, surface microstructure, and phase composition of the fabricated coatings were investigated. The results demonstrated that variations in each of these parameters had a significant effect on the formation of the barium titanate phase, surface morphology, and photocatalytic performance of the coatings. Following characterization, the coating fabricated at 300 V using a barium hydroxide concentration of 20 g/L exhibited the best photocatalytic performance while also confirming the formation of the barium titanate phase. Subsequently, to optimize the photocatalytic process conditions, the effect of solution pH on the tetracycline degradation efficiency was investigated based on an analysis of the surface charge of the coating through determination of the point of zero charge and consideration of the electrical charge of the pollutant molecule at different pH values. In addition, the effect of the initial pollutant concentration on the photocatalytic degradation kinetics was examined, and an appropriate reference concentration was selected for subsequent experiments. To elucidate the mechanism governing the photocatalytic process, scavenging experiments were conducted using ascorbic acid, isopropanol, and chloroform as scavengers to determine the relative contributions of photogenerated holes, hydroxyl radicals, and superoxide radicals to tetracycline degradation. Furthermore, the electronic properties of the optimized coating were investigated using Mott–Schottky analysis and diffuse reflectance spectroscopy to determine the semiconductor conductivity type, energy-band positions, and band-gap energy of the coating. Finally, the photocatalytic performance index of the optimized coating was compared with those reported in similar studies. The results confirmed the superior performance of the present coating compared with powdered photocatalytic systems and other coatings fabricated by plasma electrolytic oxidation. Overall, the findings demonstrate that BaTiO3 coatings produced by PEO, through the simultaneous optimization of processing parameters and reaction conditions, have significant potential for the photocatalytic removal of persistent pharmaceutical pollutants from wastewater under visible-light irradiation.

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