Improving the photocatalytic efficiency of coatings created by plasma electrolytic oxidation in copper-containing electrolyte on pure titanium.

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Improving the photocatalytic efficiency of coatings created by plasma electrolytic oxidation in copper-containing electrolyte on pure titanium.

ارائه دهنده: Provider: Alireza Saberyoun

اساتید راهنما: Supervisors: Arash Fattah-alhossieni

اساتید مشاور: Advisory Professors: Minoo Karbasi

اساتید ممتحن یا داور: Examining professors or referees: Hamid Esfehani- Omid Imantalab

زمان و تاریخ ارائه: Time and date of presentation: 5/02/2024

مکان ارائه: Place of presentation: Mavad Department in class 10

چکیده: Abstract: In the current research, the plasma electrolytic oxidation (PEO) coatings applied on the titanium substrate under the conditions of different current densities, sodium phosphate concentrations and addition of copper sulfate salt to the base electrolyte for the photocatalytic degradation of the colored pollutant methylene blue under visible light Were examined. Due to the important effect of current density on the voltage-time diagram, microstructure and photocatalytic behavior of the coatings, therefore, by examining different current densities (6, 12 and 18) ampere per square meter, the current density of 12 ampere per square meter The square decimeter with better photocatalytic activity was chosen as the optimal value. Then, the coatings were applied in the conditions of 10 minutes, current density of amperes per square meter, duty cycle of 80% and frequency of 1000 Hz. Photocatalytic behavior of different concentrations of sodium phosphate (10.5 and 15) grams per liter as The basic electrolyte was investigated, and the reason for this was due to the reaction of potassium hydroxide with copper sulfate, which resulted in a new compound in the electrolyte, which made the basic electrolyte unstable and the color of the solution changed to dark green, so potassium hydroxide was removed from the electrolyte and the electrolyte The base containing sodium phosphate was investigated in order to optimize its concentration. Finally, the photocatalytic behavior of coatings containing copper sulfate additive salt in different concentrations of 2, 4, and 6 grams in different concentrations of sodium phosphate based on optical spectroscopy, visible- Ultraviolet showed that the optimal sample containing 5 grams of sodium phosphate with 4 grams of copper sulfate addition salt showed the best photocatalytic behavior with 77% degradation of methylene blue pollutant with a rate constant equal to 3.8×10-3 min-1. The reason for this can be attributed to the high percentage of porosity with the surface of homogeneous holes, more hydrophilic surface, high contamination of copper ions in the titanium dioxide network. Characterization of the coatings applied in the PEO process by various analyzes such as X-ray diffraction (XRD), X-ray energy diffraction spectroscopy (EDS), scanning electron microscopy (SEM), wettability, Mott-Schottky spectroscopy test, photoluminescence spectroscopy (PL) and Diffuse reflectance spectroscopy (DRS) was performed. The existence of a new TiP2O7 photocatalytic phase, along with the increase of the rutile phase and the impurity of copper ions in the titania network, which cause the creation of oxygen vacancies, which in this direction leads to a higher photocatalytic activity by preventing the rapid recombination of electron-holes and the separation of charge carriers. compared to the pure TiO2 sample. Finally, the optimal coating photocatalytic test (5 grams of sodium phosphate and 4 grams of copper sulfate) with the presence of the oxidant peroxymonosulfate (PMS) in different concentrations and also other oxidants such as peroxydisulfate (PDS) and hydrogen peroxide. H2O2) under visible light in order to accelerate and improve the photocatalytic behavior for the degradation of methylene blue pollutant. The optimal sample, since it is considered as a catalyst and photocatalyst for the activation of oxidants, it was observed in the conducted investigations that the activation of PMS oxidant by creating two sulfate and hydroxyl radicals compared to The other two oxidants led to a high and fast degradation of methylene blue by about 100%. Keywords: plasma electrolytic oxidation (PEO) - copper sulfate salt - photocatalyst - methylene blue - titanium dioxide - oxygen vacancy

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