In this research, an emerging, non-metallic photocatalyst was prepared by the thermal polymerization method from three different precursors: urea, melamine, and three mixtures of melamine and cyanuric acid. Graphitic carbon nitride (g-C₃N₄) samples from urea and melamine were synthesized in a muffle furnace at three different temperatures: 450°, 500°, and 550 °C for 2 h, while the samples made of a mixture of melamine and cyanuric acid (with mass ratios of 1:1, 1:2, and 2:1) were synthesized at 550 °C for 2 h. All the samples were characterized in order to determine their chemical and physical properties, such as crystallite size and structure, and phase composition by the following techniques: Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). Nitrogen adsorption/desorption isotherms were used to investigate the Brunauer, Emmett, and Teller (BET) specific surface area and Barrett–Joyner–Halenda (BJH) pore size distribution. Band gap values were determined by diffuse reflectance spectroscopy (DRS). Furthermore, adsorption and photocatalytic degradation of the local anesthetic drug procaine were monitored under UV-A, visible, and simulated solar irradiation in a batch reactor. Kinetic parameters, as well as photocatalytic mechanisms using scavengers, were determined and analyzed. The results of the photocatalysis experiments were compared to the benchmark TiO₂ Evonik Aeroxide P25. The results indicated that the g-C₃N₄ sample synthesized from urea at 500 °C for 2 h exhibited the highest degradation rate of procaine under visible light.

In this study, the optimal microwave-assisted sol-gel synthesis parameters for achieving TiO₂ nanoparticles with the highest specific surface area and photocatalytic activity were determined. Titanium isopropoxide was used as a precursor to prepare the sol (colloidal solution) of TiO₂. Isopropanol was used as a solvent; acetylacetone was used as a complexation moderator; and nitric acid was used as a catalyst. Four samples of titanium dioxide were synthesized from the prepared colloidal solution in a microwave reactor at a temperature of 150 °C for 30 min and at a temperature of 200 °C for 10, 20, and 30 min. The phase composition of the TiO₂ samples was determined by X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Nitrogen adsorption/desorption isotherms were used to determine the specific surface area and pore size distributions using the Brunauer–Emmett–Teller (BET) method. The band-gap energy values of the TiO₂ samples were determined by diffuse reflectance spectroscopy (DRS). The distribution of Ti and O in the TiO₂ samples was determined by SEM-EDS analysis. The effects of adsorption and photocatalytic activity of the prepared TiO₂ samples were evaluated by the degradation of ciprofloxacin (CIP) as an emerging organic pollutant (EOP) under UV-A light (365 nm). The results of the photocatalytic activity of the synthesized TiO₂ nanoparticles were compared to the benchmark Degussa P25 TiO₂. Kinetic parameters of adsorption and photocatalysis were determined and analyzed. It was found that crystalline TiO₂ nanoparticles with the highest specific surface area, the lowest energy band gap, and the highest photocatalytic degradation were the samples synthesized at 200 °C for 10 min. The results indicate that CIP degradation by all TiO₂ samples prepared at 200 °C show a synergistic effect of adsorption and photocatalytic degradation in the removal process.

In this study, nanostructured cerium-doped TiO₂ (Ce-TiO₂) films with the addition of different amounts of cerium (0.00, 0.08, 0.40, 0.80, 2.40, and 4.10 wt.%) were deposited on a borosilicate glass substrate by the flow coating sol-gel process. After flow coating, the deposited films were dried at a temperature of 100 °C for 1 h, followed by calcination at a temperature of 450 °C for 2 h. For the characterization of sol-gel TiO₂ films, the following analytic techniques were used: X-ray diffraction (XRD), differential thermal analysis (DTA), thermal gravimetry (TG), differential scanning calorimetry (DSC), diffuse reflectance spectroscopy (DRS), and energy dispersive X-ray spectroscopy (EDS). Sol-gel-derived Ce-TiO₂ films were used for photocatalytic degradation of ciprofloxacin (CIP). The influence of the amount of Ce in TiO₂ films, the duration of the photocatalytic decomposition, and the irradiation type (UV-A and simulated solar light) on the CIP degradation were monitored. Kinetics parameters (reaction kinetics constants and the half-life) of the CIP degradation, as well as photocatalytic degradation efficiency, were determined. The best photocatalytic activity was achieved by the TiO₂ film doped with 0.08 wt.% Ce, under both UV-A and solar irradiation. The immobilized catalyst was successfully reused for three cycles under solar light simulator radiation, with changes in photocatalytic efficiency below 3%.

This study investigates a sustainable approach to the photocatalytic degradation of Congo red (CR) dye using titanium dioxide (TiO₂) under simulated solar radiation, with a specific focus on the UV-A component of the radiation. The aim was to optimize reaction conditions to maximize dye removal efficiency while promoting environmentally friendly wastewater treatment practices. A central composite design (CCD) was implemented, and results were analyzed using analysis of variance (ANOVA). The key factors examined included TiO₂ concentration, UV-A radiation intensity, CR dye concentration, and suspension depth. The optimal conditions determined were 222.37 mg/L TiO₂, 20 W/m² UV-A irradiation, 25 µmol/L CR dye concentration, and a suspension depth of 29 mm. Under these conditions, decolorization was achieved with the lowest absorbance (0.367 at 498 nm) and total organic carbon (0.805 mg/L) values, indicating effective dye degradation. The findings confirm that TiO₂-assisted photocatalysis is a green and promising method for wastewater treatment. The potential use of natural solar radiation could reduce operational costs, making the process more sustainable. However, challenges such as photocatalyst recovery, aggregation, and the impact of the real wastewater matrices need further investigation.

In this study, nanostructured cerium-doped TiO2 (Ce-TiO2) films with the addition of different amounts of cerium (0.00, 0.08, 0.40, 0.80, 2.40, and 4.10 wt. %) were deposited on a borosilicate glass substrate, by flow coating sol-gel process. After flow coating, deposited films were dried at the temperature of 100 °C for 1 h, followed by calcination at the temperature of 450 °C for 2 h. For the characterization of sol-gel TiO2 films, the following analytic techniques were used: X-ray diffraction (XRD), thermal gravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Sol-gel derived Ce-TiO2 films were used for photocatalytic degrada-tion of the ciprofloxacin (CIP). The influence of the amount of Ce in TiO2 films, the duration of the photocatalytic decomposition, and the irradiation type (UV-A and simulated solar light) on the CIP degradation were monitored. Kinetics parameters (reaction kinetics constants and the half-life) of the CIP degradation, as well as photocatalytic degradation efficiency, were determined. The best photocatalytic activity was achieved by the TiO2 film doped with 0.08 wt.% Ce, under both UV-A, and solar irradiation.

The goal of this research is to determine the optimal microwave-assisted sol-gel synthesis pa-rameters of TiO2 nanoparticles with the achievement of the crystalline TiO2 nanoparticles with the highest specific surface area and the lowest energy band gap. Titanium isopropoxide was used as a precursor to prepare the sol (colloidal solution) of TiO2, isopropanol as a solvent, acetylacetone for complexation, and nitric acid as a catalyst. Four samples of titanium dioxide were synthesized from the prepared colloidal solution in a microwave reactor at a temperature of 150 °C for 30 minutes and at a temperature of 200 °C for 10, 20, and 30 minutes. The phase composition of the prepared samples was determined by X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Nitrogen adsorption/desorption isotherms were used to determine the spe-cific surface area and pore size distributions by Brunauer-Emmett-Teller (BET) method. The band gap energy values of the TiO2 samples were determined by diffuse reflectance spectroscopy (DRS). CrystallineTiO2 nanoparticles with the highest specific surface area and the lowest energy band gap were obtained for the TiO2 sample synthesized at 200 °C for 10 minutes.