This study investigates the modeling and optimization of sunlight-driven photodegradation of methyl orange using a sustainable TiO2/SiO2 composite incorporating green-synthesized Fe2O3 nanoparticles prepared with Salvia officinalis extract. The photocatalytic efficiency was assessed under solar irradiation, highlighting the eco-friendly, energy-efficient design of the process. A sequential Design of Experiments strategy was employed: a Plackett-Burman design identified initial dye concentration, pH, and NaCl concentration as key operational parameters, followed by a Box-Behnken design with Response Surface Methodology for modeling and optimization. Under optimized conditions (35 mg/L dye, pH 2.8, 2 mol/L NaCl), complete degradation (100%) was achieved. The photocatalyst exhibited excellent stability and reusability over five cycles, with efficiency decreasing only slightly from 99.1% to 90.2%, primarily due to surface fouling. These findings demonstrate the robustness and strong potential of this green nanocomposite for sustainable, sunlight-driven wastewater treatment.

Water compartments that contain emerging contaminants, like antibiotics provide serious problems to human health and environment. Advanced oxidation process especially photo-Fenton process was employed for the degradation and mineralization of Metronidazole (MNZ). Individual and interaction effects between considered parameters: concentration of Fe2+, concentration of hydrogen peroxide (H2O2) and initial solution pH, were assessed through a Box-Behnken design. The optimal degradation of MNZ reached (94.10%) with a solution pH of 3.5, an initial concentration of [MNZ] of 50mgL-1, as well as 13mgL-1 of [Fe2+], and 200mgL-1 of [H2O2]. Under the same optimal parameter’s mineralization of MNZ reached 91.13% after four hours of treatment. The intermediates produced in the photo-Fenton process were examined through Direct Infusion-High Resolution Mass Spectrometry (DI-HRMS) following QuEChERS-based Dispersive Solid-Phase Extraction (d-SPE) and pre-concentration techniques. This approach helped in the identification of MNZ and its degradation by-products at low levels, allowing for the proposal of a possible degradation mechanism.

In this work, a comprehensive machine learning (ML) methodology was used to predict the degradation efficiency of different stannate and hydroxystannate photocatalysts on a wide range of waterborne pollutants. The structural, atomic features along with molecular fingerprints (MF) were used as descriptors of the crystalline phase of the photocatalysts and the organic compounds, respectively. The encoded features of the photocatalysts and contaminants along with the experimental variables of the degradation process are input to two ML models, named as RF (random forest) and KNN (K nearest neighbor). The RF model has achieved a very good prediction of the photocatalytic degradation efficiency (%) by different photocatalysts over a wide range of organic contaminants. The RF model performance was investigated by applying two different training strategies. The effects of different factors on photocatalytic degradation performance are further evaluated by feature importance analyses. Two illustrative applications on the use of the ML model for optimal photocatalyst selection and for assessing other types of photocatalysts for different environmental applications were provided.

The development of efficient and sustainable photocatalysts is a pressing priority for the remediation of persistent organic pollutants. In this study, pure cerium oxide (CeO2) nanoparticles were synthesized via a simple, scalable, and calcination-free self-combustion method and thoroughly extensively characterized. The resulting CeO2 exhibited a nanoscale crystallite size of 17.3 nm, a high specific surface area of 46.3 m2 g-1, and a narrowed band gap of 2.72 eV, along with abundant oxygen vacancies and reversible Ce3+/Ce4+ redox pairs. These features endowed the material with multifunctional properties, simultaneously acting as an efficient photocatalyst and an antioxidant. Under irradiation, the CeO2 nanoparticles demonstrated remarkable photocatalytic efficiencies: Methyl Red was degraded by 62 % (UV) and 70 % (visible light) within 150 min, while Nitrobenzene removal reached 73.3 % (visible LED) and 90 % (natural sunlight) within 180 min. The corresponding first-order rate constants were 0.00697, 0.00623, 0.00698, and 0.01035 min- 1, respectively. The catalyst maintained appreciable stability, with degradation efficiencies remaining above 49 % for Methyl Red and 61 % for Nitrobenzene after four and five reuse cycles, respectively. In addition, the nanoparticles exhibited strong antioxidant activity, with 80 % DPPH radical scavenging at 5 mg mL- 1 and an IC50 value of 2.24 mg mL-1. These findings demonstrate that self-combustion-synthesized CeO2 is a multifunctional catalyst with excellent photocatalytic and antioxidant performance, offering a cost-effective and eco-friendly route for wastewater treatment and broader environmental applications.

The BaBiO3 (BBO) perovskite oxide was prepared via a sol-gel method with different concentrations of Bi nitrate and examined as a photocatalyst for RhB degradation under sunlight, and its antioxidant and antibacterial activities were examined. X-ray diffraction (XRD) indicated the formation of a BaBiO3-BaCO3 (BBO-BCO) binary composite. For the degradation of RhB under solar radiation, high photocatalytic activity (73%) was observed. According to the antibacterial activity study, the addition of Bi enhanced the antibacterial activity of the resulting material against both Gram-positive and Gram-negative microorganisms. The Bi%-BBO (Bi 20%) inhibited 96.23% S. aureus. 10% Bi-BBO as an antioxidant agent had the most efficacious IC50 value of 2.50 mg mL(-1). These results seem to suggest that BBO-BCO is a promising catalytic material with potential application in the fields of catalysis and medicine.

A novel binary composite CeO2-CuO has been synthesized via self-combustion method employing cerium and copper nitrates, and glycine as fuel, and was investigated as photocatalyst to test the photodegradation of Rhodamine B (RhB) dye with visible light. The nanocomposite has been characterized by thermogravimetric analysis (TGA) to establish the temperature of calcination, X-ray diffraction (XRD) structural and morphologic analysis, scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which enables the chemical characterization/elemental analysis of materials, the photoluminescence (PL), UV-Vis Diffuse reflectance spectroscopy (UV-Vis DRS), measurement of specific surface (SBET ) by N-2 adsorption and temperature programmed reduction (TPR) analysis. The XRD diffractogram shows that the composite is majorly composed of 65.2% CeO2 and 34.8 % CuO. The nanoscaled-tested samples have an average particle size of 40 to 65 nm. The energy gap of the material as synthesized was 2.05 eV. The TPR curves show 2 peaks of hydrogen consumption in the sample, corresponding to the decrease (reduction) of CuO particles caused by their interaction with CeO2.The results of the photocatalytic tests show 28% conversion in the photodegradation of RhB organic pollutant during 180 min under visible light. The CeO2- CuO material could be reused for treatment of wastewater during several cycles, which demonstrates its stability for the process.

In this work, we describe a straightforward modified sol gel approach for producing zinc stannate-tin oxide (ZnSnO 3 -SnO 2 ) nanocomposite particles by combining tin chloride and zinc acetate using EDTA ammonium salt as an electrosteric inhibition agent. The acquired samples were characterized using simultaneous thermal gravimetric and differential scanning calorimetry (TGA/DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV -Vis spectroscopy and scanning electron microscopy (SEM). The catalyst activity of ZnSnO 3 -SnO 2 particles in hydrogen production was determined by the methanolysis reaction from NaBH 4 . The hydrogen generation rate TOF (Turnover Frequency) The hydrogen generation rate, activation energy (E a ), enthalpy ( Delta H) and entropy ( Delta S) values of the hydrogen production reaction were calculated as 374.11 ml min -1 . g - 1 (832.38 h -1 ), 43.19 kJ mol -1 , 40.65 kJ mol -1 and -178.96 J/mol.K, respectively. The prepared ZnSnO 3 -SnO 2 composite can be recycled and used without obvious loss of activity; This makes the procedure economical and environmentally friendly.

LaNiO3 nanopowders are synthesized by sol–gel and sol-gel combustion methods using citric acid, ascorbic acid and sucrose as chelating agents, and ethanol and water as solvents. The precursor thermal decomposition towards the final solid was analyzed by X-ray diffraction, differential thermal analysis and thermogravimetric techniques which were also used to provide the adequate temperature of calcination (800and#176;C) for achievement of the final perovskite. After calcination, the nanocomposites were characterized by powder size distribution, Fourier transform infrared spectroscopy and X-ray diffraction.

Lanthanum manganite (LaMnO3) partially substituted with Sr in the site A (0 <= x <= 0.2) were prepared by different synthesis methods (sol-gel, sol-gel combustion and auto-combustion) using citric acid or glycine as complexant or fuels and water as solvent. Thermogravimefric analysis technique (TGA) was used to explore precursor decomposition and to establish adequate calcination temperature for achievement of the perovskite structure in the nanoparticles. The samples obtained after calcination at 800 degrees C were characterized by XRD, FTIR, PSD, and UV-Vis. Structural and vibration/electronic characteristics were examined on such basis and as a function of the preparation method employed.

Lanthanum manganite (LaMnO3) partially substituted with Sr in the site A (0 ≤ x ≤0.2) were prepared by different synthesis methods (sol-gel, sol-gel combustion and auto-combustion) using citric acid or glycine as complexant or fuels and water as solvent. Thermogravimetric analysis technique (TGA) was used to explore precursor decomposition and to establish adequate calcination temperature for achievement of the perovskite structure in the nanoparticles. The samples obtained after calcination at 800°C were characterized by XRD, FTIR, PSD, and UV-Vis. Structural and vibration/electronic characteristics were examined on such basis and as a function of the preparation method employed.

Nanocomposite structures involving LaNiO3 perovskite partially substituted with iron and segregated NiO are synthesized by sol–gel method using citric acid as chelating agent. Thermogravimetric and differential thermal analysis and X-ray diffraction (XRD) techniques are used to explore precursor decomposition and to establish adequate calcination temperature for the preparation of the nanocomposites. The samples obtained after calcination at 750 °C were characterized by XRD, X-ray photoelectronic spectroscopy, Brunauer–Emmett–Teller surface area analysis, Fourier transform infrared spectroscopy and powder size distribution, and tested for the catalytic oxidation reaction of CO. Optimum catalytic properties are shown to be achieved for nanocomposites with relatively weak Fe/Ni substitution degree in the perovskite interacting with well-dispersed small NiO entities.