Coupling TiO₂ with various elements could enhance its photocatalytic activity. In this study, an innovative ultrasound-assisted sol–gel method was used to synthesize TiO₂/Ag(x%) by varying Ag–support mass (x = 9.3, 17.1, and 23.6%), followed by calcination at 450 °C for 30 min. The aim was to demonstrate that Ag compositing improves photoactivity under visible light (>400 nm). The synthesized photocatalysts were assessed for their effectiveness in the degradation and mineralization of Methylene Blue (MB) and Acid Orange 7 (AO7) using visible lamps emitting in the range of 400–800 nm. Characterization of the prepared photocatalysts was performed by using Raman spectroscopy, SEM/EDS, pH_pzc, and UV–visible spectroscopy. Raman spectroscopy confirmed the predominance of the anatase phase in all the photocatalysts. The photodegradation efficiencies of the selected dyes, MB and AO7, reached 99% (pH 6) and 95% (pH 3) after 180 min of irradiation, respectively. The best performance for the degradation of the two dyes was observed with TiO₂/Ag9.3%, showing optimal kinetics at this doping concentration. The improved photoactivity of the TiO₂/Ag composite is due to a decrease in the recombination rate of electron/hole (e⁻/h⁺) and a decrease in the band gap from 3.13 to 2.49 eV. The mineralization rate of both dyes under visible light is about 9.3%, indicating the presence of refractory by-products that resist complete degradation. Under UVA irradiation, complete mineralization is obtained. This study confirms the potential of TiO₂/Ag composite as a high-performance and cost-effective photocatalyst for solar environmental remediation, highlighting the role of silver in extending light absorption into the visible region and improving charge separation.

Metal and metal oxide nanostructured materials have been chemically and physically characterized and tested concerning methylene blue (MB) photoremoval and UV antibacterial activity against Escherichia coli and Staphylococcus aureus. In detail, silver nanoparticles and commercial BaTiO₃ nanoparticles were modified to obtain nanocomposites through sonicated sol–gel TiO₂ synthesis and the photodeposition of Ag nanoparticles, respectively. The characterization results of pristine nanomaterials and synthetized photocatalysts revealed significant differences in specific surface area (SSA), the presence of impurities in commercial Ag nanoparticles, an anatase phase with brookite traces for TiO₂-based nanomaterials, and a mixed cubic–tetragonal phase for BaTiO₃. Silver nanoparticles exhibited superior antibacterial activity at different dosages; however, they were inactive in the photoremoval of the dye. The silver–TiO_x nanocomposite demonstrated an activity in the UV photodegradation of MB and UV inhibition of bacterial growth. Specifically, TiO₂/AgNP (30–50 nm) reduced growth by 487.5 and 1.1 × 10³ times for Escherichia coli and Staphylococcus aureus, respectively, at a dose of 500 μg/mL under UV irradiation.

The increasing presence of pharmaceutical contaminants, such as paracetamol, in water sources necessitates the development of efficient and sustainable treatment technologies. This study investigates the photocatalytic degradation and mineralization of paracetamol under visible light using nickel-doped titanium dioxide (Ni–TiO2) catalysts synthesized via the sol-gel method. The catalysts were characterized through Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), and surface area measurements. Ni doping enhanced the visible light absorption of TiO2, reducing its band gap from 3.11 eV (undoped) to 2.49 eV at 0.20 wt.% Ni loading, while Raman analysis confirmed Ni incorporation with anatase as the predominant phase. The Ni(0.1%)-TiO2 catalyst exhibited the highest photocatalytic activity, achieving 88% total organic carbon (TOC) removal of paracetamol (5 ppm) after 180 min under optimal conditions (catalyst dosage, 3 g L−1). Stability tests demonstrated 84% retained efficiency over five cycles, with a kinetic rate constant of 0.010 min−1. Hydroxyl radicals were identified as the main reactive species. The catalyst maintained high performance in tap water, achieving 78.8% TOC removal. These findings highlight the potential of Ni(0.1%)-TiO2 as a cost-effective, visible light-active photocatalyst for the removal of pharmaceutical pollutants, with promising scalability for industrial water treatment applications.

This study focused on searching for more effective nanomaterials for environmental remediation and health protection; thus, coliform bacteria, yeast and the organic food dye sunset yellow were selected as target pollutants to be eliminated under solar light by Ag/Cr-TiO₂ and Pd/Cr-TiO₂. Firstly, Cr³⁺ was in situ incorporated into the anatase crystalline lattice by the sol-gel method; then, Ag or Pd nanoparticles were deposited on Cr-TiO₂ by chemical photoreduction. The scientific challenge addressed by the development of these composites was to analyse the recovery of Cr, to be employed in photocatalyst formulation and the enhancement of the TiO₂ photocatalytic activity by addition of other noble metals. By extensive characterization, it was found that after TiO₂ doping with chromium, the parameters of the crystal lattice slightly increased, due to the incorporation of Cr ions into the lattice. The TiO₂ band gap decreased after Cr addition, but an increase in the optical absorptions towards the visible region after noble metals deposition was also observed, which was dependent of the Ag or Pd loading. Generally, it was observed that the noble metals type is a factor that strongly influenced the effectiveness of the photocatalysts concerning each substrate studied. Thus, by using Ag(0.1%)/Cr-TiO₂, the complete elimination of E. coli from samples of water coming from a highly polluted river was achieved. Pd(0.5%)/Cr-TiO₂ showed the highest efficiency in the elimination of S. cerevisiae from a lab prepared strain. On the other hand, the Pd(0.1%)/Cr-TiO₂ sample shows the highest dye degradation rate, achieving 92% of TOC removal after 180 min.

This work examined the influence of UV-A light modulation on the photocatalytic process coadjuvated with H₂O₂ to mineralize phenol in an aqueous solution. A fixed-bed batch photocatalytic reactor with a flat-plate geometry, irradiated by UV-A LEDs, was employed. The successful deposition of commercial TiO₂ PC105 on a steel plate (SP) was achieved, and the structured photocatalyst was characterized using Raman spectroscopy, specific surface area (SSA) measurements, and UV–vis DRS analysis. These analyses confirmed the formation of a titania coating in the anatase phase with a bandgap energy of 3.25 eV. Various LED-dimming techniques, with both fixed and variable duty cycle values, were tested to evaluate the stability of the photocatalyst’s activity and the influence of operating parameters during the mineralization of 450 mL of a phenol solution. The optimal operating parameters were identified as an initial phenol concentration of 10 ppm, a hydrogen peroxide dosage of 0.208 g L⁻¹, and triangular variable duty cycle light modulation. Under these conditions, the highest apparent phenol degradation kinetic constant (0.39 min⁻¹) and the total mineralization were achieved. Finally, the energy consumption for mineralizing 90% phenol in one cubic meter of treated water was determined, showing the greatest energy savings with triangular light modulation.

The SARS-CoV-2 pandemic has determined a global health crisis. To control its spread, countries implemented several measures including social distancing and mask-wearing. Single-use face masks, gloves, and face shields made from various synthetic materials can significantly accumulate in the marine environment, along with other substances such as plasticizers, lubricants, and stabilizers, many of which are classified as contaminants of emerging concern (CECs). This study investigates the potential impacts of Personal Protective Equipments (PPEs) on marine environment after artificial weathering in synthetic seawater for 1, 3, and 7 days at room temperature and 50 °C. Raman spectroscopy revealed the release of polymeric additives such as plasticizers from polypropylene- and nitrile-based materials. Total Organic Carbon (TOC) and Total Carbon (TC) analyses showed a time-dependent increase in organic content, with the highest concentrations recorded in FFP2 mask leachates after 7 days. Acute toxicity assays using Artemia franciscana indicated elevated mortality in juvenile and metanauplii stages, particularly for leachates from masks. Molecular analysis further showed up- or down-regulation of defensome-related genes (e.g., hsp26, hsp60, hsp70, COXI, COXIII, NADH, ZMP) following exposure, suggesting stress responses linked to contaminant exposure. These findings provide critical insights into the environmental risks posed by PPE-derived contaminants and underscore the need for effective disposal strategies to mitigate long-term marine impacts.