In the present work, phenol was used as a model molecule to the photocatalytic evaluation of TiO₂ impregnated with iron sulphide and chlorine on a visible-light reactor. The iron–chlorine catalyst was prepared by incipient impregnation with the metal precursors, Fe (NO₃)₃ and NaCl on previously calcined TiO₂. The catalyst was sulphurized with H2S at 300 °C for 1 h. The catalysts were prepared at different chlorine concentrations using HYDRA chemical equilibrium diagrams to obtain different fractions of FeCl⁺. The oxide catalysts were characterized with diffuse reflectance (DRS UV–Vis) and temperature programmed reduction analysis (TPR). Sulphurized catalysts were characterized with Raman spectrometry and X-ray photoelectron spectrometry (XPS). The FeS–2Cl/TiO₂ catalyst presented 8.35 times higher photodegradation than TiO₂ and 6.4 times higher compared to the FeS–0.25Cl/TiO₂ catalyst. DRS and XPS showed similar results of band gap, proving that the catalyst remain stable after sulphurisation. The TPR results of FeS–2Cl/TiO₂ showed an increment of 86.29% in Fe²⁺/Fe³⁺ compared to FeS–0.25Cl/TiO₂. XPS and Raman results for oxide and sulphated iron species relation suggested that FeS–2Cl/TiO₂ decreased 4.45% compared to FeS–0.25Cl/TiO₂ catalyst. XPS semiquantitative for S/Fe results showed that the FeS–2Cl/TiO₂ catalyst increased 73.17% in comparison to FeS–0.25Cl/TiO₂. These results suggested the increment of sulphurisation degree for FeS–2Cl/TiO₂. In this regard, the catalyst characterization results showed that the presence of FeCl⁺ (0.85 fractions) in solution before impregnation promoted the active sulphide species maintaining the band gap and improved the degradation of phenol on visible light.

Gallic acid (GA), a polyphenol extensively used in the food, wine, and pharmaceutical industries, is known for its inhibitory effects on soil microbial activity. Photocatalytic degradation offers an environmentally friendly solution for GA removal from water. In this work, graphitic carbon nitride (g-C₃N₄) photocatalysts were synthesized by two methods: thermal exfoliation (CN-E) and supramolecular assembly via hydrothermal processing (HCN-II). Structural analyses by XRD, FTIR, and XPS confirmed the formation of the g-C₃N₄ framework, while SEM revealed that CN-E consisted of folded and curled nanosheets, whereas HCN-II displayed a polyhedral–nanosheet hybrid architecture with internal channels. Both materials achieved approximately 80% GA degradation within 180 min under visible-light irradiation, yet HCN-II exhibited a superior apparent rate constant (k = 0.01156 min⁻¹) compared with CN-E. Radical trapping experiments demonstrated that O₂•⁻ and h⁺ were the primary reactive oxygen species involved, with OH• making a minor contribution. The enhanced performance of HCN-II is attributed to its higher surface area, improved light harvesting, and efficient charge separation derived from supramolecular assembly. These findings highlight the potential of engineered g-C₃N₄ nanostructures as efficient, metal-free photocatalysts for the degradation of recalcitrant organic pollutants in water treatment applications.

Wireless sensor networks have recently been used to monitor bioelectric signals generated by the human body. However, since the dimensions and capabilities of the network nodes are small and limited, a problem is generated inherently by the energy consumption and radioelectric interference. In view of this, we propose two priority schemes to improve the performance of the network. In the first one, we aim at increasing the system lifetime by reducing the number of transmissions of nodes with low energy levels. In the second scheme, we aim at conveying priority data to the sink node as fast and efficient as possible. In the former scheme, users can be monitored for long time periods considering a low data generation. On the other hand, the latter scheme allows expediting transmission of important data when energy efficiency is not relevant. In this article, we mathematically model, analyze, and study the performance of the system for both priority schemes considering cognitive radio capabilities to make efficient use of resources and limit the radioelectric interference when the network transmits both continuous monitoring and event detection information. Numerical results provided in this work allow a careful parameter selection for practical implementation of BANETs.

Water contamination has become a global concern, and the prevalence of complex substances known as emerging contaminants constitute a risk to human health and the environment. This work focused on an innovative approach of integrating sonolysis and photocatalysis to remove a standard textile dye efficiently. A highly photo-active, bismuth ferrite (BiFeO₃) nanocatalyst with single particle sizes between 86 and 265 nm was obtained by a novel one-pot combustion method using a deep eutectic solvent as a precursor. The said catalyst was thoroughly characterized and evaluated for photocatalytic and sono-photocatalytic degradation of rhodamine B (RhB). Photocatalytic experiments were conducted under visible light irradiation (450–600 nm). Sono-photocatalytic (SPC) experiments were conducted, focusing on the influence of operational parameters (frequency, power, and pH) on the degradation performance. High-frequency values of 578, 866, and 1138 kHz were explored to promote cavitation dynamics and reactive species generation, improving removal efficiency. Results demonstrated that when sonolysis and photocatalysis were performed separately, the degradation efficiency ranged between 85 and 87%. Remarkably, when the combined SPC degradation was carried out, the RhB removal reached about 99.9% after 70 min. It is discussed that this behavior is due to the increased generation of OH^• radicals as a product of the cavitation phenomena related to the ultrasound-assisted process. Moreover, it is argued that SPC significantly improves reaction kinetics and mass transfer rates, facilitating catalyst dispersion and contact with the RhB molecules. Finally, the stability of the catalyst was evaluated in five repeated RhB removal cycles, where the activity remained consistently strong.