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Naphthol Green B (NGB) is a synthetic azo dye widely used in various industries, including textiles and leathers. NGB poses significant environmental and ecological concerns when released into natural water systems. This paper investigates the decolorization of NGB using UV/sulfite system. The % decolorization of NGB was optimized using 3 2 Full Factorial Design (FFD), and the ANOVA results show that the model has a good fit for the data (R 2 = 99.54 %, R 2 (adj) = 98.76 %) and the significant factors contributing to the % decolorization are A, B, A 2 , and B 2 where A = mM sulfite and B = pH. The model predicted ≥100 % decolorization with the optimum conditions 12 mM sulfite and pH 10. An actual experiment was conducted to verify the response, resulting in 96.2 % decolorization which is in good agreement with the model., (© 2024 The Author(s).)

Fe 2 O 3 /TiO 2 nanocomposites were fabricated via a facile impregnation/calcination technique employing different amounts iron (III) nitrate onto commercial TiO 2 (P25 Aeroxide). The as-prepared Fe 2 O 3 /TiO 2 nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDXS), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis (BET), electron impedance spectroscopy (EIS), photoluminescence spectroscopy (PL), and diffuse reflectance spectroscopy (DRS). As a result, 5% ( w/w ) Fe 2 O 3 /TiO 2 achieved the highest photocatalytic activity in the slurry system and was successfully immobilized on glass support. Photocatalytic activity under visible-light irradiation was assessed by treating pharmaceutical amoxicillin (AMX) in the presence and absence of additional oxidants: hydrogen peroxide (H 2 O 2 ) and persulfate salts (PS). The influence of pH and PS concentration on AMX conversion rate was established by means of statistical planning and response surface modeling. Results revealed optimum conditions of [S 2 O 8 2- ] = 1.873 mM and pH = 4.808; these were also utilized in presence of H 2 O 2 instead of PS in long-term tests. The fastest AMX conversion possessing a zero-order rate constant of 1.51 × 10 -7 M·min -1 was achieved with the photocatalysis + PS system. The AMX conversion pathway was established, and the evolution/conversion of formed intermediates was correlated with the changes in toxicity toward Vibrio fischeri . Reactive oxygen species (ROS) scavenging was also utilized to investigate the AMX conversion mechanism, revealing the major contribution of photogenerated h + in all processes.

The upsurge of antibiotic usage in the 20th century has resulted in increasing levels of pharmaceutical compounds in bodies of water. A particular antibiotic, levofloxacin, is a third-generation quinolone known to target Gram-positive organisms like atypical pathogens. Chronic toxic effects of levofloxacin to some microorganisms lead to the disruption of marine ecosystems. Unfortunately, a relatively low concentration of levofloxacin in water bodies discourages researchers from exploring potential risk assessment and removal in wastewater treatment plants. In this article, aqueous levofloxacin was degraded using hydroxyapatite catalyst under UV-irradiation. Response Surface Methodology (Box Behnken Model) was used to model and optimize the degradation efficiency parameter. The response was fitted into a 2-factor interaction equation revealing a satisfactory ANOVA evaluation (R 2 =97.08%, adjusted R 2 = 94.89, predicted R 2 =91.1%). An optimal photodegradation efficiency was determined to attain the following conditions: 1.5 g/L catalyst dose, 4 ppm levofloxacin, and a pH level of 10. The model predicted a value of 71.6% degradation efficiency, which is very close to 70.6% generated experimentally., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)

Clean water and the increased use of renewable energy are considered to be two of the main goals in the effort to achieve a sustainable living environment. The fulfillment of these goals may include the use of solar-driven photocatalytic processes that are found to be quite effective in water purification, as well as hydrogen generation. H 2 production by water splitting and photocatalytic degradation of organic pollutants in water both rely on the formation of electron/hole (e - /h + ) pairs at a semiconducting material upon its excitation by light with sufficient photon energy. Most of the photocatalytic studies involve the use of TiO 2 and well-suited model compounds, either as sacrificial agents or pollutants. However, the wider application of this technology requires the harvesting of a broader spectrum of solar irradiation and the suppression of the recombination of photogenerated charge carriers. These limitations can be overcome by the use of different strategies, among which the focus is put on the creation of heterojunctions with another narrow bandgap semiconductor, which can provide high response in the visible light region. In this review paper, we report the most recent advances in the application of TiO 2 based heterojunction (semiconductor-semiconductor) composites for photocatalytic water treatment and water splitting. This review article is subdivided into two major parts, namely Photocatalytic water treatment and Photocatalytic water splitting, to give a thorough examination of all achieved progress. The first part provides an overview on photocatalytic degradation mechanism principles, followed by the most recent applications for photocatalytic degradation and mineralization of contaminants of emerging concern (CEC), such as pharmaceuticals and pesticides with a critical insight into removal mechanism, while the second part focuses on fabrication of TiO 2 -based heterojunctions with carbon-based materials, transition metal oxides, transition metal chalcogenides, and multiple composites that were made of three or more semiconductor materials for photocatalytic water splitting., Competing Interests: The authors declare no conflict of interest.