Search Results (178)

Photocatalysis is considered to be a very promising method for the degradation of organic matter, because its process of degrading organic matter is safe. However, some problems such as weak absorption of visible light and electronic-hole recombination easily are obviously drawbacks. In this paper, three different morphologies of Bi₅O₇I (nanoball, nanosheet, and nanotube) were successfully prepared by solvothermal method, which was used for the degradation of Rhodamine B (RhB). Comparing the photocatalytic effect of three different morphologies and concluding that the optimal morphology was the Bi₅O₇I nanoball (97.8% RhB degradation within 100 min), which was analysed by the characterisation tests. Free radical trapping experiments were tested, which revealed that the main roles in the degradation process were singlet oxygen (¹O₂) and holes (h⁺). The degradation pathways of RhB were analyzed in detail. The photo/electrochemical parts of the three materials were analysed and explained the degradation mechanism of RhB degradation. This investigate provides a very valuable guide for the development of multiple morphologies of bismuth-based photocatalysts for removing organic dyes in aquatic environment. Full article

In this study, the degradation of Nile Blue dye was investigated using homogeneous and heterogeneous photocatalytic methods based on the photo-Fenton reaction. More specifically, for homogeneous photocatalysis, the classical photo-Fenton (UV/Fe²⁺/H₂O₂) and modified photo-Fenton-like (UV/Fe²⁺/S₂O₈²⁻) systems were studied, while for heterogeneous photocatalysis, a commercial MOF catalyst, Basolite F300, and a natural ferrous mineral, geothite, were employed. Various parameters—including the concentrations of the oxidant and catalyst, UV radiation, and pH—were investigated to determine their influence on the reaction rate. In homogeneous systems, an increase in iron concentration led to an enhanced degradation rate of the target compound. Similarly, increasing the oxidant concentration accelerated the reaction rate up to an optimal level, beyond which radical scavenging effects were observed, reducing the overall efficiency. In contrast, heterogeneous systems exhibited negligible degradation in the absence of an oxidant; however, the addition of oxidants significantly improved the process efficiency. Among the tested processes, homogeneous techniques demonstrated a superior efficiency, with the conventional photo-Fenton process achieving complete mineralization within three hours. Kinetic analysis revealed pseudo-first-order behavior, with rate constants ranging from 0.012 to 0.688 min⁻¹ and correlation coefficients (R²) consistently above 0.90, confirming the reliability of the applied model under various experimental conditions. Nevertheless, heterogeneous techniques, despite their lower degradation rates, also achieved high removal efficiencies while offering the advantage of operating at a neutral pH without the need for acidification. Full article

In this study, chromium ferrite (FeCr; CrFe₂O₄) nanoparticles supported on activated carbon (AC), obtained from agricultural olive mill solid waste, were synthesized via a simple hydrothermal process. The structural, morphological, optical, and chemical properties of the FeCr/AC composite were characterized using XRD, SEM, EDX, DRS, BET, and FTIR techniques. The FeCr/AC composite was applied as a heterogeneous photo-Fenton catalyst for the degradation of methylene blue (MB) dye in an aqueous solution under 25 W visible-light LED irradiation. Critical operational factors, such as FeCr/AC dosage, pH, MB concentration, and H₂O₂ levels, were optimized. Under optimal conditions, 97.56% of MB was removed within 120 min of visible-light exposure, following pseudo-first-order kinetics. The composite also exhibited high efficiency in degrading methyl orange dye (95%) and tetracycline antibiotic (88%) within 180 min, with corresponding first-order rate constants of 0.0225 min⁻¹ and 0.0115 min⁻¹, respectively. This study highlights the potential of FeCr/AC for treating water contaminated with dyes and pharmaceuticals, in line with the Sustainable Development Goals (SDGs) for water purification. Full article

Free-standing copper oxide (Cu₂O)-copper hydroxide (Cu(OH)₂) nanocomposites with enhanced catalytic and antibacterial functionalities were synthesized on copper mesh using a green method based on spinach leaf extract and glycerol. EDX, SEM, and TEM analyses confirmed the chemical composition and morphology. The resulting Cu2O-Cu(OH)₂@Cu mesh exhibited notable hydrophobicity, achieving a contact angle of 137.5° ± 0.6, and demonstrated the ability to separate thick oils, such as HD-40 engine oil, from water with a 90% separation efficiency. Concurrently, its photocatalytic performance was evaluated by the degradation of methylene blue (MB) under a weak light intensity of 5 mW/cm², achieving 85.5% degradation within 30 min. Although its application as a functional membrane in water treatment may raise safety concerns, the mesh showed significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under both dark and light conditions. Using the disk diffusion method, strong bacterial inhibition was observed after 24 h of exposure in the dark. Upon visible light irradiation, bactericidal efficiency was further enhanced—by 17% for S. aureus and 2% for E. coli. These findings highlight the potential of the Cu₂O-Cu(OH)₂@Cu microfibers as a multifunctional membrane for industrial wastewater treatment, capable of simultaneously removing oil, degrading organic dyes, and inactivating pathogenic bacteria through photo-assisted processes. Full article

Titanium dioxide (TiO₂) is a wide-bandgap semiconductor material with broad application potential, known for its excellent photocatalytic performance, high chemical stability, low cost, and non-toxicity. These properties make it highly attractive for applications in photovoltaic energy, environmental remediation, and optoelectronic devices. For instance, TiO₂ is widely used as a photocatalyst for hydrogen production via water splitting and for degrading organic pollutants, thanks to its efficient photo-generated electron–hole separation. Additionally, TiO₂ exhibits remarkable performance in dye-sensitized solar cells and photodetectors, providing critical support for advancements in green energy and photoelectric conversion technologies. Boron-doped diamond (BDD) is renowned for its exceptional electrical conductivity, high hardness, wide electrochemical window, and outstanding chemical inertness. These unique characteristics enable its extensive use in fields such as electrochemical analysis, electrocatalysis, sensors, and biomedicine. For example, BDD electrodes exhibit high sensitivity and stability in detecting trace chemicals and pollutants, while also demonstrating excellent performance in electrocatalytic water splitting and industrial wastewater treatment. Its chemical stability and biocompatibility make it an ideal material for biosensors and implantable devices. Research indicates that the combination of TiO₂ nanostructures and BDD into heterostructures can exhibit unexpected optical and electrical performance and transport behavior, opening up new possibilities for photoluminescence and rectifier diode devices. However, applications based on this heterostructure still face challenges, particularly in terms of photodetector, photoelectric emitter, optical modulator, and optical fiber devices under high-temperature conditions. This article explores the potential and prospects of their combined heterostructures in the field of optoelectronic devices such as photodetector, light emitting diode (LED), memory, field effect transistor (FET) and sensing. TiO₂/BDD heterojunction can enhance photoresponsivity and extend the spectral detection range which enables stability in high-temperature and harsh environments due to BDD’s thermal conductivity. This article proposes future research directions and prospects to facilitate the development of TiO₂ nanostructured materials and BDD-based heterostructures, providing a foundation for enhancing photoresponsivity and extending the spectral detection range enables stability in high-temperature and high-frequency optoelectronic devices field. Further research and exploration of optoelectronic devices based on TiO₂-BDD heterostructures hold significant importance, offering new breakthroughs and innovations for the future development of optoelectronic technology. Full article

Efficient photocatalysts based on composite materials are essential for addressing environmental pollution and enhancing water purification. This study presents a novel BiOI/V₂O₅ nanocomposite (BVNC) with a flower-like layered structure, synthesized via a low-temperature solvothermal process followed by high-pressure annealing for visible light (VL)-driven dye degradation and antibacterial activities. Compared to individual BiOI nanoparticles (BOINP) and V₂O₅ nanoparticles (VONP), under VL, the BVNC demonstrated significantly enhanced photocatalytic and antibacterial activity. The best-performing BVNC achieved a remarkable methylene blue degradation efficiency of 95.7% within 140 min, with a rate constant value 439% and 430% of those of BOINP and VONP, respectively. Additionally, BVNC exhibited high photocatalytic efficiencies for rhodamine 6G (94.0%), methyl orange (90.4%), and bisphenol A (69.5%) over 160 min, highlighting the superior performance of the composite materials for cationic and anionic dyes. Furthermore, BVNC established outstanding antibacterial capability against Staphylococcus aureus and Escherichia coli, demonstrating zones of inhibition of 12.24 and 11.62 mm, respectively. The improved catalytic and antibacterial capability is ascribed to the presence of a robust p-n heterojunction between BOINP and VONP, which broadens the photo-absorption range, reduces bandgap energy, and facilitates the significant separation of excitons and faster release of reactive oxygen species. Full article

Zinc oxide (ZnO), a cheap, abundant, biocompatible, and wide band gap semiconductor material with easy tunable morphologies and properties, makes it one of the mostly studied metal oxides in the area of materials science, physics, chemistry, biochemistry, and solid-state electronics. Its versatility, easy bandgap engineering with transitional and rare earth metals, as well as the diverse nanomorphology empower ZnO as a promising photocatalyst. The use of ZnO as a functional material is attracting increased attention both for academia and industry, especially under the current energy paradigm shift toward clean and renewable sources. Extensive work has been performed in recent years using ZnO as an active component for different photocatalytic applications. Therefore, a thorough and timely review of the process is necessary. The aim of this review is to provide a general summary of the current state of ZnO nanostructures, synthesis strategies, and modification approaches, with the main application focus on varied photocatalysis applications, serving as an introduction, a reference, and an inspiration for future research. Full article

Ensuring effective water purification is essential for addressing freshwater scarcity and achieving the United Nations Sustainable Development Goals (SDGs). An efficient hybrid mixture, composed of FeCr quantum dots doped into mesoporous silica SBA-15 support and activated carbon (AC) derived from olive mill solid wastes, has been developed for treating high optical density polluted aqueous environments. This hybrid, denoted as FeCr-SBA-15/AC, was examined for its efficacy in the adsorption and photo-Fenton degradation of met orange dye (MO), a model high-optical-density pollutant, under visible light exposure. Characterization of the prepared samples was conducted using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) surface area analysis, diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Key parameters investigated included catalyst dosage, dye concentration, solution pH, and H₂O₂ concentration. Remarkably, the FeCr-SBA-15/AC hybrid exhibited superior photocatalytic activity, achieving a degradation efficiency of 97% for MO under optimized conditions (catalyst dosage = 0.75 g L⁻¹, dye concentration = 20 mg L⁻¹, pH = 5.47, and 0.5 mL H₂O₂) after 180 min of irradiation with visible light. This performance surpassed that of FeCr-SBA-15 alone by 20%, due to the synergistic effects of adsorption and photo-Fenton. The adsorption of MO onto AC followed the Freundlich model equilibrium isotherm, while the experimental data for the hybrid mixture aligned well with the pseudo-first-order Langmuir–Hinshelwood kinetic model with a rate constant of 0.0173 min⁻¹. The leaching of Cr in the solution was very low—0.1 ppm—which is below the detection limit. These findings underscore the potential of the synthesized FeCr-SBA-15/AC hybrid as a cost-effective, environmentally friendly, and highly efficient photo-Fenton catalyst for treating wastewater contaminated by industrial effluents. Full article

The development of heterostructures incorporating photocatalysts optimized for visible-light activity represents a major breakthrough in the field of environmental remediation research, offering innovative and sustainable solutions for environmental purification. This study explores the photocatalytic capabilities of a SnFe₂O₄/g-C₃N₄ heterojunction nanocomposite, successfully synthesized from graphitic carbon nitride (g-C₃N₄) and tin ferrate (SnFe₂O₄) and applied to the degradation of the cationic dye brilliant cresyl blue (BCB) in an aqueous solution. These two components are particularly attractive due to their low cost and ease of fabrication. Various characterization techniques, including XRD, FTIR, SEM, and TEM, were used to confirm the successful integration of SnFe₂O₄ and g-C₃N₄ phases in the synthesized catalysts. The photocatalytic and photo-Fenton-like activity of the heterojunction composites was evaluated by the degradation of brilliant cresyl blue under visible LED illumination. Compared to the pure components SnFe₂O₄ and g-C₃N₄, the SnFe₂O₄/g-C₃N₄ nanocomposite demonstrated a superior photocatalytic performance. Furthermore, the photo-Fenton-like performance of the composites is much higher than the photocatalytic performances. The significant improvement in photo-Fenton activity is attributed to the synergistic effect between SnFe₂O₄ and g-C₃N₄, as well as the efficient separation of photoexcited electron/hole pairs. The recyclability of the SnFe₂O₄/g-C₃N₄ composite toward BCB photo-Fenton like degradation was also shown. This study aimed to assess the modeling and optimization of photo-Fenton-like removal BCB using the SnFe₂O₄/g-C₃N₄ nanomaterial. The main parameters (photocatalyst dose, initial dye concentration, H₂O₂ volume, and reaction time) affecting this system were modeled by two approaches: a response surface methodology (RSM) based on a Box–Behnken design and artificial neural network (ANN). A comparison was made between the predictive accuracy of RSM for brilliant cresyl blue (BCB) removal and that of the artificial neural network (ANN) approach. Both methodologies provided satisfactory and comparable predictions, achieving R² values of 0.97 for RSM and 0.99 for ANN. Full article

This study successfully prepared MIL-101(Fe)@MoS₂ composite photocatalysts via hydrothermal methods to address the efficient removal of refractory organic dyes in dye wastewater. Characterization using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) confirmed that molybdenum disulfide (MoS₂) was uniformly loaded onto the surface of MIL-101(Fe), forming a heterojunction that significantly enhanced light absorption capacity and charge separation efficiency. In a visible-light-driven photo-Fenton system, this material exhibited excellent degradation performance for Congo red (CR). At an initial CR concentration of 50 mg/L, a catalyst dosage of 0.2 g/L, 4 mL of added H₂O₂, and pH 7, CR was completely degraded within 30 min, with the total organic carbon (TOC) removal reaching 72.5%. The material maintained high degradation efficiency (>90%) across a pH range of 3–9, overcoming the traditional Fenton system’s dependency on acidic media. Radical-trapping experiments indicated that superoxide radicals (·O₂⁻) and photogenerated holes (·h⁺) were the primary active species responsible for degradation, revealing a synergistic catalytic mechanism at the heterojunction interface. Recyclability tests showed that the material retained 90.8% degradation efficiency after five cycles, and an X-ray photoelectron spectroscopy (XPS) analysis demonstrated the stable binding of Fe and Mo, preventing secondary pollution. This study provides a scientific basis for developing efficient, stable, and wide-pH adaptable photo-Fenton catalytic systems, contributing significantly to the advancement of green water treatment technologies. Full article

Water pollution by dyes is a major environmental problem, particularly in the textile, food, and pharmaceutical industries. These dyes are often complex chemical compounds that are difficult to remediate due to their chemical stability, their solubility in water, and their resistance to conventional treatment processes such as filtration, coagulation, or decantation. Thus, to date, there is still a need to make water treatment processes more performant and cost-efficient. The main aim of this research is to prepare photocatalytically active MFI-type zeolites from natural clays and support iron oxide nanoparticles. These catalysts were characterized and evaluated for the capture and the photo-Fenton degradation of methylene blue (MB) in aqueous solution. After 10 min under photo-Fenton conditions, Fe/MTK-MFI presented almost complete removal of MB for up to four consecutive cycles. Full article

The nano-architecture of titanium oxide is a key element of a wide range of applications, mainly optical and catalytic activities. Therefore, the current study focuses on engineering and designing three interesting nanostructures of titanium oxides: nanoplates, nanotubes, and nanoparticle-supported nanolayers. The nanoplates of titanium oxides were prepared and confirmed by TEM images, X-ray diffraction, and EDX analysis. These nanoplates have an anatase phase, with the distance across the corners in the range of 15 nm. These nanoplates were modified and developed through a rolling process with sodium doping to generate the Na-doped TiO₂ nanotubes. These nanotubes were observed by TEM images and X-ray diffraction. In addition, the doping process of titanium oxides with sodium was confirmed by EDX analysis. A novel nano-architecture of titanium oxide was designed by supporting titanium oxide nanoparticles over Zn/Al nanolayers. The optical properties and activity of titanium oxides with the different morphologies indicated that titanium oxides became a highly photo-active photocatalyst after conversion to nanotubes. This finding was observed through the reduction in the band gap energy to 2.7 eV. Additionally, after 37 min of exposure to UV light, the titanium oxide nanotubes totally broke down and transformed the green dye of NGB into carbon dioxide and water. Furthermore, the kinetic analysis verified that the green dyes’ degradation was expedited by the high activity of nanotubes. Ultimately, based on these findings, it was possible to design an efficient photocatalyst for water purification by converting nanoplates into nanotubes, doping titanium sites with sodium ions, and creating new active sites for titanium oxides through defect-induced super radical formation. Full article

Herein, anionic (sodium dodecylbenzene sulfonate, SDBS) and cationic (cetyltrimethylammonium bromide, CTAB) surfactants are involved in the synthesis of a poly(acrylic acid-co-acrylamide) copolymer, p(AA-co-AM), containing nanoceria (CeO₂). The physicochemical and optical properties of CTAB-CeO₂@p(AA-co-AM) and SDBS-CeO₂@p(AA-co-AM) nanocomposites can be studied using different techniques. The physicochemical properties of nanoceria-immobilized p(AA-co-AM) are significantly developed when handled with SDBS. Compared to the CTAB-CeO₂@p(AA-co-AM) nanocomposite, SDBS-CeO₂@p(AA-co-AM) exhibits pronounced negatively charged mesoporous surfaces with Corel reef-like morphology. SDBS-CeO₂@p(AA-co-AM) contains ceria nano-cubes of ~30 nm size, evenly dispersed along a copolymeric moiety, displaying narrower energy bandgap. The photocatalytic efficiency of this nanocomposite is performed in activating persulfate-ions (PS) under visible light irradiation, yielding reactive oxygen species that effectively treat dye wastewater. Advanced SDBS-CeO₂@p(AA-co-AM)/PS/Vis photocatalytic oxidation system possesses ~100% methylene blue degradation efficiency within 2 h for five consecutive purification-cycles with thorough mineralization performance. Such superior photo-degradability consults efficacious synergistic combinations gathering the nanocomposite, persulphate-ions, and visible light radiation, yielding an escalated synergy-index value (SI = 6) with intensive generation of reactive-oxidizing species (SO₄^•−/h⁺ synergistic ratio 1:5.6). Including anionic-surfactant molecules in the synthesis of metal-containing copolymer nanocomposites is indispensably profitable in the future for the treatment of industrial wastewater. Full article

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. Full article

Water pollution poses significant environmental challenges, particularly from dyes used in various industrial processes. Effective removal methods are essential to mitigate their impact on aquatic environments. Activated carbon (AC) is widely used for its adsorption properties, and further modifications can enhance its efficiency. In this study, we developed polystyrene sulfonate-modified activated carbon (AC@PSS) using a facile and efficient method to improve the photo-degradation of methylene blue (MB) in aquatic environments. The modification enhanced the activated carbon’s surface features and adsorption, improving its photocatalytic activity. The photocatalysts were characterized using XRD, SEM, FTIR, and TGA. Based on Tauc’s equation, the band gap value of AC@PSS was 4.0 eV. The photocatalytic efficacy of the AC@PSS catalyst was assessed by studying the degradation of MB dye under UV-rich solar irradiation. The influence of various variables on the photo-degradation of MB dye such as pH (2–12), reaction time (0–160 min), catalyst dosage (20–80 mg), and dye concentration (10–300 mg/L) was investigated. The AC@PSS catalyst demonstrated impressive degradation efficacy for MB dye of 98% in 160 min at pH 11, a temperature of 25 °C, a catalyst dose of 60 mg, and initial MB content of 10 mg/L. The superior performance of the AC@PSS catalyst could be due to the effective separation of photogenerated electron holes. Accordingly, the photo-degradation of MB is affected by the photo-produced radical ^•OH. Finally, we conclude that synthesizing AC@PSS is highly effective for the degradation of MB dye. Full article