Search Results (491)

The discharge of oily wastewater threatens the ecosystem and human health, and the efficient treatment of oily wastewater is confronted with problems of high mass transfer resistance at the oil-water-solid multiphase interface, significant light shielding effect, and easy deactivation of photocatalysts. Although traditional physical separation methods avoid secondary pollution by chemicals and can effectively separate floating oil and dispersed oil, they are ineffective in removing emulsified oil with small particle sizes. To address these complex challenges, photocatalytic technology and photocatalysis-based improved technologies have emerged, offering significant application prospects in degrading organic pollutants in oily wastewater as an environmentally friendly oxidation technology. In this paper, the degradation mechanism, kinetic mechanism, and limitations of conventional photocatalysis technology are briefly discussed. Subsequently, the surface interface modulation functions of metal doping and heterojunction energy band engineering, along with their applications in enhancing the light absorption range and carrier separation efficiency, are reviewed. Focus on typical studies on the separation and degradation of aqueous and oily phases using photocatalytic membrane technology, and illustrate the advantages and mechanisms of photocatalysts loaded on the membranes. Finally, other new approaches and converging technologies in the field are outlined, and the challenges and prospects for the future treatment of oily wastewater are presented. Full article

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

Due to its persistence and potential negative effects on ecosystems and human health, microplastic pollution in aquatic environments has become a major worldwide concern. Photocatalytic degradation is a sustainable manner to degrade microplastics to non-toxic by-products. In this review, comprehensive discussion focuses on the synergistic effects of various photocatalytic materials including TiO₂, ZnO, WO₃, graphene oxide, and metal–organic frameworks for producing heterojunctions and involving multidimensional nanostructures. Such mechanisms can include the generation of reactive oxygen species and polymer chain scission, which can lead to microplastic breakdown and mineralization. The advancements of material modifications in the (nano)structure of photocatalysts, doping, and heterojunction formation methods to promote UV and visible light-driven photocatalytic activity is discussed in this paper. Reactor designs, operational parameters, and scalability for practical applications are also reviewed. Photocatalytic systems have shown a lot of development but are hampered by shortcomings which include a lack of complete mineralization and production of intermediary secondary products; variability in performance due to the fluctuation in the intensity of solar light, limited UV light, and environmental conditions such as weather and the diurnal cycle. Future research involving multifunctional, environmentally benign photocatalytic techniques—e.g., doped composites or composite-based catalysts that involve adsorption, photocatalysis, and magnetic retrieval—are proposed to focus on the mechanism of utilizing light effectively and the environmental safety, which are necessary for successful operational and industrial-scale remediation. Full article

The efficient depolymerization of lignin has become a key challenge in the preparation of high-value-added chemicals. Graphitic carbon nitride (g-C₃N₄)-based photocatalytic system shows potential due to its mild and green characteristics over other depolymerization methods. However, its inherent defects, such as a wide band gap and rapid carrier recombination, severely limit its catalytic performance. In this paper, a g-C₃N₄ modification strategy of K⁺ doping and surface alkalinization is proposed, which is firstly applied to the photocatalytic depolymerization of the lignin β-O-4 model compound (2-phenoxy-1-phenylethanol). K⁺ doping is achieved by introducing KCl in the precursor thermal polymerization stage to weaken the edge structure strength of g-C₃N₄, and post-treatment with KOH solution is combined to optimize the surface basic groups. The structural/compositional evolution of the materials was analyzed by XRD, FTIR, and XPS. The morphology/element distribution was visualized by SEM-EDS, and the optoelectronic properties were evaluated by UV–vis DRS, PL, EIS, and transient photocurrent (TPC). K⁺ doping and surface alkalinization synergistically regulate the layered structure of the material, significantly increase the specific surface area, introduce nitrogen vacancies and hydroxyl functional groups, effectively narrow the band gap (optimized to 2.35 eV), and inhibit the recombination of photogenerated carriers by forming electron capture centers. Photocatalytic experiments show that the alkalinized g-C₃N₄ can completely depolymerize 2-phenoxy-1-phenylethanol with tunable product selectivity. By adjusting reaction time and catalyst dosage, the dominant product can be shifted from benzaldehyde (up to 77.28% selectivity) to benzoic acid, demonstrating precise control over oxidation degree. Mechanistic analysis shows that the surface alkaline sites synergistically optimize the C_β-O bond breakage path by enhancing substrate adsorption and promoting the generation of active oxygen species (·OH, ·O₂⁻). This study provides a new idea for the efficient photocatalytic depolymerization of lignin and lays an experimental foundation for the interface engineering and band regulation strategies of g-C₃N₄-based catalysts. Full article

In this study, Fe-doped SrTiO₃ powders have been synthesized using the sol-gel approach. The effect of the Fe³⁺ doping on the degradation efficiency of SrTiO₃ toward specific pollutants was studied. The obtained samples were characterized using the following techniques: XRD, SEM-EDS, FTIR, UV-Vis, and BET. Subsequently, the samples were tested for degradation of two organic pollutants—tetracycline hydrochloride and Malachite green in distilled water under different light sources—UV light and visible light. The investigated powders exhibited good photocatalytic degradation efficiency against both pollutants. A comparison of the photocatalytic abilities of the samples under different lights has been made, which emphasizes the paper’s novelty. Undoped SrTiO₃ exhibited better photocatalytic activity for TCH both under UV and visible light irradiation in comparison to the Fe-doped. The SrTi_0.15Fe_0.85O₃ shows superior photocatalytic activity under visible light irradiation for the degradation of MG dye. The antibacterial activity has been tested against two bacterial strains, E. coli ATCC 25922 and P. aeruginosa ATCC 27853. It has been found that the antibacterial efficiency of the Fe-doped sample is greater than compared of the undoped one. Full article

This paper presents the synthesis of La₂Ti₂O₇ nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH₄. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH₃CH₂OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH₃CH₂OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation. Full article

Graphite carbon nitride (g-C₃N₄) is a low band gap non-metallic polymer semiconductor that has broad application prospects and is an ideal material for absorbing visible light, as g-C₃N₄ materials have strong oxidation properties and are easy to modify. The structure formation of g-C₃N₄-based materials makes a series of photocatalytic synthesis reactions possible and improves photocatalytic reaction activity. In this paper, the development history, structures, and performance of g-C₃N₄ are briefly introduced, and the modification strategies of g-C₃N₄ are summarized to improve its photocatalytic and photoelectric catalytic properties via doping, heterojunction construction, etc. The light absorption and utilization of the catalysts are also analyzed in terms of light source conditions, and the application of g-C₃N₄ and its modified materials in photocatalysis and photocatalytic degradation is reviewed. Full article

Sustainable waste recycling continues to be one of the most significant challenges in this century, especially for the office paper sector. On top of that, photocatalysis depends on solar radiation as an unlimited and environmentally friendly energy source for removing organic pollutants from contaminated water. The obtaining of AC from office paper waste was carried out with the help of the chemical activation method using ZnCl₂ as an activation agent, followed by heating the samples in adequate conditions. In the present research, we assessed the influence of the amount of ZnCl₂ activator on the properties of AC. In our experimental conditions, a part of ZnCl₂ was transformed into ZnO, deposited onto AC, and formed a composite. We attempted to minimize aggressive chemical agents through inexpensive technical solutions and experimental approaches. The properties of the obtained AC samples were evaluated by XRD, XPS, SEM/EDX, EPR, and surface area and porosity investigations. All of the samples exhibit photocatalytic activity toward Rhodamine B. The photocatalytic mechanism was evaluated considering the existence of reactive oxygen species (ROSs), as evidenced by spin-trapping experiments. Full article

Photocatalytic hydrogen (H₂) production offers a promising solution to energy shortages and environmental challenges by converting solar energy into chemical energy. Hydrogen, as a versatile energy carrier, can be generated through photocatalysis under sunlight or via electrolysis powered by solar or wind energy. However, the advancement of photocatalysis is hindered by the limited availability of effective visible light-responsive semiconductors and the challenges of charge separation and transport. To address these issues, researchers are focusing on the development of novel nanostructured semiconductors and composite materials that can enhance photocatalytic performance. In this paper, we provide an overview of the advanced photocatalytic materials prepared so far that can be activated by sunlight, and their efficiency in H₂ production. One of the key strategies in this research area concerns improving the separation and transfer of electron–hole pairs generated by light, which can significantly boost H₂ production. Advanced hybrid materials, such as organic–inorganic hybrid composites consisting of a combination of polymers with metal oxide photocatalysts, and the creation of heterojunctions, are seen as effective methods to improve charge separation and interfacial interactions. The development of Schottky heterojunctions, Z-type heterojunctions, p–n heterojunctions from nanostructures, and the incorporation of nonmetallic atoms have proven to reduce photocorrosion and enhance photocatalytic efficiency. Despite these advancements, designing efficient semiconductor-based heterojunctions at the atomic scale remains a significant challenge for the realization of large-scale photocatalytic H₂ production. In this review, state-of-the-art advancements in photocatalytic hydrogen production are presented and discussed in detail, with a focus on photocatalytic nanostructures, heterojunctions and hybrid composites. Full article

With the rapid advancement of industrialization, the adverse impacts of organic pollutants on the water environment of aquatic ecosystems have become increasingly concerning. Consequently, the development of efficient and environmentally friendly photocatalytic degradation technologies has attracted considerable research attention. Perylene diimide (PDI)-based heterojunction photocatalysts have demonstrated remarkable potential in degrading organic pollutants, attributed to their broad spectral response, high charge separation efficiency, and exceptional stability. In recent years, substantial progress has been achieved in the field of PDI-based heterojunction photocatalysts. This paper provides an in-depth review of the existing research on PDI-based heterojunction photocatalysts. Specifically, it elucidates the principles and types of heterojunction construction, as well as the design and synthesis strategies for PDI-based heterojunction photocatalysts. Furthermore, this paper provides a comprehensive summary of the latest advancements in performance optimization and catalytic mechanisms. Finally, the existing challenges and future prospects of PDI-based heterojunction photocatalytic materials are discussed, with the aim of offering innovative solutions for the purification of resource-oriented wastewater. Full article

Nano-titanium dioxide (TiO₂) is currently the most widely studied photocatalyst. However, its rapid recombination of photogenerated carriers and narrow range of light absorption have limited its development. Crystal form regulation and polymer modification are important means for improving the photocatalytic activity of single-phase materials. In this paper, TiO₂ materials of different crystal forms were prepared by changing the synthesis conditions, and they were compounded with trimesoyl chloride–melamine polymers (TMPs) by the hydrothermal synthesis method. Then, their photocatalytic performance was evaluated by degrading methylene blue (MB) under visible light. The mechanisms of influence of TiO₂ crystal form on the photocatalytic activity of TiO₂-TMP were explored by combining characterization and theoretical calculation. The results showed that the TiO₂ crystal form, through interface interaction, the built-in electric field intensity of the heterojunction, and active sites, affected the interface charge separation and transfer, thereby influencing the photocatalytic activity of TiO₂-TMP. In the 4T-TMP photocatalytic system, the degradation rate of MB was the highest. These studies provide theoretical support for understanding the structure–property relationship of the interfacial electronic coupling between TiO₂ crystal forms and TMP, as well as for developing more efficient catalysts for pollutant degradation. Full article

Industrial growth led to the expansion of existing environmental problems, where different kinds of pollutants can enter the environment by many known routes, particularly through wastewater. Among other contaminants, pharmaceuticals, such as diazepam, once released, pose a significant challenge related to their removal from complex environmental matrices due to their persistence and potential toxicity. For this reason, it is a great challenge to find suitable methods for the treatment of wastewater. The aim of this paper was to investigate the stability of diazepam, subjecting it to various degradation processes (hydrolysis and photolysis), focusing on photocatalysis, an advanced oxidation process commonly used for the purification of industrial wastewater. The photocatalytic system consisted of UV-A and simulated solar irradiation with titanium dioxide (TiO₂) immobilized on a glass mesh as a photocatalyst, with an additional reaction performed in the presence of an oxidizing agent, i.e., hydrogen peroxide, to improve diazepam removal from water matrices. The kinetic rate of diazepam degradation was monitored with a high-performance liquid chromatograph coupled with a photodiode array detector (HPLC-PDA). The target compound was characterized as a hydrolytically and photolytically stable compound with t_1/2 = 25 h. The presence of an immobilized TiO₂ catalyst contributed significantly to the degradation of diazepam under the influence of UV-A and simulated solar radiation, with t_1/2 in the range of 1.61–2.56 h. Five degradation products of diazepam were identified at the laboratory scale by MS analysis (m/z = 267, m/z = 273, m/z = 301, m/z = 271, and m/z = 303), while the toxicity assessment revealed that diazepam exhibited developmental toxicity and a low bioaccumulation factor. The pilot-scale process resulted in significant improvements in diazepam degradation with the fastest degradation kinetics (0.6888 h⁻¹). These results obtained at the pilot scale highlight the potential for industrial-scale implementation, offering a promising and innovative solution for pharmaceutical removal from wastewater. Full article

Antibiotic residues in the marine environment pose a serious threat to ecosystems and human health, and there is an urgent need to develop efficient and selective pollution control technologies. Molecular imprinting technology (MIT) provides a new idea for antibiotic pollution control with its specific recognition and targeted removal ability. However, traditional titanium dioxide (TiO₂) photocatalysts have limited degradation efficiency and lack of selectivity for low concentrations of antibiotics. This paper reviews the preparation strategy and modification means of molecularly imprinted TiO₂ (MI-TiO₂) and its composites and systematically explores its application mechanism and performance advantages in marine antibiotic wastewater treatment. It was shown that MI-TiO₂ significantly enhanced the selective degradation efficiency of antibiotics such as tetracyclines and sulfonamides through the enrichment of target pollutants by specifically imprinted cavities, combined with the efficient generation of photocatalytic reactive oxygen species (ROS). In addition, emerging technologies such as magnetic/electric field-assisted catalysis and photothermal synergistic effect further optimized the recoverability and stability of the catalysts. This paper provides theoretical support for the practical application of MI-TiO₂ in complex marine pollution systems and looks forward to its future development in the field of environmental remediation. Full article

Advanced photocatalytic materials for environmental cleanup need to be developed in response to growing concerns about water pollution. This paper presents a novel N-doped hollow carbon spheres (NHCSs)-supported Co₂SnO₄/WS₂ heterostructure synthesized using a hydrothermal approach and examined using various characterization techniques to evaluate the crystal structures, functional groups, surface morphology, chemical properties, and optical characteristics. The photocatalytic performance of the Co₂SnO₄/WS₂@NHCSs composite was assessed by degrading Congo red (CR) under visible light, resulting in a notable degradation rate of 87.22% in 60 min. The enhanced degradation efficiency is ascribed to the Z-scheme heterojunction charge-transfer mechanism, which augments sustained charge separation while suppressing recombination under visible-light irradiation. Furthermore, the quenching experiments revealed that specific superoxide radicals (^•O₂^-) and hydroxyl radicals (^•OH) were integral to the degradation reaction, and a potential Z-scheme charge-transfer pathway mechanism for the effective Co₂SnO₄/WS₂@NHCSs photocatalysts was also suggested. The potential degradation mechanism was suggested using LC-MS analysis. This study highlights the promise of Co₂SnO₄/WS₂@NHCSs composites for practical wastewater treatment applications, providing a sustainable and effective solution for environmental remediation. Full article

The increasing presence of pharmaceuticals, particularly antiretroviral drugs (ARVs), in wastewater has raised concerns regarding their environmental and health impacts. Photocatalysis, driven by advanced photocatalysts, such as coloured TiO₂, ZnO, and composites with carbon-based materials, has shown promise as an effective method for degrading these pollutants. Despite significant laboratory-scale success, challenges remain in scaling this technology for real-world applications, particularly in terms of photocatalyst stability, the formation of toxic degradation by-products, and economic feasibility. This paper explores the current state of photocatalytic degradation for ARVDs, emphasizing the need for further research into degradation pathways, the development of more efficient and cost-effective photocatalysts, and the integration of photocatalysis into hybrid treatment systems. The future of photocatalysis in wastewater treatment hinges on improving scalability, reactor design, and hybrid systems that combine photocatalysis with traditional treatment methods to ensure comprehensive pollutant removal. Innovations in catalyst design and reactor optimization are essential for advancing photocatalysis as a viable solution for large-scale wastewater treatment. Full article