Photocatalytic removal of organic dye using green synthesized zinc oxide coupled cadmium tungstate nanocomposite under natural solar light irradiation

Enhanced photocatalytic activity of tin oxide-doped molybdenum disulfide nanohybrids under visible light irradiation: Antibiotics elimination, heavy metal reduction and antibacterial behavior

Nano-heterojunction photocatalytic can operate removal of pollutants, which is basic for the sustainable development of a clean environment. Herein, we propose a novel MoS2/SnO2 (MS) S-scheme heterojunction by a facile hydrothermal process, which is cheap, easily available, highly visible-light response, and good stability. The MS nano-heterojunction suggested superior performance with the photocatalytic degradation of 97.6% within 100 min for ciprofloxacin (CIP) removal, which was 5.74 and 4.88 folds higher than that of pristine MoS2 and SnO2, respectively. The fabricated MS photocatalysts displayed outstanding photocatalytic efficiency toward Cr (VI) reduction. The removal capability of Cr (VI) reached up to 92.5% within 60 min. The photodegradation efficiency was 5.2 folds that of pristine MoS2. In addition, the antibacterial performance approximately approached 100% for E. coli within 10 min, which was more apparent than the others. A series of excellent results implied that MS nano-heterojunction had a high ultraviolet and visible light absorbance, larger specific surface area, outstanding electron-hole pairs migration and higher capability of photo-response electrons and holes separation rate. This system offers a novel window into the evolution of nano-heterojunction for wastewater treatment and solar energy harvesting applications.

Influence of ozone supply mode and aeration on photocatalytic ozonation of organic pollutants in wastewater using TiO2 and ZnO nanoparticles

Photocatalytic ozonation, which combines the effects of lighting and ozonation, has been shown to enhance the decolorization and degradation of organic pollutants in wastewater. Dye solutions with concentrations of 10 ppm for both methylene blue and methyl orange dyes were used. The influence of ozoneation on the performance of photocatalytic activity of TiO2 and ZnO nanoparticles for the removal of organic dyes from aqueous solutions was investigated. To evaluate their efficacy for the removal of methylene blue and methyl orange dyes from aqueous solutions, the photocatalysts were exposed to UV light for 90 min, with ozone supplied either intermittently or continuously by an SDBD cold plasma reactor. The photocatalysts utilized in this study were characterized using SEM and XRD techniques. The degree of color degradation was determined using UV-Vis spectroscopy. The results demonstrate that TiO2 and ZnO nanoparticles exhibit different degrees of photocatalytic activity for the two dyes. The addition of ozone was found to enhance both the color degradation and mineralization rates of the pollutants, with intermittent ozonation proving more effective than continuous ozonation. The most significant color degradation results were obtained using TiO2 nanoparticles with intermittent ozonation for methylene blue dye (97 %) and ZnO nanoparticles with intermittent ozonation for methyl orange dye (40 %). Overall, this study provides evidence that photocatalytic ozonation represents a promising technique for water treatment.

Principles of Photocatalysts and Their Different Applications: A Review

Human existence and societal growth are both dependent on the availability of clean and fresh water. Photocatalysis is a type of artificial photosynthesis that uses environmentally friendly, long-lasting materials to address energy and environmental issues. There is currently a considerable demand for low-cost, high-performance wastewater treatment equipment. By changing the structure, size, and characteristics of nanomaterials, the use of nanotechnology in the field of water filtration has evolved dramatically. Semiconductor-assisted photocatalysis has recently advanced to become among the most promising techniques in the fields of sustainable energy generation and ecological cleanup. It is environmentally beneficial, cost-effective, and strictly linked to the zero waste discharge principle used in industrial effluent treatment. Owing to the reduction or removal of created unwanted byproducts, the green synthesis of photoactive nanomaterial is more beneficial than chemical synthesis approaches. Furthermore, unlike chemical synthesis methods, the green synthesis method does not require the use of expensive, dangerous, or poisonous ingredients, making it a less costly, easy, and environmental method for photocatalyst synthesis. This work focuses on distinct greener synthesis techniques utilized for the production of new photocatalysts, including metals, metal doped-metal oxides, metal oxides, and plasmonic nanostructures, including the application of artificial intelligence and machine learning to the design and selection of an innovative photocatalyst in the context of energy and environmental challenges. A brief overview of the industrial and environmental applications of photocatalysts is also presented. Finally, an overview and recommendations for future research are given to create photocatalytic systems with greatly improved stability and efficiency.

One-Pot Facile Synthesis of CuO-CdWO4 Nanocomposite for Photocatalytic Hydrogen Production

Hydrogen (H₂) is a well-known renewable energy source that produces water upon its burning, leaving no harmful emissions. Nanotechnology is utilized to increase hydrogen production using sacrificial reagents. It is an interesting task to develop photocatalysts that are effective, reliable, and affordable for producing H₂ from methanol and acetic acid. In the present study, CuO, CdWO₄, and CuO-CdWO₄ nanocomposite heterostructures were prepared using a cost-efficient, enviro-friendly, and facile green chemistry-based approach. The prepared CuO, CdWO₄, and CuO-CdWO₄ nanocomposites were characterized using X-ray diffraction pattern, Fourier-transform infrared spectroscopy, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction (SAED) pattern, N₂ physisorption, photoluminescence, and X-ray photoelectron spectroscopy techniques. The synthesized photocatalysts were utilized for photocatalytic H₂ production using aqueous methanol and acetic acid as the sacrificial reagents under visible light irradiation. The influence of different variables, including visible light irradiation time, catalyst dosage, concentration of sacrificial reagents, and reusability of catalysts, was studied. The maximum H₂ was observed while using methanol as a sacrificial agent over CuO-CdWO₄ nanocomposite. This enhancement was due to the faster charge separation, higher visible light absorption, and synergistic effect between the CuO-CdWO₄ nanocomposite and methanol.