Biochar-Reinforced Metal Oxide Photocatalysts for the Removal of Dyes and Pharmaceutical Pollutants: A Review

Efficient removal of high concentration organic pollutants by ZnIn2S4 with highly active sulfur vacancy

Anatase/brookite biphasic surface fluorinated Fe–TiO2 photocatalysts to enhance photocatalytic removal of VOCs under visible and UV light

The health hazards generated from textile and dye industries wastewater which are most carcinogenic and they poses a danger to human and aquatic biota. The present work investigates the degradation of dye pollutants such as Eosin yellow (EY) and Brilliant green (BG) under visible light irradiation using SnO2/Fe2O3/Ag nanocomposite. This nanocomposite was prepared by hydrothermal route and characterized by various instrument techniques like XRD, FTIR, FESEM, EDS, HRTEM, UV–Vis DRS, PL and UV–Vis spectrophotometer for determine its crystalline phase, morphology, bandgap and photocatalytic efficiency. The photocatalytic activity of nanocomposite was tested on both dyes EY and BG under visible light irradiation and the experimental results declared that this composite shown better photocatalytic activity in basic solution degraded 93% of BG and 95% of EY in 75 min and 60 min, respectively under the normalised conditions such as basic pH, 30 mg catalyst dose and 10 mg/L of dye solution concentration without any oxidants such as H2O2. This is due to lower bandgap energy of SnO2/Fe2O3/Ag nanocomposite (1.78 eV) and thus shows the red shift, making it active in the visible region, resulting in higher photocatalytic activity. This was proved by compare the photocatalytic efficiency with SnO2 and SnO2/Fe2O3 shown lesser photocatalytic degradation efficiency over EY and BG under visible light irradiation.

Efficiency of neonicotinoids photocatalytic degradation by using annular slurry reactor

Efficient and stable Nb2O5 modified g-C3N4 photocatalyst for removal of antibiotic pollutant

Photocatalytic degradation properties of V-doped TiO2 to automobile exhaust

Pulsed laser based synthesis of polymeric-inorganic nanocomposites as efficient visible light active photo-catalysts for the degradation of organic pollutants in water

Pharmaceutical pollutants, including theophylline, a prevalent xanthine-based drug, present significant risks to aquatic ecosystems owing to their persistence and resistance to standard wastewater treatment methods. This study presents the synthesis of a novel gadolinium (Gd) and nickel (Ni) co-doped alginate bead catalyst through in situ co-precipitation and sol-gel techniques, with the objective of improving the photocatalytic degradation efficiency of theophylline in aqueous media. The Gd-Ni nanoparticles were effectively immobilized in alginate matrices, resulting in stable, magnetically separable beads that exhibit enhanced surface area and light absorption characteristics. Batch experiments were performed to evaluate the effects of critical operational parameters such as pH, catalyst dosage, and initial theophylline concentration on degradation performance under visible light irradiation. The optimized 7% Gd-doped Ni-alginate catalyst demonstrated an 84% removal efficiency within 240 minutes, showing enhanced activity relative to non-doped and single-metal-doped alternatives. The photocatalyst exhibited satisfactory reusability across three cycles, showing minimal activity loss. The findings suggest that Gd-Ni nanoparticle-embedded beads may serve as effective and sustainable photocatalysts for the removal of pharmaceutical contaminants from water.

The WO3-Ag3PO4 heterojunction on carbon cloth (CC@WO3-Ag3PO4) was prepared through a facile two step approach. The photocatalysts are evaluated in the degradation of rhodamine B (RhB) under visible light irradiation; CC@WO3-Ag3PO4 exhibited enhanced photocatalytic RhB efficiency. The calculated k for the degradation of RhB over CC@WO3@Ag3PO4 is 0.03097 min−1, which is higher than those for reactions over CC@Ag3PO4 (0.01254 min−1) and CC@WO3 (0.00935 min−1). The photocatalytic efficiency is significantly enhanced after formation of the CC@WO3-Ag3PO4 heterojunction. This could be mainly attributed to improved photogenerated electron-hole pairs separation ability after formation of the CC@WO3-Ag3PO4 heterojunction. Furthermore, the carbon cloth serving as support for photocatalyst can enhance the contact area of the photocatalyst with RhB solution and visible light due to its large specific surface area. Additionally, CC@WO3-Ag3PO4 photocatalyst can be quickly and completely recycled, effectively avoiding recontamination.

Pharmaceutical pollutants, including non-steroidal anti-inflammatory drugs (NSAIDs) and antiretroviral drugs (ARVs), pose a significant threat to aquatic environments, necessitating effective remediation strategies. This comprehensive study delves into the efficacy of nanotechnological approaches, with a special focus on adsorption, in addressing the persistent issue of pharmaceutical pollution in wastewater bodies. The research covers the synthesis and characterization of a multi-template molecularly imprinted polymer (MIP) targeting key pharmaceutical compounds, namely naproxen, ibuprofen, diclofenac, emtricitabine, tenofovir disoproxil, and efavirenz, for extraction from contaminated water sources. Comparative analyses between the synthesized MIP and a commercial Solid Phase Extraction (SPE) cartridge showed comparative performance of the MIP and SPE cartridge in quantifying pharmaceutical compounds present in wastewater samples. The results highlighted both materials' consistent efficiency in the removal of pollutants, with selective pharmaceuticals exhibiting varying levels of removal efficiency during different treatment stages. Regressions analysis showcased high linearity (R2 values ranging from 0.9980 to 0.9999), alongside remarkable recoveries (90.9 % to 100 %) for the MIP and method detection limits (MDLs) ranging from (0.14-1.08 μg L-1) for all target pollutants. Recoveries for SPE samples ranged from (62 % to 98 %) with method detection limits at (0.7-4.68 μg L-1). The optimal conditions for efficient extraction of pharmaceutical compounds using the MIP were determined through a series of experiments, considering factors such as pH, mass, concentration, and contact time. Results showed high extraction efficiencies (>96%) and a notable adsorption capacity (>0.91 mg. g-1) for both ARVs and NSAIDs, confirming the MIP's potential for successful removal of these pollutants from wastewater. Additionally, adsorption kinetics were studied, revealing a second-order rate model and adherence to the Freundlich adsorption isotherm. Furthermore, this study incorporates synthesized MIP into the electrospinning technique, utilizing various polymer blends and optimized solvents to enhance the remediation process. The study explores the electrospun mats morphology, particularly those composed of polyvinyl alcohol (PVA) and polyethylene terephthalate (PET), examining their structural characteristics using techniques such as Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and adsorption time studies. Through merging advanced nanotechnological techniques with electrospinning methodologies, this study presents a robust framework for combating pharmaceutical pollutants in wastewater. The incorporation of the MIP into electrospun mats, coupled with in-depth material characterization and adsorption studies, emphasizes the potential of this innovative approach for environmental remediation and drug purification processes. This research contributes valuable insights into the effective removal and quantification of pharmaceutical pollutants, emphasizing the pivotal role of electrospinning technologies in addressing environmental challenges. In conclusion, this study sheds light on the potential of a multi-template MIP for the removal of ARVs and NSAIDs from contaminated water sources, showcasing its versatility and efficacy in enhancing water treatment processes, as well as its utility in drug purification and recovery processes. Overall, the research provides valuable insights into the complexities of pharmaceutical pollutant removal, emphasizing the significance of selecting appropriate extraction methodologies in wastewater treatment processes to ensure efficient and sustainable remediation practices.

Visible-light photocatalytic efficiencies and anti-photocorrosion behavior of CdS/graphene nanocomposites: Evaluation using methylene blue degradation

MXene coupled graphitic carbon nitride nanosheets based plasmonic photocatalysts for removal of pharmaceutical pollutant

Semiconductor photochemical treatment is expected to be a green technology for solving the environmental issues induced by organic pollutants. WO3 are generally considered as an excellent candidate for visible-light photocatalysts [1-3]. However, the activity of pure WO3 has to be improved due to the rapid recombination of the photogenerated electron-hole pairs. In this work, WO3 was loaded with hybrid MoS2-reduced graphene oxide (MoS2-rGO) to form WO3/MoS2-rGOheterojunction composites, in which MoS2 acts as another efficient light absorbing material and rGO as the charge transfer medium to enhance the photocatalytic efficiency [4-5]. In this work, WO3 was prepared by hydrothermal synthesis method with WCl6 as tungsten source and absolute ethanol as solvent, as shown in Fig. 1(a). Clearly, the synthesized WO3 is a monodispersed microsphere structure with an average size of 2-3um. The hybrid MoS2-rGO was prepared by adding graphene during the hydrothermal synthesis process of MoS2 with Na2MoO4·2H2O and thiourea as reacting materials. As shown in Fig. 1(b), the synthesized MoS2 shows a flower-like structure. Finally, the WO3/MoS2-rGO nanocomposites were also prepared by adding the prepared hybrid MoS2-rGO during the hydrothermal synthesis process of WO3. As shown in Fig. 1(c) and (d), the close contact is clearly seen between the microsphere-like WO3 and flower-like hybrid MoS2-rGO, and the second hydrothermal process had no influence on the structure of WO3 and hybrid MoS2-rGO. X-ray diffraction (XRD) patterns and Raman spectra are respectively measured to determine the crystal structure, as shown in Fig.1 (e) and (f). The photochemical behaviors of WO3/MoS2-rGO nanocomposites containing (0, 2%, 5%, 10%, and 20%) of hybrid MoS2-rGO are characterized through the degradation behaviors of rhodamine (RhB) under visible light irradiation (Fig.2). The experimental results clearly show that the degradation efficiency of WO3/MoS2-rGO nanocomposites can be improved by optimizing the mass ratio of WO3 microspheres to hybrid MoS2-rGO flowers. The degradation ratios of RhB after 6 h are 78.2%, 79.5%, 82.6%, 95.6%, 91.8%, correspond respectively to the WO3/MoS2-rGO nanocomposites containing 0, 2%, 5%, 10%, and 20% of hybrid MoS2-rGO. The possible reason is that the formed WO3/MoS2heterojunction structure and charge transfer medium of rGO is beneficial for separating electron-hole pairs for high efficiency degradation In summary, the WO3 microspheres and different WO3/MoS2-rGO nanocomposites have been prepared and characterized through adjusting the mass ratio of WO3 microspheres to hybrid MoS2-rGO flowers. The results show that the optimized degradation ratio of RhB can be greatly improved from 78.2% up to 95.6% after 6h using WO3/MoS2-rGO nanocomposites in comparison with WO3 microspheres.

Inverse spinel NiFe2O4 deposited g-C3N4 nanosheet for enhanced visible light photocatalytic activity

Rapid industrialization has resulted in a significant presence of pharmaceutical compounds in aqueous effluents, and therefore, effluents must be effectively treated before discharging them to water bodies. The removal of emerging pharmaceutical pollutants in wastewater using TiO2 via photocatalysis technique is limited because of its wide bandgap (≈3.2 eV). Herein, defect state modulation of TiO2 for degradation of pharmaceutical pollutant “antipyrine” under visible light irradiation is investigated. A simple hydrothermal technique for synthesis of TiO2 microspheres (average diameter ≈2.94 μm), followed by chemical reduction method for formation of defective‐TiO2 microspheres using NaBH4 under an inert atmosphere for different durations (3, 5, and 8 h) is used. Defective‐TiO2 microspheres are utilized for photocatalytic degradation of antipyrine under visible light illumination. Improved photocatalytic activity for the defective‐TiO2 samples is observed due to a reduction in bandgap as well as incorporation of Ti3+, acting as a trap site and resulting in reduced electron‐hole recombination. For practical application, a continuous prototype reactor comprising defective‐TiO2 particles immobilized over glass beads is developed and efficient photocatalytic degradation of antipyrine under continuous operation is observed. Excellent recyclability and efficient photocatalytic degradation indicate a promising future for the developed defective‐TiO2 particles toward real‐world wastewater treatment applications.