Novel fabrication of the recyclable MoS2/Bi2WO6 heterostructure and its effective photocatalytic degradation of tetracycline under visible light irradiation

Bi2WO6 nanoparticles anchored on membrane by grafting via in-situ polymerization for the treatment of antibiotic and pesticides wastewater

Antibiotics, natural organic matter, and pesticides are detected in the ecosystem's domestic water, surface water, and groundwater and are largely applied in pharmaceuticals and agriculture. Polymeric membranes are effectively remove the various pollutants in the water bodies, but fouling is one of the major limitations of commercial membranes. Herein, we modified the polymeric membrane surface with inorganic photocatalytic nanoparticles. In this work, the hydrothermal method is used for the synthesis of Bi2WO6 nanoparticles and as-synthesized nanoparticles grafted onto the various polymeric membranes, including polyetherimide (PEI), cellulose acetate (CA), polyvinylidene fluoride (PVDF), and polysulfone (PSF). The functional group studies confirmed the existence of nanoparticles and hydroxyl groups on the hybrid membrane. Further, finger-like voids, top-surface morphology, and roughness on the membrane surface were validated via Field Emission Scanning Electron Microscopy (FESEM) and Atomic force microscopy (AFM), respectively. The significant rejection of tetracycline, humic acid, and fulvic acid + atrazine was noted with the synthesized membranes in the following order: PVDF (81.1%, 78.8%, 80.6%) > CA (70.1%, 69.3%, 71.7%) > PSF (72.5%, 73.6%, 67.1%) > PEI (75.9%, 65.5%, 63.7%). The photodegradation efficiency of hybrid membranes against tetracycline, humic acid, and fulvic acid + atrazine was observed in the order: PEI (28.5%, 25.8%, 30.2%) < CA (46.5%, 42.4%, 40.5%) < PSF (46.9%, 37.7%, 44.7%) < PVDF (67.7%, 62.1%, 64.3%). These membranes exhibit an outstanding permeate flux recovery ratio to the neat membrane. Therefore, the grafting of Bi2WO6 nanoparticles creates a potential bonding with PVDF membranes than other polymeric membranes, thus exhibiting an outstanding rejection than hybrid and neat membranes.

Photocatalytic boron nitride-based nanomaterials for the removal of selected organic and inorganic contaminants in aqueous solution: A review

Boron nitride (BN) coupled with various conventional and advanced photocatalysts has been demonstrated to exhibit extraordinary activity for photocatalytic degradation because of its unique properties, including a high surface area, constant wide-bandgap semiconducting property, high thermal-oxidation resistance, good hydrogen-adsorption performance, and high chemical/mechanical stability. However, only limited reviews have discussed the application of BN or BN-based nanomaterials as innovative photocatalysts, and it does not cover the recent results and the developments on the application of BN-based nanomaterials for water purification. Herein, we present a complete review of the present findings on the photocatalytic degradation of different contaminants by various BN-based nanomaterials. This review includes the following: (i) the degradation behavior of different BN-based photocatalysts for various contaminants, such as selected dye compounds, pharmaceuticals, personal care products, pesticides, and inorganics; (ii) the stability/reusability of BN-based photocatalysts; and (iii) brief discussion for research areas/future studies on BN-based photocatalysts.

Bismuth Tungstate Nanoplates-Vis Responsive Photocatalyst for Water Oxidation

The development of visible-light-responsive (VLR) semiconductor materials for effective water oxidation is significant for a sustainable and better future. Among various candidates, bismuth tungstate (Bi2WO6; BWO) has attracted extensive attention because of many advantages, including efficient light-absorption ability, appropriate redox properties (for O2 generation), adjustable morphology, low cost, and profitable chemical and optical characteristics. Accordingly, a facile solvothermal method has been proposed in this study to synthesize two-dimensional (2D) BWO nanoplates after considering the optimal preparation conditions (solvothermal reaction time: 10-40 h). To find the key factors of photocatalytic performance, various methods and techniques were used for samples' characterization, including XRD, FE-SEM, STEM, TEM, HRTEM, BET-specific surface area measurements, UV/vis DRS, and PL spectroscopy, and photocatalytic activity was examined for water oxidation under UV and/or visible-light (vis) irradiation. Famous commercial photocatalyst-P25 was used as a reference sample. It was found that BWO crystals grew anisotropically along the {001} basal plane to form nanoplates, and all properties were controlled simultaneously by tuning the synthesis time. Interestingly, the most active sample (under both UV and vis), prepared during the 30 h solvothermal reaction at 433 K (BWO-30), was characterized by the smallest specific surface area and the largest crystals. Accordingly, it is proposed that improved crystallinity (which hindered charge carriers' recombination, as confirmed by PL), efficient photoabsorption (using the smallest bandgap), and 2D mesoporous structure are responsible for the best photocatalytic performance of the BWO-30 sample. This report shows for the first time that 2D mesoporous BWO nanoplates might be successfully prepared through a facile template-free solvothermal approach. All the above-mentioned advantages suggest that nanostructured BWO is a prospective candidate for photocatalytic applications under natural solar irradiation.

Type-1 α-Fe2O3/TiO2 photocatalytic degradation of tetracycline from wastewater using CCD-based RSM optimization

Antibiotic pollution in water is a growing threat to public health and the environment, leading to the spread of antimicrobial-resistant bacteria. While photocatalysis has emerged as a promising technology for removing antibiotics from water, its limited efficiency in the visible light range remains a challenge. In this study, we present a novel method for the photocatalytic degradation of tetracycline, the second most commonly used antibiotic worldwide, using α-Fe₂O₃/TiO₂ nanocomposites synthesized via rapid sonochemical and wet impregnation methods. The nanocomposites were characterised and tested using a range of techniques, including BET, TEM, FTIR, XRD, FESEM, EDS, and UV-Vis. The RSM-CCD method was also used to optimize the degradation process by varying four key variables (initial concentration, photocatalyst quantity, irradiation time, and pH). The resulting optimized conditions achieved a remarkable degradation rate of 97.5%. We also investigated the mechanism of photodegradation and the reusability of the photocatalysts, as well as the effect of light source operating conditions. Overall, the results demonstrate the effectiveness of the proposed approach in degrading tetracycline in water and suggest that it may be a promising, eco-friendly technology for the treatment of water contaminated with antibiotics.

Recent Progress in Photocatalytic Removal of Environmental Pollution Hazards in Water Using Nanostructured Materials

Water pollution has become a critical issue because of the Industrial Revolution, growing populations, extended droughts, and climate change. Therefore, advanced technologies for wastewater remediation are urgently needed. Water contaminants are generally classified as microorganisms and inorganic/organic pollutants. Inorganic pollutants are toxic and some of them are carcinogenic materials, such as cadmium, arsenic, chromium, cadmium, lead, and mercury. Organic pollutants are contained in various materials, including organic dyes, pesticides, personal care products, detergents, and industrial organic wastes. Nanostructured materials could be potential candidates for photocatalytic reduction and for photodegradation of organic pollutants in wastewater since they have unique physical, chemical, and optical properties. Enhanced photocatalytic performance of nanostructured semiconductors can be achieved using numerous techniques; nanostructured semiconductors can be doped with different species, transition metals, noble metals or nonmetals, or a luminescence agent. Furthermore, another technique to enhance the photocatalytic performance of nanostructured semiconductors is doping with materials that have a narrow band gap. Nanostructure modification, surface engineering, and heterojunction/homojunction production all take significant time and effort. In this review, I report on the synthesis and characterization of nanostructured materials, and we discuss the photocatalytic performance of these nanostructured materials in reducing environmental pollutants.