Magnetic Bi2WO6 nanocomposites: Synthesis, magnetic response and their visible-light-driven photocatalytic performance for ciprofloxacin

Photocatalytic Degradation of Antibiotics via Exploitation of a Magnetic Nanocomposite: A Green Nanotechnology Approach toward Drug-Contaminated Wastewater Reclamation

In the quest for eco-conscious innovations, this research was designed for the sustainable synthesis of magnetite (Fe3O4) nanoparticles, using ferric chloride hexahydrate salt as a precursor and extract of Eucalyptus globulus leaves as both a reducing and capping agent, which are innovatively applied as a photocatalyst for the photocatalytic degradation of antibiotics "ciprofloxacin and amoxicillin". Sugar cane bagasse biomass, sugar cane bagasse pyrolyzed biochar, and magnetite/sugar cane bagasse biochar nanocomposite were also synthesized via environmentally friendly organized approaches. The optimum conditions for the degradation of ciprofloxacin and amoxicillin were found to be pH 6 for ciprofloxacin and 5 for amoxicillin, dosage of the photocatalyst (0.12 g), concentration (100 mg/L), and irradiation time (240 min). The maximum efficiencies of percentage degradation for ciprofloxacin and amoxicillin were found to be (73.51%) > (63.73%) > (54.57%) and (74.07%) > (61.55%) > (50.66%) for magnetic nanocomposites, biochar, and magnetic nanoparticles, respectively. All catalysts demonstrated favorable performance; however, the "magnetite/SCB biochar" nanocomposite exhibited the most promising results among the various catalysts employed in the photocatalytic degradation of antibiotics. Kinetic studies for the degradation of antibiotics were also performed, and notably, the pseudo-first-order chemical reaction showed the best results for the degradation of antibiotics. Through a comprehensive and comparative analysis of three unique photocatalysts, this research identified optimal conditions for efficient treatment of drug-contaminated wastewater, thus amplifying the practical significance of the findings. The recycling of magnetic nanoparticles through magnetic separation, coupled with their functional modification for integration into composite materials, holds significant application potential in the degradation of antibiotics.

Cd-doped Ag2O/BiVO4 visible light Z-scheme photocatalyst for efficient ciprofloxacin degradation

Foreign element doping can produce new photocatalysts with different band edge positions and adsorption properties. A composite of such a doped semiconductor with another component should enhance its photocatalytic properties towards a target substrate. The present investigation used a simple hydrothermal protocol to prepare Cd-doped Ag2O nanoparticles. The Cd-doping of Ag2O nanoparticles changed its valence band maximum position from 0.8 eV (for undoped Ag2O nanoparticles) to 2.67 eV with a slight narrowing of the Ag2O bandgap. A combination of DFT calculation and XRD results showed that the dopant Cd substituted Ag in the Ag2O lattice. The doped material is an effective photocatalyst for ciprofloxacin degradation but with poor recyclability. The joining of a BiVO4 part to the Cd-doped Ag2O nanostructures gave a composite with improved photocatalytic activity and recyclability towards ciprofloxacin degradation. DFT calculations showed that BiVO4 has a higher oxygen affinity than Cd-doped Ag2O. The XPS characterization of the composite and appropriate active species scavenger experiments demonstrated a Z-scheme mechanism. Superoxide radicals play a critical role in CIP degradation.

Plasmonic Bi promotes the construction of Z-scheme heterojunction for efficient oxygen molecule activation

Reactive oxygen species (ROS) are essential to photocatalytic degradation of antibiotics in water. In this work, we prepared Ag₃PO₄/Bi@Bi₄Ti₃O₁₂ by simple in-situ reduction method and precipitation method, which improves the ability to capture visible light and increases the activity of photoinduced molecular oxygen activation, resulting in reactive oxygen species (ROS) such as superoxide radicals (•O₂^-), hydroxyl radicals (•OH), and H₂O₂. The excellent TC degradation efficiency derive from the SPR effect of the metal Bi on the surface enhances the light absorption intensity, and development of a Z-scheme heterojunction between Ag₃PO₄ and Bi₄Ti₃O₁₂ promotes the activation of molecular oxygen. A possible photodegradation mechanism of the as-prepared photocatalyst was proposed. This work provides an insight perspective to the synthesis photocatalysts with molecular oxygen activation for environmental remediation.

Enhanced solar-light-driven photocatalytic and photoelectrochemical properties of zinc tungsten oxide nanorods anchored on bismuth tungsten oxide nanoflakes

At present, sustainable water supply and energy generation are the most important challenges faced by humankind globally. Thus, it is crucial to progress ecological techniques for sustainable removal of organic pollutants from wastewater and generation of hydrogen as an alternative to fossil fuels. In this study, zinc tungsten oxide (ZnWO₄) nanorods, bismuth tungsten oxide (Bi₂WO₆) nanoflakes, and Bi₂WO₆/ZnWO₄ (BO-ZO) nanocomposites were prepared via a simple hydrothermal approach. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, diffuse reflectance spectroscopy, and electrochemical analyses were conducted to confirm the formation of the BO-ZO heterostructure. The structural and morphological analyses revealed that the ZnWO₄ nanorods were moderately dispersed on the Bi₂WO₆ nanoflakes. The bandgap tuning of BO-ZO nanocomposite confirmed the establishment of the heterostructure with band bending properties. The BO-ZO nanocomposite could degrade 99.52% of methylene blue (MB) within 60 min upon solar-light illumination. The photoelectrochemical (PEC) measurement results showed that the BO-ZO nanocomposite showed low charge-transfer resistance and high photocurrent response with good stability. The BO-ZO photoanode showed a low charge-transfer resistance of 35.33 Ω and high photocurrent density of 0.1779 mA/cm² in comparison with Ag/AgCl in a 0.1 M Na₂SO₃ electrolyte under solar-light illumination. The MB photocatalytic degradation and PEC water oxidation mechanisms of the nanocomposite were investigated.

Effective Visible Light-Driven Photocatalytic Degradation of Ciprofloxacin over Flower-like Fe3O4/Bi2WO6 Composites

Photocatalytic degradation of organic pollution is a vital path to deal with environmental problems. Here, a direct Z-scheme 2D/2D heterojunction of a Fe₃O₄/Bi₂WO₆ photocatalyst is fabricated for the degradation of ciprofloxacin by a self-assembly strategy. Furthermore, to characterize the morphology of the obtained composite photocatalysts, various kinds of characterization methods were employed like XRD, XPS, SEM, and TEM. It is indicated that the flower-like photocatalyst is composed of nanosheets. Comparable photocatalysts were prepared by controlling the hydrothermal temperature and the iron content. In the photocatalytic degradation of ciprofloxacin (CIP) in water, under visible light irradiation, FB-180 (synthesized at 180 °C with 4% iron content) presents approximately 99.7% degradation efficiency in only 15 min. Meanwhile, during photocatalytic degradation reactions, the Fe₃O₄/Bi₂WO₆ heterojunction also displayed excellent stability, which still kept above 90% degradation efficiency after five consecutive cycles. UV-Vis DRS and M-S analyses showed that the Fe₃O₄/Bi₂WO₆ catalyst has a strong visible light absorption capacity and the transfer pathway of photo-induced charge carriers. PL, EIS, and TPR showed that Fe₃O₄/Bi₂WO₆ has an efficient separation and transfer rate of the photo-generated carriers. ESR analysis proved that the superoxide radical (^•O₂ ^-) and hydroxyl radical (^•OH) play a major role in the Fe₃O₄/Bi₂WO₆ photocatalytic system. This special 2D/2D heterojunction we proposed may have huge potential for marine pollution treatment by photocatalysis degradation with dramatically boosted activities.

Synthesis of Novel Kaolin-Supported g-C3N4/CeO2 Composites with Enhanced Photocatalytic Removal of Ciprofloxacin

Herein, novel ternary kaolin/CeO₂/g-C₃N₄ composite was prepared by sol-gel method followed by hydrothermal treatment. The self-assembled 3D “sandwich” structure consisting of kaolin, CeO₂ and g-C₃N₄ nanosheets, was systematically characterized by appropriate techniques to assess its physicochemical properties. In the prerequisite of visible-light irradiation, the removal efficiency of ciprofloxacin (CIP) over the kaolin/CeO₂/g-C₃N₄ composite was about 90% within 150 min, 2-folds higher than those of pristine CeO₂ and g-C₃N₄. The enhanced photocatalytic activity was attributed to the improved photo-induced charge separation efficiency and the large specific surface area, which was determined by electrochemical measurements and N₂ physisorption methods, respectively. The synergistic effect between the kaolin and CeO₂/g-C₃N₄ heterostructure improved the photocatalytic performance of the final solid. The trapping and electron paramagnetic resonance (EPR) experiments demonstrated that the hole (h⁺) and superoxide radicals (•O₂⁻) played an important role in the photocatalytic process. The photocatalytic mechanism for CIP degradation was also proposed based on experimental results. The obtained results revealed that the kaolin/CeO₂/g-C₃N₄ composite is a promising solid catalyst for environmental remediation.