Catalytic ozonation with vanadium oxide-doped TiO2 nanoparticles for the removal of di-2-ethylhexyl phthalate

Among various plastic additives, di-2-ethylhexyl phthalate (DEHP) has been a great concern due to its high leaching potential and harmful effects on both human and the ecosystem. For the effective oxidation and mineralization of DEHP by ozone in the existing TiO₂ catalytic processes, the heterogeneous catalyst, vanadium oxide (V₂O₅)-incorporated TiO₂ (V₂O₅/TiO₂), was synthesized. The generation of hydroxyl radicals was promoted by cyclic redox reactions of vanadium atoms in V₂O₅/TiO₂ via the increase of surface oxygen vacancies by the replacement of V⁵⁺ species in the lattice of TiO₂. The catalytic ozonation in the presence of V₂O₅/TiO₂ exhibited the significantly higher degradation of DEHP with the pseudo-second-order kinetic constant of 1.7 × 10⁵ mM^-1min^-1 and the removal efficiency of 58.7% after 60 s in 2 mg/L of ozone. The degradation of DEHP was initiated by the shortening of the alkyl-side chain followed by the opening of esterified benzene moieties.

Synthesis and application of V2O5-CeO2 nanocomposite catalyst for enhanced degradation of methylene blue under visible light illumination

Methylene blue dye is among the toxic, mutagenic, and carcinogenic pollutants. Hence, its treatment via photocatalytic degradation is an important remediation method for the sake of a healthy environment. Herein, the V₂O₅-CeO₂ nanocomposite catalysts were synthesized via a simple precipitation-thermal decomposition approach and used for the photodegradation of methylene blue in the presence of H₂O₂ as an effective electron scavenger under visible light illumination. The nanocomposite catalysts were systematically characterized to investigate the effects of V₂O₅ with the aids of X-ray, morphology, light absorption, catalytic activity, and charge transfer properties of the nanocomposite catalysts. The VC-2 nanocomposite prepared with NH₄VO₃:CeO₂ molar ratios at 0.15:1 was found to be the best efficient catalyst where ≥98% of methylene blue was degraded within 25 min irradiation time. From the kinetics analysis, its rate constant was found to be higher than those of the pure V₂O₅ and CeO₂ catalysts by a factor of 12.0 and 13.5, respectively. The plausibly mechanistic elucidation of charge transfer and utilization of reactive species are conspicuous allegations of the combined effects of the nanocomposite catalyst, H₂O₂ sacrificial agent, and visible light for the photodegradation of the dye.

Zinc oxide/vanadium pentoxide heterostructures with enhanced day-night antibacterial activities

Low photocatalytic efficiency of visible light and fast recombination of photo-generated carriers are two challenges facing the applications of photocatalyst sterilant zinc oxide (ZnO). Meanwhile, both light and dark photocatalytic activities are important. It is of great theoretical and practical significance to construct a day-night photocatalytic antibacterial material, which is beneficial to the effective use of energy and to tackle the limitation of using photocatalytic bacteriostat. ZnO nanoflowers decorated vanadium pentoxide (V₂O₅) nanowires heterojunction (ZVH) was firstly fabricated using a facile water-bathing method. The designed ZVH structure efficiently produced abundant reactive oxygen species (ROS) in both light and darkness. It yielded 99.8% and 99.0% of antibacterial rate against S. aureus due to oxidative stress induced by ROS in light and darkness, respectively. The generation of ROS played a major role in the antibacterial activities against S. aureus under both light and dark conditions. The prepared ZVH with improved antibacterial properties provides an alternative for day-night antibacterial agents.

Sonochemical assisted hydrothermal synthesis of pseudo-flower shaped Bismuth vanadate (BiVO4) and their solar-driven water splitting application

Bismuth vanadate (BiVO₄) is a well-known photocatalyst due to its lower bandgap (E_g) and visible electromagnetic light absorption capacity. Herein, we reported the pulse ultra-sonochemical assisted hydrothermal approach to synthesize S-BiVO₄. For the comparison purpose, H-BiVO₄ is also synthesized via conventional hydrothermal approach. The surface morphology of S-BiVO₄ through scanning electron microscope (SEM) indicates condensed microarrays (MAs) having pseudo-flower shapes. The energy dispersive X-rays (EDX) spectrum also confirmed the elemental percent composition of Bi, V and O in BiVO₄. X-rays diffraction (XRD) pattern further confirmed the monoclinic scheelite phase of S-BiVO₄. Fourier transformed infrared (FTIR) spectrum showed Bi-O and Bi-V-O vibrational bands at 1382 and 1630cm^-1, respectively. The diffuse reflectance spectroscopy (DRS) indicated absorption edge at ∼515nm, corresponds to bandgap value (E_g) of 2.41eV, which is suitable range for water splitting applications. The photocurrent density from water splitting under artificial 1 SUN visible light source found at 60 and 50μA/cm² for S-BiVO₄ and H-BiVO₄, respectively. The stability test through chronoamperometry showed that S-BiVO₄ was more stable than H-BiVO₄. It can be depicted from the growth mechanism that ultrasonication played a definite role in the overall synthesis of pseudo-flower shaped S-BiVO₄ MAs.

One-step hydrothermal synthesis of novel Ag3VO4/Ag4V2O7 composites for enhancing visible-light photocatalytic performance

The novel Z-scheme Ag₃VO₄/Ag₄V₂O₇ heterojunction photocatalysts which constructed by one-step hydrothermal method had stable visible-light-driven photocatalytic performance and high efficiency.