Gulin Selda Pozan Soylu

Photocatalytic degradation of 2,4-dichlorophenol with V2O5-TiO2 catalysts: Effect of catalyst support and surfactant additives

Binary oxide catalysts with various weight percentage V2O5 loadings were prepared by solid-state dispersion and the nanocomposites were modified with surfactants. The catalysts were analyzed using X-ray diffraction, diffuse-reflectance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption-desorption. The photocatalytic activities of the catalysts were evaluated in the degradation of 2,4-dichlorophenol under ultraviolet irradiation. The photocatalytic activity of 50 wt% V2O5-TiO2 (50V2O5-TiO2) was higher than those of pure V2O5, TiO2, and P25. Interactions between V2O5 and TiO2 affected the photocatalytic efficiencies of the binary oxide catalysts. Cetyltrimethylammonium bromide (CTAB) and hexadecyltrimethylammonium bromide (HTAB) significantly enhanced the efficiency of the 50V2O5-TiO2 catalyst. The highest percentage of 2,4-dichlorophenol degradation (100%) and highest reaction rate (2.22 mg/(L·min)) were obtained in 30 min with the (50V2O5-TiO2)-CTAB catalyst. It is concluded that the addition of a surfactant to the binary oxide significantly enhanced the photocatalytic activity by modifying the optical and electronic properties of V2O5 and TiO2.

V2O5-TiO2 heterostructural semiconductors: Synthesis and photocatalytic elimination of organic contaminant

V2O5-TiO2 binary oxide catalysts were successfully prepared with different wt% V2O5 loading by solid state mechanical mixing (SSDMMix), and these nanocomposites were modified with hexadecyltrimethylammonium bromide (HTAB) and cetyl trimethylammonium bromide (CTAB) and polyvinyl alcohol (PVA) as surfactant. The resulting catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Braun-Emmet-Teller (BET) analysis of surface area techniques. The photocatalytic activities of all samples were evaluated by degradation of 4-chlorophenol (4CP) in aqueous solution under UV irradiation. 50 wt% V2O5-TiO2 photocatalyst exhibited much higher photocatalytic activity than pure V2O5, TiO2 and P-25. The interaction between V2O5 and TiO2 affected the photocatalytic efficiency of binary oxide catalysts. In addition, CTAB and HTABassisted samples significantly enhanced the efficiency of 50V2O5-TiO2 binary oxide catalyst. The highest percentage of 4-chlorophenol degradation (100%) and highest reaction rate (1.69mg L−1 min−1) were obtained in 30 minutes with (50V2O5-TiO2)-CTAB catalyst. It is concluded that the addition of surfactant to binary oxide remarkably enhanced the photocatalytic activity by modifying the optical and electronic properties of V2O5 and TiO2.

Formation and distribution of ZnO nanoparticles and its effect on E. coli in the presence of sepiolite and silica within the chitosan matrix via sonochemistry

In this study, a new bio-nanocomposite was prepared and characterized with a focus on the formation of hexagonal ZnO and orthorhombic zinc silicate (Zn2SiO3(OH)2) phases under ultrasonic irradiation. Chitosan/sepiolite/ZnO and chitosan/silica/ZnO bio-nanocomposites were synthesized using a simple solution method in which extreme physical and chemical conditions created by cavitation within the chitosan solution allowed for the transformation of aqueous Zn(OH)2 to crystallized ZnO and Zn2SiO3(OH)2 in room temperature. Both the loading of sepiolite and silica with the zinc precursor significantly influenced the morphology and crystalline structure of the product, however, different zinc compounds were observed. Sepiolite was exfoliated, resulting in a fine, even colloidal solution through ultrasonic dispersion. Exfoliation of sepiolite nanofibers led to the homogeneous dispersion of Zinc in the form of Zn(OH)2 in chitosan matrix. When the same procedure was conducted using the silica component, a formation of ZnO and Zn2SiO3(OH)2 was observed, components that were not observed when the procedure was conducted using sepiolite. The average crystalline size of ZnO was calculated as 36nm for ZnO. In addition, the quantities of crystalline and the ZnO phase volume was determined as 15%. Through zone of inhibition, the silica nanocomposite was discovered to have antibacterial activity. In contrast, the sepiolite compound did not exhibit these properties. We thus hypothesize that HO radicals, formed during ultrasonic irradiation trigger the formation of a silicate ion (SiO32-) and formation of ZnO and Zn2SiO3(OH)2 species in chitosan/silica/ZnO bio-nanocomposite, which causes to exhibit these antibacterial properties against Gram-negative E. coli. Chemical characterization and dispersion of the structure of the ZnO and Zn2SiO3(OH)2 phases were done using X-ray diffraction (XRD) and scanning electron microscopy techniques (SEM) with EDAX and X-ray photoelectron spectroscopy (XPS).

Preparation of surfactant-modified ZnTiO3–TiO2 nanostructures and their photocatalytic properties under sunlight irradiation

A series of ZnTiO3–TiO2 mixed oxide nanoparticles were successfully synthesized using a simple sol–gel technique and modified with hexadecyl trimethyl ammoniumbromide, sodium dodecyl sulfate, N-cetyl-NNN-trimethyl ammonium bromide as surfactant. The samples were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FT-IR), diffuse reflectance spectra (DRS) and scanning electron microscopy techniques (SEM). The photocatalytic activity of samples was investigated by degradation of 4-chlorophenol in water under sunlight and ultraviolet irradiation. The sodium dodecyl sulfate-assisted sample was found to exhibit much higher photocatalytic activity than the other surfactants. The highest photocatalytic efficiency (100 %) was obtained with ZnTi-sodium dodecyl sulfate sample in 60 min. Hexagonal form of ZnTiO3 is found to be more effective for photodegradation. Meanwhile, the processing parameters such as the light source and the amount of surfactant play an important role in tuning the photocatalytic activity. The enhancement of photocatalytic activity for ZnTi-sodium dodecyl sulfate may be attributed to its small particle size, the presence of more surface OH groups, lower band gap energy than no surfactant included sample and the presence of more hexagonal ZnTiO3 phase in the morphology.Graphical Abstract

Toluene Combustion over Metal Oxide Washcoated Monolithic Catalyst

Catalytic combustion of toluene over ceramic monolith supported Mn, Fe, Co, Cu and Zr oxide-based catalysts has been investigated. The catalysts were prepared by washcoating and characterized by Scanning Electron Microscopy (SEM) technique. The adhesion of the washcoat was evaluated using an ultrasonic technique. The increase in activity was followed by increasing metal oxide content. 6.5MnO2/CM (CM: ceramic monolith) catalyst exhibited the highest catalytic activity, over which the toluene conversion is up to 90 percent at a temperature of 291°C.