Coconut Fiber Decorated with Bismuth Vanadate for Enhanced Photocatalytic Activity.

Bismuth vanadate/coconut fiber (BiVO4/CF) composites were synthesized by coprecipitation and calcination methods. All catalysts used in this work were prepared by a simple coprecipitation method and fully characterized by means of XRD, SEM-EDS, PL, BET N2 adsorption, zeta potential, and UV-vis DRS. Degradation of indigo carmine (IC) under visible light irradiation was tracked by the UV-vis technique. It was documented that XRD patterns of BiVO4 and BiVO4/CF samples retained the monoclinic structure. From SEM, the CF sheets were visualized, covering the surface of BiVO4 particles. The specific surface area of the synthesized catalysts increased from 1.77 to 24.82 m2/g. The shift of absorption edge to a longer wavelength corresponded to a decrease in band gap energy from 2.3 to 2.2 eV. The photocatalytic degradation rate of the BiVO4/CF composite was five times higher than that of pristine BiVO4. Moreover, the photocatalyst can be separated and recycled with little change after the third times recycling. The improved activity of the composite resulted from the combination of the adsorption performance of the substrate CF and the photocatalytic activity of BiVO4. In addition, the position of the specific mechanism could occur via both the active species of superoxide radical and hydroxyl radical.

Synthesis and Characterization of WO3/CeO2 Heterostructured Nanoparticles for Photodegradation of Indigo Carmine Dye.

WO3/CeO2 heterostructured nanocomposites containing different WO3 ratios (0.1, 0.3, 0.5, and 1.0 wt %) were synthesized by a precipitation method. The coupling of CeO2 and WO3 with a high specific surface area noticeably enhanced the photocatalytic activity of indigo carmine (IC) degradation under visible-light irradiation. The degradation rate constants (k) of 0.5 wt % WO3/CeO2 nanocomposites reached 4 and 5 times higher than those of CeO2 and WO3, respectively. Regarding the experimental results, the X-ray diffraction (XRD) patterns of the CeO2 spherical nanoparticles and rod-shaped WO3 were assigned to the cubic fluorite and orthorhombic phase structures, respectively. The increasing photocatalytic activity of nanocomposite samples could be attributed to the heterojunction of the photocatalysts with efficient charge separation and strong oxidative ability, which were confirmed by the photoluminescence spectra and diffuse reflectance spectrometry. The staggered heterojunction of the nanocomposite promoted efficient electron transfer and suppressed the recombination of photogenerated electrons and holes during the process.

Glutamate Decarboxylase (GAD) Extracted from Germinated Rice: Enzymatic Properties and Its Application in Soymilk.

Glutamate decarboxylase (GAD) is an important enzyme in biological metabolisms acting on catalyzing the irreversible α-decarboxylation of L-glutamic acid to γ-aminobutyric acid (GABA) and CO2, which was focused in this study. Three rice varieties different in color were germinated at different times and used for crude GAD extraction. Crude GADs with an optimal germination time from germinated black (GBR), red (GRR), and white (GWR) rice were evaluated for enzymatic properties, including the effect of pHs, temperatures, and concentrations of both L-glutamic acid and pyridoxal 5'-phosphate (PLP). Crude GAD with optimum enzymatic properties was selected to be partially purified using ammonium sulfate (AMS) precipitation. The obtained GAD was supplemented to soymilk and determined for GABA content. All crude GADs from germinated rice at 10 germination days presented the highest enzyme activity. For enzymatic properties, crude GADs showed the highest activity at pH in a range of 5.6-6.0 at 60ºC. The Km values of crude GADs were in the range of 7.68-8.06 mM for L-glutamic acid and 0.15-0.20 µM for PLP and were the lowest in crude GAD from GBR. GAD from GBR presented the highest enzyme activity in the fraction with 50% saturation (v/v) after AMS precipitation and it was purified for 14.61 folds. The addition of this GAD (1.0%, v/v) resulted in the increasing of GABA content in soymilk to 53.79 mg/100 mL, accounted for 1.23 times compared with control.

Adsorption and Photocatalytic Processes of Mesoporous SiO2-Coated Monoclinic BiVO4.

The silicon dioxide (SiO2)-coated bismuth vanadate (BiVO4) composites as visible-driven-photocatalysts were successfully synthesized by the co-precipitation method. The effects of SiO2 coating on the structure, optical property, morphology and surface properties of the composites were investigated by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and Brunauer-Emmette-Teller (BET) measurements. The photocatalytic activity of monoclinic BiVO4 and BiVO4/SiO2 composites were evaluated according to the degradation of methylene blue (MB) dye aqueous solution under visible light irradiation. The SiO2-coated BiVO4 composites showed the enhancing photocatalytic activity approximately threefold in comparison with the single phase BiVO4.