Chamnan Randorn

Catalytic and antibacterial activities of novel colored zinc borophosphate glasses

In this report, we demonstrated the catalytic activity of colored zinc borophosphate glasses, specifically their photocatalytic activity. The catalytic activity of the colored zinc borophosphate glasses was investigated using four different methods, including photooxidation reactions, photoreduction reaction, antibacterial testing, and radical polymerization. Novel colored zinc borophosphate glasses were synthesized by a conventional melt-quenching technique at 1200 °C. The obtained zinc borophosphate glasses were white, purple and dark green, depending on the metal oxide colorants in the glass matrix. These colored zinc borophosphate glasses improved water dissolution, which is an inherent limitation of pure phosphate glasses. Characterization of the glasses was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman and UV-Visible spectroscopy.

Photocatalytic degradation of methylene blue by C3N4/ZnO: the effect of the melamine/ZnO ratios

The C3N4/ZnO composite photocatalysts were synthesized by mechanical milling combined with a calcination process. Various ratios of melamine and ZnO powders were milled by a planetary ball mill for 10 h. After heating at 540∘C for 3 h in air, melamine was converted to C3N4 but the formation of C3N4 depended on the ratios of the melamine and ZnO (M/Z) powders. From the experimental results, the conversion of melamine to C3N4 could be inhibited by ZnO particles; as there was no detectable C3N4 in the sample at low M/Z values or high ZnO contents. The photocatalytic activities of prepared samples were investigated under the illumination of blacklight and fluorescent lamps as the low wattage light source. The C3N4/ZnO showed a better photocatalytic activity than ZnO to degrade a methylene blue (MB) dye solution using blacklight lamps, but there is no significant difference in photocatalytic activities between ZnO and prepared C3N4/ZnO under visible light by the fluorescent lamps. However, the prepared C3N4/ZnO can well function under illumination by Xe lamp as the high power light source. Ecotoxicities of MB solutions before and after photocatalytic process were also studied through growth inhibition of the alga Chlorella vulgaris.

Effects of Electrode on Dielectric Properties of Barium Iron Niobate Ceramics Doped with Gallium Oxide

Ba (Fe0.8Ga0.2)0.5Nb0.5O3 ceramics were synthesized via a solid state reaction method. The Raman spectrum analysis indicated that the sample presented a cubic structure. Dielectric measurement on the ceramics with Ag-paste and Au-sputtered electrodes showed that all ceramic samples exhibited very high dielectric constants with a strong frequency dispersion. The Au-sputtered electrode samples presented higher dielectric tunability the dielectric constant than Ag-paste electrode samples.This behaviour was related with the electrode effect, occured in the studied samples.