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Titanium dioxide/graphene aerogel (TiO2/GA) was synthesized via a one-pot hydrothermal method and characterized by various spectroscopic techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscopy, Raman spectroscopy, and UV-Vis spectroscopy. The influences of pH and TiO2/GA dose on the photocatalytic performance were investigated against positive dye methylene blue (MB) under UV light control. The characterization of TiO2/GA revealed that the synthesized TiO2 nanosize of 12–22.5 nm was uniformly distributed onto the graphene layers. The bandgap of the as-prepared nanocomposite was 2.63 eV, lower than that of pure TiO2 (3.2 eV). The kinetic studies exhibited that the adsorption–desorption equilibrium was achieved after 60 min following the pseudo-second-order. Meanwhile, 99.9% of MB was eliminated after 120 min at pH 9 with a 20 mg catalyst. The degradation data were well fitted to the pseudo-first-order kinetic model. Accordingly, applying TiO2/GA as an efficient photocatalyst indicates a potential pathway for the degradation of organic contaminants in wastewater treatment.

In this study, graphene oxide (GO) was synthesized using the improved Hummers’ method, and reduce graphene oxide (rGO) was synthesized from GO with hydrazine hydrate as reducing agent. Zinc oxide (ZnO) was synthesized from zinc acetate using the precipitation method. Zinc oxide/reduced graphene oxide (ZnO/rGO) composites were synthesized using the ex-situ method. The ZnO/rGO composites with different rGO weight percents (0.05, 0.1, 0.5, 1, and 5 wt%) were used for fabrication of ZnO/rGO anodes. A control anode was fabricated from ZnO (ZnO anode). The band gaps of fabricated anodes were measured using the ultraviolet-visible spectroscopy (UV-vis). The dye-sensitized solar cells (DSSCs) were assembled and investigated by current density-voltage (J-V) curves and electrochemical impedance spectroscopy (EIS). The ZnO/rGO composite with appropriate rGO content was determined to be 1 wt%, with the efficiency of 1.55 %. The Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD) results confirmed wurzite structure of ZnO and the reduction of functional groups of GO to create rGO and ZnO/rGO. The transmission electron microscopy (TEM) showed that the ZnO nanoparticles with size of 10 - 20 nm were evenly distributed on rGO sheets. These results indicated that ZnO/rGO could be the potential material to improve the efficiency of DSSCs.

In this study, magnetic iron oxide/graphene oxide Fe3O4/GO)nanocomposites were prepare by in situ method. It was found that the suitable ratio of Fe3O4/GO for lead ions (Pb2+) removal was 2:1 (FGO2).

Red Ganoderma lucidum (G. lucidum) is a popular medicinal herb commonly used in Vietnamese traditional remedies due to its potential value for health. In this study, polysaccharides were extracted from G. lucidum using ultrasound-assisted enzymatic extraction method. The response surface methodology and Box-Behnken design were employed to investigate the effects of pH, extraction temperature, extraction time, and ultrasonic power on the content of polysaccharides. Based on ultraviolet-visible spectroscopy analysis, the highest content of polysaccharides in the extract was 32.08 mg/g under optimum experimental parameters including enzyme concentration of 3%, pH of 5.5, extraction temperature of 45°C, extraction time of 30 min, and ultrasonic power of 480 W. The Fourier-transform infrared spectroscopy was also used to identify the functional groups in the extracts. The molecular weights of polysaccharides were determined by gel permeation chromatography. The obtained extract was then evaluated for anticancer activities by using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, showing the anticancer activities with the half-maximal inhibitory concentration value of more than 512 μg/mL. This result suggested that UAEE could be considered as an appropriate and effective extraction method for bioactive crude polysaccharides from G. lucidum. [ABSTRACT FROM AUTHOR]

Red Ganoderma lucidum (G. lucidum) is a popular medicinal herb commonly used in Vietnamese traditional remedies due to its potential value for health. In this study, polysaccharides were extracted from G. lucidum using ultrasound-assisted enzymatic extraction method. The response surface methodology and Box-Behnken design were employed to investigate the effects of pH, extraction temperature, extraction time, and ultrasonic power on the content of polysaccharides. Based on ultraviolet-visible spectroscopy analysis, the highest content of polysaccharides in the extract was 32.08 mg/g under optimum experimental parameters including enzyme concentration of 3%, pH of 5.5, extraction temperature of 45°C, extraction time of 30 min, and ultrasonic power of 480 W. The Fourier-transform infrared spectroscopy was also used to identify the functional groups in the extracts. The molecular weights of polysaccharides were determined by gel permeation chromatography. The obtained extract was then evaluated for anticancer activities by using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, showing the anticancer activities with the half-maximal inhibitory concentration value of more than 512  μ g/mL. This result suggested that UAEE could be considered as an appropriate and effective extraction method for bioactive crude polysaccharides from G. lucidum., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Dat Tran Do et al.)