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The present study focused on the quantitative determination of active compounds, antioxidant and antibacterial activities of leaf extracts of different Sonneratia species. The tested species including Sonneratia alba (SA), Sonneratia caseolaris (SC), and Sonneratia ovata Backer (SO) were collected from Can Gio Mangrove Forest, Vietnam. The methanol extract of SA leaves was found to contain the highest content of total flavonoids, total phenolics and gallic acid (4344.16 ± 51.78 μg/g dry mass). The highest luteolin‐7‐O‐glucoside and luteolin amounts (5963.28 ± 59.77 and 234.33 ± 10.41 μg/g dry mass, respectively) were found in the methanol extract of SC leaves according to HPLC‐DAD analysis. The methanol extracts of all three species exhibited strong DPPH radical scavenging activity while the ethanol extracts provided strong antibacterial activity against Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli. By fractionating the extracts over a SiO2 column using CHCl3: EA: MeOH gradients, the fractions containing high purity luteolin and luteolin‐7‐glucoside from SC and high purity luteolin from SO were collected. Moreover, all fractions demonstrated significant DPPH free radical scavenging ability but the fraction enriched in gallic acid showed the highest activity. These findings show that SA is a promising source of gallic acid while SC can be potentially used for the extraction and isolation of luteolin‐7‐glucoside. [ABSTRACT FROM AUTHOR]

The present study aimed at developing ecofriendly active films from poly(vinyl alcohol) (PVA), agarose, D‐glucose and Piper betle Linn. leaf extract (PBLLE) using a solution casting method. Agarose, D‐glucose and PBLLE have been found to exhibit excellent compatibility with the PVA‐matrix and thus support desired changes in the film characteristics. The co‐addition of agarose and D‐glucose to PVA gave rise to water‐resistance as well as flexibility of the PVA‐based films. The incorporation of PBLLE imparted active functions to the PVA/agarose/D‐glucose film, such as the ability to scavenge DPPH radicals and strong antibacterial activity against both Gram‐negative and Gram‐positive bacteria. Moreover, significant improvement in both mechanical strength and flexibility of the PVA/agarose/D‐glucose films was obtained upon the addition of a sufficient amount of PBLLE. A PBLLE/PVA ratio of 1.5 was found to promote a more than 1.5‐fold increase of the elongation at break. Increasing PBLLE content in the films enhanced the UV absorption in the 300–450 nm range. Characterization results show that the PVA/agarose/D‐glucose/PBLLE films possess interesting properties for UV‐protective and active packaging applications. [ABSTRACT FROM AUTHOR]

Development of active packaging materials for food preservation has been a topic of interest over the years. Herein we report the preparation and characterization of novel active films based on the combination of poly (vinyl alcohol) (PVA), maltodextrin, agar and Piper betle Linn. leaf extract (PBLLE) for application in food preservation. Agar and maltodextrin were co‐used as cross‐linking agents aiming at improving the hydrophobicity of the PVA film. All the additives exhibited high compatibility with the PVA matrix and provided significant enhancement in film properties compared to the unmodified PVA. PBLLE was found to impart strong antibacterial activities and UV blocking property to the films. Moreover, the addition of PBLLE also remarkably increased the film flexibility owing to chemical and physical interactions between chemical compounds in the extract and the polymer network. The as‐prepared blend films showed their effectiveness in prolonging the self‐life of bread and mango, demonstrating a great potential for their practical applications in active food packaging field. [ABSTRACT FROM AUTHOR]

In the present study, we reported the codetermination of highly bioactive compounds, namely, hydroxychavicol, eugenol, and gallic acid in the Piper betle Linn. leaf extract by high‐performance liquid chromatography method. These compounds are of great interest in the pharmaceutical field and also in other food‐related applications owing to their impressive biological and pharmaceutical properties. Moreover, antibacterial and antioxidant activities of the extracts produced by different extracting solvents were also investigated in detail. The methanol extract was found to contain the highest amounts of hydroxychavicol and gallic acid thus offering the strongest antioxidant activity in 1,2‐diphenyl‐2‐picrylhydrazyl free radical scavenging assay. All the three compounds were found at low levels in the hexane extract. However, the solvent type did not affect significantly on the concentration of extracted eugenol. The ethanol, methanol, and ethyl acetate extracts exhibited strong inhibitory effects against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium whereas the hexane extract showed negligible antibacterial activity. These findings suggest that ethyl acetate is a good choice to produce a highly antibacterial extract but methanol and ethanol are more suitable when the antioxidant activity of the extract is more concerned. [ABSTRACT FROM AUTHOR]

Mixed Ni/Fe-base metal-organic framework (Ni/Fe-MOF) with different molar ratios of Ni2+/Fe3+ have been successfully produced using an appropriate solvothermal router. Physicochemical properties of all samples were characterized using X-ray diffraction (XRD), Raman, field emission scanning electron microscopes (FE-SEM), fourier-transform infrared spectroscopy (FT-IR), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), and photoluminescence spectra (PL). The photocatalytic degradation performances of the photocatalysts were evaluated in the decomposition of rhodamine B (RhB) under a compact fluorescent daylight lamp. From XRD, IR, XPS, and Raman results, with the presence of mixed ion Fe3+ and Ni2+, MIL-88B (MIL standing for Materials of Institut Lavoisier) crystals based on the mixed metal Fe2NiO cluster were formed, while MIL-53(Fe) was formed with the presence of single ion Fe3+. From UV-Vis DRS results, Ni/Fe-MOF samples exhibited the absorption spectrum up to the visible region, and then they showed the high photocatalytic activity under visible light irradiation. A Ni/Fe-MOF sample with a Ni2+/Fe3+ molar ratio of 0.3 showed the highest photocatalytic degradation capacity of RhB, superior to that of the MIL-53(Fe) sample. The obtained result could be explained as a consequence of the large surface area with large pore volumes and pore size by the Ni2+ incorporating into the MOF's structure. In addition, a mixed metal Fe/Ni-based framework consisted of mixed-metal cluster Fe2NiO with an electron transfer effect and may enhance the photocatalytic performance. [ABSTRACT FROM AUTHOR]

In this study, we investigated sulfate-modified BiVO 4 with the high photocatalytic activity synthesized by a sol-gel method in the presence of thiourea, followed by the annealing process at different temperatures. Its structure was characterized by thermal gravimetric analysis (TGA), powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The BiVO 4 synthesized in the presence of thiourea and calcined at 600 °C (T-BVO-600) exhibited the highest photocatalytic degradation efficiency of methylene blue (MB) in water; 98.53% MB removal was achieved within 240 min. The reaction mechanisms that affect MB photocatalytic degradation on the T-BVO-600 were investigated via an indirect chemical probe method, using chemical agents to capture the active species produced during the early stages of photocatalysis, including 1,4-benzoquinone (scavenger for O 2 - ), ethylenediaminetetraacetic acid disodium salt (scavenger for h + ), and tert -butanol (scavenger for HO • ). The results show that holes (h + ) and hydroxyl radicals (HO • ) are the dominant species of MB decomposition. Photoluminescence (PL) measurement results of terephthalic acid solutions in the presence of BiVO 4 samples and BiVO 4 powders confirm the involvement of hydroxyl radicals and the separation efficiency of electron-hole pairs in MB photocatalytic degradation. Besides, the T-BVO-600 exhibits good recyclability for MB removal, achieving a removal rate of above 83% after five cycles. The T-BVO-600 has the features of high efficiency and good recyclability for MB photocatalytic degradation. These results provide new insight into the purpose of improving the photocatalytic activity of BiVO 4 catalyst.

We investigated the fabrication of Co-doped BiVO 4 (Bi 1- x Co x VO 4+ δ , 0.05 < x < 0.5) by the substitution of Co ions for Bi sites in BiVO 4 . The X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) results indicated that the substitution of Co 2+ ions for Bi 3+ sites in BiVO 4 was successful, although a change in the crystal phase of BiVO 4 did not occur. UV-vis DRS and PL results suggested that the Co-incorporation could slightly improve the visible light absorption of BiVO 4 and induce the separation of photoinduced electron-hole pairs; therefore, a significant enhancement of photocatalytic performance was achieved. The Bi 0.8 Co 0.2 VO 4+ δ sample showed superior photocatalytic activity in comparison with other samples, achieving 96.78% methylene blue (MB) removal within 180 min. In addition, the proposed mechanism of improved photocatalytic activities and the stability of the catalyst were also investigated., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The present study focused on the application of response surface methodology to optimize the fabrication of activated carbon (AC) from sugarcane bagasse for adsorption of Cu 2+ ion. The AC was synthesized via chemical activation with ZnCl 2 as the activating agent. The central composite design based experiments were performed to assess the individual and interactive effect of influential parameters, including activation temperature, ZnCl 2 impregnation ratio and activation time on the AC yield and removal of Cu 2+ ion from the aqueous environment. The statistically significant, well-fitting quadratic regression models were successfully developed as confirmed by high F- and low P-values (<0.0001), high correlation coefficients and lack-of-fit tests. Accordingly, the optimum AC yield and removal efficiency of Cu 2+ were predicted, respectively, as 48.8% and 92.7% which were approximate to the actual values. By applying the predicted optimal parameters, the AC shows a surprisingly high surface area of around 1,500 m 2 /g accompanied by large pore volume and narrow micropore size at low fabrication temperature.