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This work reports a novel, facile and hydrothermal approach to prepare graphene oxide/NiO/Starch composite materials (GO/NiO/Starch). The composite materials were fully characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray analysis (EDS), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy and X-ray photo-electron spectroscopy (XPS), and Thermo gravimetric analysis (TGA-DTA). Furthermore, the antibacterial properties of NiO and starch decorated graphene oxide were tested against Staphylococcus aureus by using the well diffusion method. The obtained results show that the GO/NiO/Starch composite material has a substantial antibacterial activity against Staphylococcus aureus. This is the flowchart of synthesis, characterization and biological activity of graphene oxide based NiO and starch composite materials: [ABSTRACT FROM AUTHOR]

Mesoporous Co3O4 nanostructures, templated from different mesoporous silicas, SBA-3, SBA-5, and SBA-16, were used as catalysts for the liquid-phase selective oxidation of benzyl alcohol using molecular oxygen as the oxidant. The nanostructured Co3O4-16, templated from SBA-16, showed the best activity for the reaction, with 97.5% benzyl alcohol conversion and 100% benzaldehyde selectivity obtained after 3 h of reaction at 100°C. This could be attributed to its large number of oxygen vacancies and low surface Co3+/Co2+ ratio that were beneficial to O2 activation, together with its three-dimensional nanostructure that facilitated the adsorption of benzyl alcohol, compared to Co3O4-3 and Co3O4-15. The material could be reused without losing activity if the organics adsorbed on the surface of the used sample were removed by calcination at 300°C for 1 h. A mechanism for the reaction was proposed, considering that the activation of molecular oxygen was the rate-determining step of the reaction. [ABSTRACT FROM AUTHOR]

In the present study, chicken feathers (CFs), obtained from animal waste, were used as bio-adsorbent for the removal of hazardous Cr(VI) ions from aqueous solutions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD), adsorption of N2 at −196 °C, thermogravimetric analysis (TGA), and point of zero charge (pHpzc) determination were used to characterize the adsorbent. The N2 adsorption results revealed high surface area and microporous structure for the adsorbent. The experimental results in batch adsorption show that optimum conditions are: pH 2.5, equilibrium contact time 180 minutes, concentration of CFs 11 g L−1, and initial Cr(VI) concentration 25 mg L−1. The experimental data on Cr(VI) adsorption were fitted using the Langmuir and Freundlich equations at different temperatures. The Langmuir adsorption model showed the best fit. The maximum monolayer capacity (qmax) of CFs was found to be 333.33 mg/g. The kinetic results of Cr(VI) ion were fitted to four kinetic models: pseudo-first-order, pseudo-second-order, intra-particle diffusion, and Elovich. The pseudo-second-order chemisorption model had a higher coefficient. The thermodynamics data showed that the adsorption process of Cr(VI) on CFs was endothermic and spontaneous. The desorption efficiency and reusability of CFs were determined for three adsorption–desorption cycles, which proved to be very effective for the removal of Cr(VI) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Improvements on spectral absorption range and electron–hole (e−/h+) separation efficiency are crucial to effectively design materials for photocatalysis. To reach this objective, ternary Z‐scheme LaFe0.5Co0.5O3/Ag10/graphitic carbon nitride (LFCO/Ag10/g‐CN) heterojunctions with layered structure are designed. The obtained results show that: 1) the Ag nanoparticles (NPs) act as bridges to link LFCO and g‐CN, providing a place for recombination of useless electrons and holes; 2) some of the Ag atoms enter the LFCO lattice as Ag+, but most of them are at the surface in the form of Ag NPs, while g‐CN coats the surface of LFCO/Ag10 as a thin film; 3) LFCO/Ag10/g‐CN exhibits improved e−/h+ separation efficiency, electron transfer rate, and photocurrent response, compared to g‐CN and LFCO/Ag10 alone. Catalytic tests show that LFCO/Ag10/g‐CN is active for photo‐Fenton degradation of tetracycline hydrochloride (TC), with 87% TC conversion obtained at 40 min. Mechanistic studies show that •O2− and •OH radicals are the reactive species of the reaction, and a synergistic effect between light and H2O2 is produced by generating extra •OH radicals. LFCO/Ag10/g‐CN is also highly stable in the reaction conditions, with no appreciable activity loss up to four reuse cycles. [ABSTRACT FROM AUTHOR]

The chemical composition of wood is important to assess the quality of this raw material for the industry of cellulosic pulp production. The purpose of this work was to determine the chemical composition of Eucalyptus spp. grown for cellulosic pulp production. Ten Eucalyptus spp. clones with six years of age, located in the municipality of Itamarandiba, Minas Gerais, Brazil, were used. Quantification was obtained for extractives, monosaccharides, uronic acids, acetates, lignin, ash and the phenolic composition of the extracts. In average, clones showed around 2.7% extractives, with a predominance of polar compounds soluble in ethanol and water; 27.7% lignin and 0.3% ash. Glucose was the main sugar detected (64.2%), followed by xylose (19.3%). The main components of the extractives were steroids, fatty acids and aromatic acids, followed by smaller amounts of substituted alkanoic acids, fatty alcohols, glycerol derivatives and triterpenes. The ethanol–water extracts presented total phenol contents ranging from 321.4 to 586.6 mg EAG/g of extract, tannins from 28.1 to 65.1 mg catechin/g of extract and flavonoids from 73.6 to 256.9 mg catechin/g of extract. Clones with a higher holocellulose amount and a lower lignin content showed a higher potential for cellulosic pulp production. These findings are important for the development of high-quality wood based on important traits for the pulp and paper sector. [ABSTRACT FROM AUTHOR]

Abstract Commercial multi-walled carbon nanotubes (CNT) were functionalized by oxidation with HNO3, to introduce oxygen-containing surface groups, and by thermal treatments at different temperatures for their selective removal. The obtained samples were characterized by adsorption of N2 at -196°C, temperature-programmed desorption and determination of pH at the point of zero charge. CNT/poly(vinylidene fluoride) composites were prepared using the above CNT samples, with different filler fractions up to 1 wt%. It was found that oxidation reduced composite conductivity for a given concentration, shifted the percolation threshold to higher concentrations, and had no significant effect in the dielectric response.

Abstract Au was loaded (1 wt%) on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH)2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved). The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.