Production, characterization and application of activated carbon from brewer’s spent grain lignin

Different types of activated carbon were prepared by chemical activation of brewer’s spent grain (BSG) lignin using H3PO4 at various acid/lignin ratios (1, 2, or 3 g/g) and carbonization temperatures (300, 450, or 600 °C), according to a 22 full-factorial design. The resulting materials were characterized with regard to their surface area, pore volume, and pore size distribution, and used for detoxification of BSG hemicellulosic hydrolysate (a mixture of sugars, phenolic compounds, metallic ions, among other compounds). BSG carbons presented BET surface areas between 33 and 692 m2/g, and micro- and mesopores with volumes between 0.058 and 0.453 cm3/g. The carbons showed high capacity for adsorption of metallic ions, mainly nickel, iron, chromium, and silicon. The concentration of phenolic compounds and color were also reduced by these sorbents. These results suggest that activated carbons with characteristics similar to those commercially found and high adsorption capacity can be produced from BSG lignin.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq Brazil)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Characterization of Active Sites on Carbon Catalysts

A method based on the deconvolution of TPD spectra is proposed for the characterization of surface oxygen groups, which can act as the active sites on carbon catalysts. The method, which was previously used to characterize activated carbons oxidized in the gas phase, has been extended and applied to other materials, carbons oxidized in the liquid phase. It is shown that this method fits quite well the TPD experimental data of the original activated carbon as well as the gas-phase and liquid-phase oxidized materials and is suitable to estimate the amounts of each type of oxygen surface groups.info:eu-repo/semantics/publishedVersio

Catalytic and Photocatalytic Nitrate Reduction Over Pd-Cu Loaded Over Hybrid Materials of Multi-Walled Carbon Nanotubes and TiO2

TiO2 and carbon nanotube-TiO2 hybrid materials synthesized by sol-gel and loaded with 1%Pd−1%Cu (%wt.) were tested in the catalytic and photocatalytic reduction of nitrate in water in the presence of CO2 (buffer) and H2 (reducing agent). Characterization of the catalysts was performed by UV-Vis and fluorescence spectroscopy, X-ray diffraction, temperature programed reduction, N2 adsorption, and electron microscopy. The presence of light produced a positive effect in the kinetics of nitrate removal. Higher selectivity toward nitrogen formation was observed under dark condition, while the photo-activated reactions showed higher selectivity for the production of ammonium. The hybrid catalyst containing 20 %wt. of carbon nanotubes shows the best compromise between activity and selectivity. A mechanism for the photocatalytic abatement of nitrate in water in the presence of the hybrid materials was proposed, based in the action of carbon nanotubes as light harvesters, dispersing media for TiO2 particles and as charge carrier facilitators

Catalytic ozonation of metolachlor under continuous operation using nanocarbon materials grown on a ceramic monolith

11 figures, 4 tablesThe catalytic ozonation of the herbicide metolachlor (MTLC) was tested using carbon nanomaterials as catalysts. Multiwalled carbon nanotubes were used in semi-batch experiments and carbon nanofibres grown on a honeycomb cordierite monolith were tested in continuous experiments. The application of the carbon catalyst was shown to improve the mineralization degree of MTLC and to decrease the toxicity of the solution subject to ozonation. Degradation by-products were also followed in order to compare the two processes. The application of the carbon coated monolith to the continuous ozonation process was shown to have potential as it improved the TOC removal from 5% to 35% and decreased the inhibition of luminescent activity of Vibrio Fischeri from 25% to 12%.The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 226347Peer reviewe

Ozonation of erythromycin over carbon materials and ceria dispersed on carbon materials

Two carbon materials, multi-walled carbon nanotubes (MWCNT) and activated carbon (AC), were investigated as ozonation catalysts for the erythromycin (ERY) mineralization. In addition, in order to evaluate a possible synergetic effect between carbon materials and ceria in the ozonation of this antibiotic, two catalysts containing ceria dispersed on the surface of MWCNT and AC were prepared, characterized and tested. The results were compared with those obtained in the absence of catalyst and in the presence of ceria. The mineralization of ERY solutions was enhanced by addition of the studied catalysts. A synergetic effect between carbon materials and ceria was observed, leading to higher mineralization degrees of ERY, mainly in the presence of MWCNT containing ceria. In the catalytic ozonation with these materials both surface and bulk reactions are supposed to occur. Oxamic, oxalic and pyruvic acids were identified as final by-products during the ozonation process. Part of the original nitrogen of ERY was converted to NO3- along with small amounts of NH4- and NO2-. Microtox tests revealed that intermediates with higher acute toxicity than ERY are produced in the early stages of single and catalytic ozonation. For longer ozonation times the acute toxicity is similar whether the carbon materials are present or not, whereas it significantly decreases using carbon materials containing ceria. Successive experimental runs of ERY ozonation show that the catalysts surface suffers some limited deactivation

Carbon nanofibers doped with nitrogen for the continuous catalytic ozonation of organic pollutants

Catalytic ozonation using carbon materials, in particular nanocarbons, has been appointed as an interesting alternative for the abatement of recalcitrant emerging organic pollutants. Efforts to achieve more efficient catalysts have been carried out, including carbon doping with heteroatoms. In this study, the effect of nitrogen doping of carbon nanofibers in their catalytic activity for the ozonation of organic pollutants was assessed. For this end, pristine and N-doped carbon nanofibers were prepared, both in powder and in structured forms. The former were tested in semi-batch ozonation experiments, while the latter were used in continuous ozonation experiments. It was observed that the presence of N-containing functionalities on the surface of the carbon nanofibers enhances their capability as catalysts for the studied reaction.This work was co-financed by FCT and FEDER under Programe PT2020 (Project UID/EQU/50020/2013). CEMUP and Dr. Carlos Sá are acknowledged for XPS analysis. J. Restivo thanks FCT for research grant SFRH/BD/95751/2012.Peer reviewe