14 documents found, page 1 of 2
Diffusion of gases in metal containing carbon aerogels
L.M. Marques; F.L. Conceição; M.M.L. Ribeiro Carrott; P.J.M. CarrottCarbon aerogels containing Fe, Ni, Cu or no metal were prepared by carbonisation of polymer aerogels synthesised from 2,4-dihydroxybenzoic acid and formaldehyde and modified by CVD of benzene. Uptakes and diffusion coefficients of CO2, CH4, N2 and O2 were measured and the results compared with those obtained using a commercial carbon molecular sieve. The results indicated that the diffusion of light gas molecul...
Effect of the activating agent on physico-chemical and electrical properties of...
M.E. Ramos; P.R. Bonelli; S. Blacher; M.M.L. Ribeiro Carrott; P.J.M. Carrott; A.L. CukiermanDifferent chemical reagents (phosphoric acid, boric acid, ammonium citrate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate and trisodium phosphate) were employed to develop activated carbon cloths (ACC) by chemical activation of a lyocell precursor, in an attempt to explore their effect on main physico-chemical characteristics and electrical behaviour of the resulting A...
Influence of oxidation process on the adsorption capacity of activated carbons ...
P.A.M. Mourão; C. Laginhas; F. Custódio; J.M. Valente Nabais; P.J.M. Carrott; M.M.L. Ribeiro CarrottA set of activated carbon materials non-oxidised and oxidised, were successfully prepared from two different lignocellulosic precursors, almond shell and vine shoot, by physical activation with carbon dioxide and posterior oxidation with nitric acid. All samples were characterised in relation to their structural properties and chemical composition, by different techniques, namely nitrogen adsorption at 77 K, el...
Production of activated carbons from almond shell
J.M. Valente Nabais; C. Laginhas; P.J.M. Carrott; M.M.L. Ribeiro CarrottThe production of activated carbons from almond shell, using physical activation by CO2 is reported in this work. The used method has produced activated carbons with apparent BET surface areas and micropore volume as high as 1138m2 g−1 and 0.49 cm3 g−1, respectively. The activated carbons produced have essentially primary micropores and only a small volume of wider micropores. By FTIR analysis it was possible t...
Adsorption of volatile organic compounds onto activated carbon cloths derived f...
M.E. Ramos; P.R. Bonelli; A.L. Cukierman; M.M.L. Ribeiro Carrott; P.J.M. CarrottActivated carbon cloths (ACC) were prepared from lyocell, a novel regenerated cellulose nanofibre fabric, by phosphoric acid activation in inert atmosphere at two different final thermal treatment temperatures (864 and 963ºC). Benzene, toluene and n-hexane isotherms at 298 and 273K were measured in order to gain insight into the porous structure of the ACC and to evaluate their performance for the removal of vo...
Characterisation of the porosity of polymer and carbon aerogels containing Fe, ...
P.J.M. Carrott; L.M. Marques; M.M.L. Ribeiro CarrottPolymer aerogels were prepared from 2,4-dihydroxybenzoic acid (DHBA) and formaldehyde (F) using synthesis mixtures containing up to 17% solids content and Fe, Cu or Ni introduced by ion exchange. Carbon aerogels were then obtained by carbonisation. The materials were characterised by TEM and N2 adsorption at 77 K. The results show that increasing solids content lowered the mesopore volumes and diameters of the ...
Comparison of the Dubinin-Radushkevich and Quenched Solid Density Functional Th...
P.J.M. Carrott; M.M.L. Ribeiro Carrott; SuhasThe classical DR method and the Quenched Solid Density Functional Theory (QSDFT) approach have been used to analyse N2 at 77 K isotherms determined on activated carbons prepared by alkaline chemical activation of different lignins. The QSDFT pore size distributions are bimodal with a narrow peak below 1 nm and a broad peak from 1 to 2.5–3.5 nm. Deconvolution allows estimation of the volumes and widths of the na...
Potencialidades da cortiça na obtenção de carvões activados
P.A.M. Mourão; P.J.M. Carrott; M.M.L. Ribeiro CarrottWhen it comes to cork the first idea, the natural cork stopper which protects the best wines in the world, still remains the best known application. History shows that in 3000 BC cork was already being used in regions as far away as China, Egypt, Babylon and Persia, in applications designed for fishing, in burial artifacts, in decorative items and also in containers to store food. Despite this history, today th...
Designing activated carbons from natural and synthetic raw materials for pollut...
P.A.M. Mourão; I.P.P. Cansado; P.J.M. Carrott; M.M.L. Ribeiro CarrottOver the last decades the literature has shown the possibility of producing activated carbons (AC) from a wide variety of raw materials, and to use them as one of the most environmentfriendly solutions for waste disposal [1]. Simultaneously, it has been shown that the adsorption of pollutants from different sources by activated carbons is one of the most efficient techniques for remediating or solving this kind...
Characterization of the surface of activated carbons produced from tire residues
J.M. Valente Nabais; C. Laginhas; P.J.M. Carrott; M.M.L. Ribeiro Carrott; Galacho, Cristina; J.E.C. Amorós; A.V.N. GisbertThe surface characterisation of new activated carbons produced from tire residues by activation with carbon dioxide was studied. The activated carbons produced were mainly basic with point of zero charge values above 8.8. The main surface functional groups identified by FTIR were ether, quinones, lactones, ketones, hydroxyls (free and phenol) and pyrones. The XRD analysis shows that the materials produced have ...