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Four series of activated carbon have been prepared from carbonized olive stones. One of them, series D, was prepared using carbon dioxide as activating agent, and the other three, series AV, W, and H, with water vapor under different experimental conditions. Two of the series, D and H, were prepared in such a way that the gasification rate for both reactants was identical, in an attempt to reduce...
The possibilities for preparative separation of fullerene (C 60 /C 70 ) mixture by flash chromatography on activated carbon or activated carbon fibres as a stationary phase are shown. The effect of the nature of the activated carbon and of its specific surface area on the elution time, chromatographic peak width, amount, and purity of the recovered product (C 60...
Adsorption from binary liquid mixtures of completely miscible components of different polarity was studied, in order to characterize the adsorption properties of commercial activated carbons. The excess adsorption isotherms were measured for three binary liquid systems: acetone + n-heptane, acetone + benzene, and benzene + n-heptane on four activated carbons of various ash content. Textural characteristics...
Three series of activated carbon have been prepared by heat treatment of peach stones impregnated with solutions of phosphoric acid, in order to analyze the effect of phosphoric acid on the yield, bulk density and porosity of the resultant activated carbons. The analysis of the adsorption isotherms of N 2 at 77 K. CO 2 at 273 K and n-C 4 H 10 , at 273 K shows that the...
1 3 C NMR and FTIR analyses have been employed to follow the evolution of chemical structure in relation to porosity development, as a function of heat treatment temperature (HTT), for activated carbons produced from white oak by phosphoric acid activation. The chemical changes affected by acid treatment at low HTT are: by 50°C there is significant alteration of the lignin structure; by 100°C...
Analysis of data for the adsorption of various molecular probe molecules on a number of different microporous carbons has revealed an empirical relationship between log(n 0 ) and log(V m ), wheren 0 /mmol g -1 is the micropore capacity for a given adsorptive andV m /cm 3 mol -1 the corresponding adsorptive molar volume. It is shown...
Adsorption equilibria in slit pores are calculated using an analytic solution of the classical Ono-Kondo equation with modified boundary conditions. A new equation is developed for isotherms of gas adsorption on microporous adsorbents. This equation describes isotherms of Type I in the IUPAC classification scheme for temperatures below the critical point and also describes the unusual adsorption...
The adsorption isotherms of N 2 at 77K, CO 2 at 251, 273 and 298K, and SO 2 at 262 and 273K have been determined on a series of physically activated carbons with a wide range of micropore size distributions. Since the series includes carbons with very high burn-off, it shows the problems involved in the characterization of microporsity in superactivated carbons. On the other...
Powdered activated carbon has been prepared from lignitic coal of Lakhra (Pakistan) by a chemical activation method using ZnCl 2 as an activating agent. Different process variables have been established after a series of experiments and an impregnation ratio of 1:2, an activation temperature of 650 °C and a duration of 1 hour have been found to be appropriate for its preparation. It has been...
Activated carbons offer a large spectrum of pore structures and surface chemistry for adsorption of gases, which are being used to design practical pressure swing and thermal swing adsorption processes for separation and purification of gas mixtures. The activated carbons are often preferred over the zeolitic adsorbents in a gas separation process because of their relatively moderate strengths of...
This work presents the different effects of steam and carbon dioxide activation of a char in both the development of microporosity and the micropore size distribution using immersion microcalorimetry of liquids with different molecular size (benzene, 2,2 dimethylbutane, iso-octaine and α-pinene). The study has been carried out with three series of carbons, two of them prepared by steam activation...
A series of activated carbons was prepared from bituminous coal by chemical activation with potassium hydroxide and zinc chloride and also by physical activation with carbon dioxide. The effect of process variables such as carbonization time, temperature, particle size, chemical agents, method of mixing and impregnation ratio in the chemical activation process was studied in order to optimize those...
Five activated carbons with different porosity, prepared by chemical activation of peach stones with phosphoric acid, have been further activated in a carbon dioxide gas flow at 825°C for different periods of time to cover a wide range of burn-off. The porosity of all activated carbons was determined by adsorption of N 2 (77 K), CO 2 (273 K) and n-C 4 H 10 (273...
The effect of the coal carbonization step heating rate on the reactivity of the chars obtained, as well as on their porous structure development in the subsequent activation step, was analyzed. Different types of carbonization process were investigated, combining a low heating rate (5 K/min) and high heating rate (hundreds of K per second) in this step. Chars obtained in these processes were activated...
The surface chemistry and the porous texture of activated carbons prepared from a charred product (C Jex -600), which was obtained from rockrose (Cistus ladaniferus, L.) extracted previously into petroleum ether, were studied. Activated carbons were prepared by heating C Jex -600 between 350 and 850°C in air to 40% burnoff. Methods of chemical analysis and FTIR...
A new procedure for regenerating activated carbon based on thermal desorption with liquid water under subcritical conditions (300°C and 120 atm) is proposed. The method was assayed with three types of activated carbons exhausted with phenols (phenol and 4-nitrophenol), textile dyes (sirius red C.I.: 29080 and orange II C.I.: 15510) and pesticides (carbofuran and atrazine). In all cases, total recovery...
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