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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...
Fractal analysis of adsorption isotherms is used to study the surface roughness of carbon blacks graphitized at 3000 K. Gases of various molecular sizes (nitrogen, argon, ethane, propane, and butane) are adsorbed on different grades of carbon black. Using the molecular yardstick method, it is found that the surface fractal dimension of graphitized carbon black is 2.0±0.1 and is independent of carbon...
Coconut charcoals of different grades were studied for assessing the removal efficiency of chemical warfare (CW) agents from aqueous solutions. Oxygen analogue of sulphur mustard and phenol were used as model compounds for CW agents for adsorption studies. Freundlich and Langmuir adsorption isotherms were plotted. Equilibrium constant and maximum adsorption capacity for carbons were computed from...
The influence of surface functional groups on activated carbons on the adsorption and desorption of lithium ions, present in trace amounts in aqueous solution, has been studied in the absence and presence of an applied electric field.Application of an electric current during the experiments dramatically increased the sorption of the ions. Moreover, lithium could be released into the solution by reversing...
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...
The separation of boron compounds, boric acid and borax from aqueous solution by activated carbon before and after impregnation with various compounds was studied. A series of activated carbons was prepared from coconut shell impregnated with calcium and barium chlorides, citric and tartaric acids. The examined processes were performed in batch and continuous systems under equilibrium and dynamic...
The purpose of this study is the use of electromagnetic induction to heat activated carbon. The ultimate goal is to get an original process to regenerate adsorbants loaded with the volatile organic compounds present in air or water.The first step was to explore the possibilities of heating granular activated carbon with this technology. In order to get the best operating parameters, the methodology...
The char produced from a subbituminous coal is a cheap and effective adsorbent to remove nitrogen oxides (NO x ) from flue gas. This paper addresses the NO x adsorption on char in the presence of oxygen and moisture since there are both water vapor and oxygen present in flue gas. The experimental results of this study show that nitric oxide (NO) is catalytically oxidized to nitrogen...
A comparative study was carried out for over 20 microporous carbons using high-resolution thermogravimetry (HRTGA) and adsorption techniques. The utility of the HRTGA technique for characterization of active carbons was demonstrated by correlating the HRTGA data with adsorption measurements. The linear correlation was established between the values of the specific surface area evaluated by HRTGA...
Magic-angle spinning deuterium NMR spectra have been used to evaluate the effects of activation to different extents of nutshell and coal-based carbon substrates on the adsorption of water (D 2 O). In general, separate signals are seen for water adsorbed in the micropores and in larger channels or at particle surfaces. The unactivated carbon shows negligible micropore adsorption except when...
Fullerenes in yields as high as 15 wt% have been synthesized in a flow through reactor assembly employing the contact arc method. The yields are found to be greatly affected by arcing parameters like the flow rate of helium and current. UV radiation emitted during arcing was found to reduce fullerene yields. Steps to minimize UV scattering and decrease the residence time of the carbon vapor resulted...
Adsorption isotherms are obtained for the charcoal-nitrogen system in the temperature range 79-320 K and pressures to 5 MPa for two samples of activated charcoal. Correlations relating temperature dependence of adsorption potential are obtained using four methods of extrapolating pseudo-saturation state beyond the critical point. The values obtained are compared with literature data. Using the...
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