Characterization of diethyl ether adsorption on activated carbon using a novel adsorption refrigerator (original) (raw)
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Analysis of some adsorption experiments with activated carbon
Chemical Engineering Science, 1976
A simple method is proposed whereby the film transfer coefficient and coefficient of diffusion in the particles may be determined from finite bath adsorption experiments. The method also makes it possible to separate pore and surface diffusion. Under certain conditions it is also possible to determine the influence of particle phase concentration on the surface diffusivity. The method is based on models describing the instationary diffusion in the solids. Data from six different adsorption systems were analysed using this method. The adsorbed components were: phenol, paranitrophenol, parachlorophenol, bensoic acid, phenylacetic acid and 24dichlorophenoxyacetic acid. In all systems surface diffusion was the determining transport mechanism in the particles. In the system phenol and phenylacetic acid the surface diffusion coefficient increased by about a factor 3 with an increase in surface concentration of about 40%. For parachlorophenol the increase was somewhat less. For the other systems there was no significant increase. The increase in diffusivity is explained by a decrease in bonding forces with increasing concentration.
Evidence for the effect of the cooling down step on activated carbon adsorption properties
Microporous and Mesoporous Materials, 2016
Two activated carbons are prepared by chemical activation of olive residue using zinc chloride. The first sample is cooled down slowly after the carbonization in the furnace under a flow of nitrogen, while the second is directly removed from the furnace just after the carbonization and put at ambient temperature and pressure. The textural and structural characteristics of the two samples are determined by nitrogen adsorption at À196 C and X-ray diffraction (XRD). The oxygen functional groups are characterized via Boehm's titration and Fourier transformed infrared spectroscopy (FTIR). The cooling down step at different rates is followed by thermogravimetryemass spectroscopy analysis (TG/MS). Slow cooling down of the sample after carbonization leads to CO 2 , O 2 , and CO consumption creating more active sites, which are responsible of the formation of surface oxygen groups, and especially carboxylic groups. The latter dramatically enhance water vapor adsorption at low relative humidity. The cyclohexane adsorption on activated carbons, which is carried out by thermogravimetric analysis (TGA), shows that the cooling down step has an effect on both the initial rate of adsorption and the adsorption uptake at equilibrium.
Adsorption characteristic study of activated carbons down to 4.5 k
Materials Today: Proceedings, 2018
Adsorption characteristic study of different activated carbon samples are performed at low temperature down to 5 K by using cryocooler based low temperature facility with a micropore analyzer. This facility is now operational at Institute for plasma research (IPR). It comprises of a commercial micro pore analyzer for sample characterization at 77 K and a GM cryocooler cooling unit forholding the sample at any temperature < 77 K. The sample holder is connected to the micro-pore analyzer measurement unit through a small diameter tube for gas dosing and equilibrium pressure measurement. A PID control based temperature controller unit along with temperature sensors and heatersare used to regulate and maintain the temperature of the sample cell at any temperature between 4.5 K and 77 K. Among different kinds ofactivated carbon samples studied, the surface area and pore width for carbon cloths are found to be 3438 m 2 /gm (at 4.5 K), and it increases with lowering the temperature down to 4.5 K from 77.0 K.
Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management, 2003
This investigation was to evaluate the performance of a thermodynamic model using nonlinear driving force in conjunction with the Langmuir model exemplified by the adsorption of benzene and carbon tetrachloride onto activated carbon in mono-and binary-adsorbate systems. Results show that model-fitted adsorption and desorption rate constants could well predict the adsorption isotherms and breakthrough curves under various conditions. This numerical model can provide adsorption and desorption rate constants. The kinetic parameters are of the same order of magnitude as reported in several studies. Under high reaction temperatures, both the adsorption and desorption rate constants increased while equilibrium constants decreased. A dimensionless valuable C 0 /K can be used to describe the relationship between adsorbate and adsorbent, and predict the service cycle during the adsorption process. For adsorption in binary mixtures, a high inlet concentration or a low temperature, the weak adsorbate, C 6 H 6 , will have a high breakthrough concentration when the strong adsorbate, CCl 4 , began to break through.
Multicomponent sorption kinetics of ethane and propane in activated carbon: simultaneous adsorption
Gas Separation & Purification, 1993
Extensive experimental data of binary adsorption kinetics of ethane and propane onto Ajax activated carbon are collected by using a 'differential adsorption bed' over a range of particle sizes and shapes, bulk concentrations and temperatures. A multicomponent model incorporating macropore, surface and micropore diffusion mechanisms recently proposed by Hu and Do (Chem Eng Sci (in press)) is used to predict the binary adsorption dynamic data by using information of single-component isotherms and dynamics. The multicomponent adsorption equilibrium is calculated by using the ideal adsorbed solution theory (IAST), with the single-component isotherm described by a Unilan equation. The model is found to describe the binary adsorption kinetics well and in particular it accurately predicts the degree of the overshoot of the fast-diffusing/less-strongly adsorbed species.
Journal of Molecular Liquids, 2017
A modeling study has been effectuated on the adsorption kinetics of ethanol onto parent Maxsorb III and the two chemically modified activated carbons (H2-Maxsorb III and KOH-H2-Maxsorb III). In this work, a mathematical model of diffusion-adsorption is used to describe a nonlinear sorption equilibrium coupled with the diffusion of adsorbate in porous media. The new model equation is deduced from kinetic Boltzmann equation by using a term of diffusion and a term of trapping or adsorption of ethanol at the surface of activated carbon. The term of trapping is expressed by means of Henry model of adsorption, which is in turn deduced from the Hill model developed by using statistics physics treatment. In this study, we propose a new simulation model of a gas kinetic adsorption in a microporous solid in order to find a better correlation with the experimental data. Then, we determine the effect of diffusion term and source term or more exactly trapping term, which is depending on the physicochemical parameters like the number n of molecules per site, the density of receptor sites Nm per unit mass, the half-saturation concentration N1/2, and the residence time v on the dynamic development of ethanol adsorption on the three types of activated carbon.
Journal of Colloid and Interface Science, 1997
variables on the equilibrium amount of adsorption is not Aqueous solutions of phenol, p-chlorophenol, and p-nitrophenol extensively studied. In order to effectively design activated have been used to determine the adsorption isotherm for single carbon adsorption units and to develop mathematical models solute systems on activated carbon at different temperatures. The that can accurately describe their operation, information on experimental program has been conducted to investigate the inboth the adsorption and the desorption of individual pollutfluence of concentration and temperature. All the reported equilibants under different operating conditions is required. rium isotherm equations have been tried on present and published Extensive experimental and modeling studies have been experimental data. A generalized isotherm equation which was reported to date on the activated carbon adsorption of a broad proposed by Khan et al. (6, 10) and tested for bi-solute adsorption spectrum of hazardous compounds from aqueous solution (1, data has been modified for single-solute system. The temperature 2). Yenkie and Natarajan (3) have reported the adsorption of dependency has also been incorporated into a generalized equation. It has been noticed that the Radke and Prausnitz (7) and general-some organic compounds (phenol, aniline, o-cresol, benzoic ized isotherm equations could represent the entire data with a miniacid, and p-methoxyphenol) at 35ЊC at six different adsormum average percentage error. The influence of different adsorbents. They could not represent the entire data by any of bents, sorbate concentrations, and pH of aqueous solutions has also the well-known isotherms. They have tabulated sections of been discussed in detail. The temperature dependency has been concentration range for which the Freundlich isotherm and investigated using both the Dubinin-Astakov (13) and the modified the Langmuir isotherm could represent experimental data generalized equation. The generalized equation describes the experisatisfactorily. Chatzopoulos et al. (4) have discussed the mental and published data adequately and provides a single value mechanism of adsorption and desorption on activated carbon of differential molar heat of adsorption, DH ads , for a single solute from aqueous medium. They have tried various types of adsorption system. The Dubinin-Astakov isotherm equation has empirical reported isotherms on their experimental data and shown an increasing trend of DH ads as the loading of adsorbent has found that the Fritz and Schlunder isotherm (5) could fit increased. ᭧ 1997 Academic Press their data at high concentrations and was, therefore, selected.