The kinetics, thermodynamics and isotherms of the adsorption were used to identify the retention mechanisms. For the kinetics study, perfectly stirred batch experiments were carried out after adjustment of the parameters influencing the system, such as the pH, adsorbent dosage and initial dye concentration. Experimental results were modelled according to kinetic equations representing pseudo-first order, pseudo-second order reactions, as well as equations for external and intra-particle diffusion. The chemical surface reaction was fitted to a pseudo-second order equation, with very high regression coefficients. Intra-particle diffusion is the rate-limiting step in the process of adsorption beyond 60 min contact time.
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Directory of Open Access Journals Sweden. Hydrogen sulfide adsorption on activated carbon fiber. Tests on Parisian subway; Elimination du sulfure d'hydrogene par adsorption sur tissu de charbon actif. Essais sur site RATP.
Bouzaza, A. Hydrogen sulfide has an unpleasant odor and may cause damage to the electrical materials of the Parisian subway. The activated carbon has some intrinsic catalytic activity, so the removal of hydrogen sulfide is due to an adsorption -oxidation process. In a laboratory scale, some kinetic parameters were acquired, which allowed us to build up two dynamic reactors. These continuous reactors, equipped with activated carbon fibers, were tested on the Madeleine station of the Parisian subway.
The relative humidity of the gas phase was found to play an important role in the performance of the elimination. The durability of the pilot tested was compatible with an industrial exploitation of the process. Effets du charbon actif dans le milieu de culture sur l'induction de la Compte rendu. Projet de lutte contre le. Randriamalala, J. The forbidden fuel: Charcoal, urban woodfuel demand and supply.
Adsorption of gaseous pollutants on activated carbon filters. Modelling of the coupled exchanges of heat and mass; Adsorption de polluants gazeux sur des filtres de charbon actif. Modelisation des echanges couples de matiere et de chaleur. The aim of this work is to remove gasoline and odorous molecules vapors. Thermodynamics and kinetics studies have been carried out; they concern the fixation of representative gases on activated carbons.
Hydrogen sulfide and n-butane are chosen to represent the odorous molecules. Different activated carbons are considered: only the adsorbent impregnated by KOH has satisfying performance.
The adsorption of hydrocarbons on a granulated activated carbon is studied on four original devices specifically perfected for this work: gravimetry, calorimetry, thermal measurements and gaseous phase chromatography. The gravimetric measurements are coupled to thermal measurements inside the granulates.
Strong temperature variations have then been observed inside a granulate during the adsorption. These experimental results have been taken into account to adapt the classical Langmuir kinetic model.
The competitive nature of the adsorption sites allows then to explain qualitatively the adsorption of binary mixtures of hydrocarbons. At last, the classical Langmuir model allows to explain correctly the thermodynamic results, for the hydrocarbons alone or in binary mixture. The proposed modelling allows then to treat both on a kinetic and thermodynamic way the case of a non isothermal adsorption at the scale of an activated carbon granulate and to predict the phenomena at the filter scale.
Hydrogen storage by adsorption on activated carbon: investigation of the thermal effects during the charging process; Stockage de l'hydrogene par adsorption sur charbon actif: etude des effets thermiques lors de la charge dynamique d'un reservoir a lit fixe adsorbant.
This work presents an experimental and numerical investigation of the thermal effects occurring during the charge of adsorbent fixed bed tank. The influence of these thermal effects, which result from the exothermal character of the adsorption process and the pressure forces work, on the storage capacity is specially analysed. An experimental setup allowing the dynamic measurements of the temperature and pressure profiles has been used.
Then the numerical protocol with the Fluent software, has been validated by comparison of the simulated pressure, flow rate and temperature fields in the tank with the results obtained from an experimental investigation carried out the dynamic storage.
Several predictive simulations have been carried out in order to study the effect of the boundary conditions, as the wall temperature or effective thermal conductivity of the porous bed, on the storage capacity of the reservoir.
We searched the optimal geometry of an interbed thermal dissipator for a given industrial tank. From this optimum we studied the effect of five additional cooling tubes on the tank storage capacity. This study has resulted in the determination of the two The results were promising for the application of CLC directly to solid fuels.
Dans un. Full Text Available The adsorption properties of polyacrylamides and xanthans on mineral surfaces carrying silanol and aluminol groups such as sand and kaolinite are described. The influence of the main parameters such as the nature of adsorption sites, surface charge, chemical structure and conformation of polymer and interactions of mono- and divalent ions with polymer and mineral surface has been investigated and interpreted. Some operating parameters in polymer flooding such as pH and salinity of injected solution, the nature of the polymer and its degree of ionicity were found to be determining factors from the adsorption level.
The results give key elements for reducing adsorption by a proper choice of polymer nature and ionicity and of injection conditions. Full Text Available A series of diblock copolymers, poly tert-butyl styrene-sodium poly styrene sulfonate with different molecular weight and percentage of sulfonation have been used to study the effect of polymer structure on its adsorption behavior onto hydrophobically modified silicon wafers.
The percentage of the hydrophobic block varies from 3. Previous studies show that salt concentration is very important for the adsorption of such polyelectrolytes onto silica surfaces. Transient behaviour of an adsorption refrigerator.
Luo, L. The objective of this article is to present an experimental study of an adsorption refrigerator, accounting for the transient phenomena in each component of the machine, in particular in the adsorber. We have performed a full series of experiments to investigate the transient evolution of temperatures, pressures and the cycled mass, in a discontinuous cycle, and along the components of the refrigerating machine.
All these experimental observation are discussed and compared to transient models developed in a separate article. Sources: British Petroleum Adsorption of fission products on mediterranean mud; Adsorption des produits de fission sur des vases de mediterranee. Centre d' Etudes Nucleaires. Partition coefficients of some fission products have been measured in sea water on mud taken from the bottom of the Mediterranean sea.
A discussion follows on the behaviour of these radioisotopes. Les valeurs trouvees sont elevees. Le comportement de ces isotopes radioactifs est discutee. Full Text Available The adsorption isotherms for phenol and 4-chlorophenol from water onto asphaltenes flocculated in bulk and asphaltenes deposited on silica were established by frontal analysis chromatography at , , , and K.
The adsorption was more important with asphaltenes flocculated in bulk and corresponded to a Freundlich isotherm mechanism. The high adsorbed amount of phenols suggests possible migration of phenols through the loose asphaltene structure.
Isotherms observed with the silica coated by asphaltenes showed that adsorption occurs in two stages corresponding probably to two different organizations of solute molecules at the surface.
Nonetheless, with the present energy crisis and the rapid development of the local steel industry, all countries possessing coal deposits are undertaking research to evaluate accurately their potential resources of coal, the most traditional energy source and the indispensable raw material for the production of foundry coke. In this paper will be discussed the resources of those South Americon countries known to have coal reserves: Argentina, Brazil, Chile. Full Text Available Application of saw dust for the removal of an anionic dye, tartrazine, from aqueous solutions has been investigated.
The experiments were carried out in batch mode. Effect of the parameters such as pH, initial dye concentration and temperature on the removal of the dye was studied.
Maximum adsorption of dye was achieved at pH 3. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin—Radushkevich isotherm models. The Langmuir adsorption capacity of the adsorbent is found to be 4. Kinetic modeling of the process of removal was carried out and the process of removal was found to follow a pseudo second order model and the value of rate constant for adsorption process was calculated as 2.
Adsorption isotherms were correctly reproduced, taking into account all solution equilibria, including calcium and sodium binding constants and a solubility limit for the calcium polymer complex : the latter was determined by turbidimetric titration for various polymer molecular weights.
Our conclusion is that in the presence of divalent ions which is often the case with sparingly soluble minerals, the surface binding of the polyelectrolyte results from a precipitation rather than an adsorption phenomenon. Purification by molecular sieve of helium used as inert cover gas in nuclear reactors; Epuration de l'helium de couverture des reacteurs nucleaires par adsorption sur tamis moleculaire.
A method carried out at fairly low temperatures between and deg. C has been studied for the purification of the helium used as cover gas for heavy water in reactors. The use of the 5A molecular sieve has been adopted because of its superiority over other adsorbents in this temperature range. The particular problems connected with adsorption under dynamic conditions have been dealt with separately. The nitrogen adsorption isotherms have been plotted and the heat of adsorption calculated. C de l'helium servant de couverture inerte a l'eau lourde des reacteurs a ete etudiee.
L'emploi au tamis moleculaire 5A a ete retenu pour la superiorite de celui-ci sur d'autres adsorbants dans ce domaine de temperatures. Les problemes particuliers a l' adsorption en regime dynamique ont ete separement traites. Les isothermes d' adsorption d'azote ont ete tracees et la chaleur d'adsorp. Part One. It is not easy to obtain a full picture of the multiple chemical phenomena which occur inside a pulverized coal flame.
This bibliographie review attempts to give more than just a juxtaposition of data from the recent literature and risks making. Adsorption and activation of methane and methanol on Pt surface: a density functional study; Adsorption et activation du methane et du methanol sur la surface du platine: une etude par la fonctionnelle de la densite. The calculated adsorption energies over the top, bridge and hollow sites are small, weakly dependent on the molecular orientation.
All the sites have almost the same adsorption energy. Les experiences faites avec du charbon de bois active ont montre la superiorite du tamis comme adsorbant d'hydrogene.
Ce dernier a ete converti en eau, ensuite en butane, et compte sous forme de gaz. L'activite specifique etait toujours plus elevee que celle du tritium ayant subi 10 cycles d'absorption et de desorption sans pompage intermediaire, de sorte qu'il n'y avait pas de perte nette de gaz.
Cette activite specifique etait la meme que celle du tritium non traite provenant de l'ampoule de stockage. Il semble donc vraisemblable que le fractionnement important observe se produit surtout pendant la desorption. Cet effet isotopique ne saurait par consequent etre important lorsque le.
Full Text Available Kinetic and thermodynamic study of adsorption of methyl orange on two aquatic biomass: Crabs and Shells. Description of the subject.
Production de charbons actifs à partir de résidus agricoles pour l'élimination de micropolluants
Sous la direction de Yves Andres. The properties such as surfaces areas, elemental and ash contents, pHPZC and efficiencies for As V and tetracycline removal of these alternatives carbonaceous materials are compared with those of commercial granular activated carbons GACs. The results show that carbonaceous materials obtained from sugar beet pulp BP-H2O and peanut hulls PH-H2O could be used for the treatment of arsenic and tetracycline contaminated water. Their performances are also improved when the carbonaceous materials are prepared by physical activation steam and then modified through iron impregnation especially for As V sorption. The pore volume analysis shows that two different carbon surfaces for each by-product were obtained, an equal microporous and mesoporous volume for the BP-H2O and a predominantly microporous volume for PH-H2O.