Carbon liquid adsorption

Granular Activated Carbon (GAC) Adsorption (Liquid Phase) page -... 

Description of granular activated carbon (GAC) adsorption (liquid phase) remediation technology used to clean up pumped ground water contaminated with volatile/semi-volatile organics and PCBs. http //erb. nfesc. navy. mil/restoration/te. 

Liquid-liquid adsorption chromatography (adsorption column) a Flurosil b Alumina c Silica gel d Nuchar carbon Fats, phospholipids, pigments, polar impurities General... 

In the traditional "wood distillation industry" hardwood was preferred for production of chemicals. Hardwood distillation was formerly an important source for production of acetic acid, methanol, and acetone which were the primary products of this process. The heat required for pyrolysis was generated by burning gas, oil, or coal. In the thermal degradation of wood the volatile components are distillable and can be recovered as liquids after condensation (Fig. 10-2). The solid residue, charcoal, is mainly composed of carbon. At higher temperatures the carbon content is increased because of a more complete dehydration and removal of volatile degradation products. Charcoal is mainly used as combustible material for special purposes. A number of charcoal products are known, including activated carbon for adsorption purposes. 

Characterization of the activated carbon by adsorption nearly saturated water with benzene and activated carbon were introduced into a batch reactor with a 0.06 and 0.14 ratio of solid/liquid phases. In each experiment, the evolution ofthe concentration of benzene in water was determined spectrophotometrically and by potassium permanganate titration. Tables 3.22 and 3.23 as well as Figs. 3.82-3.84 show... 

The selectivity of activated carbons for adsorption and catalysis is dependent upon their surface chemistry, as well as upon their pore size distribution. Normally, the adsorptive surface of activated carbons is approximately neutral, such that polar and ionic species are less readily adsorbed than organic molecules. For many applications it would be advantageous to be able to tailor the surface chemistry of activated carbons in order to improve their effectiveness. The approaches that have been taken to modify the type and distribution of surface functional groups have mostly involved the posttreatment of activated carbons or modification of the precursor composition, although the synthesis route and conditions can also be employed to control the properties of the end product. Posttreatment methods include heating in a controlled atmosphere and chemical reaction in the liquid or vapor phase. It has been shown that through appropriate chemical reaction, the surface can be rendered more acidic, basic, polar, or completely neutral [11]. However, chemical treatment can add considerably to the product cost. The chemical composition of the precursor also influences the surface chemistry and offers a potentially lower cost method for adjusting the properties of activated... 

Two series of carbon molecular sieves have been prepared from coconut shells, with different pore size distribution. They have been characterised by carbon dioxide adsorption at 273 K and immersion calorimetry into liquids of different molecular sizes. The results have been related with the abihty of the CMS to separate the components of O2/N2, CO2/CH4 and n-C4H4/i-C4H4 gas mixtures. 

Influence of the porous structure of activated carbon on adsorption from binary liquid mixtures... 

Three carbon samples showing differences in pore structure are chosen to study the effect of porous texture on adsorption from liquid solutions. The benzene adsorption/desorption isotherms are applied to determine the properties of geometrical surface structure of investigated carbons. The liquid adsorption data are analyzed in terms of the theory of adsorption on heterogeneous solids. The relation between parameters of porous structure of the activated carbon samples and parameters of adsorption from the liquid phase is discussed. 

Activated carbons are the most widely used adsorbents in gas and liquid adsorption processes. They are manufactured from carbonaceous precursors by a chain of chemical and thermal activation processes. The temperature for carbonization and activation reaches up to 1100°C in thermal processes. Activated carbons develop a large surface area, between 500 and 2000m2g 1, and micropores with an average pore diameter <2nm. Mesoporosity and macroporosity is generated by secondary procedures such as agglomeration. The products are shaped as granules, powders and pellets depending on their application. 

Rubin, A. J., and D. L. Mi rci-r. 1981. Adsorption of free and complexed metals from solution by activated carbon. In Adsorption of inorganics at solid-liquid interfaces, ed M. A. Anderson and A. J. Rubin, pp. 295-325. Ann Arbor, Ml Ann Arbor Science. 

Carbon materials are used in many industrial processes involving adsorption at a liquid-solid interface. Water purification by activated carbon, liquid chromatography, and stabilization of carbon black suspensions (inks, paints) are examples of such processes. 

Chemical heterogeneity of a surface is an important property affecting adhesion, adsorption, wettability, biocompatibility, printability and lubrication behavior of a surface. It seriously affects gas and liquid adsorption capacity of a substrate and also the extent of a catalysis reaction. As an example, the partial oxidation of carbon black surfaces has an important, influence on their adsorptive behavior. In a chemically heterogeneous catalyst, the composition and the chemical (valence) state of the surface atoms or molecules are very important, and such a catalyst may only have the power to catalyze a specific chemical reaction if the heterogeneity of its surface structure can be controlled and reproduced during the synthesis. Thus in many instances, it is necessary to determine the chemical... 

FACTORS INFLUENCING ADSORPTION AT CARBON LIQUID INTERFACE... 

A salient difference in the adsorption of solutes versus gases and vapors is found in the altered role of temperature. An elevation in temperature increases the escaping tendency of a vapour or gas from the interface and invariably diminishes the adsorption. Similar action operates at the carbon liquid interface, but here it is often dwarfed by the influence of temperature on solvent affinities. This should not be taken to mean that temperature is without influence on adsorption from solution certainly, temperature can have much influence on the magnitude and direction of many factors shown in Table 2 3 and thereby alter the course of an adsorption. But the resulting action is quite specific (Table 2 4), many instances are... 

When the adsorption is considered complete, the carbon-liquid mixture is pumped to the filter, meanwhile continuing the agitation in the treatment tank so that a uniform mixture will be consistently delivered to the filter. 

Adsorption of an impurity onto a porous solid such as activated carbon, alumina, or silica is often used to purify gases and liquids. Adsorption usually is reversible, but if the heat of adsorption is high then the tendency to desorb may be low. Typically adsorption is done in a continuous process. It also may be done in a batch process for small-scale separations or to determine the parameters that control the adsorption process for a given adsorbate (the adsorbing molecule) and a given adsorbent (the porous solid). 

Liquid Adsorption. Adsorption takes place selectively because of (1) polarity differences between adsorbate and unadsorbed liquid, or (2) differences in size and structural characteristics of molecules. In the first category we may mention activated carbon, in the second one the molecular sieves. Liquid adsorption is suitable for both recovery of small amounts from dilute solutions, and for bulk separations. Purification is feasible with very selective adsorbent. Recovery of adsorbate and regeneration of the adsorbent may be performed by (1) Thermal Swing Adsorption, (2) Pressure Swing Adsorption, (3) inert-purge swing, or (4) displacement desorption. 

The next major developments occurred in 1931 when Lederer and coworkers [5,12,13] separated lutein and zeaxanthine in carbon disulphide and the xanthophylls from egg yolk on a column of calcium carbonate powder 7 cm in diameter. The technique rapidly gained interest and Khun, Karrier and Ruzicka were each awarded the Nobel Prize (1937, 1938, 1939, respectively) for their work on chromatography. Flow through chromatography rapidly gained acceptance and by the 1940s liquid adsorption column chromatography was an established laboratory separation technique on both analytical and preparative scales. 

Pore sizes and their distributions in adsorbents have to comply with requirements fi om different applications. Thus, relatively small pores are needed for gas adsorption and relatively large pores for liquid adsorption, and a very narrow PSD is required for molecular sieving applications. Macropores in carbon materials were found to be effective for sorption of viscous heavy oils. Porous carbons can respond to these widely ranged requirements from the applications, which is one of advantages of carbon materials even though pore size distributes in a certain range in the majority of porous carbons. Recent novel techniques to control pore structure in carbon materials (see Section 5) can be expected to contribute to overcome this limitation. 

As mentioned above the most important features of activated carbons for adsorption me the textural parameters. For years natural surface chemistry of carbons, however studied in details [38, 39, 40, 45], was not really strongly linked to the performance of carbons as adsorbents. Its role was rediscovered when US EPA introduced strict envirorunental regulations and activated carbons were proven to be the best adsorbents working at ppm or even ppb levels. Moreover, very often the matrix (gaseous or liquid) from which the species have to be separated can interfere with the adsorption process causing that in many cases the specific adsorption forces have to be applied. Those forces can be provided by surface chemistry of carbons. 

Another competitive process to chemical oxidation is carbon adsorption. Adsorption is defined as the takmg up of molecules by external or internal surface of solids or by the surface of liquids. Adsorption occurs on these surfaces because of attractive forces of the atoms and molecules that make up the surfaces. When impinities are adsorbed fiiom a liquid unto a surface, the adsorption process occurs at the solid-liquid interface, and the reactions occurring at the interface determine the rate and ctent of adsorption (5). 

Activated Carbons Activated carbons are the most widely used adsorbents in gas and liquid-adsorption processes. They are manufactured from... 

The alcohol to be dehydrated may have any concentration of water in it. If it has been recovered by water washing or carbon bed adsorption from air or by steam stripping from water, the alcohol to be treated will usually be of azeotropic composition or wetter. The high water content of the -propanol/ water azeotrope (29% w/w) make it attractive to use an entrainer that does double duty as a liquid/liquid extraction agent. 

WUke A, Yuan J, Antonietti M, Weber J (2012) Enhanced carbon dioxide adsorption by a mesoporous poly(ionic liquid). ACS Macro Lett 1 1028-1031... 

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