Activated carbon beds water recovery

The application of SPE has partially eliminated the above problems, particularly in the case of arsenic concentration in water samples [123]. SPE delivers better selectivity than LEE because it can be used to sequentially elute compounds from the activated carbon bed, and to separate inorganic compounds of As(III) and As (V), as well as the phenyl (PAS) and dimethyl (DMA) derivatives of arsenic (V) acid [124]. The extraction process is short, which is why it is possible to directly coimect the SPE module with the ICP MS detector [125]. Whenever modified silica is used, arsenic recovery is low (even below 50 %) owing to the formation of hydrogen bonds between the substances being separated and silanol groups [114, 126, 127]. 

Solvent Recovery. The air containing the acetone vapor is drawn out of the spinning cabinet and passed through beds of activated carbon that sorb the organic solvent. The acetone is recovered by steaming and then by separating it from the water by distillation. The efficiency of recovery is about 95 percent. 

Different designed solvent recovery systems are used. As an example there is the solvent system that consists of fixed bed adsorbers containing activated carbon and a distillation system. The carbon adsorbs the solvent vapors. Then the beds are steamed in sequence to remove the solvent. The solvent and steam are condensed into a large tank. The distillation system is then used to distill the solvent from the water to a purity of 99.99% so that it can be reused. Because of the high cost of solvent, complex monitoring equipment is used to insure a high rate of recover. 

Granular Activated Carbon, or GAC has a mean particle size between 1-5 mm. It is usually used in fixed bed adsorbers in continuous processes and with low pressure drops, in both liquid and gas phase applications. Most of the gas phase applications (gas purification, solvent recovery, air filtering and gas masks, gas separation by PSA, catalysis, etc.) use GAC. In addition, GAC is displacing PAC in many liquid phase applications such as gold extraction and drinking water treatment GAC has the advantage, compared to PAC, of offering a lower... 

Carbon Adsorption—A recovery process that captures solvent vapors from air on activated carbon. The solvent is recovered (by desorption) from the carbon by injection of steam into the carbon bed and condensing the resultant solvent and water vapor. 

What desorption of soivents from activated carbon with hot nitrogen or air accompiishes is to remove the soivent from the adsorption bed. That s aii it does not coiiect or recover the soivent. The soivent remains vaporized in the nitrogen stream. The net effect of adsorption and this method of desorption is to substitute the vapor in which the soivent vapor is carried — from air, removed from around the open-top vapor degreaser to nitrogen, from a cyiinder or suppiy pipeiine. Contrast this situation with desorption of moie sieves or siiica gei with hot nitrogen or air, where there is no interest in recovery of the water. 

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