Adsorption carbonate

Pressure Swing Adsorption. Carbon dioxide can be removed by pressure adsorption on molecular sieves. However, the molecular sieves are not selective to CO2, and the gases must be further processed to achieve the high purity required for "over the fence" use as in the urea process. Use of pressure swing adsorption for CO2 removal appears most appHcable to small, stand-alone plants (29). 

Carbon Adsorption. Carbon adsorption is a well estabflshed and widely used technology for the removal of organics from wastewaters and gaseous streams. Carbon adsorption is a proven technology for potable water treatment and capable of reducing organic concentrations to very low or nondetectable levels. 

The citric acid solution is deionised at this stage to remove trace amounts of residual calcium, iron, other cationic impurities, and to improve crystallisation. In some processes, trace-impurity removal and decolorization are accompHshed with the aid of adsorptive carbon. 

P21 Adsorption - Carbon 5 = Loss than 1 part per billion... 

P21 Adsorption - Carbon (volume/volume) for gases milligrams/Iiter for solutions or ... 

Tsumura T., Kojitani N., Umemura H., Toyoda M., Inagaki M. Composites between photoactive anatase-type Ti02 and adsorptive carbon. Appl Surface Sci 2002 196 429-36. 

Adsorption Carbon black Planar phthalocyanines Parton et al. (121)... 

N. V. Beck, S. E. Meech, P. R. Norman, and L. A. Pears, Characterisation of surface oxides on carbon and their influence on dynamic adsorption, Carbon 40, 531-540 (2002). 

Murata, K., Miyawaki, J., and Kaneko, K. (2002). A simple determination method of the absolute adsorbed amount for high pressure gas adsorption. Carbon, 40, 425-8. 

Golden, T.C. and Sircar, S. (1990). Activated carhon adsorbent for drying gases by pressure swing adsorption. Carbon, 28, 683—90. 

Pendleton, P., Wong, S., Schumann, R., et al. (1997). Properties of activated carbon controlling 2-methylisoborneol adsorption. Carbon, 35, 1141—9. 

Chen, J.P., Wu, S., and Chong, K.H., Surface modification of granular activated carbon by citric acid for enhancement of copper adsorption. Carbon, 41, 1979, 2003. 

This chapter presents different facets of adsorption. Unfortunately, there is not sufficient space to provide case studies for any of the hundreds of unique applications of adsorption. On the other hand, most of the topics discussed here are the subject of dozens of technical papers each year, many of which appear in specialized journals, including (alphabetically) Adsorption, Carbon, Langmuir, Microporous and Mesoporous Materials (formerly Zeolites), Reactive Polymers, and other more general titles. Some subjects are also treated in much greater detail in books, many of which are listed in the bibliography that follows. 

Besides providing high-energy adsorption sites for physical or specific adsorption, carbon, which consists of both small pores and functional groups, is able to catalyze surface reactions. A simple example is oxidation of sulfur dioxide where it was found that basic functional groups present on the surface of carbons... 

C. Parmele and T. Kovalcson. Adsorption carbon, in H.J. Rafson (ed.). Odor and VOC control handbook, McGraw-Hill, New York, 1998. 

Removal of adsorbed gases and vapors. It must be borne in mind that adsorptive carbon can take up a few percent by weight of CO3, H3O, etc., at room temperature. Purification is achieved by heating for many hours at 300°C in high vacuum. 

If a highly adsorptive carbon is used, as much as 15 g. of Og can be taken up by 100 g. of the carbon. Under the same conditions, steam produces acid groups whose concentration may reach 700 meq. of H+ ions per 100 g. of the preparation. The material is tested by shaking 0.1 g. of the carbon with 100 ml. of 0.05N alcoholic KOH. The H ions can be replaced by CHg groups through methylatlon with diazomethane. Because of the acidic surface oxides, the carbon is readily wetted by water and poorly by benzene, as contrasted with carbon having no acid surface oxides. Above 500°C, Og is released as CO and COg. 

These compounds are always formed when carbon comes into contact with air or Og at room temperature. Their formation can only be avoided when contact is prevented. These basic compounds may coexist on the surface of the carbon with the acid-forming O compounds. With highly adsorptive carbon these compounds may exert, in aqueous solution, an effect equivalent to a concentration of 100 meq. of OH" ions per 100 g. of carbon. 

Carbon and excess S are heated for two days at 600°C in a sealed tube. The product is then washed thoroughly In a Soxhlet apparatus with CSg, toluene and alcohol. A highly adsorptive carbon can take up as much as 30 g. of S per 100 g. of preparation. Above 500°C, the preparations release S, and as the temperature rises, CSg is also generated. 

The constants for the surface complexation of calcium, sulphate, phosphate and arsenate are included in the file minteq.dat. This data was not sufficient for the modelling of the column experiments performed and had to be augmented. Surface complexation constants for magnesia and chromate for amorphous iron hydroxide were taken from Dzombak and Morel (1990) (see Table 12.3). Van Geen (1994) showed that also carbon dioxide has to be considered for the modelling of adsorption. Carbon dioxide is not mentioned in Dzombak and Morel (1990). The database used contains complexation constants derived from data of Van Geen et al. (1994) and were reoptimized by Dr. C. A. J. Appelo (Amsterdam) for use with PHREEQC2 and amorphous iron hydroxide. This data was transferred from the database file PHREEQC.dat to Minteq.dat. 

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