Active charcoal, adsorption sulfates

Graded Adsorbents and Solvents. Materials used in columns for adsorption chromatography are grouped in Table 12 in an approximate order of effectiveness. Other adsorbents sometimes used include barium carbonate, calcium sulfate, calcium phosphate, charcoal (usually mixed with Kieselguhr or other form of diatomaceous earth, for example, the filter aid Celite) and cellulose. The alumina can be prepared in several grades of activity (see below). 

Industry uses mainly combinations of catalysts laboratory processes employ mainly Raney nickel, platinum, platinum dioxide, or palladium, the last of these often on a carrier such as charcoal or barium sulfate. Since it is only the reduced surface of a. platinum dioxide catalyst that is active and reduction of the oxide to the metal is checked by adsorption of nitro compounds (particularly if aromatic), it is advisable to reduce this catalyst in a preliminary operation. When platinum dioxide is used in solvents of differing acidities, the rate of reaction increases in the following order neutral > alkaline > acid solution > glacial acetic acid. 

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