Adsorbent forms granules

Adsorbent Type Chermcal Form Granule Size Capacity Useable pH Range... 

Solid Desiccants. The sohd desiccants used in dynamic appHcations fad into a class caded adsorbents (see Adsorption). Because they are used in large packed beds through which the gas or Hquid to be treated is passed, the adsorbents are formed into soHd shapes that adow them to withstand the static (fluid plus sohd head) and dynamic (pressure drop) forces imposed on them. The most common shapes are granules, extmded pedets, and beads. 

Activated carbon or activated charcoal Carbon in the form of charcoal granules, which has an affinity to adsorb many gases and vapors and, in so doing, removes odors. It is manufactured by exposing coal, coconut shells, or peat to steam at 800 to 900 C. 

Adsorbents are available as irregular granules, extruded pellets and formed spheres. The size reflects the need to pack as much surface area as possible into a given volume of bed and at the same time minimise pressure drop for flow through the bed. Sizes of up to about 6 mm are common. 

MultiSorb 100 adsorbent media is a new material, formed of granules of specially processed peat, and designed to be deployed in sorption columns. It is designed for adsorption of dissolved heavy... 

CaCL, in granular form (12—20 mesh), although Al or cone. HjSO adsorbed on small pumice granules can also be used. The CaCLj granules are most conveniently carried in a TJ-tube fitted with ground-glass stoppers (Fig. 63). These stoppers are pressed into position after smearing with vaseline or some compound such as Steven s cement. 

Activated charcoal was originally regarded as a relatively inexpensive adsorbent with an assortment of pores of ill-defined size and shape. However, in recent years considerable progress has been made in the development of tailor-made porous carbons such as molecular sieves, activated carbon fibres and carbon composites (Marsh et al., 1997). Superactive carbons are now made on a commercial scale with BET areas of around 3000 m2g-1. Activated carbons can be manufactured as fine particles or granules or in the form of a cloth, felt or consolidated membrane. The properties of some of these special types of activated carbon are discussed in Chapter 12. 

It was once taken for granted that adsorbents were required in the form of fine powders, porous granules or extrudates. However, other physical forms such as porous fibres are now available for special applications such as membranes for gas separation or water treatment Carbon cloth provides an interesting example of a highly active form of fibrous carbon. 

Various types of adsorbent carbon may be used in refining the syrup liquors. One type, made by activation of bituminous coal (combined with suitable binders) with high-temperature steam, is composed of 92% of carbon, and is in the form of porous, hard granules of 8 x 30 mesh (U. S. Sieve Series), or a mean particle-diameter of 1.6 mm. These carbons have —1,000 m2 of surface per g of d.s. 

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