Dubinin-Raduschkevich

Adsorption isotherms in the micropore region may start off looking like one of the high BET c-value curves of Fig. XVII-10, but will then level off much like a Langmuir isotherm (Fig. XVII-3) as the pores fill and the surface area available for further adsorption greatly diminishes. The BET-type equation for adsorption limited to n layers (Eq. XVII-65) will sometimes fit this type of behavior. Currently, however, more use is made of the Dubinin-Raduschkevich or DR equation. Tliis is Eq. XVII-75, but now put in the form... 

Having chosen a suitable refrigerant, the best adsorbent must be found. Zeolites, silica gels and chemical adsorbents have been used as well as carbons, but this chapter will concentrate on the carbon adsorbents. An indication as to the range of cop s that can be expected and the influence of the type of carbon used can be obtained by modelling the perfonnance of carbons with a range of adsorption parameters. For this purpose it is preferable to use the Dubinin-Raduschkevich... 

This expression, known as the Dubinin-Raduschkevich equation [20], has been widely used to correlate the equilibrium data for hydrocarbons and other organics on activated carbon adsorbents. 

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