Freudlich isotherms

As often noted, an unlimited amount of solutes are allowed to sorb onto solids in the linear and Freudlich isotherm formulations, whereas in reality only limited sites are available in a given system. 

Several isotherms combine aspects of both the Langmuir and Freudlich equations. One that has been shown to be effective in describing data mathematically for heterogeneous adsorbents is the T6th isotherm [Acta Chim. Acad. Sci. Hung., 69, 311 (1971)]... 

At this point, it is feasible to correlate the liquid-phase adsorption equilibrium single component data, with the help of isotherm equations developed for gas-phase adsorption, since, in principle, it is feasible to extend these isotherms to liquid-phase adsorption by the simple replacement of adsorbate pressure by concentration [92], These equations are the Langmuir, Freundlich, Sips, Toth, and Dubinin-Radushkevich equations [91-93], Nevertheless, the Langmuir and Freudlich equations are the most extensively applied to correlate liquid-phase adsorption data. [2,87],... 

Table 17.7 (cont.) Langmuir and Freudlich constants of of the adsorption isotherms of different organic solutes on modified cellulose fibres. ... 

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