Freundlich exponent

The value of the partition coefficient, Kip, is given by the product, focKioc, where/ic and Kjoc apply only to the natural organic matter into which the sorbate can penetrate. The value of Kif is less well understood, but recent observations suggest it should be related to the quantity of adsorbent present (e.g., the fraction of black carbon in a solid matrix, /bc) and the particular compound s black-carbon-normalized adsorption coefficient (e.g., Klhc). Typical values of the Freundlich exponent are near 0.7. Hence, in a first approximation the data should fit ... 

Huang et al. (1997) measured sorption isotherms for phenanthrene on 21 soils and sediments. All isotherms were nonlinear with Freundlich exponents n,- (Eq. 9-1) between 0.65 and 0.9. For example, for a topsoil (Chelsea 1) and for a lake sediment (EPA-23), interpolating the isotherm data yields the following observed sorbed concentrations, Cis, in equilibrium with dissolved concentrations, Ciw, of 1 /zg L-1 and 100 /zg-L-1, respectively ... 

Calculated from data available In literature, Strongly basic gel-type resin, quaternary ammonium functionality (Amberllte IRA 400 resin), Ki Langmuir constant, qm maximal load, Freundlich constant regarding the molecular mass, Kq Freundlich constant regarding the mass of carbon, n Freundlich exponent, PFOA perfluorooctanoic acid, PFOS perfluorooctane sulfonic acid, PFBS perfluorobutane sulfonic acid, GAC granular activated carbon, PAC powdered activated carbon... 

This functional form is consistent with the Freundlich isotherm and the Freundlich exponent rtf determined by experiment are compared with JtT in Table 3.3. Agreement between them is reasonable. 

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