and
[Oi, + (1 f)pKd] ac/at = a(C. C). [4-13]
The model may be described in terms of the dimensionless parameters
Peclet number, P; the mobile water partition coefficient, fl; and the
dimensionless, mass-transfer coefficient, w, defined as:
P = vmL/D, [4-14]
R = (0m + pfKd)/(e + pKd) and [4-15]
w = aL/q [4-16]
Additionally, the concentrations of the solutes in the two regions (Cm
and Cim) may be normalized with the original-solute pulse
concentration, CO by defining
c1 = CJ/C [4-17]
and
c2 = Cm/Co [4-18]
With these definitions of P, 0, w, c,, and c2, Eqs. [4-12] and [4-13]
become:
fR (aC,/aT + (1 P)R aC2/aT = (1/P)(a2c1/ax2) ac,/ax [4-19]
and
(1 f)R aC2/aT = w(C, C2) [4-20]
The mobile-immobile model (MIM) (Eqs. [4-19] and [4-20]) contains
four dimensionless parameters; P, R, f and w. Agreement between model
simulation and experimental data is generally accepted as verification
of the conceptual basis of the model. However, experimental methods
are generally unavailable to measure f and w independently. When
experimental techniques are inadequate to measure parameters
independently, they are frequently estimated on the basis of a best-fit