LINEAR DRIVING-FORCE APPROXIMATION FOR DIFFUSION IN SPHERICAL ADSORBENTS WITH BINARY NONLINEAR ADSORPTION

This paper presents a new linear driving force approximation applicabl e to the cyclic steady-state in the case of pore diffusion in the pres ence of binary Langmuirian adsorption for a spherical particle under a periodic boundary condition in composition, total pressure or both. T his approximation uses two parameters OMEGA, one for each solute, calc ulated for a square wave with the same period and a second pair of par ameters that correct the approximation for the phase lags. An assessme nt of the quality of the approximation was made by measuring the diffe rences between the cumulative fluxes calculated by the diffusion and t he linear driving force models through an average relative quadratic e rror. It is shown that this error is less than 5% for equilibrium, dif fusion and frequency conditions in the range of practical adsorption s ystems. The same approximation can be used in the case of homogeneous diffusion.