An equilibrium theory of the pH-parametric pump

Parametric pumping, both batch and continuous, and cycling zone adsorption are theoretically scrutinized for various operating conditions by using the concept of equilibrium stages. The model system is Haemoglobin-Albumin-CM sepharose, a physical system in which a local equilibrium between liquid and sorbent in the layers of the separating medium in the column is characterized. For the batch process, the steady-state concentrations in both top and bottom reservoirs are found to be independent of the number of equilibrium stages, provided that a = 1 (i.e., number of transfer steps/number of stages).. For continuous parapump process, separation is enhanced with decreasing top feed ratio and/or decreasing bottom feed ratio. However, steadily degrading separation is found to exist when the top or bottom feed ratio exceeds the void volume of the column. The separation obtained for the cycling zone adsorption shows that an optimum number of stages is between 10 and 16. Below the lower limit, separation steadily decreases, and above the upper limit, the separation is found to be constant. Recycle ratio () is found to have an influence on the separation below the optimum number of stages and no influence above the optimum number of stages. A computational algorithm for predicting equilibrium parametric pump performance (both batch and continuous) and cycling zone adsorption is developed. The algorithm is based on a set of exterior solute material balances and a linear adsorption isotherm for the solute-adsorbant system. The method of STOP-GO is combined with a finite difference approximation to solve the material balance equations