SIMULATION OF CHROMATOGRAPHIC RESPONSE IN COLUMNS PACKED WITH BIDISPERSE STRUCTURED PARTICLES

The coupled diffusion equations describing the response of a chromatographic column, packed with a bi-porous adsorbent such as a pelleted molecular sieve have been solved numerically by the method of orthogonal collocation. The solution provides a good representation of the experimental chromatograms for Ar in columns packed with 5A and 10X molecular sieve pellets. The adequacy of the linear driving force rate expression as a simplified representation of the dynamic behavior is investigated and it is shown that the simplified model provides an excellent approximation for a long column but breaks down when the column contains less than about twenty theoretical plates. The practical implications of this observation are briefly considered.