Adsorption kinetics of CoCl2 and PPh3 over macroreticular and gel type adsorbents by a generalized ZLC method

In this paper, we propose an alternative approach to the zero length column (ZLC) method by exploiting the practical advantages of the ZLC method in combination with the advantages of a more generalized dynamic model over the adsorbent layer and its adsorbent particles. The adsorption kinetics are modeled by a mathematical model for both mono- and bidispersed particles. In contrast with the usual ZLC methods, where adsorption in the macropores is neglected, our model allows for possible adsorption in macro- and/or micropores. Also, our model allows for non-linear adsorption isotherms. By this approach, we were able to determine the diffusivity of CoCl2 into bidisperse macroreticular Amberlyst A21 and monodisperse gel type polymerbound PPh3 and of PPh3 in bidisperse macroreticular Ag+ functionalized Amberlyst 15 by fitting the theoretical model to experimental data. It was found for CoCl2 that: (1) adsorption in both macro- and micropores contribute to the uptake in macroreticular Amberlyst A21 and (2) its diffusion into the gel matrix of polymerbound PPh3 is slower. PPh3 only adsorbs in the macroporous structure of Ag+ functionalized Amberlyst 15, because its microparticles are not accessible to PPh3.