Modelling and simulation of ternary liquid-phase adsorption onto activated carbon

A computational procedure is presented for solving the set of rigid hyperbolic and parabolic partial differential equations describing the simultaneous adsorption of a ternary system in a column packed with adsorbent particles using the non-linear adsorption isotherms of Fritz and Schluender. The model equations account for the effects of axial diffusion in the fluid and the film and internal diffusional mass-transfer resistances of the particles. Orthogonal collocation and Michelsen's modified third-order semi-implicit Runge-Kutta method combined with a step-size adjustment strategy were used to solve the general form of the resulting 6N coupled ordinary differential equations for the simultaneous adsorption of butan-2-ol, t-amyl alcohol and phenol in fixed beds. The simulated results obtained from this model were compared with experimental data. Excellent agreement between the simulated results and previously published experimental data was obtained. The breakthrough profiles were also indicative of the competitive multi-component adsorption behaviour as well as the formation of multiple adsorption layers upon the primary monomolecular layer.