A reliable methodology for the determination of kinetic parameters in the design of fixed bed adsorbers. Tanks in series model

Abstract

A methodology for the determination of kinetic parameters governing the performance of fixed-bed adsorbers, based on laboratory-scale breakthrough experiments, is presented. The approach combines a linear driving force formula for fluid-particle mass transfer with a tanks in series model to account for deviations from ideal plug flow, which are typically significant in small-scale devices. The method focuses on breakthrough curves exhib­ iting non-zero outlet concentrations at very short times after a step change in inlet concentration, a common feature in small-scale adsorption columns operating at high adsorption capacities. Under these conditions, a simple algebraic relationship was derived with the aid of Laplace transforms in order to estimate the overall volumetric mass transfer coefficient from measurable quantities, including the initial outlet concentration, linear equilibrium constant, adsorber geometry, bed porosity, and flow rate. A sensitivity analysis shows that, within a well-defined operating range, the proposed procedure yields reliable kinetic parameters with limited uncertainty, even when the degree of deviation from plug flow is unknown. The methodology is illustrated through an experimental case study involving water softening. The proposed approach provides a simple and physically meaningful alternative to conventional nonlinear regression of full breakthrough curves, enabling the rapid estimation of design-relevant kinetic parameters from short-duration experiments.