Kinetics of Diffusion-Controlled Adsorption of Adenine and Adenosine in a Carboxymethyl Diaminoethane Pvc-Mediated Column System

Abstract

The adsorption kinetics of adenine and adenosine on a ligand-exchange matrix, carboxymethyl diaminoethane poly(vinyl chloride) in cobalt form (cobalt-CMEDA-PVC), have been studied in a fixed-bed column system. The initial ligand concentrations ranged between 1.25×10−5 and 2.0×10−4 mol L−1. The kinetic studies were carried out spectrophotometrically, in order to determine the ratecontrolling step of the adsorption. The kinetic data of the single-component systems were acquired from the breakthrough curves of the ligands on the basis of the equivalent points method. In this study, the homogeneous diffusion model was adapted to a fixed-bed column system to describe the differentiation in the ligand concentration of the effluent, beginning from breakthrough point as a function of time. The results obtained for the adsorption kinetics indicated that the diffusion step plays a significant role in the adsorption kinetics of the ligands, due to the fact that the adsorption performance was strongly affected by the initial concentration of ligands.