External Mass Transfer and Homogeneous Solid-Phase Diffusion Effects during the Adsorption of Dyestuffs

A mass-transfer model has been developed to explain the adsorption of dyestuffs (Acid Blue 25 and Basic Blue 69) onto various adsorbents in agitated batch adsorbers. The model is based on two resistances, namely, external mass transfer and homogeneous solid-phase diffusion. The basis of the model has been proposed previously, but on applying this prior result over a wide range of our operating conditions the model was found to go unstable. Consequently, an analytical solution to replace a previously employed numerical solution is presented In this paper, which has been utilized with complete success over a wide range of operating conditions, provided that a suitable time interval for analytical iteration is adopted.