Branched-Pore Kinetic Model for Basic Dyestuff Adsorption onto Natural Clay

Abstract

The adsorption of Basic Blue 69 from aqueous solution onto natural clay has been studied using an agitated batch adsorber. The branched-pore kinetic model (BPKM). based on external mass transfer, macropore diffusion and micropore diffusion, has been used to predict the performance of a batch adsorber. A computer program has been developed to generate theoretical concentration-time curves and these results adjusted to experimental concentration-time curves by a ‘best fit’ approach. A sensitivity analysis has been performed to study the effect of the main mass-transfer parameters, K_s, D_s, K_b and f, on the shape of the concentration decay curves. The variables of initial dye concentration and natural clay mass have been successfully correlated using constant values of the mass-transfer parameters K_s, D_s, K_b and f. The K_s value is (3.7 ± 0.1) × 10⁻³ cm/s, the D_s value is (2.6 ± 0.1) × 10⁻⁸ cm²/s. the K_b value is (1.7 ± 0.1) × 10⁻⁷ cm/s and finally the f value is 0.56 ± 0.01. The micropore diffusion terms enable the concentration decay curves to be predicted accurately for a longer period of time than in previous models.