Two resistance mass transfer model for the adsorption of dyes onto bagasse pith

The adsorption of four dyestuffs onto bagasse pith has been studied. A method has been presented for the prediction of concentration decay vs time. The model is based on external mass transfer and pore diffusion and enables the external transport coefficients and the effective diffusivities to be determined. Constant mass transport. coefficients were obtained for each dye-pith system to correlate the effects of varying the initial dye concentration and pith mass. The external mass transfer coefficients are 1.4 × 10−2, 1.24 × 10−2, 1.5 × 10−3, and 2.5 × 10−3 cm s−1 and the effective diffusivities are 6.5 × 10−6, 2.6 × 10−6, 4.5 × 10−7, and 5.7 × 10−7 cm2 s−1 for Basic Blue 69, Basic Red 22, Acid Blue 25, and Acid Red 114, respectively.