Adsorption Isotherms and Kinetics Models of Starchy Adsorbents on Uptake of Water from Ethanol – Water Systems
Okewale, A.O.; Babayemi, K.A.; Olalekan, A.P.

Abstract
The adsorption equilibrium and kinetics of ethanol-water systems on starch-based adsorbents prepared from cassava were undertaken. These include modified cassava starch (MS), cassava starch (CS), cassava pellet (CP), and Cassava shred (AB). The adsorption equilibrium data were best represented by the Langmuir adsorption isotherm. The adsorption kinetics was found to follow second order kinetics model. Adsorption mechanism process was determined from the intra-particle diffusion model where it was seen that the boundary layer has less significant effect on the diffusion mechanism of water uptake on the starch-based adsorbents studied. The Boyd kinetic model showed that the adsorption of water from ethanol – water mixtures was mainly due to external mass transport. The monolayer adsorption capacities are found to be 4.44, 5.75, 6.41, and 7.09g/g for AB, CP, CS, and MS respectively.

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