Effect of modification of cassava starch on the kinetics of the adsorption of water from ethanol-water systems

Abstract

The importance of ethanol as a fuel and for other industrial uses has resulted in the need to produce large quantities of it with higher purity, that is, with particular reference to dehydration. The use of normal and modified starch in the dehydration of ethanol was investigated. The modification of starch was found to significantly increase its mechanical property thus having a positive effect on its rate of adsorption as shown by the scanning electron microscopy (SEM) analysis. The kinetics of the adsorptive process was also studied. It was however observed that the kinetics of the adsorption of water from ethanol-water mixture by native starch (CS) best correlated to the pseudo first order, with a rate constant of 0.0180 s^-1, while that of the modified cassava starch best correlated to the first order with a rate constant of 0.9342 s^-1. The dehydrating property of native starch was also observed to be significant, and the acidic modification of it with the use of hydrochloric acid, conferred on it much higher dehydrational properties.

Keywords: Adsorption, cassava starch, modification, kinetics, ethanol-water mixture.