Chemical Engineering Journal, Vol.133, No.1-3, 79-84, 2007
Dissolution kinetics of aluminum can in isopropyl alcohol for aluminum isopropoxide
A kinetic study of dissolution reaction of Al can waste was conducted for the synthesis of aluminum isopropoxide (AIP). With the used Al can and isopropyl alcohol (IPA) as reactants, the reaction was examined at the condition of 3 mol IPA/mol Al of stoichiometric ratio, adding 10(-3) mol HgI2/mol Al for catalyst and no agitation at the reaction temperature ranging from 70 to 82 degrees C. After 17 h, the reaction gave a 75 % yield. A two-stage dissolution mechanism was proposed in which the dissolution rate is determined first by a chemical reaction and then by ash layer diffusion. On the basis of the shrinking core model with the shape of flat plate, the first dissolution rate of Al can was controlled by chemical reaction. The concentration of isopropyl alcohol was added to the reaction at the stoichiometric ratio, then it was largely changed through the dissolution reaction. Therefore, since the conversion rate of isopropyl alcohol varies greatly depending on the reaction time, it was included as an integral term of the reaction time. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction step was determined to be 92.4 kJ mol(-1). In the second stage, the dissolution rate is controlled by diffusion control through the ash layer. The apparent activation energy of the second step was determined to be 174.9 kJ mol(-1) (C) 2007 Elsevier B.V. All rights reserved.
Keywords:kinetics;dissolution;aluminum can;flat plate;aluminum isopropoxide;chemical reaction;ash layer diffusion