Impact of water content on kinetics of Ca(OH)2 and alkyl benzene sulphonic acid neutralization reaction.

Abstract

The neutralization reaction of Ca(OH)2 and alkyl benzene sulphonic acid (ABS) is catalyzed by the water which was added about 5 to 10% by weight in start of the reaction. The operational cost for separation of water is high and so the water should be at its minimum level in the reaction system to minimize the operational cost for separation of water.  Kinetic study was completed at constant temperature 343 K and different initial water content (1.5, 4.4 and 8.7 weight percent) to determine the reaction kinetic parameters and impact of water content on the rate of reaction, conversion and reaction time for complete conversion. Integral method was used for data analysis of experimental data and to determine the rate equation from concentration time profiles. The neutralization reaction of Ca(OH)2 and ABS is the second order autocatalytic reaction and estimated values of rate constant was 0.0081 liter/mol.min at 343 K and initial water content 1.5 weight percent. The highest rate of reaction was 0.024 mol/lit.min at 343 K and 1.5 weight percent of initial water and about 99.5 % conversion was achieved in 220 min. On increasing the initial water content, the rate of reaction also increased, and almost complete conversion was achieved in 160 min and 120 min when initial water content was 4.4 and 8.7 weight percent respectively. The water content in the end of the reaction was 5.02, 7.86 and 12 weight percent determined when the initial water content was 1.5, 4.4 and 8.7 weight percent respectively charged in the start of the reaction. More than 4.4 weight percent of initial water content is not necessary because after that increment in the rate of reaction was not significant.