Study on the Activation of Saudi Natural Bentonite, Part I: Investigation of the Conditions that Give Best Results and Kinetics of the Sulfuric Acid Activation Process

• Main Authors: A.A. Al-Zahrani, S.S. Al-Shahrani, Y.A. Al-Tawil
• Format: Article
• Language: English
• Published: Elsevier 2001-01-01
• Series: Journal of King Saud University: Engineering Sciences
• Online Access: http://www.sciencedirect.com/science/article/pii/S1018363918307256

The Kingdom of Saudi Arabia has many natural clay deposits of the montmorillonite type which are susceptible to activation. The activation of the Saudi natural bentonite with sulfuric acid was studied experimentally and the activity of the produced clay for bleaching of corn oil was tested and compared with that of commercial active clay. The conditions that give best results for the sulfuric acid activation were found to be: 45% by wt acid concentration, liquid to solid ratio of 5:1 (mL/g), clay particle size of -325 mesh (95% passing), at the acid boiling point for 15 minutes and mixing rate of 200 rpm. It was found that using a lower acid concentration requires more time to reach the same degree of activation as that when a higher acid concentration was used. The produced active clay (Saudi-bentonite) has a comparable bleaching power to that used commercially. The oil bleached with Saudi-bentonite clay is of qualities similar to that bleached by commercial clays. The apparent kinetics of the heterogeneous reaction were also studied. It was found that the reaction between sulfuric acid and clay is a zero order reaction with an apparent activation energy of 430 cal/mol.