EFFECTS OF SODIUM BISULPHATE CATALYST ON THE DEHYDRATION OF CASTOR OIL FOR THE PAINT INDUSTRY

Crude castor oil seems to have many industrial applications. However, its Iodine value range <100 (82 - 88 gI2/100g) makes it not applicable in the paint industries since it is considered a non-drying oil. Experimentally, dehydration of its fatty oil is the only way of converting its non- drying attributes into a drying one. This process involves heating the oil to a temperature of 250OC in the presence of catalyst such as sulphuric acids, phosphoric acids, clays and metal oxides under an inert, atmospheric or vacuum condition. Albeit a lot of research has been carried out on the different catalyst used in dehydrating castor oil and the effect of catalyst percentage variation in an overall continuous process, this study was however on the effect of sodium bisulphate catalyst on a batch process. The change in the physiochemical properties (hydroxyl, viscosity and iodine value) with respect to time and temperature was considered. In the course of this study, Sodium bisulfate and Sodium bisulfite is chosen as the catalyst and anti-polymerization agent respectively. The dehydration of castor oil in the presence of catalyst speeds up the rate at which the maximum dehydration is obtained (60min) but at the same time, speeds up the rate of polymerization. The Iodine value rapidly decreases until it attains maximum dehydration wherein polymerization (hardening of oil) takes place simultaneously. However, dehydration reaction without catalyst takes longer time to reach maximum dehydration (180 min), but does not readily polymerize when maximum dehydration is reached