Abstract
Rice bran wax is waste material of dewaxing process in oil refining. Dewaxing is accomplished by cooling and filtrating for separating wax from the oil to avoid turbidity in the final product. The dewaxing residue may have 20 up to 80 wt% of oil, followed by a main fraction of waxes, free fatty alcohols, free fatty acids and hydrocarbons. The wax fraction of the residue is composed by long-chain fatty alcohols esterified with long-chain fatty acids. Considering that rice bran oil has 4 – 6 wt% of wax, a large amount of this natural source of fatty compounds is undervalued. Noweck and Rider (1987) describe a process based on hydrolysis of waxes with sodium hydroxide, followed by distillation of fatty alcohols and soap. According to best of our knowledge no work has been reported on the formation of fatty acids and alcohols from the hydrolysis of the dewaxing residue using supersaturated stripping steam under high temperatures and high vacuum. Therefore, present research work was carried out for studying the decomposition of the dewaxing residue of rice bran oil in a mixture of fatty acids and fatty alcohols under low pressure, high temperatures and the injection of stripping steam. Experiments were carried out in laboratory-scale batch equipment, loaded with the raw material and placed in an oven with controlled temperature. The independent variables were final oven temperature (°C), stripping steam flow (mL water/min) and time (h). Their effect on the production of fatty acids and alcohols were investigated following a simple factorial design (23 + central points). In each trial, samples were collected for the residue and distillate, and analyzed for acid value and Fourier-transform infrared (FTIR) spectra. The results showed that the formation of free fatty acids increased for higher temperatures and longer heating times. FTIR analysis evidence the occurrence of de-esterification reaction.
