Separation and characterization of waxes from crude rice bran oil

Abstract

Waxes were separated and purified from the tank settlings and bag filter cakes obtained from the refining process of crude rice bran oil as by-products. The samples of tank settlings and bag filter cakes were processed in various ways to obtain hard, non-tacky, and high melting point wax fractions which consisted mainly of fatty alcohol, fatty acid, ester of fatty alcohol and fatty acid and hydrocarbon. The procedures investigated consisted of removal of oil from the tank settlings and bag filter cakes and destruction of phosphatides through hydrolysis, hydration, saponification and fractional crystallization followed by fractionation of sole wax. Yields of the wax fractions varied from 6.2 to 6.5 \% based on the weight of bag filter cakes and 12.8 \% of tank settling. The highest value of melting point of wax obtained was 79$^\circ$C and the lowest was 76.5$^\circ$C. The samples of waxes produced were mostly black or dark brown in color and could not be bleached readily with activated carbon and clay. The waxes were bleached to white in color readily by the combined using of sulfuric acid, chromium trioxide and hydrogen peroxide. The components of waxes such as fatty alcohol, fatty acid and hydrocarbon were fractionated separately by the activated alumina and calcium carbonate column chromatography. The separated fractions were analyzed by GLC and HPLC. The results of GLC and HPLC showed that the separated fraction consisted of fatty alcohol (64.5\%), fatty acids (33.5\%) and hydrocarbon (2.0\%). The major components of fatty alcohols were saturated fatty alcohols of $C_{28}$(20.2 \%), $C_{35}$(18.0 \%) and $C_{36}$(18.1 \%). The hydrocarbons were mainly composed of the normal alkanes of $C_{29}$(6.4 \%), $C_{31}$(33.5 \%) and $C_{33}$(18.8 \%) in odd numbers and of $C_{18}$(2.5 \%), $C_{20}$(4.3 \%), $C_{22}$(3.8 \%) and $C_{24}$(2.7 \%) in even numbers. The fatty acids composed mainly of the saturated fatty acids of $C_{16}$(10.6 \%), $C_{18}$(10.6 \%), $C_{...