Abstract
Soy oil was bleached with different rice hull ashes and clays. UV-vis absorbance spectra of bleached oils were presented. The spectra indicated that the bleaching with rice hull ashes or clays were of physical adsorption. It also revealed that the bleaching with rice hulls ashed in nitrogen stream was generally more efficient than those with rice hulls ashed in air stream. Acid activated ashes showed higher bleaching capability than unactivated ones. Moreover, unwashed activated ashes were found to be more effective in bleaching than washed ones.
