How Do You Separate Completely Free Fatty Acids From Used Oils And Fats?
For obtaining free fatty acids from soap stock by first acidulating the soap stock to liberate fatty acids from the soap present, separating the resulting first acid oil and aqueous saline phases, recovering free fatty acids by vacuum distillation from this first acid oil phase, saponifyng the glyceride-rich still residue to generate additional soap, acidulating the saponified product to liberate additional fatty acids therefrom and separating the resulting second acid oil and aqueous saline phases. These additional fatty acids can be recovered as free acids by vacuum distillation from the separated second acid oil phase. It is sometimes advantageous to neutralize residual mineral acid in the first acid oil phase before distillation.
