(18g) Separation of Fatty Acids and Fatty Acid Esters Using Nanoporous Polymeric Membranes

Membrane separations are typically inexpensive and can be scaled to industrial quantities, but the development of membranes that can separate organic chemicals lag behind those that separate gasses and water. Part of the challenge in this field is that the polymeric membranes swell in the presence of organic chemicals and the swelling impacts their abilities to separate chemicals. Despite these challenges, the potential applications of membranes that separate organic liquids and solids is impressive. For instance, worldwide over 200M tons of vegetable, tall, and fish oils are isolated each year, and their fatty acids are biorenewable, safe feedstocks for the chemical community. Unfortunately, the purification of fatty acids using traditional methods such as distillation, selective precipitation, and chromatography are energy intensive or not readily scaled to separate unsaturated fatty acids. Commercial applications of fatty acids requires starting with a mixture of fatty acids that can vary based on which season the crops were grown and the plant source for the oils.

We recently developed a series of membranes based on polyepoxies that can separate some of the key fatty acids found in vegetable and fish oils. These membranes were synthesized by the addition of diamines and di or triepoxides that react to yield highly cross-linked membranes. The selectivity of the membranes can be tuned by the selection of the epoxide and diamines used in their synthesis. These membranes were able to separate saturated and unsaturated fatty acids.