Acetic Acid Recovery Using Membranes

Recovery and recycling of acetic acid from aqueous streams is an important industrial separation that is high cost and energy intensive when performed by conventional technology. This makes acetic acid recovery a tantalizing target for a more efficient, lower cost, simpler approach such as membrane technology. However, the required separation performance, combined with the need for robust chemical and thermal stability of the membrane materials, makes the use of membrane technology for acetic acid recovery very challenging. In this project, perfluorinated polymer membranes are used to dehydrate acetic acid using two new membrane processes. The membranes are stable in hot acetic acid/water mixtures and have good selectivities for separation of water from acetic acid. The proposed membrane processes will lower energy costs by more than 50% compared to conventional separations. In Phase I, we demonstrated the feasibility of the proposed technology. Stable membranes were made that met the permeation criteria required for an economical process. A few bench-scale modules were made and successfully tested with aqueous acetic acid solutions at 90-100