Low-Energy Distillation-Membrane Separation Process

A low-energy separation process combining distillation and membrane vapor permeation is introduced as an alternative to conventional distillation. The process can be applied to any liquid mixture for which appropriate selective membranes are available. However, in this paper, the discussion is limited to water/organic solvent mixtures using membranes that preferentially permeate water. Such membranes are available. The process is illustrated with two mixtures: ethanol (light component)/water (heavy component) and acetic acid (heavy component)/water (light component) mixtures. In both cases, the combination process reduces the energy consumption of the separation to half that of simple distillation.