For thousands of years, separation of mixtures has been practiced by humans. In Meteorologica, Aristotle noted that “salt water when it turns into vapor becomes sweet, and the vapour does not form salt water when it condenses again. This I know by experiment.” In 1752, Abbé Jean Antoine Nollet reported separating mixtures of “spirits of wine” using a pigskin bladder as a membrane. In 1829, Sir Thomas Graham reported that membranes made from natural rubber could remove oxygen from air, which he called “dialyzing” air: “This dialyzed air rekindled glowing wood, so as to illustrate the direct separation of oxygen gas from atmospheric air.” In modern times, polymer-based membranes have become critical to both civilian and defense applications. For example, most commercial and many military aircraft today are equipped with On-Board Inert Gas Generation Systems (OBIGGS). Air taken from the compressor in an aircraft engine is stripped of oxygen by a membrane system before being passed through the headspace in the aircraft fuel tank, reducing oxygen content in the headspace to below the flammability limit, helping limit the possibility of fuel tank fires. Equipment weight and space are critical in such applications. New membranes being explored for this application are many times more permeable than current membranes, leading to much smaller, lighter membrane systems. This presentation seeks to present recent advances in separation membranes, for both civilian and defense applications, from both historical perspective and provide a glimpse of potential future trends in this technology.

Gas separations important to the water/energy nexus

2019 Fall National Meeting

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