Space, membrane technology application

Membrane technology is also an ideal technology for application in the space because process intensification strategy is a more imperative request in the space than on the Earth, today. Volumetric efficiency, optimal remote control, energy, and waste saving are fundamental aspects in the space. Membranes could efficiently solve some of the problems of life in the space such as energy production and water and air purification, fulfilling these requirements. 

Investigations on molecular machines in solution are of fundamental importance to understand their operation mechanisms and for some use (e.g., chug delivery). It seems reasonable, however, that before such systems can find applications in many fields of technology, they have to be interfaced with the macroscopic world by ordering them in some way so that they can behave coherently and can be addressed in space. Viable possibilities include deposition on surfaces, incorporation into polymers, organization at interfaces, or immobilization into membranes or porous materials. 

The need for thin, high permeability membranes has been confirmed by a technology assessment by Ward et al. Their goal was to determine what thickness of membrane is needed for petrochemical applications. They considered only high-selectivity materials, both dense and porous, and calculated the approximate membrane thickness to provide sufficient gas flux to have a substantial impact on the process. Both H2- and 02-transporting membranes were considered, and the conditions and typical space velocities of the process. A sample of their results is presented here in Table 2. 

The first applications of Nafion membranes in SPE technology were in fuel cells for space applications, which have been developed since the end of the 1960s. The perfluorosulphonic polymer is used as a proton conductor which provides to the cathode the protons that have been generated electrochemically at the anode. Perfluorosulphonic SPE is particularly well-suited to this application ". The principle of the H2"C>2 fuel cell is shown schematically in Fig. 32.3. At the anode, gaseous hydrogen is reduced following the electrochemical reaction... 

The formation of open and porous structures with extremely large surface area is of high technological significance, because this structure type is very suitable for electrodes in many electrochemical devices, such as fuel cells, batteries and sensors [1,2], and in catalysis applications [3]. The template-directed synthesis method is most commonly used for the preparation of such electrodes. This method is based on a deposition of desired materials in interstitial spaces of disposable hard template. When interstitial spaces of template are filled by deposited material, the template is removed by combustion or etching, and then the deposited material with the replica structure of the template is obtained [4, 5]. The most often used hard templates are porous polycarbonate membranes [6, 7], anodic alumina membrane [8-10], colloidal crystals [11, 12], echinoid skeletal stractures [13], and polystyrene spheres [14, 15]. 

---