Separation using membrane

Gas Separation. During the 1980s, gas separation using membranes became a commercially important process the size of this appHcation is stiH increasing rapidly. In gas separation, one of the components of the feed permeates a permselective membrane at a much higher rate than the others. The driving force is the pressure difference between the pressurized feed gas and the lower pressure permeate. 

As an example the use of ceramic membranes for ethane dehydrogenation has been discussed (91). The constmction of a commercial reactor, however, is difficult, and a sweep gas is requited to shift the product composition away from equiUbrium values. The achievable conversion also depends on the permeabihty of the membrane. Figure 7 shows the equiUbrium conversion and the conversion that can be obtained from a membrane reactor by selectively removing 80% of the hydrogen produced. Another way to use membranes is only for separation and not for reaction. In this method, a conventional, multiple, fixed-bed catalytic reactor is used for the dehydrogenation. After each bed, the hydrogen is partially separated using membranes to shift the equihbrium. Since separation is independent of reaction, reaction temperature can be optimized for superior performance. Both concepts have been proven in bench-scale units, but are yet to be demonstrated in commercial reactors. 

Ghosh R (2002), Protein separation using membrane chromatography opportunities and challenges, J. Chromatogr. A 952 13-27. 

Zydney, A.L., Protein separations using membrane filtration New opportunities for whey fractionation, Int. Dairy J., 8, 243, 1988. 

Zydney, A.L. Protein separations using membrane filtra-... 

Several attempts to perform enantioselective separations using membranes of a chiral mobile carrier have been reported and have been extensively discussed in a recent review [185]. Various chiral carriers, mainly crown ethers, were used for this purpose but poor enantioselectivity was usually obtained and no preparative application has been described. 

As mentioned earlier, some process models are not available in the simulators such as Aspen Plus. In such situations, ACM can be used to implement models available in the literature or newly developed models. Subsequently, these ACM models can be included in Aspen Plus and/or Aspen HYSYS for use like built-in models in any process. The above model for gas separation using membrane (Section 4.2.3) can be implemented and solved in ACM see Appendix 4A for more details on the ACM model for no permeate mixing membrane module. In order to implement the membrane model in ACM, all chemicals are defined from the component list in the Aspen Properties User Interface program, and then... 

Freeman BD, Pinnau I (2004) Gas and liquid separations using membranes an overview. In Pinnau I, Freeman BD (eds) Advanced materials for membrane separations. ACS symposium series 876, American Chemical Society, Washington, DC, pp 1-21... 

Physical separation of inorganic ions and other low-molecular analytes from the particulate and dissolved macromolecular fractions of the sample is useful in different flow instruments. Dialysis and UF membrane cells are amongst practical systems for flow injection analysis (FIA), which serve to exclude any unwanted sample material so that only the analyte reaches the reaction or sensing zone. SoHd particles and large interfering molecules can be separated using membranes from the smaller species of analytical interest. Such cells can also be used in the continuous-flow, stopped-flow, and sequential injection modes of flow analysis. The membrane preseparation units are very attractive because they are simple, repeatable, require little or no pretreatment of sample, and show no interferences from sample color and turbidity in most cases no reaction in the membrane interface is involved. 

Biodiesel production via a membrane reactor has shown great performance because it overcomes the serious issues of conventional reactors. Both production and separation using membrane technology have provided a suitable opportunity for companies to manufacture biodiesel beneficially. However, there are some challenges in using membrane reactors for the production of biodiesel that need to be resolved, such as limitation caused by its material, shape, and pore size (Ned Hall), the high cost of some kind of membranes (Murphy et al., 2010), the slow rate of reaction (Dube et al., 2007), and issues related to the presence of alkaline catalyst with water (Baroutian, Aroua, Raman, Sulaiman, 2010a). 

The flow of a condensable vapor through a mesoporous membrane is a phenomenon of great complexity [29,30]. Despite the early experimental findings and the immediate impact in gas separations using membrane technology [32] the above physical process has been only recently simulated using two-... 

Lu, Z., M. Wei, and L. Yu. 2012. Enhancement of pilot scale production of L-(t>)-lactic acid by fermentation coupled with separation using membrane bioreactor. Process Biochem. 47 410-415. 

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