Separation materials, tailor-made

Source Reprinted with permission from Advanced Functionai Materials, Tailor-made polymeric membranes based on segmented block copolymers for CO2 separation, by A. Car, C. Stropnik, W. Yave, K.-V. Peinemann, 23,... 

Figure 12.16 C02/gas selectivity in single gets and different mixed gas as a function of fugacity. (-M- 0% PEC, -O- 10% PEC, -A- 20% PEG, -V- 30% PEC, 40% PEG and 50% PEC. Reprinted with permission from Advanced functional Materials, Tailor-made polymeric membranes based on segmented block copolymers for COj separation, by A. Car, C. Stropnik, W. Yave, K.-V. Peinemann, 23, 2815-2823, Copyright (2008) Wiley-VCH...

Mixed solid fertilizers can be made by either direct granulation methods (40%) or bulk blending (40%). Bulk blending is made by mechanical mixing of the separate granular intermediate materials. It is usually done in small plants near the point of use. This technique is employed because the fertilizer can be tailor-made to fit the exact requirements of the user. Fluid or liquid fertilizers (clear, suspension, and slurry) account for 20% of all NPK mixed fertilizers. 

If a membrane has a graded pore structure but is made in one processing step, frequently from the same material across its thickness, it is called an asymmetric membrane. If, on the other hand, the membrane has two or more distinctively different layers made at different steps, the resulting structure is called a composite membrane. Almost invariably in the case of a composite membrane, a predominantly thick layer provides the necessary mechanical strength to other layers and the flow paths for the permeate and is called the support layer or bulk support. Composite membranes have the advantage that the separating layer and the support layer(s) can be tailored made with different materials. Permselective and permeation properties of the membrane material are critically important while the material for the support layer(s) is chosen for mechanical strength and other consideration such as chemical inertness. The composite membranes can have... 

Membrane technology covers various chemical technology disciplines, such as material science and technology, mass transport and process design. By manipulating material properties, membranes can be tailor-made for particular separation tasks... 

Separation of CO2 from gas streams is required in four areas (1) purification of natural gas (gas sweetening), (2) separation of CO2 from enhanced oil recovery (FOR) gas streams, (3) removal of CO2 from flue gas, and (4) removal of CO2 from biogas. A fifth area vital for the space age should be mentioned removal of CO2 from life support systems onboard space ships, and also in submarines. All these applications have different specifications for the purified gas or for the recovered CO2, and future membrane applications will most likely be based on tailor-made materials. 

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