i am doing some experiment on membrane. if the permeate rate across the membrane is predetermined, then pressure also will be fixed. neglect any kind of clogging effect, which may be reasonable for a short period of time. permeate rate is in litre/area hour. also does it matter that how we have supported put the membrane.
Dear Shubham,
to reply your question one must understand principle of membrane filtration:
In the solution-diffusion model, transport occurs only by diffusion. The component that needs to be transported must first be dissolved in the membrane. The general approach of the solution-diffusion model is to assume that the chemical potential of the feed and permeate fluids are in equilibrium with the adjacent membrane surfaces such that appropriate expressions for the chemical potential in the fluid and membrane phases can be equated at the solution-membrane interface. This principle is more important for dense membranes without natural pores such as those used for reverse osmosis.
Thus Permeate rate for membrane is not fixed, it is variable and largely dependent on osmotic pressure of solution to be filter. higher the concentration of salts in solution higher the osmotic pressure thus you require higher pressure to get the permeate.
Yes there are maximum recommended permeate flow rate basically dependent on shear strength of matter supporting the membrane, if you try to get more permeate then the recommended value, membrane may get ruptured.
hope above will help you
Dinkar Saxena
thank you sir for your reply, but please elaborate your last two paragraphs which are of my concern.
suppose the maximum recommended permeate flow rate is z lit/(area hour) and pressure corresponding to that is p N/area, now if pressure is reduced than p then how the permeate rate z will change.
also if i am having shear strength of membrane then how to determine maximum recommended permeate rate, did we need to determine it practically and would it be constt over the time after regeneration of membrane.
thanks a lot again for your valuable suggestion please elaborate it further.
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