Various models and mechanisms for the solvent and solute transport mechanism through reverse osmosis membrane have been developed and proposed by a number of investigators and researchers. The flow of solvent through the membrane is defined in terms of flux as: The solvent flux of the permeate depends on the hydraulic pressure applied across the membrane, minus the difference in the osmotic pressure of the solutions of the feed and permeate side of the membrane which is written as.
While the solute flux depends on the concentration gradient as: The membrane rejection is defined as the difference between the feed concentration and permeate concentration as:
From the solvent and solute flux Equations.
…show more content…
The osmotic pressure coefficient must be determined for different solutions. It has been determined by various researchers and investigators to be less than unity and slightly increases with increasing solution concentration if the solute is not known or it is complex, we have to use mass concentration instead of molar concentration. For convenience: this model assumed to be at a constant temperature and is incorporated with the other constant Y which simplifies osmotic pressure to solute concentration coefficient. The value of Y was assumed t-o be constant over the operating range of the solute concentration. In corporation of osmotic pressure equation into the expression for the solute flux Eq. yields:
Combining the above equations. we