The Estimation of Feed Solution Composition Influence on Concentration Polarization Layer Resistance during Reverse Osmosis

The experimental determination of concentration polarization layer resistance during reverse osmosis of mineral salts solutions was carried out with the aim to estimate the influence of solution composition on the value of mentioned resistance.In experimental conditions, the membrane resistance remains constant (the mean value was 0.534•10 14 m -1 ) which means that the membrane compaction was not observed.Moreover, under experimental conditions, the hypothesis about linear dependence between the concentration polarization layer and applied pressure was confirmed for all solutions under investigations.It was defined that value of concentration polarization layer resistance different salt solutions was varied less than 10 % although under experimental conditions the diffusion coefficient values of magnesium sulfate were more than three times higher than corresponded values for other salts.The increasing of solutions concertation determines the increasing of concentration polarization layer resistance.At the same time, in previous study it was defined that changes in hydrodynamic regime in membrane module under similar conditions could determine the change in concentration polarization layer resistance in 3-5 times, while in both studies the trends of impact of hydrodynamic conditions still similar to the value of considered resistance decrease with Reynolds number increasing.Such results showed that in considered range of concentrations the hydrodynamic conditions have a lower influence on concentration polarization layer resistance than solution composition.The obtained results are in agreement with the film theory of concentration polarization.