Experimental study and modelization of reverse osmosis with salt solutes in an unstirred batch cell

The study deals with reverse osmosis of salt solutes in an unstirred batch cell at a rejection coefficient very close to 1. The experiments were performed in a stainless steel batch cell specially manufactured in order to lower the dead volume under the membrane. The operating conditions led to salt concentrations at the membrane rising from 1 to more than 100 kg.m(-3) during a given experiment. Introducing a reduced number of restrictive assumptions, a model was used in which the convection-diffusion equations associated with the osmotic theory equation are solved by a mixed-finite elements method. Unlike other charged solutes (such as proteins), this model very well describes the experimental results of salt solutes, even if salt concentration near the membrane becomes high.