Study of mass transfer mechanisms for reverse osmosis and nanofiltration membranes intended for desalination

Membrane technologies are increasingly used in water treatment. nanofiltration and reverse osmosis processes are the most common techniques for desalination of water contaminated by excess of salts. in this present study,we were interested to mass transfer mechanisms which can be made by diffusion or by convection during a filtration process with commercial membranes of nanofiltration (nf90,nf270) and reverse osmosis (bw30,bw30le and sw30hr). transport mechanisms of ions through the pores of a membrane in a solvent-salt system were studied by using the model of spiegler-kedem-katchalsky which is based on thermodynamics of irreversible processes. this approach has allowed us to model the observed retention robs of different salts (nacl,na2so4 and mgso4) with different concentrations (from 10-3m to 10-1m) and to estimate thereafter,the phenomenological parameters for each system membrane/salt: k the mass transfer coefficient,σ the reflection coefficient and ps the salt permeability. the results showed competitiveness between nanofiltration and low-pressure reverse osmosis membranes,in terms of a selective separation of ions and an important production flux. © 2017,university of mohammed premier oujda morocco.