Characterisation and modelling of transient transport through dense membranes using on-line mass spectrometry

• Method for characterising the solute transient transport through dense membranes.
• On-line mass spectrometry monitoring tool for real-time transport characterisation.
• Time-dependent diffusion coefficients were calculated in whole transient regime.
• Mathematical model estimated solute concentration profiles inside the membrane.

This work presents a methodology for characterising solute transport through pervaporation membranes or, more generally, through dense membranes, in the whole transient regime. A real-time characterisation of transport through dense membrane is obtained by using on-line mass spectrometry (MS) monitoring, which allows to acquire the concentration of solutes in the permeate compartment with time intervals of 2 s (and shorter if required). Time-dependent diffusion coefficients, D(t), were calculated for the whole operation period, including the initial transient period. Based on these values it is possible to infer about the relevance of solute–membrane interactions and rearrangement of the membrane structure due to the presence of permeant solutes. Finally, based on the information acquired, a mathematical model was developed in order to obtain solute concentration profiles inside the membrane and their evolvement along time.