Concentration polarization profile for dissolved species in unstirred batch hyperfiltration (Reverse Osmosis) - II Transient case

A previously developed theoretical model for the build-up of the dissolved solute concentration adjacent to a permselective hyperfiltration membrane is used to reconstruct interference patterns during the transient period (Mahlab, 1977). Included is a general solution for the tracing (and bending) of any electromagnetic wave propagation in an inhomogeneous medium. Experimental transient laser interferograms were obtained at different times in an unstirred high pressure batch test cell with optical windows at 28°C and at 5 atm applied pressure with 182 mg/l of NaCl. Comparison of simulated and experimental fringe patterns for each time t during the transient period, gave excellent fits with respect to the number and separation of fringes. Simulated fringes were characterized by the infinite (t=-8) intrinsic parameters v=30 cm^-1 and R=0.57 for each τ or t.