Nanofiltration of Docosane-Toluene Solutions

The first experiments were conducted with the docosane-toluene system. This is considered an eas/ binary system with which to verify the model due to the fact that nanofiltration data are available in the literature for comparison [25], and the change in viscosity with concentration is negligible [32]. 

Two concentrations of docosane (0.33 M and 0.67 M) in toluene were tested at various pressures and flow rates. The results for the permeate flux and docosane rejection are presented in Fig. 4.5 (A, A, B, B ). As can be seen from the figures, both docosane rejection and permeate flux decrease with decreasing pressure at both concentrations. The fluxes and rejections are lower at the higher docosane concentrations. This type of result is not surprising and has been observed previously with other systems [43, 44]. Experimentally, the flow rate through the crossflow cell does not have a significant effect on the flux or the rejection performance. 

For the flux data (Fig. 4.5 A, A ), the calculated values correspond better with the experimental data at higher pressures. When activity coefficients are taken as unity, the model predicts almost no flux at pressures lower than 8 bar for 

Calculated flux with activity coefficient functions, Eqs. (18), (19) 

---