**6. Applications**


During nanofiltration, the electromigration, diffusion and convection are the major transport mechanisms. The atoms ions can pass through the channels between the molecular groups in the molecular structure of the membrane. The selectivity of nanofiltration membrane was defined by nature and size of these passages, ionic size, shape, pore density, pore diameter, and membrane surface charge [50, 51].

The suitability of a thin film polyamide nanofiltration composite membrane (SNTE NF270–2540) to extract heavy metal ions (Zn (II), Cr (III), Cu (II), Fe (III), Cd (II), Pb (II), Co (II) & Ni (II)) from industrial wastewater was examined [52]. The operating conditions including feed pH value, feed metal concentration and pressure were optimized. The retention of iron at pH = 5.3 and nickel at pH = 7.2 for pressure from 6.0 to 13.5 bars was quantitative (100%). For lead at pH = 4.4 for pressure from 6.0 to 10 bars, the retention was quantitative (100%).

The influence of divalent cations on the rejection of trivalent cations was examined [52].

The membrane was characterized by using the ions transport model and the consumption energy was calculated. The effect of ionic concentration and the diffusion fluxes were studied [52].
