ABSTRACT
In general, to carry out a separation process or concentration, it is necessary to supply high quantities of energy. However, in the so-called separation processes by membranes, the energy required to perform a separation is small; therefore, these processes have become important in recent years. Certain components of a mixture can be separated in these processes by using a porous membrane selective to the crossing of some of the components of the mixture. Among these processes, inverse osmosis and ultrafiltration, which achieve separation by a semipermeable membrane, must be pointed out. The difference between these processes is difficult to discern, although the membrane in inverse osmosis usually retains molecules of low molecular weight, while in ultrafiltration, molecules with high molecular weights are usually retained. Figure 10.1 shows a classification of the separation processes according to the size of the particle retained.
