| Abstract: | Separation by membranes . The paper reviews membrane processes in general, excluding the electro-membrane processes. The authors' aim is to discuss the aspects common to all membrane processes as well as the essential differences between them. The following processes will be examined: Reverse osmosis, ultrafiltration, gas permeation through porous or diffusion type membranes, pervaporation and liquid membrane techniques. In liquid systems, mass transport at the membrane surface proves to be the limiting factor. Conditions on the permeate side tend to influence flux and quality of the permeate only when a considerable pressure drop occurs. A typical example is that of hollow-fiber modules. It is shown how the permeability and dimensions of the membrane require selective adjustment in order to establish maximum flux. |
