Influence of high operating pressures on the separation performance of nonporous membranes

For the application of reverse osmosis membranes to concentrate e.g. sugar containing solutions high operating pressures are necessary to overcome the osmotic pressures of the resulted concentrated systems. Commercial RO membranes are applicable currently up to pressures of between 120 and 160 bars. This paper describes the procedures and the investigation of flat sheet membranes which have been applied under pressure up to 300 bars. The deformation or compaction of the respective membrane layers are visualized and the resulted changes of certain separation properties affected by the applied pressures will be discussed.