The influence of mineral fillers on the membrane properties of high flux asymmetric cellulose acetate reverse osmosis membranes

Abstract

To improve the compaction resistance of high flux cellulose acetate membranes, fillers were incorporated into the casting solution. Several filler types — silicium oxides, aluminium oxides, montmorrilonite with or without an organic coating and with different physical properties — were used. During short-term reverse osmosis tests (ca. 7 hours) the water permeability-pressure relationship and the rejection properties of the membranes were investigated. During long-term reverse osmosis tests (100 hours), the flux decline at constant pressure as a function of time has been investigated. A correlation was sought between the pressure- dependency (loss of water permeability as a function of pressure) and the compaction resistance (loss of flux at constant pressure as a function of time) of the membranes tested.