Composite hollow fiber membranes for organic solvent-based liquid–liquid extraction

Instability issues of liquid membranes extraction significantly limit its wide application in industry. We report research on the application of a new composite hollow fiber membrane to stabilizing liquid membrane extraction. These type of composite membranes have either a polysulfone (PSf) ultrafiltration or an Accurel polypropylene microfiltration membrane as support and sulphonated poly(ether ether ketone) (SPEEK) as a coating layer. Applied as supported liquid membrane, the composite membranes showed significant improvement in stability compared to uncoated membranes. Applied in a membrane contactor, stable operation for more than 2.5 months was realized. A resistance model was developed to estimate the copper flux of the membrane contactor. The applicability of the model was proven for both the polysulfone and the polypropylene-based contactor systems. We further present the concept of encapsulated composite hollow fiber membranes with SPEEK layers encasing the extraction liquid into a hydrophobic support membrane.