Sea water desalination using glass hollow fibre membranes

Hollow fibre membranes suitable for the two-stage desalination of sea water have been prepared from phase-separable Na₂O-SiO₂-B₂O₃ glasses. The hollow fibres had outside diameters in the range 20 to 200 microns and corresponding wall thicknesses of 5 to 40 microns. The production of fibres from two glasses by means of phase separation, leaching and sintering is described. Using a 3.5% NaCl solution at 120 bars, product fluxes of about 1.0 m³/m²/day at 88% rejection were obtained with fibres of one glass, and fibres of the other glass withstood hydraulic compressive pressures over 200 bars. There was no evidence of compaction or hydrolytic degradation.