Preparation of silicon nitride hollow fibre membrane for desalination

The microporous Si3N4 ceramic hollow fibres with highly asymmetric structure were prepared by a combined phase-inversion and sintering method for the first time. Rod-like beta-Si3N4 grains with high aspect ratios were observed in both the sponge-like and finger-like layers, leading to the formation of a strong three-dimensional network, which could be beneficial for the mechanical properties. Hollow fibres with a porosity of 50% and a bending strength of 290 MPa have been achieved. The hollow fibres could be modified from hydrophilic to hydrophobic via grafting with fluoroalkylsilane (FAS) on the fibre surface. While conducting desalination in a vacuum membrane distillation (VMD) process, the modified membranes exhibited satisfactory membrane distillation performance, promising for practical applications. (C) 2011 Elsevier B.V. All rights reserved.