Elaboration of Superhydrophobic Nanoporous Ceramic Membranes - Application to Desalination
Ceramic membranes are usually elaborated with metal oxides like alumina, titania or zirconia. These compounds have hydroxyl groups at their surface which give them a hydrophilic behaviour. In the field of membranes, it can be interesting to use membranes owning a hydrophobic behaviour. It is the case in the membrane distillation process. This process is based on a difference of temperature between the feed side and the permeate one. A very convenient method to change this behaviour is the grafting of particular molecules like fluoromolecules. The grafting was performed by immersion of the nanoporous membranes in a solution of the fluorinated compound in chloroform. Immersion time and fluoroalkylsilane concentration are the 2 principal parameters to be controlled. The characterisation was conduced by TGA, IR and Raman spectroscopy. The hydrophobic character was determined by measuring the water permeability and the water contact angle. Contact angles measured on flat samples are in the range 150 - 160°. The hybrid ceramics are super hydrophobic. Solutions of NaCl and seawater were filtered through the new membranes. The rejection of salts is total whatever their concentration.
A.B. Larbot et al., "Elaboration of Superhydrophobic Nanoporous Ceramic Membranes - Application to Desalination", Advances in Science and Technology, Vol. 45, pp. 2049-2054, 2006