Journal of Membrane Science, Vol.102, 123-129, 1995
Rejection of Mineral Salts on a Gamma-Alumina Nanofiltration Membrane Application to Environmental Process
Nanofiltration of salt solutions through an alumina membrane prepared by a sol gel process was investigated : rejections depend on the charge of the ions and decrease in the order : (divalent cation, monoanion)>(monocation, monoanion) or (dication, dianion)>(monocation, dianion). The surface charge of the membrane in the investigated solutions was shown to be positive over a very large pH range. The rejection of ionic species can be rationalised by taking into account the low pore diameters of the membrane and its surface charge : as in the case of organic nanofiltration membranes, the rejection mechanism depends on the relative ratio of the coulombic, dielectric and hydration interactions between the membrane material and the ionic species. The use of nanofiltration through the alumina nanofiltration membrane for denitration of water is also presented.