The low ultrafiltration (UF) membranes performances depend mainly on the nature of the interactions between the solutes and the membrane material. This paper reports the filtration tests of different salts: CH3COONa, Na2HPO4 and NaF by means of a TiO2-ZnAl2O4 membrane prepared by sol-gel route deposed on a moroccan clay support. The measured rejections depend at once on the pH, on ionic strength of the solution; their interpretation needs to precise the exact speciation of the filtered species. (C) 2007 Elsevier B.V. All rights reserved.