Functionalised SBA-15 mesoporous silica in ion chromatography of alkali, alkaline eartths, ammonium and transition metal ions

The retention properties of a SBA-15 mesoporous silica functionalized with -(CH2)3COOH groups, synthesized by a co-condensation route, were investigated for the ion chromatography of different cationic species. A systematic study on the effect of different eluent compositions containing non-complexing (methanesulfonic acid) or complexing (oxalic or pyridine-2,6-dicarboxylic acids) eluents, in the presence of organic modifiers (CH3CN, CH3OH, CH3NH2) on the retention of cations (Li+, Na+, K+, Ca2+, Mg2+, Sr2+, Ba2+, NH4+, Cu2+, Ni2+, Zn2+, Cd2+, Co2+, Pb2+, Fe3+) chosen as model analytes and for their environmental importance, allowed us to elucidate the mechanisms (cation-exchange or complexation) involved in the retention on the SBA-15 phase. For the first time separations of cations on SBA-15 based stationary phases are investigated, providing the basis for further development of mesoporous silica chemistry for in-flow ion-exchange applications.