Retention properties of mesoporous silica-based materials

The partition and retention properties have been studied of mesoporous silicas prepared using a surfactant-based supramolecular templating approach towards environmental pollutants (trichloroacetic acid and haloderivatives such as chloroform, 1,1,1 -trichloroethane, trichloroethylene and tetrachloroethylene). Gas-chromatography and suppressed anion-exchange chromatography have been used to evaluate the amount of retained analytes. The effect of the composition (presence and absence of the surfactant templating agent and of aluminum) and the influence of synthesis procedure of mesoporous silicates on the sorption performances have been considered. Calcined materials do not show affinity for ionic analytes. The same materials show good affinity for non-ionic analytes: different retention properties towards the tested molecules are observed, interpreted in terms of van der Waals and hydrogen bonding interactions between silica surface and analytes. As-prepared materials show excellent retention performances towards TCA, which depend on the conditions used for the synthesis. All this provides the basis for potential applications of these materials as preconcentrators and sorptive chromatographic substrates for selective separation and/or enrichment (removal) of specific classes of analytes. (C) 2000 Elsevier Science B.V. All rights reserved.