Amino and quaternary ammonium group functionalized mesoporous silica: An efficient ion-exchange method to remove anionic surfactant from AMS

Amino and quaternary ammonium group functionalized mesoporous silicas have been obtained by extracting the surfactant from anionic surfactant templated mesoporous silica (AMS) synthesized on the basis of the electrostatic interactions between the anionic surfactant and co-structure-directing agents (CSDA) such as 3-aminopropyltrimethoxysilane (APS) and N-trimethoxylsilylpropyl-N,N,N-trimethyl ammonium chloride (TMAPS). Mineral acid (HCl) and base (ethanol amine (EA)) or salt (ammounium acetate (AAC)) extractants, proved efficient to remove anionic surfactant from AMS materials synthesized with TMAPS and APS, respectively. The extraction method of AMS materials reported here is facile and efficient based on an ion-exchange process between the extractant and the quarternized or protonated amino groups on the walls of the mesopores. After extraction, the materials possess ordered mesoporous structures with properties similar to those of calcined materials. The existence and loading amount of amino or quaternary ammonium groups on the surface of the mesopores has been characterized by solid state 13C NMR and CHN elemental analysis.