Synthesis of diamine functionalized mesoporous organosilicas with large pores

Hybrid mesoporous silicas functionalized with ethylenediamine groups have been synthesized via sol–gel process under different conditions. The best textural properties, with pore diameters up to 170 Å, have been obtained using carboxylic acids as catalysts in propanol as solvent without the need for any surfactant. The presence of the diamine moiety has been demonstrated by different characterization techniques, and the materials have been used in the adsorption of copper cations. The adsorption capacity of all the solids is high (up to 1.87 mmol/g and up to 2.47 Cu atoms/nm²), with important variations in the properties of the silica surface, besides the role of the immobilized diamine moieties as ligand for copper. In general the surface area seems to be the most important feature controlling the adsorption.