Preparation and luminescence properties of europium(III)-loaded aminosilica spherical particles

The sol-gel technique, using tetraethyl orthosilicate and bridged bissilanes as precursors, along with silanes containing amino functions, was applied for the synthesis of polysiloxane spherical particles. Four different types of aminosilica spherical particles were prepared: silica with aminopropyl and phenyl groups, silica with incorporated dipropylamine bridges, phenylene bridged polysilsesquioxane with aminopropyl groups, and ethylene bridged polysilsesquioxane with aminopropyl groups. It was shown that in the case of long or non-flexible bridges in bissilanes (with the same ratio of components) the samples with high specific surface area have formed. In the case of flexible and small bridges in bissilane or tetraethoxysilane the non-porous materials were fabricated as a result of the formation of tightly packed aggregates and primary particles up to 200 nm, respectively. The presence of amino groups was confirmed by elemental and TG analyses, IR and X-ray photoelectron spectroscopies. The dependence of the adsorption of Eu(III) on the concentration of the initial aqueous solution was investigated. The obtained isotherms were fitted to the Langmuir and Freundlich equations, and for some samples their data are in good agreement with both models. The sorption capacity of aminosilica spherical particles to Eu(III) is high and can reach up to 158 mg g(-1). The ability to absorb Eu(III) ions by aminosilica spherical particles are assessed using luminescence, and the characteristic emission of the Eu3+ ion was exhibited by Eu(III) loaded samples when exposed to UV light.