Organic-inorganic hybrid materials for boron removal from aqueous media

[EN] The present PhD thesis is centred in the design (using concepts of supramolecular chemistry), synthesis and characterization of different hybrid organic-inorganic materials for boron removal from aqueous media. The interaction between boron and organic groups, polyols, used in the development of these new adsorbents is also studied. In the first part of the thesis it is presented a brief review of supramolecular chemistry concepts, chemistry of boron and also the main methods for boron removal (first chapter) and, also, the objectives of this thesis (second chapter). The third chapter exposes the results obtained by using a ceramic foam as macroscopic support for active materials for boron removal. This support is previously "impregnated" with an inorganic silica mesoporous material (UVM-7) and, in a second step, it is functionalized with an organic group with high boron affinity (gluconamide). This organic group, which works as an adsorbent, remains anchored to a macroscopic support, which will facilitate the use of these materials in industrial applications. Once the material is synthetized their boron adsorption and elimination abailability in aqueous media is studied and its ulterior reutilization. The fourth chapter of the PhD thesis is focused on the preparation of low cost materials for boron adsorption from water. In first place, it is used, as inorganic scaffolding, UVM-7 material, a mesoporous silica phase with a bimodal pore system. This material has a high boron adsorption capacity after its functionalization with the polyalcohol (as it is shown in the previous chapter) nevertheless, the reagents used in the synthesis tetraethylorthosilicate, as silica source, and hexadecyltrimethylammonium bromide, as templating agent are so expensive that they induce a high cost of final materials. In this chapter is presented as an alternative another materials which are able to perform as inorganic scaffolds: UVM-11 (surfactant-free mesoporous material), two silica xerogels with pores within the mesoporous range and comercial high surface area silica fume were prepared. Once all the materials are synthetized they are functionalized with gluconamides which are the active compounds for boron adsorption. Finally, a comparative study of the boron adsorption capacities in water is carried out. Low cost materials present comparable boron removal to those of higher cost and comercially abailable materials. Finally, in the fith chapter of this PhD thesis, the