Zirconia is a widely used multifunctional material. Its interesting properties, such as high chemical resistance, thermal stability and high mechanical toughness, have turned this material into object of study within fields such as optics, electronics, and magnetism, among others. In recent years, the chemical properties of zirconium oxide have been used, mixed with silicon, in order to obtain more stable and robust mixed oxides, with the final application of toughening ceramics. These properties are related to the degree of mixing of the components at molecular level, therefore, the linking between Si-O-Zr. Considering the effective antimicrobial capacity of silver nanoparticles, their incorporation into different materials is very interesting, acting as biocides. The objective of this work is to obtain zirconium oxides by the sol-gel technique, using zirconium n-propoxide as precursor, and also to study the effect of different solvents (water, ethanol) and the use of various acid catalysts in the synthesis [acetic acid and a heteropolyacid (HPA), as the phosphomolybdic acid (H₃PMo₁₂O₄₀)] on the physicochemical properties of the obtained solids. Finally, the addition of a silver salt was carried out into the sample with acetic acid and heteropolyacid as catalyst, in order to incorporate it as antimicrobial filler in paints. The obtained materials were characterized by SEM, XRD, FT-IR, textural properties through the absorption of N₂ (S_BET) and potentiometric titration with n-butylamine. Homogeneous solids were obtained in all the synthesis with acetic acid as catalysts. In addition, x-ray diffraction diagrams of amorphous solids were observed. The values obtained of surface areas are influenced by the variables of synthesis. The characteristic bands of zirconia were observed by FTIR in the solids synthesized. The results show that the solids environmentally synthesized are promising additives for use in paints.

This study focused on the use of citrus bio-waste and obtention of silica-based materials through the sol-gel technique for promoting a greener and more sustainable catalysis. The sol-gel method is a versatile synthesis route characterized by the low temperatures the materials are synthesized in, which allows the incorporation of organic components. This method is carried out by acid or alkali hydrolysis combined with bio-waste, such as orange and lemon peels, generated as co-products in the food processing industry. The main objective was to obtain silica-based materials from the precursor TEOS with different catalysts—acetic, citric and hydro-chloric acids and ammonium hydroxide—adding different percentages of lemon and orange peels in order to find the influence of bio-waste on acids/alkali precursor hydrolysis. This was to partially replace these catalysts for orange or lemon peels. The solids obtained were characterized with different techniques, such as SEM, FT₋IR, potentiometric titration and XRD. SEM images were compared with pure silica obtained to contrast the morphology of the acidic and alkali hydrolysis. However, until now, few attempts have been made to highlight the renewability of reagents used in the synthesis or to incorporate bio-based catalytic processes on larger scales.

In this work, the one-pot sol-gel synthesis of novel siliceous matrixes doped with carbon from spent batteries is reported. The obtained solids with silver nitrate were characterized by their antifungal activity against Aspergillus sp., Cladosporium sp. and Chaetomium globosum, three well-known cellulolytic microorganisms responsible for the deterioration of cotton fabric. In this research it was possible to develop a methodology for the impregnation of cotton fabrics (brin type) and to evaluate the antifungal efficacy. Cotton fabric containing the highest amount of carbon showed the highest antifungal activity against C. globosum and Aspergillus sp. This may be because as the amount of carbon in the silica increases, there is an increase in the surface area that facilitates an effective distribution of the active phase to act, inhibiting the fungal growth.