Leticia Santamaría

The objective of the work studied here was to synthesize Layered Double Hydroxides (LDH) with aluminum extracted from saline slags and test their function once calcined into adsorbents/catalysts for use in the removal of emerging contaminants (pharmaceutical compounds) from aqueous media.Two different techniques for the removal of contaminants were tested, adsorption and photocatalysis. In the present work, a new procedure for the recovery of aluminum present in saline slags generated during the secondary recycling processes of aluminum as adsorbent/photocatalyst of diclofenac and salicylic acid, as examples of emerging contaminants, has been reported. Results obtained have been extensively analyzed throughout the present study.

The worldwide rise in biodiesel production has generated an excess of glycerol, a byproduct of the process. One of the most interesting alternative uses of glycerol is the production of solketal, a bioadditive that can improve the properties of both diesel and gasoline fuels. Even with its promising future, not much research has been performed on its toxicity in aqueous environments. In this work, solketal adsorption has been tested with two different commercial adsorbents: an activated carbon (Hydrodarco 3000) and a metal–organic framework (MIL-53). Diclofenac and caffeine were also chosen as emerging contaminants for comparison purposes. The effect of various parameters, such as the adsorbent mass or initial concentration of pollutants, has been studied. Adsorption kinetics with a better fit to a pseudo-second-order model, intraparticle diffusion, and effective diffusion coefficient were studied as well. Various isotherm equation models were employed to study the equilibrium process. The results obtained indicate that activated carbon is more effective in removing solketal from aqueous solutions than the metal–organic framework.

Titanium dioxide modified with Ag and Fe was synthesized using two preparation methods, characterized and applied to the photocatalytic degradation of salicylic acid in aqueous solution. The modified TiO₂ samples were prepared by the sol-gel and wet impregnation methods starting from titanium(IV) isopropoxide and using AgNO₃ and Fe(NO₃)₃·9H₂O as precursors of the modifiers, with their content varying between 0 and 5 wt.%. Catalysts characterization was based on powder X-ray diffraction (PXRD), nitrogen physisorption at 77 K, temperature programmed reduction (H₂-TPR), chemisorption of NH₃ at 343 K and X-ray photoelectron spectroscopy (XPS). The photocatalytic degradation of salicylic acid by modified TiO₂ was investigated under ultraviolet irradiation at 298 K considering various concentrations of the catalyst, between 100 and 1000 mg_catalyst/dm³, and of the organic molecule, between 0 and 15 mg/dm³. The catalysts most active in the degradation of salicylic acid were those having the highest Fe content.