RESUMEN
Herein, we demonstrated that bentonites can be incisively used to reduce wine BAs content, especially putrescine molecules. Pioneering kinetic and thermodynamic studies of putrescine adsorption onto two commercially available bentonites (optimal concentration of 0.40 g dm-3) were performed resulting in ca. 60% removal by physisorption mechanism. Both bentonites showed also promising results in more complex systems, resulting in a lower putrescine adsorption due to the competition with other molecules (as proteins, polyphenols), typically present in wines. Nonetheless, we managed to reduce the putrescine content below 10 ppm both in red and white wines.
Asunto(s)
Aminas Biogénicas , Vino , Aminas Biogénicas/análisis , Putrescina/análisis , Vino/análisis , Bentonita , PolifenolesRESUMEN
In bottled wines, haze and turbidity are phenomena to be avoided. Since bentonite fining is a common process to clarify wines removing heat unstable proteins, a theoretical study on the adsorption of three Charged Model Molecules (CMMs, egg albumin, polyphenols and riboflavin) was carried out to deep comprehend this chemical phenomenon. Four bentonites were adopted and finely characterized together with the potential release of Na+ and Ca2+ cations, revealing suitable for RT albumin removal within 120 min. Better results in terms of adsorbed quantity were achieved by adopting 12%v/v EtOH/H2O solvent and by swelling bentonites for 24 h before use. With the most performing sample (Na/Ca_0.27), a comprehensive study on simultaneous adsorption of the three CMMs was performed, resulting in polyphenols adsorption increase due to their interactions with albumin. Notwithstanding the majority of albumin and riboflavin was successfully removed, ca. 40-50% of tested polyphenols was preserved.
Asunto(s)
Bentonita/química , Vino/análisis , Adsorción , Calcio/química , Calcio/metabolismo , Cromatografía Líquida de Alta Presión , Cinética , Espectrometría de Masas , Ovalbúmina/química , Polifenoles/química , Riboflavina/química , Sodio/química , Sodio/metabolismoRESUMEN
The photodegradation of the highly toxic o-toluidine pollutant was deeply investigated both under UV and solar irradiations by using three different semiconductors: pure ZnO, Bi-impregnated ZnO, and Bi2O3 nanopowders (synthesized by precipitating method). All the samples were deeply characterized on structural, morphological, surface, and optical points of view. The disappearance and the relative mineralization of o-toluidine molecules were followed by linear sweep voltammetry (LSV) and total organic carbon (TOC) determinations, respectively. Hence, correlations between their physico-chemical properties and the photocatalytic performances, passing from UV to solar light, were drawn and a hypothesis on the photodegradation mechanism has been proposed, on the basis of the HPLC/MS results. Bare Bi2O3 samples, due to the exploitation of both their visible light absorption and the negligible intermediates formation, resulted to be higher performing under solar irradiation than either pure or Bi-doped ZnO nanopowders. Graphical abstract.
Asunto(s)
Bismuto/química , Sustancias Peligrosas/efectos de la radiación , Fotólisis , Toluidinas/efectos de la radiación , Óxido de Zinc/química , Catálisis , Nanopartículas/química , Óxidos , Semiconductores , Luz Solar , Rayos Ultravioleta , ZincRESUMEN
In order to avoid both natural and artificial stone decay, mainly due to the interaction with atmospheric pollutants (both gases such as NOx and SO2 and particulate matter), polymeric materials have been widely studied as protective coatings enable to limit the penetration of fluids into the bulk material. In the current work, an air hardening calcic lime mortar (ALM) and a natural hydraulic lime mortar (HLM) were used as substrates, and commercially available Si-based resins (Alpha®SI30 and Silres®BS16) were adopted as protective agents to give hydrophobicity features to the artificial stones. Surface properties of coatings and their performance as hydrophobic agents were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Finally, some exposure tests to UV radiation and to real polluted atmospheric environments (a city centre and an urban background site) were carried out during a wintertime period (when the concentrations of the main atmospheric pollutants are higher) in order to study the durability of the coating systems applied. The effectiveness of the two commercial resins in reducing salt formation (sulphate and nitrate), induced by the interaction of the mortars with the atmospheric pollutants, was demonstrated in the case of the HLM mortar. Graphical Abstract á .