Perfluorinated materials and photocatalytic titanium dioxide: synergies and chemical interactions in environmental applications

The main focus of this research has been the study of the interactions between TiO2 and fluorinated materials. Stability, decomposition pathways and synergisms between TiO2 and selected fluorinated material have been particularly studied. The stability of oxygen containing perfluoropolymers on UV activated anodized titanium, the photodegradation of perfluorocarboxylic acids, in particular perfluorooctanoic acid (PFOA), and the development of a TiO2-embedded fluorinated transparent coating for oxidation of hydrosoluble pollutants in turbid suspensions have been the specific research area of my PhD study. The development of a water treatment process based on a TiO2-containing perfluorinated multilayered transparent coating able to promote photocatalytic degradation of hydrosoluble organic pollutants, even in turbid solution conditions, has been the more challenging study. This approach allowed the overcoming of the problems related to the post-treatment catalyst recovery stage as well as an expected enhancement in the quantum efficiency and quantum yield guaranteed by the embedded TiO2 catalyst. Titanium dioxide powder was immobilized into an appropriate solid matrix, characterized by high chemical stability towards UV radiations and UV-activated TiO2; high transparency towards UV light in order to let UV rays reach the photocatalyst; high permeability to gases, especially to O2 and water vapor, which are required in the photocatalytic reactions; high wettability in order to optimize the interaction with the polluted aqueous solutions. In order to optimize the composition of the perfluorinated matrix, different perfluoropolymers were tested as protective coatings: their chemical stability towards UV radiations and UV-activated TiO2 was monitored and their effect on the photoactivity of TiO2 was evaluated. The following sections will be divided into three research streams, namely Protective Coating Evaluation, PFOA Degradation and Photoactive Coating Development.

La tematica centrale di questa ricerca è stata lo studio delle interazioni tra materiali fluorurati e biossido di titanio fotocatalitico. In particolare, l'attenzione è stata focalizzata su aspetti quali stabilità chimica di fluoropolimeri, analisi di meccanismi di degradazione di inquinanti persistenti perfluorurati (PFOA) e studio e successiva applicazione di sinergie tra TiO2 e perfluoropolimeri. Il principale obiettivo della ricerca è stato la realizzazione di un processo di trattamento acque innovativo, basato sull'impiego di un rivestimento perfluorurato multistrato trasparente contenente TiO2 fotoattivo. La particolare configurazione di questo coating ha reso possibile il suo impiego per il trattamento di soluzioni acquose contaminate da inquinanti organici, anche in presenza di solidi sospesi (elevata torbidità della soluzione). Inoltre, utilizzando TiO2 fotocatalitico immobilizzato all'interno di una matrice perfluorurata, è stato possibile evitare processi di separazione del catalizzatore dalla soluzione al termine del trattamento.