defended his PhD thesis on 23 June 2023
“Halloysite–titanium oxide based nanocomposites by
electrospinning as photocatalyst for water treatment“
Front of the jury:
– M. Mikhael BECHELANY, directeur de recherche CNRS, Université de Montpellier – Directeur de thèse
– M. Abdessalem BEN HAJ AMARA, professeur, Université de Carthage – Directeur de thèse
– M. Mohamed DAMMAK, professeur, Université de Sfax – Rapporteur
– M. Roland HABCHI, professeur, Université Libanaise – Rapporteur
– Mme Rym ABIDI, professeur, Université de Carthage – Examinatrice
– Mme Sophie Tingry, professeur, Université de Montpellier – Examinatrice
Nowadays, water pollution is a major problem leading to health and environmental issues. With proper water treatment, such as by heterogeneous photocatalysis, it is possible to reduce water pollution by degrading pollutants. In this work, the elaboration of halloysite–TiO2 nanocomposites fibers by combining sol–gel and electrospinning method have been performed to elaborate highly catalytic material with great stability.
The halloysite (HNTs) used was extracted from Tamra (NW Tunisia). In the first part of this thesis, TiO2–based composite nanofibers with a large amount of HNT (95%) were successfully prepared by combining the sol–gel and electrospinning methods with the aim of obtaining a good catalyst for acetaminophen degradation. In the second part, we combined electrospinning and treatment under nitrogen to produce N–HNT–TiO2 composite nanofibers and compare their photoactivity with HNT–TiO2. In the last part, we fabricated composite nanofibers by including controlled amounts of boron nitride (BN) nanosheets (5%), titanium oxide (TiO2) nanofibers and halloysite nanotubes (HNT) to improve the photocatalytic activity of acetaminophen under visible light and compared the obtained results with HNT–TiO2. The morphological and structural properties of all synthesized nanostructures were investigated by several characterization techniques such as X–ray diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM), Raman spectroscopy, Brunauer–Emmett–Teller method (BET), and X–ray photoelectron spectroscopy (XPS). The results confirmed halloysite incorporation into TiO2 nanofibers. The results show that the chemical and physical properties have a high impact on the photocatalytic properties of the synthesized hybrids and confirmed the incorporation of halloysite into TiO2 nanofibers. Moreover, it was found that the doping effect lead to a more efficient charge separation in the photocatalyst, which is an advantage for photocatalytic activities. In addition, methylene blue (MB) and acetaminophen (ACT) were used as model pollutants in degradation experiment. A significant enhancement and a long–term stability in the photocatalytic activity were observed with the doped materials compared to the non–doped ones under visible light. A better understanding of the photocatalytic oxidation pathways (based on by–product analysis) coupled with toxicity tests (Vibrio fischeri., Microtox) was investigated. The results indicate that BN/TiO2/HNT present interesting photocatalytic properties for both organic compound degradation and bacterial removal.