Abstract
Due to the increasing contamination of our natural water resources by a wide range of organic micropollutant (OMPs), there is a need for developing new energy-efficient advanced oxidation processes for the treatment of water contaminated by such refractory pollutants.Photocatalysis has attracted much attention, due to its ability to degrade toxic organic compounds in wastewater into environmental friendly compounds such as CO₂ and water. Among the various photocatalytic materials, titanium dioxide (TiO₂) has been widely used due to its high photocatalytic efficiency, high stability and low toxicity. However, fast charge recombination and the narrow absorption range in the UV spectrum; limit its photocatalytic efficiency under visible-light irradiation.In this work, the elaboration of different TiO₂ structure by combining two techniques have been performed. In the first part of this thesis, TiO2 nanofibers were synthesized by electrospinning method. In order to improve the photocatalytic activity under visible light, a developed process based on atomic layer deposition (ALD) was used to grow boron nitride (BN) and palladium (Pd) on these fibers. The second part of this work was to elaborate TiO2 nanotubes (NTs) by ALD and compare their photoactivity with TiO2 NFs. The morphological, structural and optical properties of all synthesized materials were investigated by several characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Moreover, the optical and electrochemical properties of the catalyst have been also assessed. The influence of chemical and physical properties on the photocatalytic degradation of acetaminophen has been investigated. Promising results in enhancement of the degradation of ACT were seen with nanocomposite material TiO2-BN-Pd compared to pristine TiO2 NFs. Moreover, TiO2 nanotubes (NTs) has shown better photoactivity under visible light than TiO2 NFs. In parallel, a better understanding of the photocatalytic oxidation pathways (based on by-product analysis) coupled with toxicity tests (Vibrio Fisheri, Microtox) was investigated.Hence, immobilized catalyst are of major concern, this is why in the third part of this thesis, photocatalytic membrane reactor was conceptualized. Ceramic membranes were modified by ALD and the feasibility of our membrane reactor was studied. Much work is still needed for enhancing the photocatalytic membrane reactor to respond to up-scale needs.