A highly efficient photocatalytic system for environmental applications based on TiO2 nanomaterials

Abstract

Sustainable and efficient water treatment techniques to improve the quality of water for various applications include advanced oxidation processes (AOP), mainly focusing on heterogeneous photocatalysis. Materials science and nanotechnology have contributed to tailoring the properties of photocatalytic materials to significantly enhance their photoactivity and stability. Here we report the development of a well-organized nanoporous TiO₂-based photocatalytic reactor for water treatment. Nanoporous TiO₂ materials were directly grown using a two-step electrochemical anodization process in ethylene glycol + 0.3 wt% NH₄F + 2 wt% H₂O. The prepared nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). To enhance the photocatalytic activity of the system, water scrubbing was incorporated to boost the presence of oxygen in the water, enhancing the electron uptake at the conduction band thus significantly reducing the electron–hole recombination and increasing the photocatalytic activity. To further enhance the efficiency and reduce the negative environmental impact of the technology, a UVA-LED assembly was used instead of the typical mercury-based UV lamps for photocatalysis. The nanoporous TiO₂ was tested as a catalyst for the photochemical oxidation of various categories of pollutants; dye (methylene blue), and the removal of microbes such as E. coli. The photoreactor developed in this research work was also successfully applied and tested in real-world applications such as keeping heavily used hot-tub water clean without using harmful chemicals (chlorine, bromine, ozone, etc.) or expensive equipment. The simplicity and efficacy of the new approach described in this study make possible the integration of nanoporous TiO₂ in the design of high-performance air and water purification technologies.

Keywords: TiO₂ photocatalyst; UVA-LEDs; Nanostructured materials; Photochemical oxidation; Wastewater treatment; Water scrubbing.