A. Safri, A. Fletcher
University of Strathclyde,
Keywords: solar disinfection, advanced oxidation process, photocatalysis, antimicrobial acitivity
Summary:Water remediation has been a significant issue over recent years due to increasing pollution of water sources. A recent report, published by the United Nations, states that 2.2 billion people lack access to safe drinking water, thus many people are prone to waterborne diseases. Amongst various water treatment techniques, Solar disinfection (SoDis) has already been recognised as an effective choice to render clean drinking water, especially in the developing countries. However, the advancements in water treatment processes through development in advanced materials are essential to remove organic pollutants currently not easily removed by traditional treatment methods. Synergistic water remediation with Advanced Oxidation Processes (AOP) and adsorption is one such effective technology to remove water pollutants. Titanium dioxide (TiO2) has been widely studied as a photocatalyst due to its ability to undergo AOP upon UV irradiation. This property is activated when UV light greater than the band gap of TiO2 (3.2 eV) falls on the material and results in the creation of electron and hole pairs, which generate Reactive Oxide Species (ROS). These ROS oxidise the organic pollutants, eventually converting them to CO2 and water. This offers scope for developing countries to develop low-cost technologies for water treatment, however, since only 5% of UV falls on earth, applying AOP using bare TiO2 is challenging. In this research, we have synthesized a composite material, to be utilised as a disinfectant; where AOP is stimulated by visible light photocatalysis. In tandem, we have focused on designing a material with exceptionally high surface area and porosity for maximum adsorption of the targeted pollutants. Hence, we have exploited the synergistic effect of photocatalysis and adsorption by integrating the photocatalyst TiO2 with Resorcinol (R) Formaldehyde (F) gels. RF gels are highly porous materials and can be used as a carbon source. Here, we have used RF gels as a host material to incorporate TiO2 nanoparticles and concurrently modified the electronic structure of TiO2 to absorb visible light for efficient photocatalysis and consequent disinfectant activity. The reaction mechanism of the synthesised disinfectant is based on the electronic structure of TiO2 embedded in the gel matrix, the disinfectant activates upon irradiation of light and produces ROS responsible for the pollutant degradation. Fourier-transform infrared spectroscopy confirmed the reaction of TiO2 with the RF network owing to Ti-O-C bonds observed at 1127 and 1084 cm-1. Nitrogen sorption isotherms showed the material has high surface area (301 m2/g) and was predominantly mesoporous (pore size between 2 and 10 nm). The data obtained from UV-Vis spectroscopy showed low band gap (3.09 eV) of these new materials. Mainly, disinfection capability of material was demonstrated by antimicrobial activity against reduction of Escherichia coli from contaminated water. In addition, methylene blue (MB) dye reduction has also been successfully demonstrated.