Synthesis and in-situ ATR studies of nanostructured titania photocatalysts for the degradation of aqueous organic pollutants

Abstract

Water is a crucial resource for life but only 3% of global water is fresh and this small amount is ever decreasing due to unwise human activities. Traditional biological treatments require further chemical processing to degrade recalcitrant molecules and the processing of such chemicals necessitates large energy inputs and high costs. Heterogeneous photocatalysis provides a green solution as it harnesses the power of natural sunlight. Titanium dioxide is one of the most extensively studied photocatalysts due to low toxicity, chemical stability and low cost. Despite the powerful intrinsic oxidating ability drawbacks in commercial titania materials stem from the relatively high band gap energy and low surface areas. To overcome this, in this research the aim is to synthesis a novel material which can maximize the efficiency of photocatalytic processes applied to depollution of waste water. Mesoporous silicas with tunable parameters were employed as supports for the anchoring of surface titania species, in order to improve the available active surface area of the catalyst. Highly sophisticated analytical techniques common to the fields of surface science and heterogeneous catalysis were applied to fully characterize the prepared materials and determine structure-function relationships. Screening for the photocatalytic activity of the synthesized materials was performed in jacketed quartz batch reactor irradiated by a UV-vis light source against common organic dyes. Photoactivity of the prepared materials was investigated alongside commercially available titania catalysts to act as benchmarks. In heterogeneous catalysis it is vital to study the interaction between the surface of the catalyst and the probe molecules, including adsorptive and desorptive processes occurring at the solid-liquid interface. ATR-IR spectroscopy was used to investigate this aspect of our reaction, allowing for real time monitoring of reaction kinetics with the use of an innovative flow cell chamber, fit with a quartz window allowing for in-situ UV irradiation.