Photocatalysis of Titanium Dioxide for Water Disinfection: Challenges and Future Perspectives

Abstract

The performance of metal oxides such as titanium dioxide (TiO 2 ), in the conversion of solar energy into chemical energy, is determined by semiconducting properties. The conversion process is closely related to the light-induced reactivity between oxide semiconductors and water, which may lead to partial water oxidation and consequently water disinfection. Key performance-related properties are considered here, including light absorption, light-induced ionisation over the band gap, charge separation, charge transport, charge transfer, and the chemical reactions taking place at anodic and cathodic sites. Optimisation of these interconnected performance-related properties is discussed, along with the photocatalytic application in water disinfection.

A high-performance doped photocatalysts for inactivation of total coliforms in superficial waters using different sources of radiation

“…The oxidation reactions occur between the gap of the valence band and water or hydroxyl ions, producing the radical OH . The reduction reactions can occur between the electron conduction band and oxygen, producing O 2 À , which produces H 2 O 2 (Fu et al, 2005;Chong et al, 2010;Bak et al, 2012;Wang et al, 2014;Wu et al, 2014). The higher the energy dose, the greater the combination of pairs eÀ/hþ.…”

“…Furthermore, the reaction between free residual chlorine compounds and natural organic acids, such as humic acids and fulvic acids (precursors) leads to the formation of several byproducts. Some of these compounds can cause potentially carcinogenic effects, as trihalomethanes and haloacetic acids are the main products formed (Zhang et al, 2010;Dyck et al, 2015;Wu et al, 2014).…”

“…Titanium dioxide (TiO 2 ) materials of different types and forms have shown great potential as an ideal and a powerful semiconductor photocatalyst for various significant reactions due to their chemical stability, low cost, nontoxicity, and high reactivity (Lopes et al, 2011;Gulyas, 2014;Schneider et al, 2014;Wu et al, 2014;Wang et al, 2014). Other semiconductors have also been studied in photocatalysis, namely zinc oxide (ZnO), tungsten trioxide (WO 3 ), ferric oxide (Fe 2 O 3 ), zinc sulfide (ZnS), etc.…”

Application of ultraviolet light assisted titanium dioxide photocatalysis for food safety: A review

“…Moreover, TiO 2 is relatively inexpensive and has a strong oxidizing power under UV light (<385nm) (Bonetta et al, 2013;Wu et al, 2014). The United States Food and Drug Administration (US FDA) has approved the use of TiO 2 as an additive in human food, drugs, cosmetics and food contact materials (FDA, 2015a;Kim et al, 2009).…”

“…TiO 2 -assisted ultraviolet treatment is a well-established technique for water disinfection (Kim et al, 2013a;Wu et al, 2014). Recently, the application of TUV technology for disinfection of food products has gained attention with a special focus on replacing the conventional chlorine washing of fresh produce (Chai et al, 2014;Cho et al, 2007;Kim et al, 2009;Yoo et al, 2015a).…”