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

Abstract

Photocatalytic water treatment has a currently elevated electricity demand and maintenance costs, but the photocatalytic water treatment may also assist in overcoming the limitations and drawbacks of conventional water treatment processes. Among the Advanced Oxidation Processes, heterogeneous photocatalysis is one of the most widely and efficiently used processes to degrade and/or remove a wide range of polluting compounds. The goal of this work was to find out a highly efficient photocatalytic disinfection process in superficial water with different doped photocatalysts and using three sources of radiation: mercury vapor lamp, solar simulator and UV-A LED. Three doped photocatalysts were prepared, SiZnO, NSiZnO and FNSiZnO. The inactivation efficiency of each synthesized photocatalysts was compared to a TiO2 P25 (Degussa(®)) 0.5 g L(-1) control. Photolysis inactivation efficiency was 85% with UV-A LED, which is considered very high, demanding low electricity consumption in the process, whereas mercury vapor lamp and solar simulator yielded 19% and 13% inactivation efficiency, respectively. The best conditions were found with photocatalysts SiZnO, FNSiZnO and NSiZnO irradiated with UV-A LED, where efficiency exceeded 95% that matched inactivation of coliforms using the same irradiation and photocatalyst TiO2. All photocatalysts showed photocatalytic activity with all three radiation sources able to inactivate total coliforms from river water. The use of UV-A LED as the light source without photocatalyst is very promising, allowing the creation of cost-effective and highly efficient water treatment plants.

Effect of Titanium Dioxide Film Thickness on Photocatalytic and Bactericidal Activities Against Listeria monocytogenes

“…TiO 2 photocatalysts as fine particles have already been studied to fight against bacteria in various environments such as medical environments , water disinfection field or food plants . However, the use of TiO 2 suspension presents a disadvantage in the postcatalytic catalyst removal .…”

Recent advances on the application of UV‐LED technology for microbial inactivation: Progress and mechanism

“…Claro, Bidoia, and de Moraes (2016) assessed the heterogeneous photocatalysis using a UVA‐LED as a source of UV light in the presence of three synthesized photocatalysts SiZnO, N‐SiZnO, and F‐N‐SiZnO. The photocatalytic inactivation efficiency of the three catalysts was then compared to TiO 2 added at a concentration of 0.5 g/L.…”

N‐doped TiO2 photocatalysts for bacterial inactivation in water

“…This may be accomplished using titania (titanium dioxide), which is the most popular catalyst, after a suitable modification of its substrates that involves doping with nonmetals and/or noble and transition metals . Those materials have been showing promising results over the last years, regarding the inactivation of microbial pathogens and the disinfection of various aqueous matrices . Nitrogen‐doped TiO 2 (N‐TiO 2 ) catalysts exhibit successful performance for water/wastewater purification and several nitrogen precursors have been employed, such as TiCl 4 or titanium tetra‐isopropoxide and urea or ammine .…”

“…9 Those materials have been showing promising results over the last years, regarding the inactivation of microbial pathogens and the disinfection of various aqueous matrices. 10,11 Nitrogen-doped TiO 2 (N-TiO 2 ) catalysts exhibit successful performance for water/wastewater purification and several nitrogen precursors have been employed, such as TiCl 4 or titanium tetra-isopropoxide and urea or ammine. 12 However, only a few reports have dealt with this group of catalysts and the inactivation of tolerant pathogens such as species belonging to the genera Pseudomonas and Bacillus.…”