Photocatalytic inactivation of Gram-positive and Gram-negative bacteria by reactive plasma processed nanocrystalline TiO2 powder

Nanocrystalline TiO2 powder is synthesized using a novel reactive plasma process in which the precursor TiH2 powder is oxidized through thermal plasma in-flight route to generate nanocrystalline TiO2 powder. The synthesized powder consists of nano-sized TiO2 particles, both anatase and rutile phases, in which anatase is the predominant phase. An additional feature of the plasma synthesized TiO2 powder is the higher surface concentration of Ti3+ state and hydroxyl group that enhance its photocatalytic activity. The photocatalytic inactivation of Gram-positive Enterococcus and Gram-negative Klebsiella bacteria is studied using the plasma synthesized TiO2 nanopowder with 365 nm ultraviolet (UV) light. The mechanism behind the photocatalytic disinfection of bacteria is discussed. The plasma synthesized TiO2 nanopowder catalyst is found effective in killing Enterococcus and Klebsiella. The results corroborated that the plasma synthesized TiO2 powder can be used for waste water treatment and water purification.

► Nanocrystalline TiO2 power is synthesized using reactive thermal plasma process. ► Photocatalytic properties of plasma synthesized TiO2 power are studied. ► Presence of Ti3+ and –OH on TiO2 particles is responsible for photocatalytic activity. ► Bacterial inactivation by plasma synthesized TiO2 powder is effective under UV light.