Visible light activated bactericidal effect of TiO2/Fe3O4 magnetic particles on fish pathogens

The purpose of this research is to develop a bactericidal photocatalytic TiO2 that can be activated by visible light and can be conveniently recollected for reusing. This research synthesizes the 22 to 33 nm TiO2/Fe3O4 particles with magnetization of 2.9emu/g using modified sol-gel method followed by 500 degrees C calcinations. The experiment verifies that both household fluorescent light (HFL, contains minor UV-A) and visible fluorescent light (VFL, contains no UV-A) can activate the photocatalytic activity of TiO2/Fe3O4 particles as did ultraviolet A light (UV-A, 360 nm). Regular magnets can be used to separate TiO2/Fe3O4 particles from solution. There have not been any significant weight and photocatalytic activity lost during 2 reusings. After 60 min and 120 min VFL irradiation, the bactericidal efficiencies of TiO2/Fe3O4 are 35% and 72% for Streptococcus iniae and 35% and 53% for Edwardsiella tarda, respectively. The results indicate that VFL irradiated TiO2/Fe3O4 particles can disinfect fish pathogens in the absence of UV-A and the issue of TiO2/Fe3O4 recollection from water for reusing is also resolved. (C) 2009 Elsevier B.V. All rights reserved.