Preparation of TiO2/AgNPs by photodeposition method using Ag(I) present in radiophotography wastewater and their antibacterial activity in visible light illumination

Abstract

Radiophotography wastewater is a potential source of Ag(I) that so far has not been utilized. We study on the use of radiophotography wastewater containing [Ag(S2O3)2]3− as a source of Ag(I) for preparation of Ag nanoparticle-doped TiO2 (TiO2/AgNPs) for visible light responsive photocatalyst, that is examined as an antibacterial agent. The TiO2/AgNPs was prepared by photoreduction of Ag(I) ion in the wastewater suspended with TiO2 under UV light irradiation. The photocatalysts produced were characterized using XRD, TEM, FTIR and DR-UV methods. The visible light activity of TiO2/AgNPs has been investigated for bacterial disinfection in contaminated well water. The research results revealed that by photoreduction of the wastewater containing [Ag(S2O3)2]3- over TiO2 photocatalyst under UV light has successfully resulted in Ag nanoparticle doped on TiO2 structure. Doping TiO2 by Ag(I) has decreased the crystallinity and extended its optical absorption to visible light. The smallest crystallinity lost, well dispersion and the largest absorption shift into visible light, were revealed by TiO2/AgNPs(1.5) containing 69.5 mg (or 46.4 mg g-1) Ag, that was prepared by setting 1.5 g TiO2, pH 4, and 24 h of time. The TiO2/AgNPs photocatalyst exhibited excellent antibacterial activity under visible light compared to TiO2 did. The efficiency of the bacterial disinfection was influenced by Ag content in the photocatalyst, exposure time and the photocatalyst dose. The 100% bacterial combating in the well water that was infected by 1800 CFU of E.coli was achieved by 0.25 g L-1 of the dose of TiO2/AgNPs(3) photocatalyst, in 60 min of the irradiation time.