AWWA WQTC69251

Silver doped TiO₂ nanoparticles (Ag/TiO₂) were synthesized by the photochemical reduction of silver nitrate with oxalic acid and ultraviolet (UV) radiation in the presence of TiO₂ (Degussa P- 25). Inactivation of Bacteriophage MS-2 by the Ag/TiO₂ nanoparticles, the parent TiO₂ material, and silver nanoparticles (nAg) were assessed in small batch systems subjected to UV-A radiation. The viral suspensions were assayed via the double agar layer method. The results obtained with silver doped TiO₂ were compared with those obtained with TiO₂ alone, nAg alone, and UV-A alone to determine if the presence of Ag enhances viral inactivation by TiO₂ and if a synergism exists between the antiviral activity of nAg and that of TiO₂. Chick's law was used to model the inactivation kinetics. Ag/TiO₂ initially inactivated MS-2 faster than bare TiO₂, with a rate constant of 0.17 s^-1 vs. 0.12 s^-1, respectively. However, a tailing effect was observed with the Ag/TiO₂, and the inactivation rate slowed after 20 s of irradiation, corresponding to approximately 3.5 LOG removal. nAg alone and UV-A alone were not found to significantly inactivate MS-2, supporting the hypothesis that a synergism occurs between nAg and TiO₂ when combined. The understanding of the inactivation mechanisms will be used for the development of highly efficient Ag/TiO₂ materials for virus inactivation. Includes 22 references, figures.