Visible light activity of Ag-loaded and guanidine nitrate-doped nano-TiO2: degradation of dichlorophenol and antibacterial properties

Abstract

To utilize visible light, Ag loaded and C, N-doped nano-TiO₂ was prepared using a “one pot” synthesis utilizing mild reaction conditions and benign precursors. The synthesis was optimized using appropriate experiment design that took the silver content and calcination temperature into account. The optimized nanocatalyst was characterized by XRD, BET, TEM, TGA, XPS as well as UV-DRS. Nanocatalysts were predominantly anatase as confirmed by XRD, thermally stable up to 1100 °C, as revealed by TGA studies and exhibited absorption in the visible light region as verified by UV-DRS analysis. Moreover, XPS results proved that Ag was dispersed on the surface of the TiO₂ nanoparticles and nitrogen, as well as carbon from guanidine nitrate was interlaced into the matrix of TiO₂. Co-doping of TiO₂ suppressed charge recombination and improved the visible light photo-activity up to the complete degradation of dichlorophenol (DCP) in 4 h of the reaction. Degradation followed first order reaction kinetics with k_app ranging from 1.1 to as high as 15.1 × 10⁻³ min⁻¹ depending on the silver content and calcination temperature. Demineralization of the solution in terms of TOC was up to 92%. A complete elimination of Vibrio fischeri was accomplished with 1 mg L⁻¹ of the nanocatalyst regardless of the Ag content.