Performance of Ag-Cu/TiO2 photocatalyst prepared by sol-gel method on the inactivation of Escherichia coli and Salmonella typhimurium

Abstract

The photocatalytic performance of Ag-Cu/TiO2 materials was evaluated on the inactivation of two gram-negative bacteria that are commonly present in wastewater, namely Escherichia coli and Salmonella typhimurium. The Ag-Cu/TiO2 catalysts at incorporation percentages of 0.3, 1.2 and 2.1 wt.% of each metal were prepared by the sol-gel method. Copper and silver incorporated as Cu2+ and Ag° were analyzed by X-ray photoelectron spectroscopy (XPS) technique. The incorporation of the metal ions causes the reduction of the band gap energy that was evidenced by UV–Vis diffuse reflectance spectroscopy measurements, allowing the activation of the catalyst in the visible region. Complete inactivation of both microorganisms was achieved in 10 min using the co-doped materials at a catalyst load of 0.5 g/L under simulated solar radiation. The co-doped photocatalysts also showed high antimicrobial activity in the absence of light, allowing the treatment to remain effective even in dark conditions. Heterogeneous photocatalysis with Ag-Cu/TiO2 materials demonstrated to be more effective in eliminating from water the gram-negative bacteria than solar disinfection and undoped or individually doped TiO2 catalysts (TiO2, Ag-TiO2 and Cu-TiO2).