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

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 AgCu/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 degrees 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).