Novel integrated approach of adsorption and photo-oxidation using Ag–TiO2/PU for bioaerosol removal under visible light

Abstract

We investigated a novel approach by synthesizing an integrated material, which could act as both adsorbent and photocatalytic material, for bioaerosol purification under visible light conditions. Agwas used as a dopant agent to enhance photocatalytic activity of TiO2, leading to high photocatalytic activity of the doped TiO2 even under visible light. Under visible light, the doped TiO2 photocatalyst could produce oxy radicals, oxidative agents, that participate in oxidation reactions to decompose important organic components of bacteria, leading to death or removal of bacteria from an aerosol. Adsorption property was integrated into the enhanced TiO2 photocatalyst by using polyurethane (PU), a honeycomb structure material, as a substrate for coating process of the doped TiO2. Three materials including pristine PU, TiO2 coating on PU (TiO2/PU), and Ag-doped TiO2 coating on PU (Ag–TiO2/PU) were used to remove Escherichia coli in an aerosol under visible light. Under dark conditions, the removal capacities of E. coli in the aerosol by PU, TiO2/PU, and Ag–TiO2/PU were 1.2×105, 2.7×105, and 6.2×105 (CFU/cm3), respectively. Under visible light irradiation, the removal capacities of E. coli in an aerosol by PU, TiO2/PU, and Ag–TiO2/PU were 1.2×105, 2.7×105, and 1.8×106 (CFU/cm3), respectively. The improvement of the removal capacity by TiO2/PU and Ag–TiO2/PU, versus PU, is due to adsorption alone and the combination of adsorption plus photocatalytic activity, respectively.