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In this paper, TiO2 and Ag-doped TiO2 photocatalysts were coated on the cylindrical cordierite honeycomb monolith (CHM) to evaluate their photocatalytic disinfection against Escherichia coli (E. coli) bacteria under artificial sunlight irradiation. The X-ray diffraction (XRD) patterns showed a single-phase anatase structure for TiO2 samples calcined at 500 °C for 2 h. With the presence of Ag, the bandgap of TiO2 becomes narrower, and the absorption edge shifts toward the visible region. 6 mol% Ag-doped TiO2 (6Ag-T) showed a reduction of bandgap energy to 2.2 eV. TiO2 and Ag-doped TiO2 solutions were prepared and coated on the channels' surface of CHM for antibacterial applications. Although monolithic TiO2 caused a slight decrease in the number of alive E. coli, Ag dopant showed significant improvement in antibacterial properties. 6 mol% Ag-doped TiO2 coated on CHM (6Ag-T/S10/M) showed strong antibacterial effectiveness against E. coli that the bacterial cell concentration dropped to zero after 1 h of exposure. Impressively, reusability tests with these materials showed superior performance, where the antibacterial remains unchanged after five or seven successive operation cycles. [ABSTRACT FROM AUTHOR]

Copper nanoparticles (CuNPs) possess a promising antibacterial and antifungal activity with low-cost reagent and fabrication. In this study, we report the antifungal activity of pure CuNPs against Fusarium oxysporum (F. oxysporum) and Phytophthora capsici (P. capsici). CuNPs were prepared by reducing Cu2+ from copper(II) chloride dihydrate via a green chemical reduction agent using ascorbic acid as both reducing agent and antioxidant agent in aqueous media and polyvinylpyrrolidone as a stabilizer. The effect of the solution pH, reduction time, ascorbic-acid-to-Cu2+ molar ratio, role of stabilizing agent polyvinylpyrrolidone to particle size of CuNPs were studied. The antifungal activity of CuNPs at different concentrations and different particle sizes against two plant pathogenic fungi F. oxysporum and P. capsici has been tested by the agar disc diffusion technique. Characterizations were carried out by X-ray diffraction measurements, transmission electron microscopy, and ultraviolet–visible light, which revealed that the CuNPs obtained at different synthesis conditions have different particles size, resulting in different antifungal activities. The synthesized CuNPs demonstrated significant antifungal activity against F. oxysporum and P. capsici. F. oxysporum and P. capsici were entirely inhibited at the concentration of CuNPs of 30 ppm after 3 days of incubation and 7.5 ppm after 1 day of incubation, respectively. Our results suggest that synthesized CuNPs can be used as a novel antifungal agent in agriculture to control the plant pathogenic fungi of F. oxysporum and P. capsici. [ABSTRACT FROM AUTHOR]