Synthesis and characterization of Ag/AgBr–activated carbon composites for visible light induced photocatalytic detoxification and disinfection

• Ag/AgBr–AC composite adsorbent photocatalysts were prepared and investigated.
• Photoactivity under visible light irradiation was tested against MO dye and phenol.
• Photocatalytic inactivation of E. coli K-12 was studied under visible light.
• A mechanism based on SPR and semiconductor photocatalysis was proposed.

A novel Ag/AgBr–activated carbon (AC) composite photocatalyst was proposed and investigated. The composite was prepared by impregnation–precipitation–photoreduction, and characterized by X-ray diffraction, scanning electron microscopy, N2 sorption, and ultraviolet–visible light diffuse reflectance spectroscopy. The prepared material possessed an “egg-shell” structure, where the photocatalyst formed heterogeneous agglomerates on the outside surface of the adsorbent host material. Ag/AgBr–AC exhibited enhanced absorption in the visible light region, and photocatalysis was studied for the degradation of model organic pollutants (methyl orange dye (MO), phenol) and a model microorganism (Escherichia coli K-12). Photocatalytic degradation of organic pollutants under visible light occurred with pseudo-first order rate constants of 0.0491 min−1 and 0.007 min−1 for MO and phenol, respectively using a catalyst loading of 0.5 g L−1. Photocatalytic inactivation of 50 mL of a 106 CFU mL−1 bacterial suspension induced a 3-log loss of culturability in 60 min with a catalyst loading of 5 g L−1. The mechanism of photocatalytic action for Ag/AgBr–AC composites was discussed with respect to the adsorption, localized surface plasmon resonance, and conventional semiconductor photocatalysis processes that took place under visible light.

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