Preparation and Investigation on Photocatalytic Activity of TiO₂/Ag₂CrO₄ Nanocomposites under Visible-Light Irradiation for Degradation of Some Organic Dye Pollutants

Feizpoor, Solmaz (2017) Preparation and Investigation on Photocatalytic Activity of TiO₂/Ag₂CrO₄ Nanocomposites under Visible-Light Irradiation for Degradation of Some Organic Dye Pollutants. Masters thesis, University of Mohaghegh Ardabili.

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Text (تهیه و بررسی فعالیت فتوکاتالیزوری نانوکامپوزیت¬های TiO2/Ag2CrO4 تحت تابش نور مرئی برای تخریب چند آلاینده¬ی رنگی آلی) Solmaz Feizpoor.pdf Download (1MB) | Preview

Abstract

In recent decades, almost entire of the earth is facing drinking water scarcity, due to contamination of water and discharge of untreated wastewaters to the environment. As a “green” technology, semiconductor-based photocatalysis, has attracted much more interests for degradation of environmental pollutants. Among various semiconductors, titanium dioxide (TiO2) has been the most used photocatalyst in the heterogeneous photo-catalytic processes, because of its considerable stability, non-toxicity, and abundant resources. However, the worst drawback of this semiconductor is its poor activity under visible-light irradiation. This is related to the wide band gap of about 3.20 eV and high recombination rate of the photogenerated electron-hole pairs. One effective method to increase visible-light harvesting ability of TiO2 is combination of it with narrow band gap semiconductors. For this reason in this thesis, nanocomposites of TiO₂/Ag₂CrO₄, TiO₂/Ag₂WO₄/AgBr and TiO₂/Fe₃O₄/CoWO₄ were prepared by refluxing method. The structure, morphology, purity, specific surface area, and electronic properties of the as-prepared samples were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDX), UV–vis diffuse reflectance spectroscopy (DRS), Fourier transform-infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) and photoluminescence (PL) techniques. Photocatalytic activity of the nanocomposites was examined by degradation of various pollutants under visible-light irradiation. The TiO₂/Ag₂CrO₄ (50%),TiO₂/Ag₂WO₄/AgBr (15%) and TiO₂/Fe₃O₄/CoWO₄ (30%) nanocomposites had highest activity in comparision with the other weight percents. Effects of different parameteres such as preparation time and scavengeres of reactive species on the kinetic of photodegradation reaction were investigated.

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