• K Byrappa

      Articles written in Bulletin of Materials Science

    • Photocatalytic degradation of rhodamine B dye using hydrothermally synthesized ZnO

      K Byrappa A K Subramani S Ananda K M Lokanatha Rai R Dinesh M Yoshimura

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      The sunlight mediated photocatalytic degradation of rhodamine B (RB) dye was studied using hydrothermally prepared ZnO (𝑇 = 150°C and 𝑃 ∼ 20–30 bars). Zinc chloride was used as the starting material along with sodium hydroxide as a solvent in the hydrothermal synthesis of ZnO. Different durations were tried to obtain pure ZnO phase, which was later confirmed through powder X-ray diffraction. The photocatalytic behaviour of the prepared ZnO was tested through the degradation of RB. The disappearance of organic molecules follows first-order kinetics. The effect of various parameters such as initial dye concentration, catalyst loading, pH of the medium, temperature of the dye solution, on the photo degradation of RB were investigated. The thermodynamic parameters of the photodegradation of RB, like energy of activation, enthalpy of activation, entropy of activation and free energy of activation revealed the efficiency of the process. An actual textile effluent containing RB as a major constituent along with other dyes and dyeing auxiliaries was treated using hydrothermally synthesized ZnO and the reduction in the chemical oxygen demand (COD) of the treated effluent revealed a complete destruction of the organic molecules along with colour removal.

    • Photocatalytic degradation of indigo carmine dye using TiO2 impregnated activated carbon

      A K Subramani K Byrappa S Ananda K M Lokanatha Rai C Ranganathaiah M Yoshimura

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      The photocatalytic degradation of indigo carmine dye was studied using hydrothermally prepared TiO2 impregnated activated carbon (TiO2 : AC). A comparison between the degradation of the indigo carmine dye using commercial TiO2 and TiO2 : AC revealed the efficiency of the title compound. The degradation reaction was optimized with respect to the dye concentration and catalyst amount. The reduction in the chemical oxygen demand (COD) revealed the mineralization of dye along with colour removal. The active compound like TiO2 was impregnated onto the activated carbon surface under mild hydrothermal conditions (< 250°C, P ∼ 40 bars). The impregnated activated carbon samples were characterized using powder X-ray diffraction (XRD) and scanning electron microscope (SEM).

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