The photocatalytic decoloration of an organic dye, ethyl violet (EV), has been studied in the presence of TiO2 and the addition of β-Cyclodextrin (β-CD) with TiO2 (TiO2-β-CD) under UV-A light irradiation. The different operating parameters like initial concentration of dye, illumination time, pH and amount of catalyst used have also been investigated. The photocatalytic decoloration efficiency is more in the TiO2-β-CD/UV-A light system than TiO2/UV-A light system. The mineralization of EV has been confirmed by Chemical Oxygen Demand (COD) measurements. The complexation patterns have been confirmed with UV–Visible and FT-IR spectral data and the interaction between TiO2 and β-CD have been characterized by powder XRD analysis and UV–Visible diffuse reflectance spectroscopy.

We present the photocatalytic decoloration of Rhodamine B (RhB) dye with the nanocomposites such as TiO 2 , ZnO, TiO 2 /b-cyclodextrin (b-CD) and ZnO/b-CD. Band gap energy of nanocomposites was calculated by UV-DRS analysis and the results showed that the band gap energy of ZnO/b-CD nanocomposite is lower than that of other catalysts. The microstructures of the nanocomposites have been characterized by PXRD and FE-SEM analyses. The results showed that crystallinity and surface morphology of metal oxides (MO) (say, TiO 2 and ZnO) are not changed in MO/b-CD nanocomposite systems. GC-MS results showed that the photocatalytic decoloration of RhB follows the steps such as N-deethylation, cleavage of chromophore and mineralization of dye.Keywords RhB Á TiO 2 Á ZnO Á TiO 2 /b-CD Á ZnO/b-CD

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In this work, we attempt a new approach for the study on photocatalytic ability of (ZnO/CeO 2 ) improved by b-CD under UV light irradiation for the photodecolorization of RhB. The (ZnO/CeO 2 ) composite was prepared by mixing ZnO with CeO 2 in a weight ratio of 4:1. The surface interaction of (ZnO/CeO 2 ) with b-CD was determined by characterizing their structural, morphological and optical properties. The formation of an inclusion complex between RhB dye and b-CD was confirmed by UV-visible spectral analyses. The photocatalytic activity of (ZnO/CeO 2 )-b-CD system was evaluated by the decolorization of RhB dye in aqueous solution under UV light irradiation. The effects of operational parameters like the ratio of (ZnO/CeO 2 ), initial concentration of dye, catalyst dose, irradiation time and pH have been analyzed. The photocatalytic decolorization of RhB follows pseudo-first order kinetics. The mineralization of RhB has been confirmed by COD measurements. A possible mechanism for the photocatalytic decolorization of RhB by (ZnO/CeO 2 )-b-CD system under UV light irradiation was also discussed.

In the current work, the commercially available ZnO photocatalyst was used to investigate the photodecoloration of Acid yellow 99 (AY99) dye under solar light radiation. Promising enhancement of photodecoloration of AY99 dye was also achieved by the addition of b-cyclodextrin (b-CD) with the ZnO (ZnO-b-CD). The effects of process parameters such as initial concentration, pH, catalyst loading, and illumination time on the extent of decoloration were investigated. The optimum catalyst loading was observed at 2.0 g/L. The higher photoactivity of ZnOb-CD/solar light system than ZnO/solar light system can be ascribed due to the ligand to metal charge transfer (LMCT) from b-CD to Zn II . The complexation patterns have been confirmed with UV-visible and FT-IR spectroscopy and the interaction between ZnO and b-CD has been characterized by FE-SEM, powder XRD analysis, and UV-visible diffuse reflectance spectroscopy.

An attempt has been made to enhance the photocatalytic activity of CeO(2) for visible light assisted decoloration of methylene blue (MB) dye in aqueous solutions by β-cyclodextrin (β-CD). The inclusion complexation patterns between host and guest (i.e., β-CD and MB) have been confirmed with UV-visible spectral data. The interaction between CeO(2) and β-CD has also been characterized by field emission scanning electron microscopy analysis. The photocatalytic activity of the catalyst under visible light was investigated by measuring the photodegradation of MB in aqueous solution. The effects of key operational parameters such as initial dye concentration, initial pH, CeO(2) concentration as well as illumination time on the decolorization extents were investigated. Among the processing parameters, the pH of the reaction solution played an important role in tuning the photocatalytic activity of CeO(2). The maximum photodecoloration rate was achieved at basic pH (pH 11). Under the optimum operational conditions, approximately 99.6% dye removal was achieved within 120 min. The observed results indicate that the decolorization of the MB followed a pseudo-first order kinetics.

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