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Water, the primary source of life, is contaminated with various organic/inorganic impurities in the course of development. Organic dyes, a waste product from dying industries, have evolved as one of the major contributor to water pollution. The present work involves the photocatalytic degradation of malachite green dye as a model substrate using zinc oxide nanoparticles (ZnO NPs) and its composite with β-cyclodextrin (β-CD). ZnO NPs are found to be a worthy catalyst due to their bandgap and easy availability. The role of β-CD in ZnO photocatalyst is explored. With ZnO NPs, electron–hole recombination takes place very easily; hence, to restrict this recombination β-CD has been used. We have characterized the synthesized nanomaterials by using powder X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, diffuse reflectance spectroscopy (DSR), scanning electron microscopy and transmission electron microscopy (TEM). Various parameters, such as the concentration of dye, pH and amount of catalyst have optimized for the photocatalysis process. More basic medium adsorption is more favourable than degradation, which decreases the reusability of the catalyst. Based on the photodegradation efficiency and rate constant (k), we observed that ZnO–β-CD showed better photocatalytic activity than ZnO NPs. The plausible mechanism for photocatalytic degradation has also been reported with the help of photoluminescence spectra and scavenger activity. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of dyes using metal oxides and their composite has become a smart process for detoxification of pollutants from wastewater system. The coupling of metal oxides increases the efficiency due to its broad light absorption, fast dynamic process and natural p-n characteristics. Sol-gel method was selected to prepare the binary nanocomposite Copper Oxide/Zinc Oxide (CuO/ZnO) & its ternary nanocomposite with beta cyclodextrin (β-CD), β-CD-CuO/ZnO. The synthesized materials were characterized using PXRD, FT-IR, TEM, TGA-DTA and Uv–Visible spectroscopy. For both the materials photocatalytic performance was studied for of model textile dyes pollutants degradation, malachite green (MG) and methylene blue (MB). The efficiency of the prepared catalysts and degradation mechanism are discussed. The involvement of various active species in degradation process is confirmed by applying suitable scavengers. Further the limitation of electron hole recombination was improved by β-CD addition. The photocatalytic activity of β-CD-CuO/ZnO was observed superior to CuO/ZnO catalyst. The degradation efficiency was observed up to 89.15 and 79.90% for MB and MG dyes after 180 min of irradiation using β-CD-CuO/ZnO. In addition to that, β-CD-CuO/ZnO has good adsorption tendency because of its hydrophilic exterior and hydrophobic interior cavity due to which they can encapsulate pollutant molecules in cavity. [Display omitted] • Synthesis of ternary nanocomposite with beta cyclodextrin (β-CD), β-CD-CuO/ZnO. • Properly characterization of β-CD-CuO/ZnO with various techniques. • Role of β-CD in photocatalytic activity is enlightened. • Performance of β-CD-CuO/ZnO as photocatalyst is measured by MG and MB dyes. • Study of Efficiency, Kinetic, Reusability and Photocatalytic degradation mechanism of β-CD-CuO/ZnO is accomplished. [ABSTRACT FROM AUTHOR]