Novel Pd/TiO2 nanocomposite prepared by modified sol–gel method for photocatalytic degradation of methylene blue dye under visible light irradiation

•Chitosan (CS) has no obvious effect on the crystallizing process of the main form, anatase.•Crystallite size of TiO2/CS (18 nm) was smaller than that of pure TiO2 (116 nm).•CS prevents the agglomeration of both TiO2 and Pd/TiO2 with dispersion of Pd over TiO2.•CS and Pd significantly improved the visible light photocatalytic activity of TiO2.

TiO2 nanoparticles were prepared using the modified sol–gel method. TiO2 impregnated with Pd and/or chitosan (CS) was prepared using the impregnation method. The Pd/TiO2 composite photocatalyst was characterized by XRD, TEM, UV–Vis, Pl, and BET. A methylene blue dye (MB) was used as a model pollutant to study the photocatalytic activity of TiO2 under visible light irradiation. The influence of the type and amount of catalyst as well as the initial concentration of MB was investigated. The results indicate that CS can effectively prevent the agglomeration of TiO2 nanoparticles. UV–Vis spectra demonstrated that the composite’s ability to absorb visible light is greatly improved. The photocatalytic degradation of MB was found to follow first-order kinetics. Recycling experiments confirmed the relative stability of the catalyst.

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