Efficient photocatalytic degradation of an organic dye by the fabrication of a novel ternary composite based on zeolitic imidazolate framework via a facile in-situ synthetic approach

Abstract

The dye contamination in waste water is a primary concern for the present sustainable society needs. Tremendous upsurge of industries is one of the major reasons for the increased level of dye pollution found in water systems, thus making it unfaithful for drinking and other agricultural practices. In this paper, we report a facile in-situ synthetic approach for the design of a novel ternary composite comprising of Zeolitic imidazolate framework (ZIF-8) under ambient reaction conditions. The structure, morphology, surface area and optical properties of the as-synthesized nanocomposite was studied through a number of characterization techniques including polycrystalline (or power) X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmet-Teller (BET) and ultraviolet diffused reflectance spectroscopy (UV-DRS). The as prepared composite (ZnO-CeO 2 @ZIF-8) showed excellent photo-catalytic activity compared to the pristine ZIF-8 for the degradation of crystal violet (CV) from aqueous medium in presence of green oxidant H 2 O 2 . Moreover, the influence of several reaction parameters such as catalyst dosage, initial solution pH and concentration of H 2 O 2 were investigated on the degradation kinetics of CV. 97% degradation of CV was achieved with ZnO-CeO 2 @ZIF-8 in 15 min under optimized reaction conditions of catalyst dosage 12 mg and H 2 O 2 concentration of 8 mM. The degradation of CV by ZnO-CeO 2 @ZIF-8 followed first order kinetics with a rate constant of 0.2373 min −1 . Besides this, the active participation of hydroxyl radicals on the degradation mechanism was confirmed by the quenching and photoluminescence studies. Also, the fabricated photocatalyst displayed excellent stability upto 5 cycles as revealed by XRD analysis .

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