Influence of calcination temperature on the structural, adsorption and photocatalytic properties of TiO2 nanoparticles supported on natural zeolite

• TiO2/zeolite calcined under various temperatures was prepared and characterized.
• The morphology and structure of the composite were investigated.
• The adsorption and photocatalysis properties towards Cr (VI) were studied.

TiO2 nanoparticles supported on natural zeolite (TI-ZE) are prepared via a simple hydrolysis of TiCl4 and then calcined at various temperatures. The as-prepared catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller analysis (BET), scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The adsorption and photocatalysis ability was evaluated towards Cr (VI) in dark or under UV light. The XRD analysis showed that the increasing temperature destroyed the original framework structure of zeolite (over 500 °C) and the anatase TiO2 formed at 500 °C. It was found that the calcination temperature influenced the adsorption behavior and photocatalytic activity. The sample calcined at 300 °C presented the optimum adsorption performance because of its highest specific surface area, and the adsorption process followed pseudo-second-order kinetic. The maximum adsorption capacity of different samples has been calculated based on the Langmuir model. The kinetics for the photodegradation of Cr (VI) has been determined in terms of Langmuir–Hinshelwood model. The photocatalysis test indicated that the TI-ZE calcined at 500 °C remained the original zeolite structures and possessed the highest removal ratio because of its relatively larger adsorption capacity and better crystallinity of TiO2. Furthermore, the removal efficiency of TI-ZE-5 towards Cr (VI) was still more than 75% after five times cycling, which confirms the durability of TiO2/zeolite catalyst.

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