Comparison of the Phase Transition and Degradation of Methylene Blue of TiO2, TiO2/Montmorillonite Mixture and TiO2/Montmorillonite Composite.

Li Zeng,Li Zeng,Hongjuan Sun,Tongjiang Peng,Xia Lv

doi:10.3389/fchem.2019.00538

Li Zeng, Li Zeng + Show 3 more

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https://doi.org/10.3389/fchem.2019.00538

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Abstract

Nano-TiO2 (T), TiO2/montmorillonite mixture (Mix), and TiO2/montmorillonite composite (Com) were prepared by using TiOSO4•2H2O as the precursor of TiO2 and montmorillonite as the matrix. The phase transition process of TiO2 and the degradation of methylene blue (MB) in T, Mix, and Com were studied by x-ray diffraction (XRD), infrared spectrum (IR), scanning electron microscopy with energy spectrum (SEM-EDS), and other methods. The results show that, except for the fact that the heating temperature has a great influence on the phase transition and grain growth of TiO2, the introduction of montmorillonite has an obvious inhibition effect on the phase transition and grain growth of TiO2, and the inhibition effect of the Com is obviously stronger than Mix. In Com, Ti–O–Si chemical bond was formed between TiO2 and oxygen atoms with negative charge on the bottom of the structure layer of montmorillonite, which is the main reason for inhibition effect. However, in Mix, TiO2 only covers the surface of montmorillonite without breaking the degree of order of montmorillonite and forming no chemical bond with montmorillonite, so the inhibition effect is small. From degradation of MB, it was found that before the structure of montmorillonite was destroyed (400–600°C), the total degradation percentage in Mix (85.3–99.5%) was higher than T and Com. At high temperature (above 700°C), because of the inhibition effect, the total degradation percentage of MB in Com is much larger than T and Mix, even above 1,100°C, the total degradation percentage can still reach at 47%. Therefore, in industrial applications, Mix and Com can be selected to degradation MB, according to the actual application temperature range.

Highlights

With the rapid development of society and the fast growth of economy, the discharge of industrial and dye stuff production into wastewater is increasing, making the water pollution problem more and more serious
After drying the titanium oxide hydrate gel at 80◦C for 6 h in the oven, TiO2 nano-powder was obtained, which was labeled as T (Figure 1B)
The x-ray diffraction (XRD) pattern of Com (Figure 1D) showed that the d001 diffraction peak of Mt disappeared, indicating the sample was intercalated montmorillonite, the polymeric titanium ion entered into the interlayer of montmorillonite through cation exchange, and the layered structure of montmorillonite was destroyed by the hydrolysis of the polymeric titanium ion to form hydrated titanium oxide

Summary

INTRODUCTION

With the rapid development of society and the fast growth of economy, the discharge of industrial and dye stuff production into wastewater is increasing, making the water pollution problem more and more serious. As a photocatalyst with high efficiency, Phase Transition and Degradation Percentage non-toxic, stability, high catalytic activity, and strong oxidation ability, TiO2 has antibacterial and bactericidal functions and can effectively degrade organic pollutants in water. It is a photocatalyst with the most potential and has a broad application prospect (Klaysri et al, 2015; Li D. et al, 2015; Calia et al., 2017; Shi et al, 2018; Kim et al, 2019). Montmorillonite is a common layered aluminosilicate mineral with large specific surface area and specific volume, strong adsorption capacity and stable chemical properties. The phase transition of TiO2 at different temperature and the degradation of methylene blue under ultraviolet light of these three samples were studied

EXPERIMENTAL PROCEDURE

Experiments

RESULTS AND DISCUSSION

CONCLUSION