Nano-TiO2 Decorated Radial-Like Mesoporous Silica: Preparation, Characterization, and Adsorption-Photodegradation Behavior

doi:10.1016/j.jmst.2016.09.013

Abstract

Abstract:

Supported nanocrystalline TiO₂ with a diameter of 15-30 nm was prepared from previously synthesized radial mesoporous silica (RMS) by a post-synthesis method. In addition, their adsorption-photocatalytic activity toward the degradation of methylene blue (MB) was determined. RMS was tailor-made with the main template of CTAB and the SiO₂ precursor of TEOS through a facile self-assembly process. The structural, morphological and textural properties of the well-designed TiO₂/RMS samples were characterized. The RMS structure was retained after loading TiO₂, but its surface area and pore diameter decreased as a result of partial pore blocking. The removal activity of MB for TiO₂/RMS was significantly higher than that of commercial TiO₂ nanoparticles. The optimal TiO₂ loading (20 wt%) on the support could achieve the complete removal of MB within 70 min. The prepared TiO₂/RMS particles can be easily separated and display good durability after six reaction cycles.

Key words: Radial-like mesoporous silica, Nano-TiO₂, Adsorption-photocatalytic degradation

Qian Tingting, Yin Xiaoping, Li Jinhong, Nian Hong’en, Xu Hui, Deng Yong, Wang Xiang. Nano-TiO₂ Decorated Radial-Like Mesoporous Silica: Preparation, Characterization, and Adsorption-Photodegradation Behavior[J]. J. Mater. Sci. Technol., 2017, 33(11): 1314-1322.

Figures/Tables 11

Fig. 1. Characterizations of RMS by (a) SEM photographs and (b, c) TEM images. (d) Nitrogen adsorption/desorption isotherms and pore size distributions (inserts) of RMS and TiO2/RMS composites and (e) TGA curve of RMS and the corresponding DTG.

Table 1 Chemical and textural properties of RMS and x%TiO2/RMS materials

Sample	TiO₂ (wt%)	BET (m² g^-1)	Pore volume (cm³ g^-1)	Mean pore diameter (nm)
RMS	0.0	284.7	0.543	7.62
P-25	100	54	-	-
5%TiO₂/RMS	5.3	254.1	0.412	6.83
10%TiO₂/RMS	10.2	221.7	0.373	6.57
15%TiO₂/RMS	14.7	198.6	0.322	6.53
20%TiO₂/RMS	20.4	182.6	0.290	6.35
25%TiO₂/RMS	25.3	156.3	0.183	5.83
30%TiO₂/RMS	29.8	122.9	0.147	4.58

Fig. 2. XRD patterns of the RMS, TiO2/RMS and the standard data of anatase (JCPDS No. 86-1157) as reference.

Fig. 3. (a, b) SEM images, (d, e) TEM images, and (c, f) EDS spectra of the TiO2/RMS hybrid sample.

Fig. 4. TEM image (a) and high resolution TEM (b) of the nano TiO2 loaded on RMS.

Fig. 5. FT-IR spectra of RMS and TiO2/RMS samples.

Fig. 6. (a) Removal activities on different catalysts: blank, commercial P-25, RMS supports, and 20%TiO2/RMS. (b) Kinetics of MB removal of 20%TiO2/RMS and P-25 (linear transform ln(C0/C) vs. t). Experimental conditions: 1 g L-1 of catalyst, 25 °C, C0 = 20 ppm.

Fig. 7. (a) MB adsorption in dark of the x%TiO2/RMS (x = 0-30 wt%) samples, (b) MB adsorption in dark and photodegradation under UV irradiation on the x%TiO2/RMS (x = 0-30 wt%) samples, (c) the removal rate of the x%TiO2/RMS (x = 0-30 wt%) samples, and (d) kinetics of MB removal (linear transform ln(C0/C) vs. t). Experimental conditions: 1 g L-1 of catalyst, 25 °C, C0 = 20 ppm.

Fig. 8. Removal efficiency of MB over 20%TiO2/RMS: (a) effect of catalyst amount and the minimum time required (inset), and (b) effect of substrate concentration and kinetics of MB removal (linear transform ln(C0/C) vs. t (inset)).

Fig. 9. Process for the removal process of MB over RMS and TiO2/RMS hybrid catalyst.

Fig. 10. (a) Recycling activity and characterization of samples after 5th cycle by (b) XRD patterns, (c) SEM photographs and EDS spectrums (inset), and (d) TEM images for 20%TiO2/RMS. Experimental conditions: 1 g L-1 of catalyst, 25 °C, C0 = 20 ppm. (e) Picture of suspension.

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Nano-TiO₂ Decorated Radial-Like Mesoporous Silica: Preparation, Characterization, and Adsorption-Photodegradation Behavior

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