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Procedia Engineering
Procedia Engineering 00 (2011) 000–000 Procedia Engineering 24 (2011) 663 – 666 www.elsevier.com/locate/procedia
2011 International Conference on Advances in Engineering
Features and Application of Titanium Dioxide Thin Films in Water Treatment Ban Yunxiaoa,b, Wang Xiaochangc,a * ac
Key Laboratory of Northwest Water Resource , Environment and Ecology ,MOE , Xi’an University of Architecture and Technology , Xi’an 710055,China b Lanzhou Jiaotong University of Environmental and Municipal Engineering ， Gansu Lanzhou 730030, China
Abstract The purpose of the investigation was to study TiO2 thin films and photocatalytic degradation of phenol in water treatment. It turned out that thin films are uniform distribution, dense, continuous without fracture on the surface of carriers. It was an average of 60nm thick. The experimental results indicated that the photocatalytic activity of thin film is higher than powers in removing phenol. The former is quite three times as much the latter in efficiency.
© 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. Selection and/or peer-review under responsibility of ICAE2011. Keywords: vacuum evaporation coating; titanium dioxide thin films; photocatalysis;Introduction
1. Introduction Nomenclature η
rate of phenol degradation
Titanium dioxide (TiO2) as photo catalyst has widely been used to photodegrade the organic pollutants for its relatively high catalytic reactivity, physical and chemical stability, avirulence and cheapness [1,2]. But, there are two key technical problems what need to be solved in water treatment. Firstly, it is to improve the utilization efficiency of incident light[3-5]. Secondly, it can be conveniently recycled using[6]. 2. Experimental 2.1 Materials Titanium dioxide powders, common glass plate, steel plate, titanium plate, phenol ， 4-amino * Corresponding author. Tel.: E-mail address
[email protected]
1877-7058 © 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. doi:10.1016/j.proeng.2011.11.2714
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antipyrine (C11H13N3O) , red potassium prussiate(K3F(CN)6) and potassium dichromate (K2Cr2O7) were used in this study. 2.2 Instrumentation Vacuum evaporation coating machine (ZDL1603, made in Lanzhou Jiaotong University national green coating technology and equipment engineering technology research center), photocatalytic reactor (organic glass, effective cubage 1L), UV lamp (15W), electronic scales (TG-328A), 721 spectrophotometer, scanning electron microscopy (JSM-5600）) and energy dispersive spectrum analyzer (JOEL/Oxford）, SE400 ellipsometer（made in Germany）. 2.3 Photocatalytic reaction e
c
a d b
Fig.1 the schematic of photocatalytic reactions a. UV light b. pump c. cover activities d. the card slot e. sampling mouth
It is homemade reactor that is produced using organic glass. Reflectors set at four inwall. The mass volume of reactor is 1.6 L. Light comes from 15W lamp. It was shown in Fig.1.There is substrate in which titanium dioxide thin films was load. It was clung at reactor walls and fixed with slot. The experiments were run in intermittent sequencing batch method. 3. Results and discussion 3.1 The thin films characterization Titanium dioxide thin films is produced using large vacuum evaporation coating machines that is made in Lanzhou Jiaotong University national green coating technology and equipment engineering technology research center. Titanium dioxide thin films were scanned by electron microscopy loaded with glass plate, stainless steel plate or titanium plate. So it can be analysed in the surface topography. The results were shown in Fig. 2. The glass surface is smooth, flat and even coating from Fig.2.a. There are irregular convex in stainless steel plate or titanium plate surface from Fig.2.b or Fig.2.c relative glass plate. There are some white spots in both plates that are titanium dioxide clusters. They were conducted because of uneven accumulation in sedimentary of titanium dioxide. Overall, titanium dioxide thin films are so even, dense, continuous without fracture in three carrier surface.
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Ban Yunxiao and Wang Xiaochang / Procedia Engineering 24 (2011) 663 – 666 Ban Yunxiao.et al./ Procedia Engineering 00 (2011) 000–000
b Titanium dioxide/stainless steel plate thin films
a Titanium dioxide/glass plate thin films
Fig.2 the surface SEM of titanium dioxide
c Titanium dioxide/titanium plate thin films
Tab.1The element component of different parent metal
thin films / material kind
chemical composition w% Ti
O
Fe
Na
Mg
Al
Si
Ca
Cr
39.50
2.09
---
---
---
17.02
TiO2 /glass plate
0.62
37.48
---
11.2
5.41
3.70
TiO2 /stainless steel plate
0.50
---
82.49
---
---
---
The component of films was analyzed by energy dispersive spectrum analyzer（EDS）. The results were shown in Tab.1. There have Mg, Al, Si and Ca elements except Ti, O in titanium dioxide thin films on glass plate. The test results are similar to the situation to titanium dioxide thin films on stainless steel plate. It was an average of 60nm thick by ellipsometer measuring thin films. 3.2 Activity of thin films The test of photocatalytic is done though phenol as degradation target in water treatment. The determine phenol degradation rate as η, η=（C0-C）/C0 (1) The experiment using suspended titanium dioxide as photocatalyst catalysts that also is commodity used coated. The concentration of power titanium dioxide is 3.0g/L. It has the best effect to photocatalytic degradation phenol in experiment. The initial concentration of phenol is C0, and C0=100 mg/L.
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The same reactor with titanium dioxide thin films on common glass as photocatalyst catalysts at the same conditions was used in this experiment. The effect of contrast to gradate phenol of titanium dioxide thin films and power were shown in Fig.3. 60
pulverulent body titanium dioxide Titanium dioxide/common glass plate
The removal rate of phenol (%)
50
40
30
20
10
0 0
1
2
3
4
Time (h) Fig.2 the contrast of effect to gradate phenol of titanium dioxide thin films and power Fig.3 shown that, the photocatalyst activity of thin films is three times than powers of titanium dioxide at the same conditions.
4. Conclusions Firstly, it is dense, continuous without fracture to thin films. There are some other elements in the membrane surface which has relation to base material. Secondly, the photocatalytic activity of thin films is higher than powers. The former is quite three times as much the latter in efficiency. References [1] Junshui Chen, Meichuan Liu, Li Zhang, et al. Application of nano TiO2 towards polluted water treatment combined with electro-photochemical method. Water Research,2003.37(16):3815-3820. [2] Susana Flores Villanueva, Susana Silva Mart´nez. TiO2-assisted degradation of acid orange 7 textile dye under solar light. Solar Energy Materials & Solar Cells,2007,91(15-16): 1492–1495. [3]Jun Wang, Ronghe Li, Zhaohong Zhang, et al. Efficient photocatalytic degradation of organic dyes over titanium dioxide coating upconversion luminescence agent under visible and sunlight irradiation. Applied Catalysis A: General ,2008,334 (1-2): 227– 233. [4] Chien-Cheng Tsai, Hsisheng Teng. Chromium-doped titanium dioxide thin-film photoanodes in visible-light-induced water cleavage. Applied Surface Science ,2008,254 (15):4912–4918. [5] HaiqiangWang, ZhongbiaoWu, Yue Liu. Effect of filler types and calcination temperature on the microstructure and the nitric oxide photocatalytic activity of composite titanium dioxide films Journal of Hazardous Materials ,2009,164 (2-3) 600–608. [6] Jun Wang, Ronghe Li, Zhaohong Zhang,et al. Efficient photocatalytic degradation of organic dyes over titanium dioxide coating upconversion luminescence agent under visible and sunlight irradiation. Applied Catalysis A: General ,2008,334 (1-2):227– 233.
