preparation of nano-tio2 in inverse microemulsion system with tioso4 as raw material

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Preparation of Nano-TiO 2 in inverse Microemulsion system with TiOSO 4 as raw material Xingxin JIA 1,a , Wenyuan GAO 1,2,b , Meihong Niu 3,c 1. Department of Material Science and Engineering,Dalian Polytechnic University, Dalian 116034, China 2. Liaoning Province Key Laboratory of Advanced Material and Material Modification, Dalian 116034, China 3. Department of Environmental and Light Chemical Engineering,Dalian Polytechnic University, Dalian 116034, China a [email protected], b [email protected], c [email protected] Keywords: microemulsions; nano meter; titanium dioxide; anatase. Abstract. The nanosized TiO 2 was prepared by microemulsion process in the system of cyclohexane/[Span80 combine with Tween40]/water with TiOSO 4 as raw material. The synthesis process of the powder was investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and laser particle size analysis (LPSA). The results showes that TiO 2 with the average size of 19.5nm and narrow size distribution was prepared under these conditions of Span80 of 8g and Tween40 of 2g as the emulsifier, water/oil mass ratio of 1/4, amount of TiOSO 4 of 10mL with the consistency of 0.8mol/L, calcination temperature of 480 ˚C for 20min. Introduction Nano TiO 2 has been widely used in solar cells, waste water treatment, cosmetics and paints and various other areas because of its good corrosion resistance, chemical stability, high photocatalytic activity, high whiteness and advantages such as cheap, non-toxic, no second pollution [1]. Preparation of anatase nano TiO 2 with the better performance of photocatalytic degradation[2] has become the focus of the research due to the urgency of the problems of sewage treatment. Therefore, it has been pursued the main objective to obtain high-performance anatase nano TiO 2 from cheap raw materials and simple preparation methods in recent years. In this work, nano TiO 2 with small particle size and narrow particle size distribution was prepared in micro-emulsion composed of cyclohexane/ [Span 80 combined with Tween40]/water, the non-ionic surfactant synergistic effect of Span80 and Tween40[3] which could increase the stability of emulsion was made full use of. As the raw material of reaction, TiOSO 4 was non-toxic and cheap [4]. Surfactants, Span80 and Tween40 were food additives, as solvent, cyclohexane could be recycled. The preparation method had the advantages of safe, low toxicity, pollution-free, simple process and gentle reactionconditions. Experiment Reagents. Titanyl sulfate and cyclohexane used in the experiment both were AR, surfactants such as Span80 and Tween40 were industrial supplies, laboratory water was deionized water. Preparation of nano-titanium dioxide powder. Span80 and Tween40 were added into 50g cyclohexane, mixed them evenly for 30min. Then divided the mixture into two copies of the same volume, 10mL ammonia of 3 mol/L was added in one par, made of the stable emulsion A; Another was added to 10mL TiOSO 4 solution, mixing evenly, obtained emulsion B. Under the condition of strongly mixing, emulsion A was added to emulsion B by 3mL/min by drops, stirring for 1h, the white translucent emulsion was obtained. Applied Mechanics and Materials Vols. 174-177 (2012) pp 747-750 Online available since 2012/May/14 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.174-177.747 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 128.210.126.199, Purdue University Libraries, West Lafayette, United States of America-13/03/13,18:53:48)

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Page 1: Preparation of Nano-TiO2 in Inverse Microemulsion System with TiOSO4 as Raw Material

Preparation of Nano-TiO2 in inverse Microemulsion system

with TiOSO4 as raw material

Xingxin JIA 1,a, Wenyuan GAO 1,2,b , Meihong Niu 3,c 1.Department of Material Science and Engineering,Dalian Polytechnic University, Dalian 116034,

China

2. Liaoning Province Key Laboratory of Advanced Material and Material Modification, Dalian 116034,

China

3.Department of Environmental and Light Chemical Engineering,Dalian Polytechnic University,

Dalian 116034, China

[email protected],

[email protected],

[email protected]

Keywords: microemulsions; nano meter; titanium dioxide; anatase.

Abstract. The nanosized TiO2 was prepared by microemulsion process in the system of

cyclohexane/[Span80 combine with Tween40]/water with TiOSO4 as raw material. The synthesis

process of the powder was investigated by differential thermal analysis (DTA), X-ray diffraction

(XRD) and laser particle size analysis (LPSA). The results showes that TiO2 with the average size of

19.5nm and narrow size distribution was prepared under these conditions of Span80 of 8g and

Tween40 of 2g as the emulsifier, water/oil mass ratio of 1/4, amount of TiOSO4 of 10mL with the

consistency of 0.8mol/L, calcination temperature of 480 ˚C for 20min.

Introduction

Nano TiO2 has been widely used in solar cells, waste water treatment, cosmetics and paints and

various other areas because of its good corrosion resistance, chemical stability, high photocatalytic

activity, high whiteness and advantages such as cheap, non-toxic, no second pollution [1]. Preparation

of anatase nano TiO2 with the better performance of photocatalytic degradation[2] has become the

focus of the research due to the urgency of the problems of sewage treatment. Therefore, it has been

pursued the main objective to obtain high-performance anatase nano TiO2 from cheap raw materials

and simple preparation methods in recent years.

In this work, nano TiO2 with small particle size and narrow particle size distribution was

prepared in micro-emulsion composed of cyclohexane/ [Span 80 combined with Tween40]/water, the

non-ionic surfactant synergistic effect of Span80 and Tween40[3] which could increase the stability

of emulsion was made full use of. As the raw material of reaction, TiOSO4 was non-toxic and cheap

[4]. Surfactants, Span80 and Tween40 were food additives, as solvent, cyclohexane could be

recycled. The preparation method had the advantages of safe, low toxicity, pollution-free, simple

process and gentle reactionconditions.

Experiment

Reagents. Titanyl sulfate and cyclohexane used in the experiment both were AR, surfactants such as

Span80 and Tween40 were industrial supplies, laboratory water was deionized water.

Preparation of nano-titanium dioxide powder. Span80 and Tween40 were added into 50g

cyclohexane, mixed them evenly for 30min. Then divided the mixture into two copies of the same

volume, 10mL ammonia of 3 mol/L was added in one par, made of the stable emulsion A; Another

was added to 10mL TiOSO4 solution, mixing evenly, obtained emulsion B. Under the condition of

strongly mixing, emulsion A was added to emulsion B by 3mL/min by drops, stirring for 1h, the white

translucent emulsion was obtained.

Applied Mechanics and Materials Vols. 174-177 (2012) pp 747-750Online available since 2012/May/14 at www.scientific.net© (2012) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMM.174-177.747

All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 128.210.126.199, Purdue University Libraries, West Lafayette, United States of America-13/03/13,18:53:48)

Page 2: Preparation of Nano-TiO2 in Inverse Microemulsion System with TiOSO4 as Raw Material

Precipitation was obtained by centrifuging it for 15min with a centrifugal speed of 4500r/min.

The precipitate was washed in deionized water for three times and then dried for 2h under 60˚C.

Grounded it to powder, put it into muffle furnace and calcined it, then the product was obtained.

Characterization. Calcination temperature system for preparation of anatase nano TiO2 was

determined by DTA. Crystalline form was examined by XRD. The particle size and distribution were

determined by LPSA.

Results and Discussion

Determination of the mass ratio of surfactants and calcination temperature.

The choice of surfactants. The particle size of TiO2 was directly impacted by the stability of the

emulsion system[5], while the surfactant was the key to stable emulsion. Mixture of Span80 and

Tween40 was used as the surfactant by calculating the surfactant hydrophilic-lipophilic balance

(HLB) value, based on the synergies of surfactants [6]. The micellar sizes in the emulsion as mass

ratios of Span80: Tween40 of 9:1, 8:2 and 7:3 were examined while other factors remain unchanged.

Results were shown in Table1.

The average particle size of micelles was small, but the distribution was wide when the ratio was

9:1. The reason was that lack of the amount of Tween40, whose hydrophilic was better, resulting in

the water core coated not solid. When it was 7:3,average particle size of micellar was large and

distribution was wide, due to inadequate amount of the Span80 with better lipophilic, resulting in

surfactant water nuclear was not formed completely covered. So, the best ratio was 8:2.

Table 1 Micella sizes with different mixture ratios of Span80 and Tween40

m(Span80):m(Tween40 9:1 8:2 7:3

average particle size[nm] 14.8 17.6 90.2

particle size distribution[nm] 5~200 15~30 55~300

Determination of calcination temperature. TiO2 precursor was prepared under the conditions

of mixture of Span80 and Tween40 of 10g with the mass ratio of 8:2, TiOSO4 of 10mL with the

concentration of 0.8mol/L, ammonia of 10mL with the concentration of 3mol/L. It was examined by

DTA after dried, and the result was shown in Figure1. There was an endothermic peak at 135˚C ,

which resulted from the demyelination of free water, bound water and residual organic solvent

evaporation. There was a wide exothermic peak at 296˚C , which was caused by degradation of

residual solvents and surfactants organic matter. There was a sharp and large exothermic peak at

474˚C , and no obvious peak appeared behind it, showed that the crystal of TiO2 changed from

amorphous to anatase at 474˚C .

0 200 400 600 800 1000-50

0

50

100

150

200474℃

296℃DT

A

Temperature/℃

135℃

10 20 30 40 50 60 70

0

100

200

300

400

500

600

700

CP

S

2θ/°

Figure 1 Differential thermal curve of Titania precursor Figuer 2 X ray diffraction pattern

of TiO2 at 480˚C

748 Advanced Building Materials and Sustainable Architecture

Page 3: Preparation of Nano-TiO2 in Inverse Microemulsion System with TiOSO4 as Raw Material

Figure2 was contrasted with card 40-477 of the standard pattern library, there was the most

obvious diffraction peak at 25.36°, which should be attributed to the diffraction plane of (101) of

anatase TiO2, and the conclusion that the crystal formation of TiO2 was gotten.

Influence of the amount of surfactant on the particle size. The stability of emulsion, micellar

water pool sizes, which affect the particle size of titanium dioxide both were influenced directly by

the amount of surfactant [7]. The particle sizes of anatase nano TiO2 samples prepared with surfactant

of 5g, 10g and 15g while other parameters remain unchanged, the results as a, b, and c were shown in

Figure3.

When the surfactant amount was 5g, such as “a”, the particle size distribution was wider, and the

average particle size was larger. When it was 10g shown in “b”, nano TiO2 with narrow distribution

and average particle size of 19.5nm was prepared. When the surfactant amount increased to 15g,

although part of particles with smaller size generated, but the reunion of particles generated, and the

production was reduced. The reasons, insufficient amounts of surfactant resulted in water nuclear

particle size too large, then particle size of titania generated in water nuclear was large; the exchange

of components between nano-droplets was inhibited by the superfluous surfactant, and the results that

emulsion was too stable and not conducive to the formation of precipitation was caused in, while the

powders were easy to reunite when the emulsion coat washed away. Thus the optimal amount of

surface could be determined to be 10g.

a b c

Figure 3 Particle size distributions of TiO2 by different amounts of surfactant

Influence of mass ratio of water /oil on the particle size. Water/oil mass ratio directly affect the

stability of emulsion and water nuclear size [7]. Four different ratios of water/oil obtained by

changing the dosage of cyclohexane while water was 20g were tested: 1/2, 1/3, 1/4 and 1/5. The

results were shown in Table2. Emulsion was opaque when the mass ratio was large, which was

caused from the inadequate of oil phase, inadequate water nuclear dispersion and the reunion of

precipitation. Emulsion gradually became translucent after the mass ratiowas smaller than 1/4, but the

particle size changed little. But too small mass ratio would reduce the yield. So, the optimal mass ratio

of water/oil should to be 1/4 taking both the factors of preparation of powders with smaller sizes and

thrift of cyclohexane into consideration.

Table 2 The impact of water / oil ratios on the products

mass ratio of water /

oil

average particle size of

TiO /nm

emulsion

appearance 1/2 221.8 opaque

1/3 75.5 opaque

1/4 20.2 translucent

1/5 19.6 translucent

Influence of concentration of titanyl sulfate solution on particle size. Reactant concentration

had a direct impact on the particle size and the distribution. Particle sizes of titanium dioxide prepared

with five TiOSO4 concentrations were discussed in the work: 0.4mol/L, 0.6mol/L, 0.8mol/L,

1.0mol/L and 1.2mol/L. Trend of the average particle size was shown in Figure4.

Size distribution(s)

5 10 50 100 5001000 5000Diameter (nm)

10

20

% in c

las

s

Size distribution(s)

5 10 50100 5001000 5000Diameter (nm)

20

40

60

80

% in c

lass

Size distribution(s)

5 10 50100 5001000 5000Diameter (nm)

5

10

% in c

las

s

Applied Mechanics and Materials Vols. 174-177 749

Page 4: Preparation of Nano-TiO2 in Inverse Microemulsion System with TiOSO4 as Raw Material

0.4 0.6 0.8 1.0 1.20

20

40

60

80

100

120

140

160

Th

e av

erag

e par

ticl

e si

ze o

f T

iO2/n

m

The concentration of titanyl sulfate/mol*L-1

Figure 4 Particle Distributions with the different concentrations of reactant

When the TiOSO4 concentration was less than 0.8mol/L, the average particle size increased with

the increase of the concentration of TiOSO4, but changed little; the particle size increased rapidly with

the increase of the concentration of TiOSO4 while it was larger than 0.8mol/L. The reason was that the

reaction rate was too fast when the concentration of TiOSO4 e was too large, which led to particle

agglomeration. So, the titanyl sulfate concentration was determined to be 0.8 mol / L.

Conclusions

Several factors of the microemulsion system affecting the size distribution of TiO2 were discussed:

the amount of surfactant, mass ratio of water/oil, reactant concentration and calcination parameters.

Concluded that: precipitation of TiO2 precursor prepared under the conditions of mixture of Span80

and Tween40 with the mass ratio of 8:2 of 10g, mass ratio of water/oil of 1/4, TiOSO4 solution of

0.8mol/L of 10mL, and anatase nano TiO2 with average particle size of 19.5nm could be obtained by

calcining the precipitation of TiO2 precursor at 480˚C for 20min.

Acknowledgements

The authors gratefully thank Bureau of Municipal and Rural Construction of Dalian and The Key

Laboratory program of Liaoning Province institution of higher education (LS2010009) for the

financial supports

References

[1] G. Yi, R.H. Deng and J.L. Nie: Nonferrous Metals. Vol. 59(2007), p. 46.

[2] T.Y. Cao, Q.P. Liu and J.S. Hu: Principles of Polymer Emulsion Properties and Applications

(Chemical Industry Publisher, Beijing, China, 2007).

[3] F.A.Deorsola,D.Vallauri: Powder Technology. Vol. 190(2009), p. 304.

[4] H.S. Zou, J.F. Chen, and W.B. Chen: Journal of South China University of Technology (Natural

Science Edition). Vol. 36(2008), p. 32.

[5] Y.H. Chen,A.Lin,F.X.Gan: Powder Technology. Vol. 167(2006), p. 109.

[6] C.H. Lu, W.H.W, R.B.Kale: Journal of Hazardous Materials.Vol. 154(2008), p. 649.

[7] K.D. Kim, H.T. Kim: Colloids and Surfaces A. Vol. 255(2005), p. 131.

750 Advanced Building Materials and Sustainable Architecture

Page 5: Preparation of Nano-TiO2 in Inverse Microemulsion System with TiOSO4 as Raw Material

Advanced Building Materials and Sustainable Architecture 10.4028/www.scientific.net/AMM.174-177 Preparation of Nano-TiO2 in Inverse Microemulsion System with TiOSO4 as Raw Material 10.4028/www.scientific.net/AMM.174-177.747