Synthesis and characterization of TiO2/ quartz sand composite using sol-gel method
for photo-catalytic degradation of organic substances
201221209
林暁村（Xiaocun Lin）
1. Introduction
Nanosized TiO2 is considered to be an important photocatalytic material to deal with
organic pollutants in wastewater. However, due to separation problem it can’t be well
applied in practice. Quartz sand has been proven to be a promising materials
supporting TiO2. As for the process used for preparation of supported TiO2, sol-gel
method is the most appropriate way as it allows for mild reaction conditions and
flexible control of the catalyst properties. This study aims to prepare a new
photocatalyst in larger size (0.2-0.6mm) by using a simple process called sol-gel
method, namely TiO2/ quartz sand composite which could be separated easily from
water.
2. Materials and Methods
2.1 Pre-preparation of quartz sand
The quartz sand particles with average particle size of 0.2-0.6mm were selected
through sieving process. Then the quartz sand was washed first with hydrochloric acid
and then with deionised water till neutral pH. Later, prepared quartz sand was stored
in a desiccator for future use after being dried at 120 ℃for 2h.
2.2 Preparation of photocatalyst
(1) Solution A contained H2O, CH3COOH and CH3CH2OH.
(2) Solution B was obtained when Ti(OC4H9)4 was added into CH3 CH2 OH and after
being stirred for 120 min.
(3) Solution A was dropped into solution B slowly and stirred for 30 min. The
mentioned above prepared quartz sand was added into the resultant solution, then
dipped for 24h. The product then was dried at 120℃ for 24h. After being sieved and
washed with deionised water and absolute ethanol, the samples were dried at 120℃
for 2 h and calcined for 2h at different temperature.
3. Main results and conclusion
(1) TiO2 could be coated on the surface of quartz sand successfully by sol-gel method.
This new photo-catalyst TiO2/quartz sand composite had photo-catalytic ability on the
degradation of methyl orange (MO) under UV light irradiation which followed
pseudo- first-order kinetics.
(2) Although the photo-catalyst activity of TiO2/ quartz sand was only about 50% of
powdered TiO2 products sold commercially and made by sol-gel method in
suspension, this new photo-catalyst could be separated from water easily, leading to
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an easy and inexpensive operation process.
(3) Calcination temperature has significant influence on the photo-catalytic ability of
TiO2/ quartz sand composite. High calcination temperature might lead to instability of
the TiO2 aggregates on the surface of quartz sand.
(4) High ratio of TTB to sand might contribute to more TiO2 coated on the surface of
quartz sand, but repeated coating process had little contribution. Considering
utilization rate of TTB, low ratio (10ml/30g) and one time of coating process is
preferred.
Table 1 Variation of TiO2 coated onto quartz sand at different ratios of TTB to sand and
kinetics parameters for their degradation of MO
Ratio of TTB to sand
10mL/30g
10mL/20g
10ml/10g
10ml/5g
mTiO2 (g)
TiO2 (wt.%)
MO removal rate (%)
k(h-1)
R2
1.26
4.2
56
0.099
0.988
1.46
7.3
59
0.107
0.987
1.43
14.3
51
0.090
0.994
1.06
21.2
69
0.149
0.988
Reaction condition: Initial concentration of methyl orange (MO) was 10mg/L; dosage of
photo-catalysts was 1g/30mL; light irradiation: was 750μW/cm2; 8 hours reaction.
100%
94%
93%
P-25
TiO2 by sol-gel
1-Ct/C0
80%
60%
56%
40%
20%
0%
TiO2/SiO2-30-800-1
Fig.1 Photocatalytic activity of TiO2/quartz sand composites (TiO2/SiO2-G30-T800-C1)
powered TiO2 prepared by sol-gel method and powered TiO2 purchased commercially
Reaction condition: Initial concentration of methyl orange (MO) was 10mg/L; dosage of
TiO2/SiO2-30-800-1 was 1g/30mL; dosage of powered TiO2 was 0.042g; light irradiation was
750μW/cm2; 8 hours reaction.
Reference:
(1) Roberto L. Pozzo, Rodolfo J. Brandi, Fluidized bed photoreactors using
composites of titania CVD-coated onto quartz sand as photocatalyst: 118 (2006) 153–
159
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