1. The International Istanbul Textile Congress 2013
May 30th to June 1th 2013, Istanbul, Turkey
1
PHOTOCATALYTIC ACTIVITY OF TIO2 NANOFIBERS FABRICATED
FROM POLYVINYL ACETATE (PVAC)
F. MEMARIAN1
, M. AMANI TEHRAN1
, M. LATIFI2
1
Textile Engineering Department, Amirkabir University of Technology, Tehran, Iran
2
Textile Excellence & Research Centers, AmirKabir University of Technology, Tehran, Iran
fmemariyan@aut.ac.ir
Abstract: Electrospinning of TiO2 nanofibers is remarkably reported in the last decade. It is because of its
high surface to volume ratio which makes it a good choice for catalytic activities. We have used PVAc to
fabricate TiO2 nanofibers using Titanium tetra isopropoxide in the sol gel process with the aid of Acetic Acid
to control hydrolysis reaction of the solution. Electrospinning is performed by choosing a proper feed rate,
High voltage value and distance of nozzle to the collector. Process is continued till a thick layer of nanofiber
webs are achieved and then calcined at 450 c for 3 hours to attain anatase phase of TiO2. The obtained
web has enough strength and flexibility to be lifted gently by clamp. 6 mg of the catalyst was able to degrade
10 ppm Rhodamine B solution throughly in almost 6 hours under UV irradiation. The catalysts preserve its
shape after the 6 hours test when it is electrospun by PVAc..
Keywords: electrospinning; TiO2 nanofibers; photocatalytic activity; PVAc
1. Introduction
Titania is a wide bandgap semiconductor with many interesting properties, such as transparency to visible
light, high refractive index, low absorption coefficient and catalysis[1]. One-dimensional nanostructures of
Titania have been a subject of intense research because of their high specific surface area which makes
them a good choice to purify waste water[2, 3].
Webs of TiO2 nanofibers have been electrospun in different research works using different auxiliary polymers
like Polyvinyl pyrrolidone(PVP)[4-6] and polyvinyl acetate(PVAc)[2, 3, 7]. Ethanol is used as the polymer
solvent in the solution. A titanium sol is used in the solution to attain pure TiO2 in the final product after heat
treatment of nanofibers. The obtained nanofibers are brittle. Therefore for good ability of the catalyst to
degrade the water pollutants to organic materials, a powder of nanofibers are dispersed in waste water using
sonication. Thus a centrifuge stage is needed to remove the nanofibers from the water.
In this paper we have presented the best ratios of materials in electrospinning process to attain TiO2
nanofibers. These solution ratios will be sufficient for fabricating TiO2 in other structures like yarn which can
mentain its structure after heat setting. The purpose of this study is to have a photocatalysis test without a
sonication and centrifuge step. The reuseability of the catalyst will be in the long-term application.
Photocatalysis tests are performed using Rhodamine B(RhB) as a model pollutant.
2. Materials
PVAc (sigma-aldrich) with Mw=100000 is the polymer used in this paper. From different solvents of PVAc
ethanol was the best solvent in electrospinning of nanofibers. Glacial Acetic acid (sigma-aldrich) is used to
prevent hydrolyzing Titanium sol. Titanium tetra iso propoxide (TTIP 97%, sigma Aldrich) is used as a
titanium sol in the solution.
2.1 Method
0.17 gr of PVAc is solved in 1 cc of ethanol and stirred for 10 hours. Then 0.5 cc of acetic acid is added to
the solution with stirring for 15 min. Then TTIP is added to the solution and then it is stirred for another 30
hours. The solution becomes milky when it is ready to electrospin.
Electrospinning is carried out by setting the distance between the nozzle to collector to 9 cm, feeding rate of
0.2 ml/hr and High voltage of 13 KV.

2. The International Istanbul Textile Congress 2013
May 30th to June 1th 2013, Istanbul, Turkey
2
Electrospun nanofibers need to be annealed for 450 c for 3 hours. During this process, remained polymer
and solvents are omitted from the electrospun nanofibers. Furthermore the amorph TiO2 is converted to the
anatase crystalline phase of TiO2.
The photocatalytic activities of TiO2 nanofibers were investigated by an analysis of the degradation of dyes
under UV illumination. 6 mg of pure TiO2 nanofibers were placed in a glass dish. Then dye solution with the
concentration of 10 ppm was poured on catalyst. This dish is then settled in an aluminium enclosed cell
(17cm×25cm×10 cm). UV irradiation was provided by three 6W light bulb (6W×3) on top of the dish. The
changes in the solution colour show the degradation of dye in the water solution.
2.2 Characterization
The nanofiber samples were sputter- coated with gold (SC7620, Quorum Technologies) and their
morphology was studied with a scanning electron microscope (Philips XL30) at an accelerating voltage of 25
kV. Analysis of the crystalline structures after heat treatment was performed by XRD diffractometer (X'pert
Philips) with Cu Kα radiation (λ=0.15406 nm) in 2Ө range from 10˚ to 80˚ by 0.03˚ sec-1 steps.
3. Results
SEM image of the fabricated nanofibers before and after heat treatment is shown in figure 1. The diameter of
the nanofibers is calculated using image j software. The fibers have an average diameter of 220-280 nm
when they are electrospun. The nanofibers diameter is reduced to 170-180 nm after heat treatment in 450 c
for 3 hours.
Figure 1. electrospun PVAc/TiO2 hybrid nanofiber (left), TiO2 nanofibers after heat treatment at 450 c for 3 hours(right)
As it is clear from the XRD pattern in figure 2, the crystalline TiO2 in anatase phase appears by heating at
450 °C for 3 hours.
Figure 2. XRD image of electrospun nanofibers
Figure 3a shows the initial dye solution on the catalyst sample without UV irradiation. Photocatalytic
degradation of organic dye with UV irradiation after 5 hours is indicated in figure 3b. It is clear that most of

3. The International Istanbul Textile Congress 2013
May 30th to June 1th 2013, Istanbul, Turkey
3
the dye has been degraded in the catalyst dish. After 6 hours of UV irradiation it was found that 6 mg of the
catalysts is able to disintegrate dye with 10ppm concentration from the water.
Figure 3. dye degradation of the photocatalyst after (a)0 hr-start, (b) 5hr, (c) 6hr
4. Conclusion
PVAc is used as the auxiliary polymer for electrospinning of pure TiO2 nanofibers. The heat treated fibers
were able to be moved in the petri dish. Dye solution has been poured on the catalyst so that powdering the
catalyst is not necessary and it eliminates the need for sonication and centrifuge step in dye degradation.
This method can be promoted by putting the catalyst in a gradient to the horizon, and recycle dye solution to
pass through the catalyst several times.
Fabricating the TiO2 structure with sufficient strength makes it possible to use the catalyst in water without
dispersing it.
References
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