Advances in Ma terials Physics and Che mist ry, 2012, 2, 274-276
doi:10.4236/ampc.2012.24B070 Published Online December 2012 (
Copyright © 2012 SciRes. AMPC
Photocatalytic Degradation of Ethylene Dichloride in Water
Using Nano TiO2 Supported on Clinoptilolite as a
Photocatalys t
Mano uc he hr Nikaza r, Soheil Jalali Farahani, Mastan eh R ez a Soltan i
Chemical Engineering Department of Amirkabir University of Technology, Tehran, Iran
Received 2012
In this article one of the advanced oxidation processes (AOP) combined methods, photocatalyst /H2O2, is utilized in order to study
photodegradation of ethylene dichloride (EDC) in water. Nano Titanium (IV) Oxide, supported on Clinoptilolite (CP) (Iranian natural
zeolite) using solid-state dispersion (SSD) method for improvement of its photocatalytic properties. The results show that the
TiO2/Clinoptilolite (SSD) is an active photocatalyst. The effects of five important photocatalytic reaction parameters including the
initial concentration of ethylene dichloride, the ratio of TiO2/Clinoptilolite, the catalyst concentration, H2O2 concentration and pH in
photodegradation of ethylene dichloride were examined. In this experiments, the design and also the optimum parameters were ob-
tained by Taguchi Method, using Design Expert8® software. Taguchi's L27 (5^3) orthogonal array design was employed for the
experimental plan. Four parameters were found to be significant whereas, pH was found to be an insignificant parameter after con-
ducting experiments. A first order reaction with K = 0.007 min-1 was observed for the photocatalytic degradation reaction.
Keywords: Photodegrada tion; Photocatalysts; TiO2/Clinoptilolite; Ethylene Dichloride
1. Introduction
Effects of several different pollutions such as phenol com-
pounds, alcohols, organic acids, hydro-carbonic sulfur com-
pounds, pesticides and insecticides compounds, dyes, output
wastewater from various industries and et c. using p hotocatal yt-
ic oxidation has been investigated on sewage treatment. All of
these experiments show high efficiency in degradation and
removal of these pollutions from water and sewage by this me-
thod [1,2]. Usual biological treatment methods for hazardous
compounds such as chlorinated hydrocarbons are not efficient,
because of high toxicity of these compounds which results in
destroying microorganisms. TiO2 is one of the most effective
photocatalysts due to its biological and chemical inertness and
photo stability in near- UV band ener gy gap, and can be u s ed as
a fine powder or crystals dispersed in water and wastewater
treatment applications. However, the need to filter TiO2 par-
ticles after reaction makes such a process troublesome and
costly. Thus, in order to solve this problem, many researchers
have examined several methods for fixing TiO2 on supporting
materials including glass beads [3-5], fiber glass [6-8], silica
[9,10], and zeolite [11,12]. When using zeolite as TiO2 support,
care should be taken that TiO2 does not lose its photo activity
and the adsorption properties of zeolite are not affected. Mat-
thews [4] showed that the photo efficiency of TiO2 is sup-
pressed when TiO2 is in interaction with the zeolite.
In this work TiO2 was supported on a zeolite without losing
photo efficiency and affecting the adsorption properties of zeo-
lite u sing the exact metho d suggest ed by Nikazar et. al. [13] for
supporting TiO2 on Clinoptilolite. This mixture was used for
photodegradation of aqueous EDC.
2. Experimental
2.1. Materials
Degussa P-25 titanium dioxide with a crystallographic mode of
80% anatase and 20% rutile, a 50 m2g-1 BET surface area and
an average p article si ze of 30 n m (accord ing to the manufactur-
er’s specifications) and the raw material was an Iranian com-
mercial Clinoptilolite (CP) (Afrand Tuska, Iran) from deposits
in the region of Semnan. According to the supplier’s specifica-
tions, it contains about 90 wt% CP (based on XRD internal
standard quantitative analysis) and the Si/Al molar ratio is 5.78.
The concentration of Fe2O3, TiO2, MnO and P2O5 impurities
has been reported to be 1.30, 0.30, 0.04 and 0.01 wt% respec-
tively, and were used for preparation of the photocatalyst.
Merck H2O2 with 30% purity, and Ethylene dichloride (EDC)
produced by Bandar Imam Petrochemical Comlex, with 96%
purity for making reacting solution.
2.2. Preparation of TiO2-supported on C P Catalysts
The Solid State Dispersion (SSD) method was applied for sup-
porting photocatalyst on zeolite. In this method, nano titanium
peroxide was mixed with CP using ethanol as a solvent and
mixture was grinded for 3 hours. Ethanol was then removed by
evaporation. Samples were dried at 110°C in the oven and cal-
cined at 450°C in the furnace for 5 hours to obtain
TiO2-supported zeolite photocatalysts [13].
2.3. Apparatus
Photocatalytic reaction was performed in a batch Pyrex double
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wall reactor of 1.5 L in volume with two 8-W UV-C mercury
lamps locat ed in qu artz tub es inside th e reactor. The tub es were
made from quartz because UV-C light cannot pass through
glass and Pyrex.The photo reactor used in this experiment is
shown in Figure 1. Circulator has been used for temperature
adjustment and GC VARIAN CP-3800 was used for EDC con-
centration measur ement.
2.4. Procedures
A solution containing known concentration of EDC was pre-
pared; subsequently 800 cc of this solution was poured into the
reactor. The solution pH value was adjusted at desired level
using dilute NaOH and H2SO4. Then certain amount of pre-
pared photocatalyst and H2O2 was added to the solution. Pho-
tocatalytic reaction took place under the radiation of mercury
lamps while agitation and aeration was maintained to keep the
suspension homogeneous and oxygenized. Sampling was per-
formed at specified times and concentration of EDC was de-
termined using GC.
3. Design of Experiments
Effects of five parameters that influence the efficiency of pho-
tocatalytic reaction have been studied in these experiments.
Initial concentration of pollutant (EDC), H2O2 concentration,
catalyst amount, TiO2% and pH, each of them in three levels,
are shown in Table 1.
Because of numerous studying parameters, each at 3 differ-
ent levels, Taguchi method for design of experiments using
Figure 1. Schematic of photo reactor.
Table 1. Experimental parameters and their levels.
Process Parameters Level 1 Level 2 L evel 3
Catalyst Concentration g/L A 0.1 0.25 0.5
H2O2 Concentration (ppm) B 0 50 100
Initial Concentration of EDC (ppm) C 200 400 600
pH D 4 7 10
TiO2% E 10 15 20
Design Expert 8.0.5® was employed to decrease the number of
experiments to 27 for obtaining optimum terms. Temperature is
one of the effective parameters on photocatalytic reactions that
are usually set at ambient temperature, but due to high volatility
of ethylene dichloride in the ambient temperature and aeration
during process, large amount of EDC would be vaporized from
the solution. Therefore, reaction’s temperature was set at 5°C
using circulator.
Temperature is one of the effective parameters on photoca-
talytic reactions that are usually set at ambient temperature, but
due to high volatility of ethylene dichloride in the ambient
temperature and aeration during process, large amount of EDC
would be vaporized from the solution. Therefore, reaction’s
temperature was set at 5°C usi ng circulator.
4. Results and Discussion
4.1. Taguchi Method
ANOVA analysis is shown in the Table 2.
SUM of Squares: sum the squared differences between the
average val ues for the blocks and the overall mean.
DF: degrees of freedom attributed to the blocks, generally
equal to one less than the number of blocks.
Mean square: estimate of the block variance, calculated by
the bock sum of squares divided by block degrees of freedom.
The F -value of 33.10 implies the model is significant Values
of “Prob > F” less than 0.0500 indicate mod el terms are si gnif-
icant. In this case A, B, C, E are sign ificant model terms.
In the Figure 2 we can see a grap h of the predict ed response
Table 2. ANOVA analysis report.
Source Sum of Squares DF Mean Squa re
F Value Prob. > F
Model 52.27853 8 6.5348162 33.101924 < 10-4
A-[Catal] 10.67263 2 5.336314 27.030945 < 10-4
B-[H2O2] 4.036541 2 2.018270 4 10.223491 0.0011
C-[EDC]0 31.6 9998 2 1 5.849991 80.287672 < 10-4
E-TiO2% 5.86938 2 2.9346898 14.865587 0.0002
Residual 3.55 347 18 0.197415
Cor Total 55.832 26
Predicted vs. Actual
2.00 3.00 4.00 5.00 6.00 7.00 8.00
Figure 2. Predicted vs. Actual plot.
Copyright © 2012 SciRes. AMPC
values versus the actual response values. It is clear that all of
the values are predicted by the model.
Responses should be assigned as “larger is better” for en-
hanci ng optimized parameters as showed below:
[Catal] [H2O2] [ EDC]0 pH TiO2% R1 Desirability
0.25 50 200 7 15 0.739634 1
4.2. Kinetics of Photocatalytic Degradation of EDC
Several experiment al res ul ts ind icated t hat the d egradat ion rates
of photocatalytic oxidation over illuminated TiO2 fitted by the
fir st-order kinetic model [14-16]. Figure 3 shows the plot of
ln([EDC]0/[EDC]) vs. irradiation time for EDC. The linearity of
plot suggests that the photodegradation reaction approximately
follows the pseudo-first order kinetics with K = 0.007 min-1.
4.3. Effects of UV Irradiation and Photocatalyst
In Figure 4 the comparison of four experiments is shown. First
column is degradation efficiency of EDC using only UV light
without photocatalyst, this column shows the importance of
photocatalyst because eliminating photocatalyst from reaction
caused decrease in efficiency about 47%. Second column is
about degradation efficiency of EDC employing 15% wt TiO2
photocatalyst without UV irradiation, this column shows influ-
ence of UV light in activating photocatalyst, reaction efficiency
with elimination of UV light cause 45% efficiency reduction.
Third column is shown degradation efficiency of EDC using
pure TiO2 (degussa P25 without zeolite) catalyst with UV ir-
radiation, supporting catalyst on zeolite increase reaction effi-
ciency about 37%. In last column degradation efficiency of
EDC with optimum parameters has been brought for compari-
son. All of the other parameters are the same.
Figure 3. Plot of reciprocal of pseudo-first order rate constant
against initial concentration of EDC = 200 ppm, concentration of
photocatalyst (15 wt% TiO2/CP) = 0.25 g/L, [H2O2]=50 ppm, T =
278 K, pH = 7.
Figure 4. Comparison of degradation efficiency in four different
experiment in T= 278 K, pH=7, [H2O2]=50 ppm, [EDC] 0=200 ppm,
[catalys t] = 0.25 g/ L.
5. Conclusion
1. SSD method is an effective method for supporting TiO2
on Clinoptololite.
2. The following optimum terms obtained with Taguchi
method :
Initial concentration of EDC 200 ppm, catalyst concentration
0.25 g/L, H2O2 concentration 50 ppm, TiO2% 15 and effect of
pH and two parameters interactions were not significant
3. Initial concentration of EDC, Catalyst concentration,
TiO2% and H2O2 concentration were effective in reaction effi-
cienc y, respectively.
4. Maximum efficiency of 74% for photocatalytic degrada-
tion of EDC was obtained with optimized parameters.
5. The kinetic of photocatalytic degradation of EDC is of the
pseudo-first order with K = 0.007 min-1.
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