This document investigates the photocatalytic degradation of p-chlorophenol using TiO2 nanoparticles. It finds that P-25 TiO2 and sol-gel synthesized anatase TiO2 show similar degradation rates of p-chlorophenol in both slurry and supported reactor systems. However, P-25 TiO2 supports exhibited greater durability over multiple degradation cycles compared to anatase TiO2 supports. The sol-gel anatase TiO2 particles were found to agglomerate more than P-25, which may explain its slightly lower degradation rate in slurry form.

1. Photocatalytic Degradation of p-chlorophenol: Influence of Supports and Sol-gel Synthesised TiO2
George Fox N0427541@my.ntu.ac.uk
Supervised By Dr Valeria Puddu
Introduction
Research Aims Reactor Configuration
Results and Discussion
References
Chlorophenols are toxic, water persistent
pollutants found in the effluent of
pharmaceutical and paper industries (1).
TiO2 nanoparticles have shown promise
for the photocatalytic degradation of p-
chlorophenol (p-cp) in aqueous solution
(2). The use of TiO2 slurry in AOP’s has
lead to scaling up difficulties, with
constant system filtration required.
Degussa P-25 TiO2 is considered the
benchmark photocatalyst for degradation
of most organic pollutants. Pure anatase
phase TiO2 has been synthesized using
the simple sol-gel technique.
Photocatalysis of p-cp has been
performed with both P-25 (~70%
anatase, 30% rutile) and anatase TiO2 in
slurry and support systems.
1. To investigate the photocatalytic
degradation rate of TiO2/UV systems
on p-cp in slurry and support reactor.
2. To analyse support durability and
catalytic lifetime.
3. To synthesize pure anatase phase
TiO2 using the sol-gel method and
compare its activity to Degussa P-25
TiO2.
Methodology
Degradation was performed in a simple
photocatalytic reactor. An initial p-cp
concentration of 80mgL and TiO2 loading
of 0.3gL were employed.
After system equilibration regular samples
were withdrawn and analysed with a Perkin
Elmer Lambda 25 UV-vis spectrometer at
279nm.
TiO2 supports were manufacture following a
variation on the heat-attachment method (3).
Figure 2 – Diagram of photoreactor
configuration.
Photoreactor conditions were constant
throughout the study, with the only change
being the replacement of TiO2 slurry for
immobilized glass supports. Before
degradation of p-cp the light source was
equilibrated to achieve constant output.
1) A. Zhihui, Y. Peng, and L. Xiaohua, Chemosphere, 2005, 60,
824-827
2) A.T. Nguyen, R. Juang, Journal of Environmental
Management, 2015, 147, 271-277
3) M. A. Behnajady, N. Modirsshahla, M. Mirzamohammady, B.
Vahid, B. Behnajady, Journal of Hazardous Materials, 2008,
160, 508-513
0.5
0.6
0.7
0.8
0.9
1
1.1
0 50 100 150 200 250 300
C/Co
Time (mins)
P-25 Slurry
P-25 Supports
Sol-gel Slurry
Sol-gel Supports
Figure 1 – P-25 coated glass support
Amorphous TiO2 nanoparticles were
synthesised using a sol-gel method utilizing
stoichiometric amounts of solvent and Ti
precursor. Particles were dried and
calcinated at 400°c.
p-cp Degradation
Figure 3 – % p-cp degradation by slurry and
support systems (P-25 & anatase)
p-cp was successfully degraded by 41%
using P-25 slurry. Applying Langmuir-
Hinshelwood Kinetics to the first order
reaction showed the rate of degradation to
be 1.8 x 10-3 min-1. The rate and %
degradation were discovered to be
comparable to that shown by P-25 supports
(36% and 1.63 x 10-3 min-1).
XRD analysis of sol-gel TiO2
Figure 4 – XRD spectrum of sol-gel TiO2
showing anatase peak at 101
XRD showed sol-gel TiO2 was purely
anatase, with an average crystallite size of
2nm. SEM imaging showed particle
agglomeration between 0.5 to 3.0um.
Agglomeration resulted in a poor anatase
.
TiO2 slurry accounting for the lesser
activity of 1.1 x 10-3min-1 and lower %
degradation (32%) observed.
Support Durability
Total P-25 Mass
P-25 lost after 1st
deg
Total Anatase
Mass
Anatase lost after
1st deg
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
MassofTiO2(g)
Figure 5 – Comparison of mass lost from
P-25 and anatase supports
P-25 and anatase supports show large
differences in durability. After one
degradation there was a five fold increase
in mass lost from anatase supports.
Conclusions
1. P-25 and anatase TiO2 show similar
rates of p-cp degradation in slurry and
support systems respectively.
2. P-25 supports exhibited superior
durability to respective anatase
support, and show good catalytic
lifetime over three degradations.
3. Pure anatase TiO2 nanoparticles can
be synthesised following a simple sol-
gel method. Particles showed
agglomeration between 0.5-3.0um,
providing explanation for the slightly
decreased rate of anatase slurry.