This research poster presents a study on scaling up photocatalytic reactors. The objectives were to determine the relationship between photocatalysis parameters like reactor volume, hydrogen peroxide dosage, catalyst loading and time. It also aimed to quantify the hydroxyl radicals required to treat methyl orange. A factorial design experiment was conducted varying the reactor volume from 200 to 1100mL, hydrogen peroxide dosage and catalyst loading. Results showed reactor volume was the most influential factor. A hydroxyl quantification study was then performed using 7-hydroxycoumarin to better understand parameter limits for scaling up from 200mL to 5000mL reactors.

1. RESEARCH POSTER PRESENTATION DESIGN © 2015
www.PosterPresentations.com
Heterogeneous photocatalysis is an emerging
technology with potential use in numerous
chemical transformations (oxidation &
reduction). Photocatalysis started in the 1970s
when it was highly considered for the production
of hydrogen through water splitting.
Background
 To determine the existing relationship between photocatalysis parameters
such as
 Reactor volume
 Hydrogen peroxide dosage;
 Catalyst loading and
 Time
 To determine how many units of hydroxyl radicals are required to treat a
given unit of methyl orange
Objectives
 Chemicals were used without any further
purification: Sigma-Aldrich H2O2 30wt% and
pure titanium dioxide P25 with a particle size
of 150-200 nm as well as Methyl Orange.
 Magnetic Stirrer; Double jacketed Glass
Reactor; Syringe for sampling and a
Centrifuge to remove catalyst after sampling.
 500W tungsten lamp & 80mg/L of Methyl
Orange
 Citra 2020 UV-Vis spectrometer for analysis
Materials & Methods
Results
Discussion
Figure a). Shows the summary of the factorial design which contains factors studied and
their design limits. Figure b) and figure c) provide confirmation that factor C (volume) was
the most influential factor contributing about 63.09% compared to 9.26% and 4.79% of B
(Peroxide) and A (Catalyst) respectively. The inclusion on the Factors A and B in the Model
together with their respective combinations (AB; AC; and ABC) resulted in an insignificant
model. That being the reason why figure d) only contains factor C and is significant,
However, this is not the desired result and, therefore, the design limits of factors A and B
need to be reviewed. As a result, Figure e) and Figure h) only show the interaction
between volume and the response (reaction rate) and not the interaction between all three
factors.
In order to gain more understanding as to how to review the limits of factor A and factor B,
a hydroxyl quantification study was conducted as seen on Figures f). The main findings
observed in this study resulted in the ability to achieve a photocatalysis scale-up from
200mL to 5 Liters and an intermediate point of 500mL as seen on figure g).
References
Braham, R.J. & Harris, A.T. 2009. Review of major design and scale-upconsiderations for solar
photocatalytic reactors. Industrial & EngineeringChemistryResearch, 48(19):8890–8905.
Chowdhury, M., Ntiribinyange, M., Nyamayaro, K. & Fester, V. 2015. Photocatalytic activities of
ultra-small β-FeOOH and TiO2 heterojunction structure under simulated solar irradiation. Materials
Research Bulletin, 68: 133–141.
Czili, H. & Horváth, A. 2008.Applicability of coumarin for detectingand measuring hydroxyl
radicals generated by photoexcitation of TiO 2 nanoparticles. Applied Catalysis B: Environmental,
81(3): 295–302.
Satuf, M.L., Brandi, R.J., Cassano, A.E. & Alfano, O.M. 2007. Scaling-up of slurry reactors for the
photocatalytic degradation of 4-chlorophenol. Catalysis Today, 129(1): 110–117.
Acknowledgements
 The Cape Peninsula University of Technology for the opportunity & facilities
 National Research Fund for Funding
 Supervisors, Colleagues & staff for continued support.
Z. Gwele, V.G. Fester & M.R. Chowdhury
Flow Process and Rheology Centre, Cape Peninsula University of Technology, Cape Town, South Africa
NanoAfrica 2016 Conference University of South Africa Florida Campus: Apr 3rd – Apr 6th
Development of scale-up models for prototype photocatalytic reactor for treatment of textile effluent
The ability of this technology is well demonstrated in the laboratory scale.
However, lack of knowledge in scaling-up hinders the progress from laboratory
scale to industrial application. According to Braham & Harris (2009),
fundamentals that have been established by literature are far from being
employed in actual application. Previous studies have focused on issues such as
catalyst loading; light intensity; effect of pH; effect of temperature and effect of
Initial dye concentration. In this work, a scale-up study is going to be carried out
to investigate parameters such as volume; hydrogen peroxide dosage and
catalyst dosage under a simulated solar light. This poster, in particular, will cover
results of a factorial trial and a hydroxyl quantification study.
 7-hydroxycoumarin and coumarin were
used in their pure forms and grades of
99.5% and >=99% respectively for the
hydroxyl quantification study
 A PerkinElmer LS 55 luminescence
spectrometer was used to quantify the
hydroxyl radicals
Photocatalysis Material Hydroxyl Quantification Material
Design-Expert® Software
Factor Coding: Actual
Original Scale
Reaction Rate (mol/L.s)
Design Points
X1 = C: Volume
Actual Factors
A: Cat Load = 3.00
B: Peroxide = 0.44
C: Volume (mL )
200.00 290.00 380.00 470.00 560.00 650.00 740.00 830.00 920.00 1010.00 1100.00
ReactionRate(mol/L.s)
-0.05
0
0.05
0.1
0.15
One Factor
a) b)
0.00
1.00
2.00
3.00
4.00
1 2 3 4 5 6 7
Pareto Chart
Rank
t-Valueof|Effect|
Bonferroni Limit 3.99706
t-Value Limit 2.44691
C-Volume
c) d) Design-Expert® Software
Factor Coding: Actual
Original Scale
Reaction Rate (mol/L.s)
Design Points
X1 = C: Volume
Actual Factors
A: Cat Load = 1.00
B: Peroxide = 0.09
C: Volume (mL )
200.00 290.00 380.00 470.00 560.00 650.00 740.00 830.00 920.00 1010.00 1100.00
ReactionRate(mol/L.s)
-0.05
0
0.05
0.1
0.15
One Factor
e)
h)f) g)
Contacts
Photocatalysis was conducted as per method stipulated by Chowdhury et al. (2015) and the hydroxyl quantification study was conducted as per method stipulated by Czili &
Horváth (2008)
Author: Z. Gwele
Email:
gwele.zuqa@gmail.com
Institution: Cape Peninsula
University of Technology
Supervisor: Prof. V.G. Fester
Email: festerv@cput.ac.za
Institution: Cape Peninsula
University of Technology
Co-supervisor: Dr. M.R. Chowdhury
Email: chowdhurym@cput.ac.za
Institution: Cape Peninsula University
of Technology
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 20 40 60 80 100
COU[mg/L]
Time [min]
200mL
0.2mL H2O2 & 0g TiO2 0.2mL H2O2 & 0.06g TiO2
0.2mL H2O2 & 0.1g TiO2 0.2mL H2O2 & 0.14g TiO2
0mL H2O2 & 0.1g TiO2 [5000mL]
0
0.2
0.4
0.6
0.8
1
1.2
0 100 200 300 400
Ct/Co
Time [min]
Photocatalysis Scale-up
200mL Reactor + 0.2mL H2O2 + 0.06g TiO2
500mL Reactor + 3mL H2O2 + 0.35g TiO2
5000mL Reactor + 1000mL H2O2 + 10g TiO2