Response Surface Modelling and its application in supercritical fluid processes to support the contaminated land remediation
technologies
Muhammad Baig
Third European DOE User MeetingLucerne, Switzerland May 31st - June 3rd, 2010
University of Birmingham
Chemical Engineering at Birmingham is one of the
three largest postgraduate research centres in the UK.
It is one of the top departments in the UK on research.
The Formulation Engineering is part of the School of
Chemical Engineering and is divided into four main
sections according to the research discipline.
Formulation Engineering Research Centre
Formulation Engineering
Speciality Chemical Products
Particle & Solids processing
Structured Materials
Pharmaceutical processing
Bio-engineering
Bio-processing
Tissue repair
Environmental Engineering
Product structure & function
Food Safety &Hygiene
Food health & Nutrition Energy
Hydrogen energy
Catalysis & reaction Engineering
Supercritical Fluid
Formulation Engineering Research Centre
Formulation Engineering Research Centre
Formulation Engineering
Speciality Chemical Products
Particle & Solids processing
Structured Materials
Pharmaceutical processing
Bio-engineering
Bio-processing
Tissue repair
Environmental Engineering
Energy
Hydrogen energy
Catalysis & reaction Engineering
Supercritical Fluid
Formulation Engineering Research Centre
Research Theme
Main interest is in the fundamentals and engineeringaspects of various processes which employsupercritical fluids as solvents, reaction media oranti-solvents.
Our focus is on utilising the fundamental principlesof thermodynamics, mass transfer, chemistry andreaction engineering to design, build, operate andscale up SCF processes.
Supercritical Fluid Group
Main Collaborations
IndustrialGlaxoSmithKline, Phytatec Unilever, AstraZeneca, Johnson Matthey, Qinetiq.
National AcademicUniversity of Cambridge, University of London,
Imperial College, University of Nottingham, University of
Liverpool and University of Cardifff.
International AcademicMIT, University of Tokyo, Tohoku University, Kumamoto University,
University Melbourne, University of Twente, University of Lodz,
University of Delft, TUHH, Arkansas.
Supercritical Fluid Group
Super Critical Fluids
Supercritical fluids (SCFs) are highly compressed gases, whichdisplay properties that are intermediate between a liquid and agas.
These fluids show interesting properties and have foundapplication in a range of areas as alternative solvents.
Supercritical fluids can be regarded as ‘hybrid solvents’ withproperties between those of gases and liquids. They have:
• Low viscosity• High diffusion rates• No surface tension
C.P
Super Critical Fluids ?
Triple Point
SCF
Boiling Curve VAPOUR
SOLID
LIQUID
CO2 Supercritical region Temperature 31.1 C and Pressure 73.8 bar
H2O Supercritical region Temperature 373.8 C and Pressure 220 bar
Extraction & Fractionation
Catalytic Reactions
Particle Production
Polymer Processing
Wet Air Oxidation
Supercritical Water oxidation
Gasification
Hydrolysis
Carbon Dioxide Water
Research Activities
Extraction
High ValueProducts
MatrixImprovement
MatrixRecovery
• Specialist oils
• Fatty acids
• Bioactive lipidcomponents
• Removal of wax
from plant leaves
to improve diffusion
properties
• Regeneration of
activated carbon
for wastewater
treatment by
desorption for
re-use purposes
Research Activities
A Question of Scale
Research Activities
Contaminated Soil-sampling probe
To design a sampling probe which will be able to provide a more rapid and comprehensive assessment of site
contaminants and locate ‘hot-spots’ using a non-invasive in situ process for contaminant removal with integrated analysis. This will reduce sample time to 30
min with 65% cost saving over existing technologies
Project Partners
The project is supported by DTI/TSB-Project No: TP/5/CON/6/I/H0570D in partnership with Pera Innovations,
University of Birmingham, Lankelma Ltd and PJH Ltd
• Solubility Measurementsof contaminants typically found
in soil over range of pressure
temperature conditions.
• Extraction
Set up model soil systems with
contaminants and various soil
types. Analyse and model
solubilities and mass transfer
rates
• Probe Design
Assist in the design of the
prototype unit.
• Characterise soil variationsMoisture content, pH, trace elements, temperature -How these impact on pollutant removal
Our Involvement
Contaminated Land Remediation Technologies
Contaminated Soil
What is contaminated soil
Manufacturing processes, building construction and water treatment applications.
Air and water contamination may in many cases affect the land in indirect ways.
Identification
Mixture of organic and inorganic materials.
Different soil textures like sand, silt and clay absorb pollutants at different rates.
In the form of chemicals or solids, and may be organic or inorganic in nature.
Pollutants
Heavy metals, solvents, pesticides and hydrocarbons.
Pesticides, underground storage tanks and landfills.
Smoke stack emissions can also contain pollutant particles.
• Thermal treatment
• Biological treatment
• Chemical extraction & soil washing
Critical Fluid Extraction (Supercritical CO2)
Soil Cleaning Techniques
In Situ & Ex Situ treatment
Sampling Probe
Soil Extraction
Pressure Vessel
(700 ml)
Soil Extraction Pressure Vessel
(700 ml)Cylinders for supplying liquid and supercritical CO2
Outlet port to sample detector
Reinforced jacketed sampling unit to be introduced into ground
Supercritical Extraction Equipment
CO2 Delivery
Ho
t C
O2
Co
ld C
O2
Extraction Rig
Sample Collection
Soil Container
Soil removal
Lifting jack
Supercritical Extraction Using Frozen Plug
Soil Container
Extraction vessel
Lifting jack
Supercritical Extraction Using Frozen Plug
Liquid CO2
SC-CO2
Soil sample
Detector
Filter
Supercritical Extraction Using Frozen Plug
2000
700
188
600/
500100
Supercritical Extraction Using Frozen Plug
Soil Extraction
Pressure Vessel
(700 ml)
Supercritical Extraction Using Frozen Plug
Soil Extraction
Pressure Vessel
(700 ml)
Soil sampling
(120 ml)
Working Pressure : 400 bar
Working Temp: 250 deg C
35
Sampling Probe
Soil Extraction
Pressure Vessel
(700 ml)
Soil Extraction
Pressure Vessel
(700 ml)
Soil Textural Classification
Temperature
Pressure
Extraction Time
CO2 flow rate
Moisture Content
Soil acidity
Extraction parameters
50 – 300 bar
40 – 100 deg C
Up to 20 min
1 – 5 kg/h
5 – 30 wt%
4 – 8 pH
Extraction results
Plot of cumulative extraction concentration at 75 C (Soil 1)
100 150 200 250 300
1500
1000
500
0
PAH (Poly Aromatic Hydrocarbon) extraction profile @75 C
PAH
co
nce
ntr
atio
n (
µg/
g)
Pressure (bar)
PAH
(µ
g/g)
Pressure (bar)
0
500
1000
1500
2000
2500
3000
100 120 140 160 180 200 220 240 260 280 300
Extraction Results
Plot of cumulative extraction concentration at 150 C (Soil 1)
PAH (Poly Aromatic Hydrocarbon) extraction profile @150 C
Pressure (bar)
PAH
co
nce
ntr
atio
n (
µg/
g)
0
500
1000
1500
2000
2500
3000
100 120 140 160 180 200 220 240 260 280 300
Pressure (bar)
PAH
(µ
g/g)
Evaluation of effects of Multiple parameters alone or in combination on response variables and also
predict the behaviour under given set of condition
Process Optimization
(0,0)
(+1,+1)
(0,+ )
(- ,0)
(0,- )
(+ ,0)
(-1,+1)
(-1,-1) (+1,-1)
Design require 5 levels of each factor: -Alpha, -1, 0, +1, and +Alpha
Central Composite DesignNumber of factorial points F=2K+2K+10
= (F)1/4
F=86
Experimental Design
RunNo.
Temp[deg C]
Pressure[bar]
Time[min]
CO2 flow rate [kg/h]
Moisture content [%] [pH]
Predictedextraction
efficiency [%]
Observedextraction
efficiency [%]Kinetic Modelling
[%)1 40 50 5 1 5 4 40.5 36.0 35.22 100 50 5 1 5 8 53.8 52.0 51.63 70 175 13 3 15 6 83.3 86.0 83.84 100 300 20 1 5 4 85.4 87.0 84.55 100 300 20 1 30 4 80.5 80.0 82.36 100 300 20 5 30 8 79.5 79.0 78.07 70 175 13 3 15 8 88.1 85.0 81.98 70 175 13 5 15 6 81.5 78.0 79.99 70 175 13 3 15 4 88.3 87.0 85.3
10 40 300 20 5 30 8 59.2 62.0 61.511 100 300 5 1 5 4 84.8 86.0 82.312 70 175 13 3 15 6 83.3 84.0 83.913 100 50 20 5 5 8 53.3 54.0 52.114 100 50 5 1 30 8 46.4 47.0 48.415 40 50 5 5 5 8 40.7 36.5 35.416 40 50 20 5 30 4 31.4 31.0 29.917 100 50 20 5 5 4 54.5 52.0 52.618 100 300 20 1 5 8 86.4 87.0 84.519 70 175 20 3 15 6 87.7 86.5 83.620 100 50 5 1 30 4 44.8 47.0 45.721 40 300 5 1 5 8 67.8 67.0 69.1A 70 195 1 2 10 8 100 87.5 84.1
Model Equations
Soil sample 1 (Sandy clay loam, high hydrocarbons)
Extraction efficiency (%) = 0.57858 - 0.25377 X1 + 0.068345 X2 - 2.54239 X3 + 21.31001 X4 +0.00037 X1·X2 + 0.015167 X1·X3 + 0.033125 X1·X4 + 0.00273 X2·X3 + 0.014750 X2·X4 +0.00416667 X3·X4 + 0.00056140 X12 – 0.000102175 X22 + 0.069396 X32 -3.89912 X42
Soil sample 2 (Silty clay loam, moderate hydrocarbons)
Extraction efficiency (%) = -5.66510 - 0.26113 X1 + 0.10062 X2 - 1.69088 X3 + 21.61199 X4 +0.00029 X1·X2 + 0.016167 X1·X3 + 0.029375 X1·X4 + 0.0014 X2·X3 + 0.010750 X2·X4 - 0.0041667X3·X4 + 0.000750877 X12 – 0.0000718596 X22 + 0.042261 X32 -3.78070 X42
Extraction efficiency (%) = -19.25273 + 0.093746 X1 + 0.81925 X2 + 0.37346 X3 - 9.04199 X4 –0.41727 X5 + 1.24315 X6 - 0.00017 X1·X2 + 0.0065 X1·X3 + 0.016875 X1·X4 - 0.00825 X1·X5 +0.00833333 X1·X6 +0.00373333 X2·X3 +0.012000 X2·X4 – 0.0012 X2·X5 -0.00633333 X2·X6 +0.23333 X3·X4 – 0.073333 X3·X5 – 0.083333 X3·X6 + 0.12500 X4·X5 + 0.85417 X4·X6 + 0.27500X5·X6 + 0.000409858 X12 – 0.002142 X22 – 0.026229 X32 – 0.36884 X42 + 0.00667643 X52 –0.43349 X62
Soil sample 3 (Artificial soil)
Model Equation
Soil TypeTemp
[deg C]Pressure
[bar]Time[min]
CO2 flow rate [kg/h]
Moisture content [%] [pH]
Predictedextraction
efficiency [%]
Spiked Soil (Soil 3) 70 195 1 2 13.61 7.3 95.99Spiked Soil (Soil 3) 70 195 1 2 13.61 7.7 97.53
Soil 1 70 195 1 2 13.61* 7.3* 77.84
Soil 1 70 195 20 2 13.61* 7.3* 82.72
Spiked Soil (Soil 3) 70 195 1 2 31.62 7.3 90.64Spiked Soil (Soil 3) 70 195 1 2 31.62 7.7 92.22Soil 2 70 195 1 2 31.62* 7.7* 71.60
Soil 2 70 195 20 2 31.62* 7.7* 77.18
Results generated using individual model equations for each soil system
* Actual values
Statistical Results
Plot of actual versus predicted values
Actual
Pre
dic
ted
ANOVA Results
Counter Plots
Pressure [bar]
Extr
acti
on
effi
cien
cies
[%]
Temperature [ C] Temperature [ C]Moisture content [%]
Extr
acti
on
effi
cien
cies
[%]
Temperature [ C]
Time [min]
Extr
acti
on
effi
cien
cies
[%]
Temperature [ C]CO2 Flow rate [kg/h]
Extr
acti
on
effi
cien
cies
[%]
Fig A Fig B
Fig C Fig D
Conclusion
• For the artificial soil the process conditions that predicted a 100% extraction
efficiency were: temperature 70 C, pressure 195 bar, extraction time 1 min, CO2
flow rate of 2 kg/hr, moisture content of 10 wt% and pH of 8. Experiments
conducted under these conditions gave an extraction efficiency of 87.5%.
• Supercritical extraction is best suited to silt type soils (soil 2) which have a low
adsorption capacity.