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.