Mini-fluidic Silver Based Solvent Extraction

1
MINI-FLUIDIC SILVER BASED
SOLVENT EXTRACTION OF EPA/DHA
FROM FISH OIL
Kirubanandan Shanmugam
MASc in Chemical Engineering
Presented on Thesis Defense, 8th Jan 2015, Dalhousie Univeristy,Halifax,Canada.
Dr. Adam. A. Donaldson
Supervisor

Contents
2
1. Introduction
2. Objective
3. EPA/DHAYields
4. Hydrodynamics
5. Conceptual Process Design
6. Conclusion and Discussion

Concentration and Extraction of Omega 3
PUFA
4

Introduction
5
Chemical Structure of Eicosapentaenoic Acid (EPA)
Chemical Structure of Docosahexaenoic Acid (DHA)
Double Bond -
Reaction Site
Reaction Involved:
DHA/EPA +AgNO3 DHA/EPA :Agn+ Complex + Fish Oil
Aqueous Phase Organic Phase

6
Miniaturization of Liquid-Liquid Extraction
Process
* American Institute of Chemical Engineers, USA.
Stirred Tank Reactor* Mini-fluidic Reactor*
*Mini-fluidic experimental set up at Lab of Multiphase Process Engineering,
Dalhousie University, Canada.

Research Objective
7
• To perform the Liquid–Liquid Extraction of Omega 3
PUFA in a mini-fluidic channel and compare the
performance to an idealized system.
• To compare extraction yield in both systems.
• To investigate the hydrodynamics.
• To verify the feasibility at an industrial scale.

8
Experimental Method
Process
Inputs
Contacting
Collecting
Settling
Raw
Extract
• 18/12 Fish Oils EE (Organic Phase)~1.5 ml/min
• 50%wt.AgNO3 (Aqueous Phase)~5 ml/min
• Temperature = 10±0.5°C
• Residence times varies from 0.6 to 7.3 mins
• Phase inversion observed at “Y” Junction
• Stratification of flow has been observed.
• Samples are collected at specified location.
• Gravity settling has been allowed.
• Exiting ethyl ester of fish oil –Oil layer
• Isolation of Emulsion phase (Oil +AgNO3)
• Exiting silver nitrate aqueous phase enriched with
Omega 3 PUFA.
• Silver ions in the solutions bound to double bond of
these fatty acids (EPA/DHA).

9
Separation of Omega 3 PUFA from Raw Extract
Oil Residual
Separation
from LLE
Experiments
De-emulsification
using Hexane
Fraction 1
De -complexation
using Hexene
Fraction 2
Sample
Preparation for
Analysis
(drying &
filtering)

Experimental Components
10
Fish Oil
(Organic Phase)
AgNO3
(Aqueous
Phase)
Coolant Inlet
Coolant
Outlet to
Refrigeration
Dual Syringe pump
Immersion Vessel
Sample PortTygon minichannel

Mini-fluidic Reactor Batch Reactor
tResidence
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt.
%
tReaction
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt.%
0.6 42.3 30.5 81.3 15 41.5 27.1 81.8
1.2 39.8 29.0 77.5 30 41.6 27.0 81.9
2.4 40.4 29.2 78.5 60 39.8 25.9 78.9
4.8 37.9 26.8 73.7 90 42.0 27.4 82.5
7.3 40.3 27.8 78.5 120 40.1 26.6 78.7 11
EPA/DHA Yields
Composition of 18/12 EE fish oils ethyl esters
Organic Phase EPA–Et Wt.% DHA–Et Wt. % Ώ 3 Wt. %
Fish Oil-EE 15.0 10.1 30.9
Weight percent EPA/DHA/Total Omega 3 in Fraction 2 collected at
different contact times from LLE experiments.

12
Omega 3 PUFA content in the Residual Oil Layer
tResidence
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt.
%
tReaction
(mins)
EPA–
Et
Wt.%
DHA–
Et
Wt.%
Ώ 3
Wt.%
0.6 1.15 0.17 4.50 15 0.33 0.06 2.19
1.2 1.14 0.15 4.38 30 0.19 0.06 1.05
2.4 1.21 0.18 4.47 60 0.41 0.06 2.34
4.8 0.58 0 2.80 90 0.46 0.06 2.42
7.3 0.35 0.02 2.39 120 0.74 0.10 3.10

13
tResidence
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt.
%
tReaction
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt.
%
0.6 64.2 68.5 59.9 15 81.8 79.1 78.2
1.2 79.3 85.7 74.9 30 96.4 92.8 92.0
2.4 78.6 84.4 74.2 60 82.0 79.0 78.2
4.8 60.0 63.0 56.7 90 82.5 79.7 78.7
7.3 79.3 81.2 75.1 120 82.2 80.9 78.3
Approximate yield of Omega 3 PUFA (wt% of feed extracted)

Reported Results from Literature
 Kamio et al 2011 confirmed that slug flow
provides faster extraction at 268 K (-5°C). In
this case, Pure DHA-Et dissolved in organic
solvent extracted with silver ions in micro-
fluidic device which has dimension of 0.5 mm
 They were able to recover ~40% of a
10 mol/m3 feed solution after 20 seconds.
14

Deviation from Slug Flow Pattern
15
Fish Oil EE –Silver nitrate
solution interface
Dimensionless
numbers
Definition Formula Values Significance
Weber Number Inertial force
Interfacial tension force σ
ρ 2
ud
We H
=
21.778 We << 1 → stable interface
We >> 1 → unstable interface
Capillary
Number
Viscous Force
Intenfacial tenstion force σ
µu
Ca =
0.450 Ca << 1 → reduce inter. area
Ca >> 1 → parallel flow
Bond Number Gravity Forces
Interfacial Tension σ
ρ Hgd
Bo
2
∆
=
54.937 Bo >> 1, Gravity Force
dominates
Bo << 1, Interfacial tension
dominates
Reynolds
Number
Inertia force
Viscous force µ
ρudH
=Re
48.345 Re<2100 – Laminar flow
Re>2300 – Transition Flow

Hydrodynamics Studies
17
Liquid–Liquid
Extraction
Mass Transfer Heat Transfer
Kinetics
Solubility
Hydrodynamics

Interfacial Tension Studies
18
Spinning drop tensiometry. In this method, the light phase is injected into the
heavy phase and forms droplet in the capillary. The drop of fish oil ethyl ester in
a narrow capillary tube elongates as the tube is spun along its long axis
demonstrating the Vonnegut equation.
4
)( 32
RlightphaseheavyPhase ωρρ
γ
−
=
Vonnegut equation

Role of Interfacial Tension in Hydrodynamics
19

Flow patterns in Tygon Mini-channels
20
QOil
ml/min
Q Aq
ml/min
Fish Oil Water
System
Fish Oil Silver nitrate
System
10% Hexane 90% Fish
Oil
Silver Nitrate System
50%Hexane 50%Fish Oil
Hexane –AgNO3
3.33
3.33
3.33
3.33
10
10
10
10
1.47
1.47
1.47
1.47
5
5
5
5
1.47 4
1.16 3.5
1.00
1
1
3
3
3
0.83
0.83
0.833
2.5
2.5
2.5
0.67
0.67
0.67
0.67
2
2
2
2
0.333
0.333
0.333
1
1
1

Flow patterns in PFA mini-channels
21
Q Oil
(ml/min)
QAque
(ml/min)
Fish Oil Water
System
Fish Oil Silver nitrate
System
10% Hexane 90% Fish
Oil
50%Hexane 50%Fish
Oil
Hexane- Silver
Nitrate system
3.33
3.33
3.33
10
10
10
1.47
1.47
1.47
1.47
5
5
5
5
1 3
0.833 2.5
0.666
0.666
0.666
0.666
2
2
2
2
0.5
0.5
0.5
1.5
1.5
1.5
0.33
0.33
0.33
1
1
1

Mini-fluidic Silver Based Solvent Extraction

Conceptual Process Design – A base case
25
Silver Based
Solvent
Extraction
• The reaction between AgNO3 and Fish Oil Ethyl Esters
• Mass Transfer Limited, Fast and Exothermic Reactions
• Enhanced Mixing and good contacting b/w fish oil ethyl
esters and AgNO3
Separation of
Oil Phase
and Aqueous
Phase
De-
complexation
of Aqueous
Phase
•Removal of Bound
Omega 3 PUFA from
Aqueous Phase
Distillation of
Organic
Fractions
Omega 3
PUFA
De-emulsification
of Oil Phase Oil
Layer

Process Cost for LLE
28
Item Case 1
(CSTR in
parallel)
US $
Case 2
Continuous
Processes
US $
Total Direct Plant
Costa
8,500,000 6,053,800
Total Indirect Cost 1,496,220 1,066,500
Total Direct and
Indirect Plant Costb
10,000,000 7,120,200
Fixed capital
investment
11,500,000 8,190,000
Working Capital 2,300,000 1,638,000
Start up 1,000,000 655,100
Total Capital
Investment
15,000,000 10,481,000

Process Design for Recovery Silver
29
6.5.2. Electrochemical Oxidation Process
Figure 6.5. Process Design for Electro chemical Oxidation Process
Case- 1 Case- 2
Case- 3
Case- 4

Process Capital for silver recovery
30
Raw materials Price Case 1 Case 2 Case 3 Case 4
NaOH Tons/shift
Cost in US$
9.6
$4032
9.6
$4032
9.6
$4032
9.6
$4032
HNO3 14.5
$3123
14.5
$3123
14.5
$3123
14.5
$3123
H2O2 N/A 3.9
$2093
N/A N/A
NaCl 13.2
$660
Formaldehyde 3.4
$ 12157
Net Cost per shift $7200 $9200 $20000 $7200
Raw material price for Silver Recovery
Item Case 1 Case 2 Case 3 Case 4
Total Direct Plant
Cost
2,627,150 2,125,500 2,312,730 2,275,595
Total Direct and
Indirect Plant Cost
3,145,930 2,545,220 2,769,420 2,724,960
Fixed capital
investment
3,617,820 2,927,000 3,184,900 3,133,700
Working Capital 723,600 585,400 637,000 626,800
Start up 289,500 234,200 254,800 250,700
Total Capital
Investment
4,630,800 3,746,600 4,076,600 4,011,200

Feasibility Analysis
 The anticipated capital cost of setting up a 10 ton/day facility with a
continuous mini-fluidic type system and a case 1 based recovery system is
expected to approach ~ 14.5 million dollars. Assuming minimal silver loss
within the process, recovery of the silver ion’s activity will require
approximately ~$7000 in raw materials for every 10 tons of fish oil
processed, corresponding to the minimum recovery cost.
 The cost of recovery of spent silver nitrate solution is approximately $0.70
per kg of fish oil. Raw 18/12 EE fish oil sells for approximately $2/kg.
Retail price of refined fish oils range from $20 to $30 per kg.
31

33
Conclusion
• The equilibrium concentration at 10°C has been reached in less than 36
seconds in the mini-fluidic reactor, and less than 15 min in stirred tank
reactor.
• The extract typically contained >80% omega 3, with yields above 75%.
This is beyond the capability of current molecular distillation practices
(~55%), and appears to be better than urea precipitation performance
(~65%).
• To perform the Liquid–Liquid Extraction of Omega 3 PUFA in a mini-
fluidic channel and compare the performance to an idealized system.
• To compare extraction yield in both systems.

Conclusion
34
• The flow patterns observed in a real fish oil / AgNO3 system was significantly
different than previously reported for a synthetic DHA/AgNO3 system.
• The addition of organic solvent into the fish oil ethyl ester increase the
interfacial tension between fish oil and silver nitrate system, However, the
increase was not sufficient to produce slug flow. This would suggest that
practical processing of fish oils with AgNO3 will require the handling of
stratified flow within the processing units.
• To investigate the hydrodynamics.

Conclusion
35
• A conceptual process design for silver based solvent extraction for omega 3
PUFA at an industrial scale was presented, and suggests that this process can
be feasible with appropriate silver recycling strategies.
• The approximate raw material cost of recovering and regenerating the silver-
based solvent would be ~$0.70 per kg of fish oil processed.
• To verify the feasibility at an industrial scale.

Acknowledgements
36
Dr. Adam Donaldson,
Dr. Amyl Ghanem,
Dr. Clifton Johnston,
Dr. Mark Gibson.

37
Reference
Benz, K.; Jäckel, K.P.; Regenauer, K.J.; Schiewe, J.; Drese, K.; Ehrfeld,W.; Hessel,V.;
Löwe,H., (2001) “Utilization of Micromixers for Extraction Processes”, Chem. Eng.
Technol. 24 :1.
Lembke,P., (2013) “Production Techniques for Omega3 Concentrates” Omega-6/3 Fatty
Acids: Functions, Sustainability Strategies and Perspectives, Edited by: F. De Meester et
al.(eds.), DOI 10.1007/978-1-62703-215-5_29, 353-364.
Ratnayake, WMN.; Olson, B.; Matthews, D.; Ackman, RG., (1988) “Preparation of
omega-3 PUFA concentrates from fish oil via urea complexation”. Eur J Lipid Sci Tech.;
90(10):381–6.
Seike, Y.; Kamio, E.; Ono, T.; Yoshizawa, H., (2007) Extraction of ethyl ester of
polyunsaturated fatty acids by utilizing slug flow prepared by microreactor. J Chem Eng
Jpn. 2007;40:1076–1084.

40
Limitation of Conventional Extractors
Power Input Requirement for Various
Liquid–Liquid Contactors*
Contactor Power Input KJ/m3
Agitation Extraction
Column
0.5 -150
Mixer Settler 150 -250
Rotating disk
impinging streams
contactor
175 -250
Impinging stream
extractor
35 -1500
Centrifugal extractor 850 - 2600
Micro reactor* 0.2 -20
Hydrodynamics Problem
• Inability to condition the drop size
precisely and the non uniformities that
result because of the complexities of the
underlying hydrodynamics
• As consequence, it affects optimal
performance
Solvent Inventory
• Solvent Inventory is the main problem
in Conventional Extractors
• In large size conventional industrial
extractors, large amount of solvent is
required
• Less solvent is required in minichannel
Overcoming Limitation
• Reduction of characteristic plant dimensions in micro/mini reactors offers a powerful for
overcoming bottlenecks in heat and mass transfer
• Well defined flow patterns
• Better temperature conditions
*M.N.Kashid et al. /Chemical Engineering Science 66 (2011) 3876 -3897.

Slug Flow Based Mini -Fluidics
41
• Slug Flow offers a well defined environment for Mass Transfer
• Provides a high efficiency way to improve the mass transfer performance
• Internal Circulation reduces the thickness of Interfacial boundary layer

42
Sample masses after solvent evaporation, in grams, for the mini-fluidic tests. Positive material
losses attributed to residual water present in Fraction 2.
Process 0.6 min 1.2 min 2.4 min 4.8 min 7.3 min Avg.
18/12 Feedstock 10.85 10.28 10.24 11.38 11.03 10.76
Residual Oil 7.6324 6.922 7.204 5.527 7.799 7.017
De-emulsification
Fraction 1
0.4386 0.5554 0.3151 0.8790 0.2470 0.4870
De-complexation
Fraction 2
2.4574 3.0519 2.972 2.6906 3.2425 2.8829
Material Losses
(Extracts–
Feedstock)
0.3216 -0.2493 0.255 2.2865 -0.2557 -0.3731

43
Sample masses after solvent evaporation, in grams, for the batch reactor tests
Process 15 min 30 min 60 min 90 min 120 min Avg.
18/12 Feedstock 13.21 13.21 13.21 13.21 13.21 13.21
Residual Oil 6.741 6.2916 6.741 5.3928 6.2916 6.2916
De-emulsification
Fraction 1
2.2373 0.8762 1.112 1.6498 1.3822 1.4515
De-complexation
Fraction 2
3.8835 4.5633 4.0605 3.8718 4.0396 4.0837
Material Losses
(Extracts–
Feedstock)
-0.3482 -1.4789 -1.2965 -2.2956 -1.4966 -1.3832

44
tResidence
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt. %
tReaction
(mins)
EPA–
Et
Wt.%
DHA–
Et Wt.
%
Ώ 3
Wt.%
0.6 16.2 17.2 - 15 3.72 1.8 22.4
1.2 15.6 16.4 - 30 3.35 5.3 26.1
2.4 18.4 19.7 - 60 5.04 2.52 25.2
4.8 8.1 9.8 - 90 5.3 2.27 25.5
7.3 10.8 10.6 - 120 - - -
Yield of Omega 3 PUFA in Hexane Fraction 1 after de-emulsification.

Physical Properties of Experimental fluids
45
Experimental Fluids Density
Kg/m3
Viscosity
Kg/m.sec
Surface Tension or
Interfacial Tension
mN/m
Fish Oil EE 898.8 0.0057 17.5
Silver Nitrate Solution 1751.4 0.0015 77.4
Hexane 695 0.00036 20.4
Hexene 673 0.0002 20.5
10% Hexane90% Fish Oil EE 872.4 0.0051
50% Hexane 50% Fish Oil 811.2 0.0030
10%Hexene 90% Fish Oil EE 872.4
50% Hexene 50% Fish Oil EE 811.2
Fish Oil Water System 969.4 0.0029 2.5
Fish Oil Silver Nitrate System 0.0027 0.34
10% Hexane 90% Fish Oil Silver
Nitrate System
808 0.0030 0.34
50% Hexane 50% Fish Oil Silver
Nitrate System
869 0.0024 0.65
Hexane–Silver Nitrate System 1030 0.0016 56

Limitations in Evaluating IFT for
Experimental Fluids
46
Behavior of Fish Oil
Water System in
SDT.
The behavior of fish oil –AgNO3 and Hex-fish Oil - AgNO3 in
SDT

Evidence of Existing of IFT between Fish
oil/AgNO3 & Experimental fluids
47

Mini-fluidic Silver Based Solvent Extraction

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