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Application of Anion Exchange Membranes in Microbial Fuel Cells
Richard Burkitt and Eileen Yu
School of Chemical Engineering and Advanced Materials, Merz Court, University of Newcastle, Newcastle upon Tyne, NE1 7RU, United Kingdom
Introduction and Background Microbial Fuel Cell principle Anion exchange membranes in MFC
• Experimental setup Aim Membrane fixation and treatment Model of charge movement in non-precious metal MEA
• Half-Cell MEA Impedance Spectroscopy of MEA – General response Impedance Spectroscopy of MEA – Components of impedance
• Applicability of EIS for prediction of MFC performance Batch MFC tests vs. AC impedance of MEA
Conclusions
Outline
Microbial Fuel Cell (MFC) Principle
Use of wastewater for
Anolyte substrate
1) Organic removal
2) Power or H2 generation
Mixed charge carriers.
Charge Carriers in wastewater
Conc. mg/L Conc. mM/L Total Dissolved Solids 780 n/a
Bicarbonate Alkalinity, as CaC03 240 n/a Na+ 160 6.96 K+ 1.7 0.043
Calcium 76 1.9 Magnesium 33 3.1
Cl- 220 6.2 SO4
2- 88 0.916 Fl- 0.48 0.025
NO3- 24 0.387
NO2- ~2.5 0.054
Phosphorus, as PO4 0.081 0.0026
pH 7.2-7.4 Specific Conductance 2700 μS cm-1
Anion Exchange Materials in MFC
Ionomers;
2011 Watson and Logan Ionomer coatings Radel(Quartenized) vs Nafion. Power
Improvement factor 2.66.
Membranes;
2010 Zhang and Logan, and 2009 Kim and Guwy. International Membranes
CEM vs AEM for power production in MFC. Power Improvement factor 1.44 and
1.22 respectively.
2009 Sleutels and Buisman. Fumasep FKA (CEM) vs FAA (AEM) for H2
production. H2 production Improvement factor 5.25.
2008 Rozendal and Buisman. Charge carrier identification – H+/OH- ≈ Phosphate
2009 Mo and Cao. Tianwei CEM vs AEM, ΩCathode improvement factor 2.27.
2013 Piao and Cheng. Phosphate vs Bicarbonate, interfacial resistance
Anion Exchange Materials in MFC
Introduction and Background Microbial Fuel Cell principle Anion exchange membranes in MFC
• Experimental setup Aim Membrane fixation and treatment Model of charge movement in non-precious metal MEA
• Half-Cell MEA Impedance Spectroscopy of MEA – General response Impedance Spectroscopy of MEA – Components of impedance
• Applicability of EIS for prediction of MFC performance Batch MFC tests vs. AC impedance of MEA
Conclusions
Outline
Aim of study
• To compare the MFC batch performance with performance predicted
from MFC half cell – MFC reactors in artificial wastewater, Impedance Spectroscopy
• To examine the sources of interfacial resistance and examine the influence
of anionic charge carrier – Impedance Spectroscopy
• Test a variety of commercial membranes to produce recommendations for
material selection specific to MFC – Impedance Spectroscopy
• To assess how OH- produced from the oxygen reduction reaction influences
the diffusion boundary – Impedance Spectroscopy
Commercial Membranes
Membrane / Manufacturer Functional X-change group / Solvated ion Backbone
Thickness (wet) / (μm) IEQ / meq/g Reported κ / (Ω cm2)
@ Me+ MolesWorking
pHPrice / ( m-2)
Cation Exchange MaterialF-930 / Fumatech PerFluo-SO3
2- / H+ PTFE-Co-polymer 30 1.11 <0.2 @ 500mM NaCl N/A € 833CMI-7000 / International Membran SO3
2- / Na+ Gel Polystyrene/DVB 450 1.60 <30 @ 500mM NaCl (1-10) $97
Anion Exchange MaterialFTAM-A (PA) / Fumatech NH3
+ / Cl- Polyamide (Nylon) 500-600 1.70 <8 @ 500mM NaCl (5-13) € 333FAA (PEEK) / Fumatech NH3
+ / Cl- PEEK reinforced 130-150 1.43 <2 @ 500mM NaCl (1-14) € 583AMI-7001 / International Membran NH3
+ / Cl- Gel Polystyrene/DVB 450 1.30 <40 @ 500mM NaCl (1-10) $97
Morgane ADP® / Solvay NH3+ / Cl- PTFE - Xlink 150 1.65 1.5-4.5 @ 600mM NaCl (0-10)
QDPSU / made in house Dabco / Cl- Polysulfone 30 N/A N/AFAD-PET / Fumasep 2NH3
+ / Cl- Polyester reinforced 90 1.50 <0.8 @ 500mM NaCl (0-9) € 500FAB / Fumasep 2NH3
+ / Cl- PEEK reinforced 115 1.30 <1 @ 500mM NaCl (0-13) € 583
SeparatorRhinohide / Entek None / Oil content Polyethylene (long) 250ª 0.06 @ 1000mM H2SO4 N/A
MEA assembly
Impedance spectroscopy to evaluate membranes
The discrepancy between the applied signal and the phase-lag and reduction
In amplitude in the obtained current response produces data on the nature of
the impedance. This can be applied to a Membrane Electrode Assembly
100kHz>f>0.05Hz
10mV amplitude
Charge movement in air cathode AEM
Cathode Catalyst
Iron Phthalocyanine
(FePc)
Introduction and Background Microbial Fuel Cell principle Anion exchange membranes in MFC
• Experimental setup Aim Membrane fixation and treatment Model of charge movement in non-precious metal MEA
• Half-Cell MEA Impedance Spectroscopy of MEA – General response Impedance Spectroscopy of MEA – Components of impedance
• Applicability of EIS for prediction of MFC performance Batch MFC tests vs. AC impedance of MEA
Conclusions
Outline
Charge movement in catalyst layer
Z' / Ohm150 200 250 300 350 400
- Z"
(imag
inar
y) /
Ohm
0
50
100
150
200
250
300
0.4V0.24V0.20V-0.2 V
Without O2
WE potential
R2 > 0.9991 at all E
Thin Film Electrode (TFE)
Warburg impedance
at higher frequency;
• Charge Movement
• Capacitive upon charge saturation of entire film, large Z.
100Hz Electrolyte; Phosphate
Z' (real) / Ohm cm2
60 80 100 120
-Z"
(imag
inar
y) /
Ohm
cm
2
0
10
20
30
40SS-Mesh MembranelessETFE-QAmmonium JK80L Surrey
Rm
Warburg controlIon diffusion
Rdl R???
RAC = Rm + Rdl + R??
Key features of MEA response to EIS
E = -0.05V
50mM NaHCO3
F-93
0 / F
umas
ep
CM
I-700
0 / I
M
ADP
/ Mor
gane
FAA
/ Fum
asep
FTAM
-A /
Fum
asep
AMI-7
001
/ IM
QD
PSU
/ In
hou
se
Rm
/ O
hm c
m2
0
20
40
60
80
100
120
140
160
18050mM Na-Phosphate - MEA500mM NaCl - 2 electrode50mM NaCl - MEA50mM NaHCO3 - MEA
Ionic resistance in membrane phase
E = OCP
Similar trend to thickness
But not exactly
F-93
0 / F
umas
ep
CM
I-700
0 / I
M
ADP
/ Mor
gane
FAA
/ Fum
asep
FTAM
-A /
Fum
asep
AMI-7
001
/ IM
QD
PSU
/ In
hou
se
FAB
/ Fu
mas
ep
FAD
-PET
/ Fu
mas
ep
Rm
per
mic
ron
/ Ohm
cm
2
0.0
0.5
1.0
1.5
2.050mM Na-Phosphate - MEA500mM NaCl - 2 electrode50mM NaCl - MEA50mM NaHCO3 - MEA
Ionic resistance in membrane phase
Rm normalised to membrane
Thickness
The graph is not flat for all
membranes.
Rises indicate;
• Constrained flux
• Irreversible adsorption of
anion to fixed charge
Uniformity of membrane response
Z' (real) / Ohm cm260 80 100 120 140 160 180 200
-Z"
(imag
inar
y) /
Ohm
cm
2
0
10
20
30
40
50
Morgane ADPFAA (PEEK)SS-Mesh MembranelessRhinohideFTAM-A (PA)AMI-7001 QDPSUMeshless MebranelessETFE-QAmmoiun JK80L SurreyETFE-TMA CranfieldFAB-FumasepFAD-PET Fumasep
Bi-carbonate solution E = -0.05V
Z' (real) / Ohm cm260 80 100 120 140 160 180 200 220
-Z"
(imag
inar
y) /
Ohm
cm
2
0
10
20
30
40
50
Morgane ADPFAA (PEEK)SS-Mesh MembranelessRhinohideFTAM-A (PA)AMI-7001 QDPSUMeshless MembranelessETFE-QAmm JK80L SurreyETFE-TMA CranfieldFAB-FumasepFAD-PET Fumasep
OCP
E / V (Ag|AgCl)-0.4 -0.2 0.0 0.2 0.4
War
burg
co-
effic
ient
/ O
hm c
m2 s
-0.5
0
2
4
6
8
10
12
Morgane ADP FAA (PEEK) Membranelss SS-Mesh Rhinohide (separator)FTAM-A (PA) AMI-7001 HDPE-TMA Cranfield
Trend for membranes that saturate with OH- over Cl-
Trend for membranes that saturate with Cl- over OH-
Faster diffusion
Unbuffered NaCl electrolyte
Warburg impedance a relatively minor source of impedance in pure electrolytes
– used to harness transference data
Ion specificity – alternate qualitative means of evaluation
E / V (Ag|AgCl)-0.4 -0.2 0.0 0.2 0.4
RA
C /
Ohm
cm
2100
1000
NaClNa-PhosphateNaHCO3
FAA electrode
Total AC impedance (RAC) response
of the MEA is significantly
influenced by anion type.
The electrode performs well in chloride at high overpotential only
Total AC impedance vs. anion
Introduction and Background Microbial Fuel Cell principle Anion exchange membranes in MFC
• Experimental setup Aim Membrane fixation and treatment Model of charge movement in non-precious metal MEA
• Half-Cell MEA Impedance Spectroscopy of MEA – General response Impedance Spectroscopy of MEA – Components of impedance
• Applicability of EIS for prediction of MFC performance Batch MFC tests vs. AC impedance of MEA
Conclusions
Outline
Membrane / Manufacturer Ecat / mV (Ag|AgCl)
Vcell / mV
# of batch cylces
Anion Exchange Material
FTAM-A (PA) / Fumatech -23 289 13 FAA (PEEK) / Fumatech 0 324 18 AMI-7001 / Membranes International -54 309 6 QDPSU / made in house -63 307 13
Separator Rhinohide / Entek -121 257 13
Batch performance of MFC
Medium ; 0.5g/L CH3COONa, 50mM Phosphate, trace nutrients
Peak stabilised Vcell and Ecat over a batch cycle - Ωext = 300Ω
FTAM
-A /
Fum
atec
h
FAA
/ Fum
atec
h
AMI-7
001
/ IM
Rhi
nohi
de /
Ente
k
J cel
l at 3
00 O
hms
/ A m
-2
0.6
0.7
0.8
0.9
AC im
peda
nce
( RA
C) a
t E =
-0.0
5V /
Ohm
cm
2
100
200
300
400
500
600
Current Density (Jcell) at 300 OhmAC impedance in Phosphate at E = -0.05VAC impedance in NaCl at E = -0.05VAC impedance in NaHCO3 at E = -0.05V
Batch performance vs AC impedance from EIS
Steady State Polarisation curves
J / A m-20.0 0.2 0.4 0.6 0.8 1.0 1.2
E cat (
mV
v A
g|A
gCl)
50
100
150
200
250
300
AMI-7001 (AEM) QDPSU (AEM)F-930 (PEM)FTAM-A (AEM)FAA-PEEK (AEM)Rhinohide
Medium ; 0.5g/L CH3COONa, 50mM Phosphate, trace nutrients
AEM for Microbial Fuel Cells
And thank you for listening
From Newcastle MFC group
Group Website http://www.staff.ncl.ac.uk/eileen.yu/