characteristics, mechanisms, and barriers Sarah Burch ... · Motivation for Biochar/Bioenergy...
Transcript of characteristics, mechanisms, and barriers Sarah Burch ... · Motivation for Biochar/Bioenergy...
6/20/2019
1
Evaluating biochar in sustainable stormwater
treatment of heavy metals: characteristics, mechanisms, and barriers
Sarah Burch
Jeffrey Nason
Motivation for copper remediation
• Copper present in stormwater runoff
• brake pad wear• Pipes, fungicide, algaecide
• Low concentration of copper toxic to some aquatic organisms
• Concentrations as low as 2 parts per billion (ppb) inhibit olfactory system in juvenile coho salmon
• Current BMPs reduce copper to as low as 5 ppb
http://static.ddmcdn.com/gif/brake-pads-4.jpg
McIntyre et al. 2012
6/20/2019
2
Motivation for Biochar/Bioenergy production
Lehmann (2007)
Biochar for water treatment
http://www.aqsolutions.org/
Objectives/Approach
• Relate physical and chemical biochar properties to metals sorption performance
• Characterization
• Batch Performance Evaluation
• Evaluate mechanisms for removal of metals
• Electrostatic Modelling
• Potentiometric Titration
• pH Sorption Edge
• Evaluate barriers to field‐scale implementation
• Column performance evaluation and prediction
• Identify questions in biochar supply, production, and applications preventing advancement
Performance
Biomass Source
Pyrolytic Temperature
Characterization
6/20/2019
3
Production of thermally altered biomass
• Feedstock
• Douglas Fir chips (debarked)
• Hazelnut Shells
• Pre‐treatment• Coarse Grinding
• Pyrolysis Conditions
• T = 300, 500 and 700 ˚C• Time = 1 hour
• N2 atmosphere
• Post‐treatment• Grinding and sieving to 40 ×50 mesh size
Characterization
• Proximate Carbon Analysis• Volatiles, Fixed Carbon, Ash %
• Thermogravimetric Analysis• % Weight vs Temperature
• N2 BET Surface Area
• pH
• FTIR Spectroscopy• Surface functional groups
• Electrophoretic Mobility (EPM)• Surface charge
6/20/2019
4
Methods: Batch Experiments
• Synthetic Stormwater• 1 mM NaCl
• 0.185 mm NaHCO3
• 100‐1500 ppb Cu
• pH 6 for isotherms
• pH 2 to 10 for pH sorption edge
• Suwannee River Natural Organic Matter (SRNOM)
• Sorbent• 40 – 50 mesh size sieved biochar and GAC
• Tumble/equilibrate for 48 hours
• Analyze• Dissolved Copper with ICP‐OES
• pH
Prepare Media and Synthetic Stormwater
Add 80 mL stormwater
and sorbent to HDPE Bottles
Tumble Mixtures
Filter and Analyze Samples
Batch Isotherm Results
0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5
Solid
Concentration (mg/g)
Liquid Concentration (mg/L)
Hazelnut Shell
H300
H500
H700
0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5
Solid
Concentration (mg/g)
Liquid Concentration (mg/L)
Douglas Fir
D300
D500
D700
6/20/2019
5
Batch Isotherm Results compared to GAC
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20
qe (mg/g)
Ce (mg/L)
H700
H500
GAC
D700
D500
H300
D300
Batch Isotherm Results compared with SRNOM
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
qe (mg/g)
Ce (mg/L)
H700 H700 SRNOM
H500 H500 SRNOM
6/20/2019
6
Proximate Carbon Analysis
• ↓Vola les with ↑ T
• Doug Fir>Hazelnut>GAC Volatiles
• GAC >Hazelnut > Doug Fir ash content
• ↑ Fixed Carbon with ↑ T
• Hazelnut > Doug Fir fixed carbon
0
10
20
30
40
50
60
70
80
90
100
H300 H500 H700 D300 D500 D700 GAC
Percent of Total M
ass (%
)
Volatile Matter (%) Fixed Carbon (%) Ash Content (%)
• ↑ SA with ↑ T
• Doug Fir > Hazelnut
• Highest SA for GAC
Surface Area
0.1
1
10
100
1000
10000
300 500 700 1200
Su
rfac
e A
rea
(m2/
g)
Production Temperature (°C)
Hazelnut Shells Douglas Fir Chips GAC
6/20/2019
7
Electrophoretic Mobility (EPM)
‐6
‐5
‐4
‐3
‐2
‐1
0
1
0 2 4 6 8
Mobility ((um/s)/(V/cm))
pH
‐6
‐5
‐4
‐3
‐2
‐1
0
1
0 2 4 6 8
Mobility ((um/s)/(V/cm))
pH
Hazelnut Shell Biochar Douglas Fir Chip Biochar
• Hazelnut > Doug Fir
• Ash content
• ↑ pH with ↑ T
• pHmax at intermediate T for Hazelnut Shells• Also seen for cottonseed husk biochars (Uchimiya et al. 2011)
pH
0
2
4
6
8
10
12
300 500 700
pH
Production Temperature (°C)
Hazelnut Shells Douglas Fir Chips
6/20/2019
8
Discussion
• ↑Fixed Carbon (PCA and TGA)
• ↓Nega ve Mobility (EPM)
• SA and pH ↑ with ↑ T, as does performance, but
• GAC highest SA
• Doug Fir > Hazelnut Shell SA
• pH trends alone do not describe performance trends (H300)
• High production temperatures reduce quantity of surface functional groups as measured by FTIR
Performance
Biomass Source
Pyrolytic Temperature
Characterization
Electrostatic Modeling
• Incorporates both chemical bonding (surface) and electrostatic interactions (solution)
∆ ∆ ∆
∗
• Mass law equations for all possible surface reactions
• A mole balance equation for total surface sites
• An equation for computation of surface charge
• A set of equations representing the constraints imposed by the model chosen
for electrical double layer (EDL)
6/20/2019
9
Metals Binding and pH Dependence
Fraction Sorbed
Potential
Solid
Surface
pH
Diffuse Layer Model
Bulk Solution
Dissolved Ions
Potentiometric Titration
‐2.0E‐05
0.0E+00
2.0E‐05
4.0E‐05
6.0E‐05
8.0E‐05
1.0E‐04
1.2E‐04
3 4 5 6 7 8 9 10
Adsorbed Hydrogen (M)
pH
Net Titration (Adsorbed H+) 1 mM ionic strength
Experimental
Model
pKa
7.2pKa
4.8
‐
6/20/2019
10
Potentiometric Titration Validation
‐2.0E‐05
0.0E+00
2.0E‐05
4.0E‐05
6.0E‐05
8.0E‐05
1.0E‐04
1.2E‐04
2 3 4 5 6 7 8 9 10
Net Hydrogen Adsorbed
(M)
pH
Exp1mM
Model1mM
Exp10mM
Model10mM
0
0.5
1
1.5
2
2.5
3
3.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
qe (mg/g)
Ce (mg/L)
pH Effects on Copper Removal
Langmuir Model
6/20/2019
11
H700 Isotherms described by pH dependence
0
10
20
30
40
50
60
70
80
90
100
5 6 7 8 9 10
Percent Sorbed %
pH
experimental
model
pH Sorption Edge – Calibration Data Set
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12
Percent Sorbed %
pH
Initial [Cu2+] = 1500 ppb
Experimental
Model
pKa
7.2
pKa4.8 ‐
6/20/2019
12
pH Sorption Edge – Validation Data Set
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12
Percent Sorbed %
pH
Initial [Cu2+] = 900 ppb
Experimental
Model
Copper and Hydrogen Binding Equilibrium
6/20/2019
13
0
0.5
1
1.5
2
2.5
3
3.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
qe (mg/g)
Ce (mg/L)
DLM Predicts Isotherm Sorption based on pH
0
0.5
1
1.5
2
2.5
3
3.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
qe (mg/g)
Ce (mg/L)
DLM Predicts Isotherm Sorption based on pH
6/20/2019
14
0
0.5
1
1.5
2
2.5
3
3.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
qe (mg/g)
Ce (mg/L)
DLM Predicts Isotherm Sorption based on pH
6/20/2019
15
Rapid Small Scale Column Tests (RSSCTs)
Symbol Column Test ParameterRSSCT
(small)
Field‐scale
(large)units
R particle radius 0.179 0.42 mm
D column diameter 0.01 NA m
Across‐sectional column
area7.85E‐05 0.465 m2
Q flow rate/infiltration rate 0.0108 27.26 m3/day
l bed depth length 0.043 0.103 m
EBCT empty bed contact time 0.46 2.53 minutes
V superficial linear velocity 137.5 58.7 (m/d)
Vol Bed Volume 0.003 48 L
Crittenden et. al. 1986
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.5 1.0 1.5 2.0
Copper Breakthrough
Fraction
Elapsed Time (days)
1.35 mg/g
GAC
H700 Biochar
Influent Concentration = 100 ppb Copper
0.55 mg/g
6/20/2019
16
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.5 1.0 1.5 2.0
Copper Breakthrough
Fraction
Elapsed Time (days)
Influent Concentration
Diffuse Layer Model
H700 BiocharExperimental50% Breakthrough
Langmuir Model
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20
Copper Breakthrough
(%)
Elapsed Volume (L)
GAC in River Water
H700 Biochar in Deionized Water
H700 Biochar in River Water
DUAL GAC/H700 COLUMNS IN RIVER WATER
Treatment Requirement
6/20/2019
17
Field‐Scale Predictions (Constant Influent 100 ppb, Effluent Treatment 20 ppb)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
H700 SSW GAC SSW H700 RW GAC RW
Field Scale Treatment Time (days)
RSSCT Treatment Time (days)
Conclusions• ↑Fixed Carbon and ↓Nega ve Mobility
determined as best indicators of copper removal performance
• Biochar exceeds performance in copper removal of industry standard, GAC, in batch and fixed-bed column experiments in SSW and performs similarly to GAC copper removal in river water and metals competition
• DLM predicted RSSCTs results which are scaled to predict field scale capacity under variable field solution conditions
Performance
Biomass Source
Pyrolytic Temperature
Characterization
6/20/2019
18
Acknowledgements
QUESTIONS: [email protected]
• Jeff Nason, Oregon State University‐ PhD Advisor
• Markus Kleber, Todd Jarvis, Meghna Babbar‐Sebens, David
Myrold – PhD committee
• Mark Johnson, EPA‐ Biochar Production and Characterization
assistance
• Jessica Steigerwald and Joy‐Marie Gerould, Oregon State
University – Honors Undergraduate Researcher Collaborators
• Nason Lab Group – shared laboratory equipment, skills, and
knowledge
• Friends, Family, and Sick Town Derby Dames for support
Douglas Fir Biochar
• 300oC functional groups:• Phenols• Aromatic Ethers
• 300oC and 500oC• Aliphatic Amino Acids• Aliphatic Hydrocarbons
• 500oC Only• Inorganic Sulfates
Hazelnut Shell Biochar
• 300oC functional groups:• Aliphatic Primary Amines
• 300oC and 500oC• Aliphatic Hydrocarbons
• 500oC Only• Inorganic Carbonate• Aliphatic Carboxylic Acid Salts
FTIR‐ ATR
0.0
0.2
0.4
0.6
0.8
1.0
0 1000 2000 3000 4000
Absorbance (a.u.)
Wavenumber (1/cm)
D300 Biochar
D500 Biochar
D700 Biochar
0.0
0.2
0.4
0.6
0.8
1.0
0 1000 2000 3000 4000
Absorbance (a.u.)
Wavenumber (1/cm)
H300 Biochar
H500 Biochar
H700 Biochar
6/20/2019
19
For GAC, H700 and D700:
• FTIR‐ATR results show no identifiable peaks that would correspond to surface functional groups
In attenuated total reflectance (ATR) mode:
• The detection depth is generally 1‐2μm deep, but varies based on material. Black, highly absorbing materials have smaller sampling depths and sometimes provide too weak a signal as a result. (Anderson Materials Evaluation, Inc.)
FTIR‐ATR GAC Results
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 1000 2000 3000 4000
Absorbance (a.u.)
Wavenumber (1/cm)
Proton Binding
→ ;
→ ;
→ ;
• Proton binding constants determined via titration data by graphical extrapolation or
objective curve fitting routines (MINEQL+ and MINFIT)
6/20/2019
20
• Hazelnut > Doug Fir
• ↑ pHfinal with ↑ T
Role of adsorbent pH on final equilibrium batch pH
5.0
5.5
6.0
6.5
7.0
7.5
8.0
D300 D500 D700 H300 H500 H500SRNOM
H700 H700SRNOM
GAC
Final Batch Equilibrium pH
Methods: Potentiometric Titration
• Proton Binding
• Titrant additions vs. pH
• 1 and 10 mM ionic strength
• pH 3 to 10
• Point of Zero Salt Effect (PZSE) determined as intersection of titrations at 2 ionic strengths
6/20/2019
21
Potential for Release of Adsorbed Copper
0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Concentration (ppb)
Elapsed Time (Days)
Influent H700 2/17 Effluent H700 2/17
• Agrees with proximate carbon analysis
• Most mass is lost between approximately 250‐350 ˚C
Thermogravimetric Analysis (TGA)
0
20
40
60
80
100
0 200 400 600 800
Weight Remaining (%
)
Temperature (°C)
Hazelnut Shells
Douglas Fir
6/20/2019
22
pKa of Functional Groups
FTIR Detection
• In attenuated total reflectance (ATR) mode, the detection depth is generally 1‐2μm deep, but can be much less or a bit more dependent upon the material. Black, highly absorbing materials tend to have smaller sampling depths and sometimes provide too weak a signal as a result. [Anderson Materials Evaluation, Inc.]
6/20/2019
23
FTIR Results – Douglas Fir Biochar
00.10.20.30.40.50.60.70.80.9
1
0 500 1000 1500 2000 2500 3000 3500 4000
Abs
orba
nce
(cor
rect
ed u
nits
)
Wavenumber (cm-1)
D300 Biochar D500 Biochar D700 Biochar
FTIR Results – Hazelnut Shell Biochar
00.10.20.30.40.50.60.70.80.9
1
0 500 1000 1500 2000 2500 3000 3500 4000
Ab
sorb
ance
(co
rrec
ted
un
its)
Wavenumber (cm-1)
H300 Biochar H500 Biochar H700 Biochar
6/20/2019
24
Evaluating Column Results
Time or Volume Treated
Effluen
t Concentration
Fraction
Total Removal
Partial RemovalExh
austio
n
Treatment Requirement