dnapls: above-ground remediation chang chang yul cha, cha … · 2005-09-14 · @ regeneration rate...
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University of Arizona, Prof. Eric A. Betterton
11
DNAPLsDNAPLs: Above: Above--Ground RemediationGround Remediation
ChangChang YulYul Cha, Cha CorporationCha, Cha CorporationEricEric BettertonBetterton, University of Arizona, University of Arizona
Dept. Atmopsheric Sciences 1
22
University of Arizona, Prof. Eric A. Betterton
Microwave Technology for Superfund Site Remediation
National Institute of Dr. C. Y. Cha
Environmental Health Sciences CHA Corporation
Research Triangle Park, NC 27709 Laramie, WY 82072
Dept. Atmopsheric Sciences 2
University of Arizona, Prof. Eric A. Betterton
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Reaction of Activated CarbonReaction of Activated Carbon to Microwave Energyto Microwave Energy
Dept. Atmopsheric Sciences 3
University of Arizona, Prof. Eric A. Betterton
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Carbon SparklesCarbon Sparkles
Dept. Atmopsheric Sciences 4
Microwav
University of Arizona, Prof. Eric A. Betterton
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Advantages of Using MicrowaveAdvantages of Using Microwave EnergyEnergy
•• Rapid Desorption ofRapid Desorption of VOC’sVOC’s
•• Destructive Reaction ofDestructive Reaction of NOx and CarbonNOx and Carbon
•• Microwave DecompositionMicrowave Decomposition of Large Moleculesof Large Molecules
•• Low TemperatureLow Temperature OxidationOxidation
Conventional Heating
e HeatingHeating
Microwave
1) Activated Carbon – VOC desorption
2) NOx & SOx– Chemical Reaction with Carbon
3) Decompose (because of heat) heavy molecules, when contacted with carbon and microwaves. – Waste rocket fuels
4) Carbon mixed with catalyst – causes low temp oxidation, chemical and biological warfare agents (or medical waste).
Dept. Atmopsheric Sciences 5
University of Arizona, Prof. Eric A. Betterton
66
Microwave Induced
Solvent Desorption
Dept. Atmopsheric Sciences 6
University of Arizona, Prof. Eric A. Betterton
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Small Batch RegeneratorSmall Batch Regenerator
•• 1,100 watt microwave1,100 watt microwave ovenoven
Dept. Atmopsheric Sciences 7
University of Arizona, Prof. Eric A. Betterton
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Small Batch RegeneratorSmall Batch Regenerator
Carbon Filter
1100 Watt Microwave Oven
Collector
Sweep Gas IN
Sweep Gas OUT
Dept. Atmopsheric Sciences 8
University of Arizona, Prof. Eric A. Betterton
99
Regeneration of GACRegeneration of GAC(Saturated with Gasoline)(Saturated with Gasoline)
Dept. Atmopsheric Sciences 9
University of Arizona, Prof. Eric A. Betterton
1010
MicrowaveMicrowave--Induced DesorptionInduced Desorption
0
5000
10000
15000
20000
25000
30000
0 2 4 6 8 10 12 14 16
Time (minutes)
TH
C C
on
cen
tra
tion
(p
pm
)
300 Watt Applied Power
350 Watt Applied Power
400 Watt Applied Power
500 Watt Applied Power
- 2 inch bed height
- Quartz Tube ID = 7/8 inch
- 10 SCFH nitrogen purge
CHA Corporation
Dept. Atmopsheric Sciences 10
University of Arizona, Prof. Eric A. Betterton
1111
0
100
200
300
400
500
600
700
800
900
1000
0 2 4 6 8 10 12 14 16 18 20
Regeneration Cycle
BE
T S
urf
ace
Are
a, m
2 /g
ram
0.00
5.00
10.00
15.00
20.00
25.00
Ad
sorp
tion
Ca
paci
ty,
g M
EK
/10
0 g
GA
C
Sample 1
Sample 2
GHSV= 20,000 hr -1
Inlet Conc . = 200 ppm
GAC Adsorption/RegenerationGAC Adsorption/Regeneration Cycling for MEKCycling for MEK
CHA Corporation
How many times can you regenerate carbon, without losing adsorption capability.
After about 7 cycles with steam, adsorption capacity decreased enough to replace carbon. Not the case with microwaves, still good after 20 cycles.
Dept. Atmopsheric Sciences 11
University of Arizona, Prof. Eric A. Betterton
Advantages of Microwave UnitAdvantages of Microwave Unit
•• Does not rDoes not reequire a long starquire a long startup periodtup periodDoes not produce any air emission or wastewater•• Does not produce any air emission or wastewater
•• Requires much smaller space than conveRequires much smaller space than convenntionaltional technologiestechnologies
•• Can be easily installeCan be easily installed on a trailer or skidd on a trailer or skid•• Recovers PERC and other sRecovers PERC and other soolvlvents and fuels for recycleents and fuels for recycle•• Eliminate greenhousEliminate greenhouse gas pre gas productionoduction•• CostCost--effective means to replace currently operatingeffective means to replace currently operating
catalytic oxidizerscatalytic oxidizers
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Dept. Atmopsheric Sciences 12
University of Arizona, Prof. Eric A. Betterton
Potential ApplicationsPotential Applications
•• Recover gasoline and oRecover gasoline and otther fuel vher fuel vaaporspors generated during the loading of fuel tankers atgenerated during the loading of fuel tankers at bulk fuel terminalsbulk fuel terminals
•• Recover and recycle fuel, solvents, and otherRecover and recycle fuel, solvents, and other chemicals from soil vapors produced duringchemicals from soil vapors produced during remediation operations of contaminated sitesremediation operations of contaminated sites including old gas stationsincluding old gas stations
•• Recover and recycle PERC and other solventsRecover and recycle PERC and other solvents used in dry cleaning and part washing as well asused in dry cleaning and part washing as well as painting operationspainting operations
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Dept. Atmopsheric Sciences 13
University of Arizona, Prof. Eric A. Betterton
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Field Demonstration of Microwave Technology atField Demonstration of Microwave Technology at Former McClellan Air Force Base in SacramentoFormer McClellan Air Force Base in Sacramento
CaliforniaCalifornia(NIEHS SBIR Phase I Program)(NIEHS SBIR Phase I Program)
Dept. Atmopsheric Sciences 14
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University of Arizona, Prof. Eric A. Betterton
IC 34/35/37
Dept. Atmopsheric Sciences 15
University of Arizona, Prof. Eric A. Betterton
Specific AimsSpecific Aims
•• OperaOperatte the protoe the protottype microwave uype microwave unnit ait attMcClellan IC 34/35/37 FTO site for two monthsMcClellan IC 34/35/37 FTO site for two months to regenerate carbon onto regenerate carbon on--site and recoversite and recover solvents, fuels and other chemicals contained insolvents, fuels and other chemicals contained in the soil vaporsthe soil vapors
•• Demonstrate that microDemonstrate that microwwave technology can beave technology can be a costa cost--effective solution for the treatment of soileffective solution for the treatment of soil vaporsvapors
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Dept. Atmopsheric Sciences 16
University of Arizona, Prof. Eric A. Betterton
Dept. Atmopsheric Sciences 17
1717
Prototype Microwave Reactor System
Sweep Gas
Condenser 1
MicrowaveGeneratorMicrowave
Applicator
QuartzReactor
RotaryValve
Makeup NitrogenContaminated Air from SVE System
Cleaned Air to SVE System's FTO
Pneumatic Conveyor Flow Path
RotaryValve
BlowerExcess Sweep Gas
LEGEND
CARBON
RECYCLE SWEEP
AIR
CarbonFines
Compressor
Condenser 2
KnockoutPot 1
KnockoutPot 2
CompressedNitrogenCylinder
Adsorber
Cyclone
Receiver Hopper
Feed Hopper
University of Arizona, Prof. Eric A. Betterton
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Front View of IC 34/35/37 FTO Facility
Dept. Atmopsheric Sciences 18
University of Arizona, Prof. Eric A. Betterton
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Overall View of Microwave Reactor System Setup
Dept. Atmopsheric Sciences 19
University of Arizona, Prof. Eric A. Betterton
2020
Adsorber and Pneumatic Conveying System
Dept. Atmopsheric Sciences 20
University of Arizona, Prof. Eric A. Betterton
2121
Multimode-Cavity, Tuning Device and Top Hopper
Dept. Atmopsheric Sciences 21
University of Arizona, Prof. Eric A. Betterton
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Bottom Hopper and Multimode-Cavity
Dept. Atmopsheric Sciences 22
University of Arizona, Prof. Eric A. Betterton
Field Demonstration ResultsField Demonstration Results
•• Adsorption Test ResultsAdsorption Test Results–– InitialInitial responresponssee timetime of hyof hydrocarbonsdrocarbons–– TOTO--1155 analyses of influent and effluent gasanalyses of influent and effluent gas samplessamples
2323
Dept. Atmopsheric Sciences 23
University of Arizona, Prof. Eric A. Betterton
Microwave Field Testing Results I n t i a l R e s p o n s e T i m e v s . C y c l e
3 0 . 0 0
2424
0 . 0 0
5 . 0 0
1 0 . 0 0
1 5 . 0 0
2 0 . 0 0
2 5 . 0 0
0 2 4 6 8 1 0 1 2 1 4 C y c le
Re
s p
on
s e
Ti m
e (
hr )
B a t c h A B a t c h B
Dept. Atmopsheric Sciences 24
University of Arizona, Prof. Eric A. Betterton
Field Demonstration ResultsField Demonstration Results
•• Microwave Regeneration TestsMicrowave Regeneration Tests–– Hydrocarbon liquidHydrocarbon liquid recovered fromrecovered from eaeach regeneratch regeneratiionon–– Repeated regenerationRepeated regeneration–– RegRegeenneeratiorationn without sweep gawithout sweep gas recycles recycle
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Dept. Atmopsheric Sciences 25
University of Arizona, Prof. Eric A. Betterton
Microwave Field Testing ResultsMicrowave Field Testing ResultsLiquid Recovery vs. Cycle
Liq
uid
Rec
ove
ry (
kg)
20
18
16
14
12
10
8
6
4
2
0
0 2 4 6 8 10 12
Note: Cycle 11A and B were regenerated twice prior to readsorption in cycle 12. The liquid recovery presented is the sum recovered in both regeneration cycles
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14
Cycle
Batch A Barch B
Dept. Atmopsheric Sciences 26
University of Arizona, Prof. Eric A. Betterton
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Liquid Recovered During MicrowaveLiquid Recovered During Microwave RegenerationRegeneration
Dept. Atmopsheric Sciences 27
University of Arizona, Prof. Eric A. Betterton
Recovered LiquidRecovered Liquid
•• Trichloroethane = 3.2 mole%Trichloroethane = 3.2 mole%•• HydrocarbonsHydrocarbons
•• C5C5 –– C8 =C8 = 2211.3 mole.3 mole%%•• C8C8 –– C1C10+0+ == 75.575.5 mole%mole%
•• Specific GrSpecific Gravity = 0.787avity = 0.787•• JP fuel Specific Gravity = 0.75JP fuel Specific Gravity = 0.75 –– 0.800.80
2828
Dept. Atmopsheric Sciences 28
University of Arizona, Prof. Eric A. Betterton
GAC Balance
GAC Added Batch A Batch B 9/24/2003 200 lb 9/27/2003 200 lb
10/16/2003 24.92 lb 11/20/2003 15.25 lb
Total 215.25 lb 224.92
GAC Removed Batch A Batch B Fines 7.83 6.72 End of Testing 208.47 216.24
Total 216.22 222.96
Difference 0.45% -0.87%
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Dept. Atmopsheric Sciences 29
University of Arizona, Prof. Eric A. Betterton
Tests After Field TestingTests After Field Testing
•• MeasMeasure Adsorption Capacure Adsorption Capaciity of GAty of GAC after 13C after 13thth
Adsorption/Regeneration CycleAdsorption/Regeneration Cycle•• DeterminDetermine the the Effect of Sweep Ge Effect of Sweep Gaas Velocity ons Velocity on
the GAC Regeneration Efficiencythe GAC Regeneration Efficiency•• Determined Size DistriDetermined Size Distribution of GAC after 13bution of GAC after 13thth
Adsorption/Regeneration CycleAdsorption/Regeneration Cycle
3030
Dept. Atmopsheric Sciences 30
University of Arizona, Prof. Eric A. Betterton
Adsorption Capacity (gHC/100g carbon)Adsorption Capacity (gHC/100g carbon)
•• Batch A after 1Batch A after 133thth RegeRegenerationeration = 2n = 222..00•• Batch BBatch B after 1after 133thth RegeRegenerationeration = 2n = 222..00•• Fresh Carbon = 29.0Fresh Carbon = 29.0
3131
Dept. Atmopsheric Sciences 31
2.36” Quartz Tube
3-kW Microwave Generator
University of Arizona, Prof. Eric A. Betterton
3232
Note: Chemicals used for adsorption tests were collected during Field Demonstration at McClellan Air Force Base
GAC Regeneration Efficiency @ Regeneration Rate of 26-38lb/hr
0
20
40
60
80
100
120
0 10 20 30 40 50 60 70 80 90
N2 Sw e ep Gas Flow Rate , scfh
Ad
so
rpti
on
Ca
pa
city
(%
of
Ori
gin
al
Ad
sorp
tio
n C
apa
cit
y)
Dept. Atmopsheric Sciences 32
University of Arizona, Prof. Eric A. Betterton
GAC Size AnalysisGAC Size Analysis
Sieve AnalysisSieve Analysis
Fresh GACFresh GAC Batch ABatch A Batch BBatch B
+20 mesh+20 mesh 0.1%0.1% 3.9%3.9% 3.6%3.6%
+10 mesh+10 mesh 99.6%99.6% 95.9%95.9% 96.3%96.3%
+3 mesh+3 mesh 0.4%0.4% 0.1%0.1% 0.1%0.1%
3333
Dept. Atmopsheric Sciences 33
University of Arizona, Prof. Eric A. Betterton
NIEHS SBIR Phase II ProgramNIEHS SBIR Phase II Program
•• Design and Construct a 50Design and Construct a 50--kg/hr Mkg/hr Moobilebile Microwave UnitMicrowave Unit
•• Field Demonstration of MoField Demonstration of Mobile Microwave Unitbile Microwave Unit–– Chlorinated Solvent Contaminated SiteChlorinated Solvent Contaminated Site–– Fuel Contaminated Site (FFuel Contaminated Site (Fuel depot or gasuel depot or gas station)station)–– Dry Cleaning FacilDry Cleaning Facilityity
•• CharCharacterize and Purifyacterize and Purify Recovered Solvents andRecovered Solvents and FuelsFuels
3434
Dept. Atmopsheric Sciences 34
3535
University of Arizona, Prof. Eric A. Betterton
Mobile 50Mobile 50--kg/hr Microwave Carbon Regeneratorkg/hr Microwave Carbon Regenerator
Dept. Atmopsheric Sciences 35
University of Arizona, Prof. Eric A. Betterton
3636
Preliminary Process Flow DiagramPreliminary Process Flow Diagram
Dept. Atmopsheric Sciences 36
University of Arizona, Prof. Eric A. Betterton
Experimental Work Required to Build aExperimental Work Required to Build a 5050--kg/hr Mobile Unitkg/hr Mobile Unit
•• Conduct a series of experiments toConduct a series of experiments to devdeveeloplop the design for microwave reactorthe design for microwave reactor configuration capable of regenerating 50configuration capable of regenerating 50--kg/hr activated carbonkg/hr activated carbon
•• Design and construct supporting syDesign and construct supporting systems onstems on the trailerthe trailer
3737
Dept. Atmopsheric Sciences 37
University of Arizona, Prof. Eric A. Betterton
3838
New Slotted WaveguideNew Slotted Waveguide
Dept. Atmopsheric Sciences 38
University of Arizona, Prof. Eric A. Betterton
3939
Slotted Waveguide In Mailbox CavitySlotted Waveguide In Mailbox Cavity
Dept. Atmopsheric Sciences 39
University of Arizona, Prof. Eric A. Betterton
4040
Inside View of New Applicator SystemInside View of New Applicator System
Dept. Atmopsheric Sciences 40
University of Arizona, Prof. Eric A. Betterton
Advantages of New Applicator SystemAdvantages of New Applicator System
•• Slotted Waveguide Distributes Energy Along theSlotted Waveguide Distributes Energy Along the Length of the TubeLength of the Tube
•• CurvCurved Ced Caavity Wvity Waallll ReflectsReflects EnerEnergy Back Towardgy Back Toward the Tubethe Tube
4141
Dept. Atmopsheric Sciences 41
University of Arizona, Prof. Eric A. Betterton
4242
ScaleScale--up Test Systemup Test SystemCompleted Test SystemCompleted Test System
Dept. Atmopsheric Sciences 42
University of Arizona, Prof. Eric A. Betterton
4343
Laboratory AdsorberLaboratory Adsorber
Dept. Atmopsheric Sciences 43
University of Arizona, Prof. Eric A. Betterton
Scale Up Testing ResultsScale Up Testing ResultsTestTest
(lb/hr)(lb/hr)1A1A 3535 33 9090 98981B1B 3535 33 6060 96962A2A 3535 3.53.5 9090 99992B2B 4040 3.53.5 8585 97973A3A 4040 3.53.5 7070 98983B3B 4040 4.54.5 8080 98984A4A 4040 44 8080 1011014B4B 4545 44 7070 98985A5A 4545 4.54.5 8585 1021025B5B 5050 4.54.5 5555 1091096A6A 5050 55 8080 1011016B6B 5050 55 3535 1081087A7A 5050 55 8080 102102
“Note” %Recovery = (Fresh GAC wt./Reg. GAC wt.)x100
4444
Carbon RateCarbon Rate Power (kW)Power (kW) Sweep Gas (SCFH)Sweep Gas (SCFH) % Recovery% Recovery
Dept. Atmopsheric Sciences 44
University of Arizona, Prof. Eric A. Betterton
Scale Up Regenerator Performance 120%
4545
70%
80%
90%
100%
110%
600 650 700 750 800 850 900 950
Microwave Power (J/g GAC dry basis)
% r
ec
ov
ery
Carbon Mass Recovery
Dept. Atmopsheric Sciences 45
University of Arizona, Prof. Eric A. Betterton
4646
Additional Field Testing At McClellanAdditional Field Testing At McClellan Air Force Base (IC19 and OUD Site,Air Force Base (IC19 and OUD Site,
Chlorinated Solvents)Chlorinated Solvents)
Dept. Atmopsheric Sciences 46
University of Arizona, Prof. Eric A. Betterton
Annual Cost Savings, dollarsAnnual Cost Savings, dollars
ItemItem Quantity SavingsQuantity Savings Cost savings, $Cost savings, $
Natural GasNatural Gas 188,431188,431 thermtherm 131,902131,902
ElectricityElectricity 418,522418,522 kwhkwh 37,66737,667
WastewaterWastewater 4.756 M gallons4.756 M gallons 10,60810,608
Utility waterUtility water 5.675.67 M gallonsM gallons 3,0613,061
GACGAC changeoutschangeouts 120,000120,000
Labor and suppliesLabor and supplies 100,740100,740
Total Annual SavingsTotal Annual Savings 403,978403,978
4747
Dept. Atmopsheric Sciences 47
University of Arizona, Prof. Eric A. Betterton
Prepare Field Testing at FormerPrepare Field Testing at Former McClellan AFBMcClellan AFB
•• Build a SBuild a Shhelelter to protect microwave equipter to protect microwave equipmmentent from rainfrom rain
•• Modify previous microwave unit to allowModify previous microwave unit to allow –– Carbon transportation fromCarbon transportation from/to the/to the portable adsorbportable adsorberer–– Higher recyclHigher recycle gae gas flow rates flow rate–– Isolate theIsolate the ssyystestemm frofromm the adthe adsorption unitsorption unit–– Install the automatic shuInstall the automatic shuttdowndown system in thesystem in the microwavemicrowave
generatorgenerator
4848
Dept. Atmopsheric Sciences 48
University of Arizona, Prof. Eric A. Betterton
4949
Microwave Unit at McClellan AFBMicrowave Unit at McClellan AFB
Dept. Atmopsheric Sciences 49
University of Arizona, Prof. Eric A. Betterton
5050
Volume of VOCs Recovered
0
2
4
6
8
10
12
14
16
18
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Regeneration Number (Cycle)
Vo
lum
e R
eco
vere
d (
L)
OU D Vessel A
OU D Vessel B
Dept. Atmopsheric Sciences 50
University of Arizona, Prof. Eric A. Betterton
5151
Breakthrough at OU D VGAC Vessels
0%
25%
50%
75%
100%
125%
150%
0 2 4 6 8 10 12 14
Days
Per
cen
t B
reak
thro
ugh
Drum A Cycle 1 Drum B Cycle 1 Drum A Cycle 2 Drum B Cycle 2 Drum A Cycle 3 Drum B Cycle 3 Drum A Cycle 4 Drum B Cycle 4 Drum A Cycle 5 Drum B Cycle 5
Dept. Atmopsheric Sciences 51
University of Arizona, Prof. Eric A. Betterton
Dry Cleaning FacilityDry Cleaning Facility
•• PurposePurpose–– To remove PTo remove PEERC by thRC by the ae acctivtivaated carbted carbon from dryon from dry cleaner’scleaner’s
vented airvented air–– ToTo demondemonsstrate the featrate the feassibilibility ofity of recovering PERCrecovering PERC from saturatedfrom saturated
carbon by microwavescarbon by microwaves
•• Test LocationTest Location–– Deluxe CleanDeluxe Cleaneers andrs and TailorsTailors
1614 House Ave.1614 House Ave.Cheyenne, WYCheyenne, WY
5252
Dept. Atmopsheric Sciences 52
University of Arizona, Prof. Eric A. Betterton
5353
Dept. Atmopsheric Sciences 53
University of Arizona, Prof. Eric A. Betterton
Carbon RegenerationCarbon RegenerationFresh GAC, kgFresh GAC, kg 37.237.2 37.737.7
GAC afterGAC after 49.549.5 44.144.1saturation, kgsaturation, kg
GAC afterGAC after 38.438.4 37.037.0regeneration, kgregeneration, kg
Liquid recovered,Liquid recovered, 5.655.65 4.964.96kgkg
5454
Dept. Atmopsheric Sciences 54
University of Arizona, Prof. Eric A. Betterton
5555
Recovered PERC After WaterRecovered PERC After Water Extraction (PERC is Bottom Layer)Extraction (PERC is Bottom Layer)
Dept. Atmopsheric Sciences 55
University of Arizona, Prof. Eric A. Betterton
5656
Questions?Questions?
Dept. Atmopsheric Sciences 56
University of Arizona, Prof. Eric A. Betterton
5757
Innovative Technologies forInnovative Technologies for Destruction of ChlorinatedDestruction of Chlorinated
SolventsSolventsDepartments of Chemical & Environmental EngineeringDepartments of Chemical & Environmental Engineering
Atmospheric SciencesAtmospheric SciencesThe University of Arizona, Tucson, AZThe University of Arizona, Tucson, AZ
• Dr. Robert Arnold • Dr. Eric Betterton • Dr. Wendell Ela • Dr. Eduardo Saez
• Brian Barbaris • Kate Candillo • Xiumin Ju • Cary Leung • Ozer Orbay • Lei Wang • Rohit Tripathi
Dept. Atmopsheric Sciences 57
University of Arizona, Prof. Eric A. Betterton
Systems SummarySystems SummaryZero-valent metals Complete, e.g., Env. Sci. Technol., 34,
804-811 (2000)
Electrolytic reduction (conventional cell) Complete, e.g., Ind. Eng. Chem. Res., 43 (25), 7965 -7974 (2004); Ind. Eng. Chem. Res. 43, 913-923 (2004 )
Electrolytic oxidation (conventional cell) Complete, e.g., J. Appl. Electrochem., 961–970, 29 (1999)
Continuous-flow electrolytic reactor (1-dimensional) Complete, manuscript prepared
Continuous-flow electrolytic reactor (2-dimensional) In progress - manuscript in preparation
Modified fuel cell reactor In progress, e.g., Env. Sci. Technol., 35, 4320-4326 (2001)
Photo-initiated dehalogenation in 2-solvent system Complete, e.g., Env. Sci. Technol., 34, 1229-1233 (2000); Water Res. 38, 27912 (2004); Environ. Sci. Technol., 39, 2262-2266 (2005)
Membrane air stripping reactor Complete, e.g., J. Env. Eng. 130, 12321241 (2004)
Redox catalysis In progress
5858
Dept. Atmopsheric Sciences 58
University of Arizona, Prof. Eric A. Betterton
5959
ParkPark--Euclid WQRF Site: PCE, TCEEuclid WQRF Site: PCE, TCE and Dieseland Diesel
Typical Soil Vapor Analysis
PCE ≈ 300 ppmv
TCE ≈ 30 ppmv
cis-1,2-DCE ≈ 3 ppmv
O2 ≈ 18% v/v
Dept. Atmopsheric Sciences 59
University of Arizona, Prof. Eric A. Betterton
Redox Catalytic Destruction:Redox Catalytic Destruction: Oxidative and Reductive DehalogenationOxidative and Reductive Dehalogenation
•• PCE + 5PCE + 5HH22catalyst
CC22HH66 + 4HCl+ 4HCl
catalyst•• 2PCE + 3C2PCE + 3C33HH88 2C2C22HH66 + 2HCl + 9C+ 2HCl + 9Ccatalyst
•• CC22HH66 ++ 3/23/2OO22 2CO2CO22+ 3H+ 3H22OOcatalyst
•• 2H2H22 + O+ O22 2H2H22OOcatalyst
•• 2HCl + ½ O2HCl + ½ O22 HH22O + ClO + Cl22
6060
Dept. Atmopsheric Sciences 60
University of Arizona, Prof. Eric A. Betterton
6161
Redox Catalytic Destruction:Redox Catalytic Destruction:Laboratory WorkLaboratory Work
Dept. Atmopsheric Sciences 61
University of Arizona, Prof. Eric A. Betterton
6262
Catalytic ConverterCatalytic Converter
•• 2 alumina honeycomb monolith2 alumina honeycomb monolith support s (2" long x 4.7" majorsupport s (2" long x 4.7" major axis 3.15" minor axis).axis 3.15" minor axis).
•• Pt/Rh or Pd/Rh withPt/Rh or Pd/Rh with cerium/zirconium oxygen storagecerium/zirconium oxygen storage additives.additives.
•• Surface area = 4400 mSurface area = 4400 m22
•• Normal automotive flow rate: 20Normal automotive flow rate: 20 cfm to 300 cfm.cfm to 300 cfm.
•• Minimum temperature for 50%Minimum temperature for 50% activity = 415activity = 415 00CC
Dept. Atmopsheric Sciences 62
University of Arizona, Prof. Eric A. Betterton
6363
Ceramic Honeycomb SupportCeramic Honeycomb Support
Dept. Atmopsheric Sciences 63
University of Arizona, Prof. Eric A. Betterton
6464
PCE Removal: Laboratory T and H2/O2 Ratio
(500 mL/min, 1.2 s retention)
0
20
40
60
80
100
120
0 50 100 150 200 250 300 350 400 450
Honeycom b temperature (C)
PC
E %
rem
ov
ed
5.17 3.2 2.75 2.27 1.55 0.95 0.36 0.36
Dept. Atmopsheric Sciences 64
University of Arizona, Prof. Eric A. Betterton
6565
0.0E+00
5.0E-05
1.0E-04
1.5E-04
2.0E-04
2.5E-04
3.0E-04
0 50 100 150 200 250 300 350 400
Time (min)
Co
nc
. (m
ole
/L)
0
100
200
300
400
500
Tem
p.
(C)
Ethane PCE Total C Furnace T Honeycomb T
PCE Removal: Laboratory T vs.PCE Removal: Laboratory T vs. EthaneEthane
(8.64 mL/min H2, 25 mL/min O2, 500 T mL/min, 1.2 s retention)
Dept. Atmopsheric Sciences 65
University of Arizona, Prof. Eric A. Betterton
6666
0.0E+00
5.0E-05
1.0E-04
1.5E-04
2.0E-04
2.5E-04
3.0E-04
0 100 200 300 400 500 600 700 800
Time (min)
Co
nc
. (m
ole
/L)
0
50
100
150
200
250
300
350
400
450
Te
mp
. (C
)
Ethane out
PCE out
Furnace T
Honeycomb T
PCEin
Redox Catalyst: PCE DestructionRedox Catalyst: PCE Destruction(300 C; 500 mL/min total flow, 50 mL/min H2, 25 mL/min O2, 1.2 s retention time
Dept. Atmopsheric Sciences 66
University of Arizona, Prof. Eric A. Betterton
6767
0
20
40
60
80
100
120
0 4 8 12
% Hydrogen
PC
E %
rem
ove
d
0
100
200
300
400
500
Ho
ney
com
b (
C)
PCE
PCE @ 400 C
Catalyst T
Redox Catalyst: PCE Reduction HRedox Catalyst: PCE Reduction H--EffectsEffects
Dept. Atmopsheric Sciences 67
University of Arizona, Prof. Eric A. Betterton
6868
0
20
40
60
80
100
120
0 5 10 15 20 25
% H2
% R
emo
ved
0
1
2
3
4
5
% O
2 i
n −
% O
2 o
ut
TCE PCE O2 in - O2 out
PCE Removal: ParkPCE Removal: Park--EuclidEuclid((H2 and O2)
Dept. Atmopsheric Sciences 68
University of Arizona, Prof. Eric A. Betterton
6969
Catalyst Poisoning: OxidativeCatalyst Poisoning: Oxidative450 0C, O2 =21%, Pd/Rh Catalyst
0
5
10
15
20
25
30
0 5 10 15 20
Time (h)
PC
E %
Rem
ova
l
Dept. Atmopsheric Sciences 69
University of Arizona, Prof. Eric A. Betterton
7070
Catalyst Poisoning: Reductive (propane, O2= 0 %; residence time:1.08 s, run time:410 min
0
20
40
60
80
100
380 400 420 440 460 480 500 520 540
Honeycomb Temp. (C)
PC
E %
Re
mo
va
l
Dept. Atmopsheric Sciences 70
University of Arizona, Prof. Eric A. Betterton
7171
Redox Catalyst: PCE with propaneRedox Catalyst: PCE with propane (21% O2)
0
20
40
60
80
100
380 430 480 530 580
Honeycomb temp(C)
%p
ce r
emo
val
2% propane
4%propane
0% propane
Dept. Atmopsheric Sciences 71
University of Arizona, Prof. Eric A. Betterton
7272
Redox Catalyst: Methane vs.Redox Catalyst: Methane vs. Propane and TPropane and T
(21% O2)
0
10
20
30
40
50
60
70
80
90
100
340 360 380 400 420 440 460 480 500 520
Honeycomb temp(C)
Rem
ova
l per
cen
t
2% methane
1% propane
Dept. Atmopsheric Sciences 72
University of Arizona, Prof. Eric A. Betterton
7373
Redox Catalyst: PCE and TCE withRedox Catalyst: PCE and TCE with HH22/O/O22 ratioratio
(410 0C)
0
10
20
30
40
50
60
70
80
90
100
0 0.05 0.1 0.15 0.2
H2/O2 ratio
Rem
ova
l p
erce
nt
PCE
TCE
Dept. Atmopsheric Sciences 73
University of Arizona, Prof. Eric A. Betterton
Fuel CellFuel Cell
H2 PEM O2
anode
CC
cathode 2H+ +2 e O2 + 4 H+ + 4 e− 2H2OH2
l4 + H+ + 2e− CHCl3 + Cl−
Pt-black on carbon cloth
PEM: Nafion proton-exchange membrane
7474
Dept. Atmopsheric Sciences 74
Valve
N2
water
TCEGC
Anode Cathode
Flow meter
H2
water
discharge
potentiostat
lveAnode Cathode
Flow meter
discharge
potentiostat
lveAnode Cathodet
Flow meter
discharge
University of Arizona, Prof. Eric A. Betterton
7575
Va
N2
water
TCE GC
H2
water Va
N2
water
TCEGC
Anode Ca hode
H2
water
potentiostat
flow meter
val ve
Fuel Cell Experimental Set upFuel Cell Experimental Set up
Dept. Atmopsheric Sciences 75
University of Arizona, Prof. Eric A. Betterton
TCE ReductionTCE Reduction –– Fuel Cell PotentialFuel Cell Potential(room temp., Patm, 18 mL/min, res. time = 2.3 s)
0.0
0.5
1.0
1.5
2.0
2.5
Mol
ar F
low
Rat
e (µ
mol
/min
)
0.1 -0.1 -0.5-0.3
Cell Potential (V)
TCE effl. Ethane Effl.
TCE + Ethane (effl.) TCE infl.
7676
This slide showed an experiment conducted under room temperature, atmospheric pressure, inlet flow rate 18 ml/min, TCE concentration of 2500ppmv. The left graph showed TCE and reaction product concentration in the effluent. TCE concentration was reduced monotonically with respect to cell potential. Ethane as the product of TCE degradation increased to a maxima, and then decreased with respect to cell potential. This was caused by increase of flow rate due to hydrogen evolution in the cathode. No Chlorinated intermediates were detected.
The right graph showed the molar flow rate of TCE and ethane and the sum of two in the effluent. The solid red line represented the inlet TCE molar flow rate. We can see that a good mass balance was obtained here, and thus proved that ethane was the major product of TCE degradation. The variation of effluent data around inlet data probably due to experimental error.
Dept. Atmopsheric Sciences 76
University of Arizona, Prof. Eric A. Betterton
7777
TCE ReductionTCE Reduction –– Fuel CellFuel Cell Current EfficiencyCurrent Efficiency
(room temp., Patm, 18 mL/min, res. time = 2.3 s)
0.0
0.2
0.4
0.6
0.8
1.0
-0.5-0.3-0.10.1
Cell Potential (V)
Co
nve
rsio
n a
nd
cu
rre
nt
eff
icie
ncy
conversion
current efficiency
Here in this graph the current efficiency was plotted with respect to cell potential, and TCE conversion was also plotted. Current efficiency here is defined as the ratio of the current used for TCE reduction to total current. As you can see, the current efficiency is relatively low due to large amount of hydrogen generated.
Dept. Atmopsheric Sciences 77
University of Arizona, Prof. Eric A. Betterton
7878
ElectrolysisElectrolysis -- Annular AnodeAnnular Anode
V
anolyte
Porous electrode (copper foam)
Anode (carbon cloth)
Reference electrode
Potentiostat
Catholyte (influent)
Nafion membrane
+− +→− HOeOH 2 2
12 22
Anode Reaction
−−+ +→++ ClCHeHCCl 484 44
−− +→+ OHHeOH 22 2
1
Cathode Reaction
Dept. Atmopsheric Sciences 78
University of Arizona, Prof. Eric A. Betterton
7979
ElectrolysisElectrolysis –– Cu foamCu foam
Dept. Atmopsheric Sciences 79
University of Arizona, Prof. Eric A. Betterton
8080
Conductivity = 0.067 S/m (tap water)
0 5 10 15 20 25 0.0
0.2
0.4
0.6
0.8
1.0
E = -0.2V E= -0.4V
C/C
0
Distance (cm)
Conductivity = 2.7 S/m
0 5 10 15 20 25 0.0
0.2
0.4
0.6
0.8
1.0
E = -0.2V E = -0.4V
C/C
0
Distance (cm)
CT Electrolysis: Applied Potential andCT Electrolysis: Applied Potential and ConductivityConductivity
(velocity = 0.0349 cm/s, cathode = 22.5 cm)(velocity = 0.0349 cm/s, cathode = 22.5 cm)
Dept. Atmopsheric Sciences 80
University of Arizona, Prof. Eric A. Betterton
8181
CT Electrolysis: Applied PotentialCT Electrolysis: Applied Potential and Conductivityand Conductivity
cathode = 22.5 cm; -0.4 V; 0.05 S/m; solid and dashed lines correspond to mathematical model
Residence time (min)
Cbin--Inlet concentration. Cb—Bulk concentration
Dept. Atmopsheric Sciences 81
University of Arizona, Prof. Eric A. Betterton
8282
Electrochemical CT Reduction: pHElectrochemical CT Reduction: pH(Ni foam)
Dept. Atmopsheric Sciences 82
University of Arizona, Prof. Eric A. Betterton
8383
Photochemical Treatment at ParkPhotochemical Treatment at Park--Euclid SiteEuclid Site
Dept. Atmopsheric Sciences 83
University of Arizona, Prof. Eric A. Betterton
8484
0
20
40
60
80
100
250 300 350 400 450
Wavelength (nm)
% T
ran
smit
tan
ce a
nd
% R
efl
ecta
nc
e
0
0.5
1
1.5
2
En
erg
y (
W/m
2 nm
)
Acetone % Reflectance 2-Propanol Glass Energy
Photochemical Treatment: PCE atPhotochemical Treatment: PCE at ParkPark--Euclid Spectral PropertiesEuclid Spectral Properties
Dept. Atmopsheric Sciences 84
University of Arizona, Prof. Eric A. Betterton
Photochemical MechanismPhotochemical Mechanism
H H H
O Me OH (2) Me OHhvO
H H Me Me
acetone photon excited actone 2-propanol 2-propanol
radical radical
Acetone in its excited state, extracts a hydrogen atom from a suitable donor, such as 2-propanol, producing a highly reduced 2-propanol radical that is capable of reducing a variety of halogenated targets.
OH Cl Cl H OH Cl Cl Cl Cl
Me Me OHHOH MeMe OHMe Cl Cl Me
Me Cl Cl
PCE 2-propanol
MeMe Me Cl Cl
2-propanol 3,3,4,4-tetrachloro- 2-propanol radical 2-methyl-butan-2-ol radical
1. Alkene-radical chemistry suggests that the 2-propanol radical may add to the chlorinated alkene to produce a chloro-methyl alcohol (3,3,4,4-tetrachloro-2-methyl-butan-2-ol).
2. Data also support electron donation to PCE and/or the chloro-methyl alcohol by the 2-propanol radical accompanied by chloride elimination, similar to carbon tetrachloride mechanism (Betterton et al., ES&T 2000).
8585
Dept. Atmopsheric Sciences 85
University of Arizona, Prof. Eric A. Betterton
8686
0
0.5
1
0 10 20 30 40 50 60 70 80 90 100 110 120
Exposure Time (min)
Rel
ativ
e C
on
cen
trat
ion
15-Mar
20-Mar
23-Mar
24-Apr
25-Apr
30-May
31-May
20-Sep
28-Sep
PCE Photochemical Treatment:PCE Photochemical Treatment: ParkPark--EuclidEuclid
Dept. Atmopsheric Sciences 86
University of Arizona, Prof. Eric A. Betterton
SummarySummary
• Catalyzed thermochemical reduction is feasible – H2 costs may be high but propane may be viable substitute.
• Electrolytic reduction of chlorinated solvents appears feasible using annular anode/cathode – even in low-conductivity water.
• Gas-phase treatment of solvents is fast using fuel cell – system requires scale up/additional design work.
• Photocatalytic system effective but scale up for volatile liquids may be unattractive.
8787
Dept. Atmopsheric Sciences 87
University of Arizona, Prof. Eric A. Betterton
8888
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