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Technical Advisory Group Meeting “Investigation of Energized Options for Leachate Management”
By D.E. Meeroff, C.T. Tsai, F. Gasnier, and T. Martin (Florida Atlantic University) Funded by the Florida Center for Solid and Hazardous Waste Management (FCSHWM)
DATE: Friday, October 27, 2006 TIME: 11:00 am WHERE: Solid Waste Authority 7501 N. Jog Road, West Palm Beach, FL 33412
Sign-In Sheet
Name: Joe Lurix Title: DEP Waste Program Administ. Address: 400 N. congress Avenue WPB, FL Email: [email protected] Phone: 561‐681‐6672 Name: Fred Bloetscher Title: Assistant Professor, FAU Address: 777 Glades Road Boca Raton, FL 33431 Email: [email protected] Phone: 561‐297‐0744 Name: Marc Bruner Title: Dir.Env.Programs/SWA Address: 7501 N. Jog Road West Palm Beach, FL 33412 Email: [email protected] Phone: 561‐640‐4000 Name: Shaowei Chen Title: Assistant Research Professor Address: 250 S. Ocean Blvd. Boca Raton, FL 33401 Email: [email protected] Phone: 561‐368‐0128 Name: Matt Zuccaro Title: Project Engineer CDM Address: 1601 Belvedere Road, Ste. 211 S West Palm Beach, FL Email: [email protected] Phone: 561‐689‐3336
Name: Richard Meyers Title: Project Manager III Address: 1 N. University Drive, Ste. 400 Plantation, FL 33324 Email: [email protected] Phone: 954‐474‐1848 Name: Manuel Hernandez Title: Project Engineer CDM Address: 1601 Belvedere Road, Ste. 211 S West Palm Beach, FL Email: [email protected] Phone: 561‐689‐3336 Name: Ray Schauer Title: Director Engineering, SWA Address: 7501 N. Jog Road West Palm Beach, FL 33412 Email: [email protected] Phone: 561‐640‐4000x4603 Name: John Booth Title: Executive Director, SWA Address: 7501 N. Jog Road West Palm Beach, FL 33412 Email: [email protected] Phone: 561‐640‐4000 Name: C.T. Tsai Title: Professor, FAU Address: 777 Glades Road Boca Raton, FL 33431 Email: [email protected] Phone: 561‐297‐2824
Minutes 1. Opening Address (11:15 PM) by Dr. Meeroff followed by introduction of the group members
and participants 2. Introduction of Landfill Leachate Project by Dr. Meeroff
- Objectives - Overview
3. Discussion of Study Methodology by François Gasnier - Literature review - Landfill surveys - Evaluation of leachate quality data - Evaluation of management strategies - Discussion of Photochemical Iron‐Mediated Aeration (PIMA) laboratory experiments
4. Discussion of Photocatalytic Nanoparticles by Dr. Shaowei Chen 5. Discussion of Future Work by Dr. Meeroff
- Summary of Energized Processes (in lay terms) - Management Model - Broader Impacts - Project Website - Acknowledgements
6. Discussion of TAG Input Needs (Open Forum)
‐ Previous Experiences ‐ General Discussion ‐ Dr. Bloetscher commented about upcoming reuse standards for permitting new deep
well injection systems ‐ Marc Bruner commented about residuals generated in the process and the possibility of
needed a TCLP analysis to determine if the residuals generated can be landfilled. ‐ John Booth asked for several clarifications about the potential applications of these new
technologies. ‐ Joe Lurix volunteered to provide additional information concerning leachate volumes
discharged as well as information concerning management technologies and contacts for solid waste management personnel not represented at this TAG meeting (i.e. Okeechobee, Medley, St. Lucie, Martin County)
7. Adjourn (12:35 PM), thank you for participating
1
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
““Investigation of Energized Options Investigation of Energized Options For For LeachateLeachate ManagementManagement””
D.E. MEEROFF, Ph.D., E.I.Assistant Professor, Department of Civil Engineering, Florida Atlantic University
Director, Laboratories for Engineered Environmental SolutionsC.T. Tsai, Ph.D., S. Chen, Ph.D.
Professor, Department of Mechanical Engineering, Florida Atlantic UniversityF. Gasnier
MSCE, Florida Atlantic University
Presentation to the FCSHWM Technical Advisory GroupSolid Waste Authority of Palm Beach County, West Palm Beach, FL, October 27, 2006
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
AgendaAgenda
1. Introductions/Opening Remarks1. Introductions/Opening Remarks
2. Preliminary Results2. Preliminary Results
3. Photocatalytic Nanoparticles3. Photocatalytic Nanoparticles
4. Future Work/Open Forum4. Future Work/Open Forum
Dr. Meeroff
F. Gasnier
Dr. Chen
Everyone
2
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Leachate IssuesLeachate Issues
• Leachate quality is highly variableType of solid waste (MSW, Ash monofill, C&D)Maturity of landfill
Color
Elevated TDS, BOD, NH3, VOCs
High COD/BOD
ratio
pH toxicity
Heavy metalsPb, As, Cd, Hg
PathogensOdor
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
RationaleRationale• All-inclusive solutions are not currently
available for leachate management• Need for sustainable options to safely
discharge to the environment• Futuristic energized processes developed
for detoxification of groundwater and soils may be the answer:
Photochemical Iron-Mediated Aeration (PIMA)TiO2-magnetite
3
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Objectives of the ResearchObjectives of the Research
DevelopManagement Tool
DevelopManagement Tool
Evaluate EPs
Evaluate EPs
Evaluate AlternativesEvaluate
Alternatives
Objective 1Objective 1 Objective 2Objective 2 Objective 3Objective 3
• Review & collect leachate quality data
• Identify trends• Rank alternatives
(performance, risk, environmental and economic factors)
• Technical data (with the goal of achieving sewer discharge limits )
• PIMA• TiO2-Magnetite
• Preliminary cost analysis
• Preliminary risk assessment
• Web-based BMP guide
• Interactive and goal-based
Year 2Year 1
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
““Investigation of Energized Options Investigation of Energized Options For For LeachateLeachate ManagementManagement””
D.E. MEEROFF, Ph.D., E.I.Assistant Professor, Department of Civil Engineering, Florida Atlantic University
Director, Laboratories for Engineered Environmental SolutionsC.T. Tsai, Ph.D., S. Chen, Ph.D.
Professor, Department of Mechanical Engineering, Florida Atlantic UniversityF. Gasnier
MSCE, Florida Atlantic University
Presentation to the FCSHWM Technical Advisory GroupSolid Waste Authority of Palm Beach County, West Palm Beach, FL, October 27, 2006
4
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Future WorkFuture Work1. Design TiO2-magnetite reactor2. Complete scoping tests on Pb, TDS,
conductivity, ammonia, and COD3. Begin performance testing with
mixtures & actual leachate from SWA4. Develop cost analyses and risk
assessments for BMP guide5. Develop management tool
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Management ToolManagement ToolUser
InterfaceProfileModule
User Input Profile
UserID
ContactInfo
LandfillType
LandfillAge
WasteGenRate
CurrentTechnology
TrtCapacity
ClimateData
BMPModule
ReportModule
InteractiveGoal-based
5
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Benefits to the UniversityBenefits to the University• Stimulate progress
in technologies for reducing toxics
• Strengthen the cooperative relationship between FAU and SWA
• Hands-on student training in solid waste management
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Additional SupportAdditional Support• FAU College of Engineering and Computer Science
Generous equipment donationNew ME/CE Nanoparticle Applications Laboratory
• Lanny and Kay Hickman Internship Program with the Solid Waste Authority of Palm Beach County
• USF Center for Biological Defense project• Leverage related work in technology development
for water quality restorationIn-situ remediation of hazardous waste sitesEDCs, DBPs, and membrane concentrate treatment
6
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
LabLab‐‐EES EES
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
NanoparticleNanoparticle Applications LabApplications Lab
Nanoparticle ApplicationsLaboratory
7
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
Web SiteWeb Site
www.civil.fau.edu/~daniel/labees/html/index.html
Daniel E. Meeroff, Ph.D. Daniel E. Meeroff, Ph.D. ▪▪ FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL FCSHWM Technical Advisory Group Meeting, West Palm Beach, FL ▪▪ Oct. 27, 2006Oct. 27, 2006
AcknowledgmentsAcknowledgments
1
Investigation Of Energized Options For Leachate
ManagementPresentation to the Technical Advisory Group
MeetingOctober 27, 2006, Solid Waste Authority of Palm Beach County,
West Palm Beach, FL
D.E. MEEROFF, Ph.D., E.I.Assistant Professor, Department of Civil Engineering, Florida Atlantic University
Director, Laboratories for Engineered Environmental SolutionsC.T. Tsai, Ph.D.
Professor, Department of Mechanical Engineering, Florida Atlantic UniversityF. Gasnier
MSCE, Florida Atlantic UniversityDr. Shaowei Chen
Post-Doctoral Researcher
Outline Part 1
• Literature reviewLandfill surveysEvaluation of leachate quality dataEvaluation of management strategies
2
Literature Review (1/12)
• Goals:Collect leachate quality dataIdentify management alternatives with emphasis on energized options for leachate treatmentRank these alternatives according to:
Environmental sustainabilityEfficiencyRisksEconomic factorsPerformance experience (TAG member input)
Literature Review (2/12)
• Methodology, tools usedFAU S.E. Wimberley Library services:
Electronic databases (FirstSearch)WorldCatElectronic journals
Internet:Reliable sources such as government or schools web sites (www.epa.gov, www.dep.state.fl.us)
Record Review at the FDEP of Palm Beach
3
Literature Review (3/12)
• Landfill survey in Florida:25 million tons of MSW were generated across the State in 2000 (FDEP 2002)58% is landfilled in
60 Class I landfills34 Class III landfills11 ash monofill landfills
Literature Review (4/12)
• ResultsLeachate quality data worldwide and more precisely in Florida
Florida leachate characteristics Worldwide leachate characteristics
Parameters Range Average
Lead in mg/L
pH
Conductivity in μS/cm
TDS in mg/L
Ammonia in mg/L as N
COD in mg/L as O2
BOD5 in mg/L
TSS in mg/L
Concentrations
BDL - 0.1 0.03
1,000 - 95,000 11,600
n/a n/a
900 - 88,000 9,300
BDL - 1,350 500
55 - 14,000 3,000
BDL - 445 150
2.0 - 11.3 7.5
Parameters Range Average
BOD5 in mg/L
pH
0.11
5.2 - 95,000 13,000
0 - 88,000 11,000
Lead in mg/L
Conductivity in μS/cm
TDS in mg/L
BDL - 5.0
Ammonia in mg/L as N
COD in mg/L
Concentrations
TSS in mg/L n/a n/a
0.1 - 8,750 850
2.0 - 11.3 7.5
0.4 - 152,000 10,600
BDL - 80,800 4,100
4
Literature Review (5/12)
• Results, continuedCompilation of several sources across the world and FloridaLarge range of concentrations for all constituentsFlorida leachate is lower strength than the worldwide average: one explanation is the dilution due to climate impactsCan one technology handle this special type of wastewater?
• Evaluating existing alternatives
Literature Review (6/12)
• Existing alternatives1. MUNICIPAL SEWER DISCHARGE:
A common optionDoes not address bio-toxicsA flow > 5% will disrupt WWTP’s due to high COD and ammonia, (Boyle and Ham 1974, Chain and DeWalle 1977)
2. NATURAL ATTENUATIONDeep well injection (monitoring problems)Evaporation ponds (does not work in Florida due to the climate)
5
Literature Review (7/12)
• Existing alternatives, continued3. HAULING OFF-SITE
Does not address the problem, just displaces itHigh transportation risk and cost: $110 per 1,000 gal (Polk County)
4. LEACHATE RECIRCULATIONUnder study by the Florida Center, showed great reduction capacities (Morris et al. 2003)Mass balance issue: the leachate cannot be recirculated endlessly
Literature Review (8/12)
• Existing alternatives, continued5. ON-SITE TREATMENT:
Biological processes› Equivalent to discharge to a WWTP› Does not address bio-toxics
Physical and chemical processes (air stripping, precipitation, ion exchange, filtration, etc.)
› Transfer pollutants to another media› Issue with concentrates and residuals
6
Literature Review (9/12)
• Comparative statement of the onsite treatment alternatives
Technology % COD removal Source
Acclimated sludge
Coagulation and flocculation
Coagulation and flocculation
93 Anagiotou et al. (1993)
Silva et al. (2003)
Wu et al. (2004)
Slater et al. (1983)
23
60
68Reverse osmosis
Literature Review (10/12)
• Advanced Oxidation Processes (AOP’s) or Energized Processes (EP’s) can be the solution
AOP = near ambient temperature and pressure water treatment processes which involve the generation of hydroxyl radicals in sufficient quantity to effect water purification, Glaze et al. (1987)
H2O2, Fenton (H2O2/Fe2+) , O3, IMAEP = AOP + UV energy
UV, UV/ H2O2, Photo-Fenton, PIMA, TiO2-magnetite
7
Literature Review (11/12)
• Comparative statement of the AOP’s and EP’s% COD removal Source
PIMA ?
Technology
H2O2
H2O2
Fenton
16
60
35
Fenton
Ozone
Loizidou et al. (1993)
Shu et al. (2006)
Loizidou et al. (1993)
Englehardt et al. (2005)
UV / H2O2 65 Shu et al. (2006)EP
Photo-Fenton 70 Soo-M. Kim et al. (1997)
IMA 56 Englehardt et al. (2005)
UV / O3 / H2O2 89 Ince (1998)
AOP
UV / H2O2 59 Ince (1998)
UV / O3 54 Ince (1998)
61
35 Imai et al. (1998)
Literature Review (12/12)
• Several treatment options available• All show pros and cons• None seems totally efficient, but EP’s show
the best results
Developing other technologies such as the PIMA process could offer a future alternative.
8
Outline Part 2
Photochemical Iron Mediated Aeration Process (PIMA)
PrincipleLaboratory scale reactorMethodologyPreliminary results
PIMA principle
• Reaction mechanism not completely known, but evidence suggests:
The oxidation of Fe to Fe2+
The creation of hydroxyl radical HO• by 2 paths:Photo-Fenton reaction Interaction of UV energy with water
The removal action of HO•
9
PIMA reactor (1/3)
PIMA reactor (2/3)
10
PIMA reactor (3/3)
Humidifier Test tubes and lamp
Methodology (1/2)
• Pilot reactor used to develop preliminary testing conditions with simulated leachate:
Air requirementsMass of catalyst/reactantUV intensityReaction times: sampling after 0, 2, 6, 16 and 24 hours of treatmentpH monitored (~6), but not adjusted
11
Methodology (2/2)
• Pilot reactor used to generate performance data that are currently not available for the PIMA process on these five constituents:
AmmoniaCODBOD5
Conductivity and TDSLead
Preliminary Results (1/6)
• Scoping tests on simulated leachateEvaluation, adjustments, validation of the reactorMethod development for the monitoring of the pollutantsValidation of expected results with simulated leachate prior to using real leachate samples
12
Preliminary Results: COD (2/6)• 3 Scoping tests conducted on low (1,500 mg/L),
medium (3,300 mg/L) and high (11,000 mg/L) levels
• Best overall removal efficiency of 44% after 24 hrs on COD with the PIMA process and 54% on the low level
C / C0 versus Time
0.00
0.20
0.40
0.60
0.80
1.00
0 5 10 15 20 25
Time in hrs
C /
C0
UV, x = 10.2 cm IMA, x = 10.2 cm PIMA, x = 6.3 cm PIMA, x = 10.2 cm PIMA, x = 15.2 cm
Preliminary Results: Ammonia (3/6)• 3 Scoping tests conducted on low (110 mg/L),
medium (550 mg/L) and high (925 mg/L) levels
• Despite the air stripping, a low removal of ammonia has been observed
C / C0 versus Time
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0 5 10 15 20 25
Time in hrs
C /
C0
UV, x = 10.2 cm IMA, x = 10.2 cm PIMA, x = 6.3 cm PIMA, x = 10.2 cm PIMA, x = 15.2 cm
13
Preliminary Results: BOD5 (4/6)• 3 Scoping tests conducted on low (55 mg/L),
medium (125 mg/L) and high (425 mg/L) levels
• Best removal efficiency of 56% after 16 hrs on BOD5 with the PIMA process
C / C 0 v e r s u s T im e
0 .0 0
0 .2 0
0 .4 0
0 .6 0
0 .8 0
1 .0 0
1 .2 0
0 2 4 6 8 1 0 1 2 1 4 1 6 1 8
T im e in h rs
C /
C 0
IM A , x = 1 0 .2 c m PIM A , x = 1 0 .2 c m
Preliminary Results: TDS (5/6)• 2 Scoping tests conducted on medium (8,125
mg/L) and high (40,000 mg/L) levels
• No removal observed. Increase probably due to dissolving iron.
C / C0 versus Time
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
0 5 10 15 20 25
Time in hrs
C /
C0
UV, x = 10.2 cm IMA, x = 10.2 cm PIMA, x = 6.3 cm PIMA, x = 10.2 cm PIMA, x = 15.2 cm
14
Preliminary Results: Conductivity (6/6)• 2 Scoping tests conducted on medium (16,250
µS/cm) and high (81,600 mg/L) levels
• Same conclusion than for TDS
C / C0 versus Time
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
0 5 10 15 20 25
Time in hrs
C /
C0
UV, x = 10.2 cm IMA, x = 10.2 cm PIMA, x = 6.3 cm PIMA, x = 10.2 cm PIMA, x = 15.2 cm
Conclusion
• Literature review almost complete• PIMA reactor fully operational• Reactor parameters are being measured and
will be checked regularly.• Monitoring program of experiments established• 2 more scoping tests to be performed followed
by simulated mixtures and then real leachate.
15
Conclusion
• Comparative statement of the AOP’s and EP’s, including the PIMA process
Low level experiment reduced COD concen-tration below the Boca Raton sewer discharge limit.
% COD removal Source
PIMA 54 Present work
Technology
H2O2
H2O2
Fenton
16
60
35
Fenton
Ozone
Loizidou et al. (1993)
Shu et al. (2006)
Loizidou et al. (1993)
Englehardt et al. (2005)
UV / H2O2 65 Shu et al. (2006)EP
Photo-Fenton 70 Soo-M. Kim et al. (1997)
IMA 56 Englehardt et al. (2005)
UV / O3 / H2O2 89 Ince (1998)
AOP
UV / H2O2 59 Ince (1998)
UV / O3 54 Ince (1998)
61
35 Imai et al. (1998)
Next Steps
• 1 scoping test on Pb, and 1 on TDS and conductivity
• Scoping tests on simulated mixture (BOD5 & COD, ammonia & TDS)
• Collect real leachate samples from the Solid Waste Authority of Palm Beach County (FL) and evaluate the PIMA process
• Rank the available alternatives including the new PIMA process (TAG input)
16
Investigation Of Energized Options For Leachate
ManagementPresentation to the Technical Advisory Group Meeting
October 27, 2006, Solid Waste Authority of Palm Beach County, West Palm Beach, FL
D.E. MEEROFF, Ph.D., E.I.Assistant Professor, Department of Civil Engineering, Florida Atlantic University
Director, Laboratories for Engineered Environmental SolutionsC.T. Tsai, Ph.D.
Professor, Department of Mechanical Engineering, Florida Atlantic UniversityF. Gasnier
MSCE, Florida Atlantic UniversityDr. Shaowei Chen
Post-Doctoral Researcher
Discussion
• Questions without answer, yet!Statistics and process performance data concerning the treatment methods used in Florida:
Leachate quantitiesCurrent management practicesLeachate quality data (influent and effluent)
Rank the viable alternatives (the alternatives table is being constructed)
• Previous experiences/issues• General discussion
17
Goals: Sewer limits
• City of Boca Raton Sewer Use Policy Limits Regulated Pollutants:
Iron: 21.0 mg/LLead: 0.37 mg/LTotal Dissolved Solids: 2000.0 mg/LCOD: 800.0 mg/LBOD5: 400.0 mg/LpH: 6.0 – 8.5(Maximum allowable value over any 24 hrs period)
1
Photocatalyst TiO2 Coated Magnetic Composite Nanoparticle
And Potential Application in Leachate Treatment
Dr. Shaowei Chen and Dr. C.T. TsaiFlorida Atlantic University
October 27, 2006
Background
– Magnetic TiO2 nanoparticles• Larger surface area in unit volume (~100-400 sqm/g)• Higher efficiency in treating environmental
contamination• TiO2 is extractable and reusable.• TiO2 is currently the most popular and effective
photocatalyst for a number of applicationsOxidation of organic pollutantsRemoval of inorganic pollutants in waterPhotoreduction of N2 or CO2 Photodestruction of cancer cells, bacteria and virus
2
Possible Application In Landfill Leachates Treatment
• photocatalytic oxidation (PCO) to break down and destroy many types of organic pollutants.
• It has been used to purify drinking water• destroy bacteria and viruses• remove metals from waste streams, and • breakdown organics into simpler components of
water and CO2. • The treatment of non-biodegradable organics • The photocatalytic process (UV/TiO2) has
proved to be effective for the decolourisation as well as mineralization of humic acids solution
Process - Results1. The process occurs under ambient
conditions2. The formation of photocyclized intermediate
products3. Oxidation of the substrates to CO2 is
complete 4. TiO2 can be supported on suitable reactor
substrates 5. The process offers great potential as an
industrial technology to detoxify wastewaters
3
Photocatalytic Principle• Irradiated with UV light (sun light or near λ< 400 nm)
semiconductor TiO2 produces electron-hole pairs that can initiative reductive & oxidative reactions on the surface
• The injection of these electrons and holes into fluid region surrounding the TiO2 particles causes electrochemical modification of substance within the region
• Redox reaction – produce hydroxyl radicals that can oxidize most organic pollutants or microbial agents
• The pollutant could be dissolved (organic/inorganic)
Problems• If TiO2 is in solution then some sort
of recovery system is necessary in order to reuse the catalyst
• TiO2 particles are electrical insulator
• Difficult to extract and recycle
4
Synthesis of Titania Coated Magnetic Nanoparticle
• Methods– Sol-Gel technique
• The core particles (Fe3O4) are produced by a chemical process and then dispersed in the coating solution
• Hydrolysis of titanium butoxide (Ti4O2) in the presence of seeds particle (4-10 nm) – deposition
• Size hard to control (>300nm) – in bulk solution• Clustered magnetite • TiO2 porosity – incomplete encapsulation of
magnetite core surface
General procedure of sol-gel technique
• Alkoxides dissolved an alcoholic solution to form the corresponding hydroxide
• Condensation of the hydroxide molecules by elimination of water leads to formation of a network of metal hydroxide. When all hydroxide species are linked in one networklike structure, gelation is achived
• The gel is a polymer of 3-dimensional skeleton surrounding interconnected pores
• Removal of the solvents and appropriate drying of the gel results in an ultrafine powder the metal hydroxide.
• Further heat treatment the hydroxide leads to the corresponding nanosize metal oxide
5
Sol-Gel MethodsFe3O4 seed EtOH
(half)(half)
H2O HClTBOT
Alcoholic solutionof TBOT & Fe3O4
Hydrolysis &condensation
Gel at 295K
Dry at 338k
Thermal treatment at 723 K
TiO2-Fe3O4
– Proposed Novel Microemusion Process • W/O emulsion to create “Microreactor” or
“Water pool”, reactionTiCl4 + H2O → TiOCl2 + 2HCl
control heating and ageing Time, Temperature, pH, pool compositions
• Controlling the size and shape of the assemblies – Mixing, Surfactant
• Effectively control the resulting nanoparticlesize by control the dimension of “Microreactor”
6
Organic Solvent
Surfactant
FeCl2 aqueous solution
Microemultion
NH4OH
Organic phaseWater phase
Surfactant
Fe3O4 nanoparticle
Formation of Fe3O4 nanoparticlesin microemulsion
Aging at 50∼100 °C
TiOCl2 aqueous solution
TiO2
Formation of TiO2 coating on nano Fe3O4
TiO2 Fe3O4
Nanoparticles composed of a Fe3O4 core and a TiO2 shell
Heat treating
Centrifuging, washing and drying
Schematic showing the w/o microemulsion process for synthesizing TiO2 coated Fe3O4 nanoparticles.
Advantages of Microemulsionmethod
• uniform size – Limited within the “microreactor”
• spherical shape • Homogeneous precipitation of TiO2
• Heterogeneously onto the magnetic (Fe3O4) nanoparticles
• complete encapsulation of Fe3O4
magnetite by TiO2
• no aggregation
7
Control of particle size and agglomeration
• No work has been found on synthesizing TiO2 coated Fe3O4 composite nanoparticles
• Related reports – SiO2/Fe3O4 (see Fig.)
Particles by Sol-Gelmethod
Fig2 TEM morphology of the sample (d)
Sample ( d) is the hydrolysis of Titanium Butoxide in absolute alcohol medium
(d)
280nm
Fig1 TEM morphology of the sample (c)
Sample (c) is prepared by hydrolysis
of Titanium Butoxide in 95% alcohol acidic medium
200nm
(c)
8
TEM photographs of SiO2 coated Fe3O4 nanoparticles
prepared using a w/o microemulsion method
Conclusion• TiO2/Fe3O4 core-shell structure magnetic nanoparticle
can:– Apply magnetic stir to increase photocatalyst efficiency and – Low-cost inorganic metal salt will be used rather than commonly
used expensive metal-alkoxides– Subject to be reuse (recycle) to lower cost
• Collection by megnetic field• Calcination to remove contaminants
• The non-hazardous, reusable catalyst (TiO2), solar energy (UV) and atmospheric oxygen
• The photocatalytic process can occur in ambient condition make it feasible to construct an efficient landfill leachate treatment system