Adsorption of surfactant on pyrite mineral and degradation of pyrene by pyrite fenton reaction

Adsorption of surfactant on pyrite mineral and degradation of
pyrene by pyrite-Fenton reaction 
Meherunnesha Binte Mannan
Advisor: Professor Woojin Lee
Master’s Thesis Presentation
2010.06.08

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Hazardous Substances Control and Environmental Remediation Laboratory 
1
2
3
4
Introduction
Hypothesis and Objectives
Materials and Method
Results and Discussion
Contents
Conclusions and Implication5

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Introduction
1 Environmental Problems
1.1 Scenario 1. Surfactant Contamination
1.2 Scenario 2. Pyrene Contamination
2 Pyrite as an Environmental Clean Up Tool

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Scenario 1.Surfactant Contamination
Text1
Text6
Uses of Surfactant
Household detergents
Colloidal Stability
Paints and coatings
Lubrication
Emulsion and polymerization
Mineral flotation
Metal flotation
Pesticides
Consumer Products
Environment (natural waters)
Effluent from WWTP Industrial/Household
discharge
✓Foaming problems on river
✓Sublethal toxic effects on zooplankton
✓Vulnerable for plants and animals
✓Hormonal problems for human
Introduction.

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Scenario 2. Pyrene Contamination
Characteristics
Entrance to
Environment
Environmental and
Health Impact
✓Four ring polycyclic aromatic hydrocarbon
✓Water solubility is 0.135 mg/L
✓Binds well to organic compounds in the soil
✓Combustion of Petroleum, coal, tobacco
✓Wastewater and sludge from these processes
✓Oil spills and underground gasoline storage
leakages
✓Soil and groundwater contamination
✓Reincreased risk of cancer
✓Productive difficulties
Pyrene
Introduction.

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Scenario 2. Pyrene Contamination
Entrance to
Environment
Environmental and
Health Impact
Pyrene
Introduction.
Soil washing with
surfactant
Pyrene in soil
Pyrene in
surfactant

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Pyrite as an Environmental Clean up Tool
✓ For scenario 1. Adsorption of surfactant on pyrite surface
✓ For scenario 2. Degradation of pyrene solubilized in surfactant by pyrite-Fenton reaction
Pyrite as an Adsorbent ?
Introduction.
+ + + +
+
+ + +
+
+ +
+
Pyrite surfaces at <PZC Pyrite surfaces at >PZC
✓ Natural minerals.
✓ Possesses surface charge (+/-)
▪ Fe vacancies – hydrophilic
▪ S-S-H site - hydrophobic
✓ Point of zero charge (PZC) at pH (6.2 – 6.9).
✓ Below PZC, surface is positively charged.
✓ Above PZC, surface is negatively charged.
Pyrite
Micelles
✓Consists of hydrophobic tail groups and
hydrophilic head groups.
✓A single molecule – monomer.
✓It has a critical micelle concentration
(CMC), above that conc it aggregates to form
micelle.
Surfactant
-+Hydrophilic Head
Hydrophobic Tail
Monomers

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Introduction-Pyrite as an Environmental Clean up Tool
Plausible reaction mechanism in pyrite-Fenton system for pyrene degradation
H2O2
OH- + ●OH
!
!
Pyrite surface Fe (II)Fe (III)
✓ Natural iron mineral – available source for Fe(II)
✓ Production of hydroxyl radical (•OH ) by introducing hydrogen
peroxide (H2O2 )
▪ FeS2(s) + 7/2 O2(aq) + H2O = Fe+2 + 2SO4
-2 + 2H+
▪ Fe +2 + H2O2 = •OH + OH- + Fe+3
✓ Recycle of Fe (II)
!
(Moses, C.O., et al., 1990)
Introduction.
Pyrite for Pyrene Degradation ?
Pyrene in surfactant
Products

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Hypothesis and Objectives 
Hypothesis
Objectives
✓Surfactant adsorption depends on the PZC of pyrite surface
✓Pyrene solubilized into surfactant could be significantly degraded
using pyrite through the Fenton reaction mechanism
✓To determine the adsorption capacity of pyrite at different pH
✓To support the adsorption phenomena conduct zeta potential and
phreeqc analysis
✓To determine the kinetic degradation of pyrene by pyrite-Fenton
reaction
✓To observe the effect of pyrite loading, H2O2, NaCl and initial pH

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Materials and Method 
Teflon-lined rubber septum
24 mL amber Vial
Open-top Cap
Analysis - Adsorption
✓Pyrene by High performance liquid
chromatography, HPLC
▪HPLC mobile phase -80%
Acetontrile with DDIW
▪Flow condition-Isochratic flow at
2 ml/min
▪Wave length for UV
detection-254 nm
✓Ferrous and ferric iron by ferrozine
method at 562 nm
✓H2O2 by titanium sulfate method at
405 nm
Materials
✓Cationic surfactant
▪cetylpyridinium chloride (CPC)
✓Pyrene
✓Adsorbent and source of Fe - Pyrite
✓Classic Fenton-Iron(II) sulfate heptahydrate
✓Fenton reaction initiator - H2O2
Experimental condition
✓Batch type reactor
✓Aerobic condition
✓Room temperature (25 ℃ ±1 ℃)
✓CPC by UV-vis spectroscopy at 258 nm
Analysis - Degradation
✓Zeta potential of pyrite by photal zeta
potential analyzer

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Scenario 1. 
Adsorption of CPC on pyrite surface 
 

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Maximum Adsorption Capacity
Figure 1. Adsorption isotherms (a) below and (b) above the point the PZC and (C) Maximum
adsorption capacity at different pH
Decrease in
Adsorption
Decrease in
Adsorption
pH5< pH 6< pH 7> pH 8> pH 9
Adsorption
Equilibrium CPC Concentration (mmol/L)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
AmountCPCAdsorbed(mmol/Kg)
0
100
200
300
400
pH > PZCpH 7
pH 8
pH 9
0.0 0.2 0.4 0.6 0.8 1.0 1.2
0
50
100
150
200
250
pH < PZC
pH 6
pH 5
(a) (b)
pH
4 5 6 7 8 9 10
MaximumAdsorptionCapacity(mmol/Kg)
0
50
100
150
200
250
300
350
400
(c)

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Zeta Potential Analyses
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
ZetaPotentialValue(mV)
-20
-10
0
10
20
30
40
pH 7
pH 8
pH 9
pH > PZC
✓ Positive zeta potential value – hydrophobic
adsorption
✓ Initially negative value changed to positive with
adsorption progress.
▪ A charge reversal – existence of a double layer.
Figure 2. Zeta potential value at pH 5 and 6. Figure 3. Zeta potential at pH 7, 8 and 9.
Adsorption
zero charge
0.0 0.2 0.4 0.6 0.8 1.0 1.2
0
5
10
15
20
25
30
pH 6
pH 5
pH < PZC

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Phreeqc Analysis
✓ At pH 7, iron complexes layer on surface (Fe vacancies site – hydrophilic site)
▪ Multilayer adsorption
✓ pH > 7, the activity of charged surface becomes lower due to precipitation tendency
✓ pH<7, only the S-S-H site (hydrophobic) is responsible for adsorption
▪ The lower the pH, the higher the surface as protonated
▪ Single layer adsorption
Solution pH
5 6 7 8 9
SaturationIndices(SI)
-12
-10
-8
-6
-4
-2
0
2
4
ConcentrationofSpecies(molality)
0.0
5.0e-9
1.0e-8
1.5e-8
2.0e-8
2.5e-8
3.0e-8
3.5e-8
Hematite (Fe2O3)
Goethite (FeOOH)
Fe+2
SO4
-2
Supersaturated
ZoneMetastable ZoneUndersaturated Zone
✓ Dominating phase (minerals)
▪ Hematite and goethite
✓ Dominating species
▪ Ferrous and sulfate
✓ Metastable zone starts from pH 7
(constant species release is an indication
of metastable phase)
✓ Supersaturation zone starts from pH 8.1
(Saturation indices = 0 )
Figure 4. Distribution of solution species and saturation indices at pH 5 to 9.
Adsorption

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Electrolyte Effect
0.0 0.2 0.4 0.6 0.8 1.0
0
100
200
300
400
Control (pH 7)
0.01 M NaCl (pH 7)
0.1 M NaCl (pH 7)
Control (pH 5)
0.01 M NaCl (pH 5)
0.1 M NaCl (pH 5)
0.0 0.2 0.4 0.6 0.8
-30
-20
-10
0
10
20
30
pH 5
pH 7
Adsorption
Figure 6. Zeta potential at pH 5 and 7 with NaCl.Figure 5. Adsorption isotherm at pH 5 and 7 using
Langmuir model with NaCl.
✓ Whatever the pH, NaCl decreased the adsorption
✓Zeta potential value at high CPC conc is always negative
Electrolyte reduce adsorption by shielding effect

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Scenario 2. 
Degradation of Pyrene in Pyrite Fenton Reaction

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Degradation of Pyrene by Pyrite Fenton Reaction
✓ Pyrite only - 20% pyrene adsorption on pyrite by CPC
✓ Classic fenton system - 68% pyrene degradation and 2nd order kinetic rate = 0.0019 liter mg-1 min-1
✓ Pyrite-Fenton system -100% pyrene degradation within 90 min and 1st order kinetic rate constant
0.029 min-1
Time (min)
0 40 80 120 160 200 240 280 320 360 400
Concentrationofpyrene(ppm)
0
2
4
6
8
10
12
Control 1. CPC+Pyrene
Control 2. CPC+Pyrene+H2O2
Control 3. CPC+Pyrene+Pyrite
Classic Fenton
Pyrite + H2O2
Classic Fenton system
Fe +2 + H2O2 = •OH + OH- + Fe+3
•OH + C16H10 (Pyrene) = CO2 + H2O
Pyrite Fenton system
Degradation
Figure 7. Degradation of pyrene by classic and Fenton reaction.
Fe+2 + •OH = OH- + Fe+3
Pyrene or Ferrous?

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Effect of Fe(II)
✓ Given source of Fe(II) with same concentration
▪ Reaction of Fe(II) with •OH predominates in classic Fenton system.
▪ Reaction of pyrene with •OH predominates in pyrite Fenton system due to less release of
initial Fe(II).
Media Initial
Concentration of
Fe(II), mM
Classic Fenton 25
Pyrite Fenton 0.22
✓Both Fe(II) and pyrene can contribute to scavenge •OH
✓For Fe(II)
✓Fe+2 + •OH K1 OH- + Fe+3
✓•OH scavenging factor = K1 * CFe+2 = 3.2*108 M-1 S-1 * CFe+2 , (Here,CFe+2 = Total Fe(II) conc.)
✓For pyrene
✓Pyrene + •OH K2 Product
✓•OH scavenging factor = K2 * Cpyrene = 1.5 * 1010 M-1 S-1 * Cpyrene , (Here, Cpyrene = Total pyrene
conc.)
•OH scavenger Value of
scavenging
factor,
Pyrene 8.91 * 10
Fe (II) (Classic
Fenton)
8.00 * 10
Fe (II) (Pyrite
Fenton)
7.04 * 10
Degradation
Table 1. Concentration of Fe(II) Table 2. Scavenging factor of •OH

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Effect of Pyrite Loading
Time (min)
0 100 200 300 400
ConcentartionofPyrene(mg/L)
0
2
4
6
8
10
12
0 g/L Pyrite
0.5 g/L Pyrite
1 g/L Pyrite
2 g/L Pyrite
3 g/L Pyrite
RateConstant(min-1)
0
0.0075
0.015
0.0225
0.03
Pyrite Loading (g/L)
0 1 2 2 3
✓Increasing pyrite loading increased pyrene degradation and the increase of rate constant was linear.
▪Production of Fe(II) is the rate limiting factor in pyrite Fenton system.
▪Higher concentration of pyrite provides higher surface for Fe(II) production
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Degradation
Figure 8. Effect of pyrite loading on pyrene degradation. Figure 9. Kinetic rate constant vs pyrite loading.

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Effect of H
2
O
2
Time (min)
0 100 200 300 400
ConcentrationofPyrene(mg/L)
0
2
4
6
8
10
12
0 mM H2O2
0.043 mM H2O2
0.22 mM H2O2
0.43 mM H2O2
0.86 mM H2O2
1.83 mM H2O2
Concentration of H2O2 (mM)
0 1 2 3 4
RateConstant(min-1
)
0.00
0.02
0.04
0.06
0.08
0.10
✓ Increasing H2O2 concentration gave an exponential rise to a maximum rate constant upto 0.86 mM
and after that it reached to a saturation system.
▪ H2O2 + •OH = HO2• + H2O
▪ HO2 • + •OH = H2O + O2
Degradation
Figure 10. Effect of H2O2 on pyrene degradation. Figure 11. Kinetic rate constant vs H2O2 .

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Effect of NaCl
Concentration of NaCl (M)
0.00 0.05 0.10 0.15 0.20 0.25
RateConstant(min-1
)
0.00
0.02
0.04
0.06
0.08
0.10
Time (min)
0 100 200 300 400
0
2
4
6
8
10
12
0 M NaCl + H2O2
0.001M NaCl + H2O2
0.01M NaCl + H2O2
0.055 M NaCl + H2O2
0.1M NaCl + H2O2
0.2 M NaCl + H2O2
✓ Increasing NaCl concentration gave an exponential rise to rate constant upto 0.1M and after
that it reached to a saturation system.
✓ Kinetic rate constant of pyrene degradation with 0.1 M NaCl was 2.9 times higher than
without NaCl.
!
Degradation
No NaCl
0.1 M NaCl
Figure 13. Kinetic rate constant vs NaCl.Figure 12. Effect of NaCl on pyrene degradation.

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Effect of Initial pH
Time
0 100 200 300 400
0
2
4
6
8
10
12
pH 11
pH 9
pH 7
pH 5
pH 3
✓ Rate constant at pH 3 was observed 2.78 times higher than at pH 11
✓ Release of Fe(II) decrease as pH increase which eventually reduce •OH production
Degradation
Figure 14. Effect of initial pH on pyrene degradation.
pH
2 4 6 8 10 12
RateConstant(min
-1
)
0.00
0.02
0.04
0.06
0.08
Figure 15. Kinetic rate constant vs pH

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Conclusions and Application
✓ Adsorption
▪ The maximum adsorption was at pH 7.
▪ Zeta potential and phreeqC analyses supported the adsorption
phenomena.
✓ Degradation
▪ 100% pyrene could be degraded in pyrite Fenton system.
▪ Increased pyrite loading, presence of NaCl and low initial pH
could enhance pyrene degradation.
✓ These systems could be applied to treat the wastewater
contaminated by surfactant and surfactant containing pyrene.

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Further Study
✓Intermediates of pyrene degradation
✓Degradation of other PAHs
!

Thank You !
✓ KAIST Fellowship and GAIA project (173-081-026, Ministry of Environment) – financial support
✓ Entire lab members – special suggestions and mental support.

Adsorption of surfactant on pyrite mineral and degradation of pyrene by pyrite fenton reaction

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