1. 7th International YWP conference, Taipei Chinese Taiwan
Adsorption of heavy metals by an iron coated natural Australian zeolite Thuy Chung Nguyen Paripurnanda Loganathan, Tien Vinh Nguyen, Jaya Kandasamy, Ravi Naidu, Saravanamuthu Vigneswaran
Good afternoon
7th International YWP conference, Taipei Chinese Taiwan

2. content Objectives Introduction Materials and methods
Results and discussion
Conclusions
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3. OBJECTIVES
Determine the adsorptive removal of heavy metals (Zn, Cd, Cu, Pb and Cr) from synthetic water using zeolite and iron- coated zeolite (ICZ)
Model equilibrium adsorption
Model kinetic adsorption
Determine the breakthrough adsorption capacity in fixed-bed columns
Model fixed-bed column adsorption
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4. Introduction
Heavy metals may enter natural water bodies (lakes, rivers) from industries, roads, and agricultural activities
At elevated concentrations, many heavy metals can be toxic to aquatic organisms and humans
Therefore, they should be removed from the water
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5. Introduction
HM removal technology
Membrane filtration
Oxidation reduction
Ion exchange
Electro-dialysis
Adsorption
Reverse osmosis
Several methods are available for the removal of heavy metals. Of these, adsorption is an attractive method because it is a simple, environmentally friendly and effective method
Low cost and locally available absorbents are attractive
Zeolite is one of the popular adsorbent used to remove heavy metals. However, its effectiveness can be increased by chemical modification such as coating with metal oxides
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6. Introduction
Zeolites exist in large amounts in Australia and many other countries. It has large cation-exchange capacity and is capable of removing large quantities of heavy metals from contaminated water.
The modifications of zeolites such as coating of hydrous ferric oxide (HFO) or manganese oxide on zeolite can enhance the ligand sorption capacity of heavy metal ions.
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7. Method of preparation of Iron-coated zeolite (Doula 2009)
MATERIALS AND Method
Method of preparation of Iron-coated zeolite (Doula 2009)
Structure of Zeolite
Zeolites (natural and synthetic) are materials in which (SiO4)4 and (AlO4)5 tetrahedra are linked by sharing oxygen atoms to give ring structures, which, in turn, are linked to give
an overall three-dimensional structure which contains regular channels and cavities (like honeycomb) of sizes similar to those of small to medium-sized molecules.

8. MATERIALS AND Method Batch equilibrium adsorption
Single metals and mixed metals (pH 6.5)
Langmuir adsorption isotherm model
Batch kinetic adsorption
Pseudo-first and pseudo-second order models
Column adsorption
Single metals and mixed metals (pH 5.0), column height 10 cm, flow rate 0.52 m/h, duration of experiments (for single hrs, for mixed metals ~ 24hrs)
Thomas model

9. MATERIALS AND Method Model Equation
Graphical method used to calculate model constant
Langmuir
q e = q max K L C e 1+ K L C e
C e q e = 1 q max K L + C e q max
C e = equilibrium concentration of HM (mg/L), q e = amount of HM, C e = equilibrium concentration of HM (mg/L), q e = amount of HM adsorbed (mg/g), q max = maximum amount of HM adsorbed (mg/g); KL = Langmuir constant related to the energy of adsorption (L/mg)
Pseudo-first order kinetic
dq t dt = k 1 ( q e − q t )
ln ( q e − q t) =ln q e − k 1 t
q e = amount of HM adsorbed at equilibrium (mg/g); q t = amount of HM adsorbed at time, t (min) (mg/g) and k 1 = equilibrium rate constant of pseudo-first order sorption (1/min)
Pseudo-second order kinetic
dq t dt = k 2 ( q e − q t ) 2
t q t = 1 k 2 q e t q e
q e = amount of HM adsorbed at equilibrium (mg/g); q t = amount of HM adsorbed at time, t (min) (mg/g) and k 2 = equilibrium rate constant of pseudo-second order (1/min)
Thomas
𝒍𝒏 ( 𝑪 𝒐 / 𝑪 𝒕 −𝟏)= 𝒌 𝑻𝒉 𝒒 𝒐 𝐌/𝐐−𝒌 𝑻𝒉 𝑪 𝒐 𝐭
𝒌 𝑻𝒉 = Thomas rate constant (mL/min mg), 𝒒 𝒐 = equilibrium HM uptake per g of zeolite (mg/g), 𝑪 𝟎 = inlet HM concentration (mg/L), 𝑪 𝒕 = outlet HM concentration at time t (mg/L), M = mass of zeolite (g),
Q = filtration velocity (mL/min) and t = filtration time (min)

10. Fixed bed column experimental set-up
MATERIALS AND Method
Flow rate: 0.52 m/h, height 10 cm
Up flow
Mass of zeolite and ICZ: 40 grams
pH 6.0 (for single) and pH 5.0 (for mixture)
Fixed bed column experimental set-up

11. results FTIR XRD SEM EDS Surface area (BET)
Similar XRD and FTIR between zeolite and ICZ
EDS:
Zeolite Fe content 3.42%
ICZ Fe content %
Surface area: Zeolite m2/g ICZ m2/g
SEM: Iron coated on the surface of zeolite
FTIR
XRD
SEM
EDS
Surface area (BET)
Zeolite X
ICZ X

12. Isotherm adsorption experiment for single and mixed metals
results
Zeolite
ICZ
Isotherm adsorption experiment for single and mixed metals

13. results Adsorption capacity for all HMs: ICZ > Zeolite
Pb > Cu > Cd > Zn > Cr
Mixed metals competition for adsorption at high concentrations
Single metal adsorption higher than mixed metals
Zero point of charge: Zeolite pH < 3.0; ICZ pH 5.8
Zeta potential values
Langmuir model parameters for HM adsorption on zeolite and ICZ at pH 6.5
Qmax Pb Cu Cd Zn Cr
Langmuir
Zeolite
Sinlge
9.97
8.53
6.72
5.83
5.03
Mixture
6.54
4.34
4.20
3.72
4.01
ICZ
11.16
9.33
7.24
6.22
5.47
7.63
6.11
4.42
4.61
3.89

14. results Kinetic experiment (single)
Qe (mg/g) Pb Cd Cu Zn Cr
Zeo
Qe exp.
4.70
3.90
4.40
4.00
2.50 Qe
6.17
5.32
4.61
4.54
4.04
ICZ
5.29
4.13
4.92
3.96
2.56
5.20
4.50
4.10
3.70
The kinetic adsorption data fitted satisfactorily to both pseudo 1st and pseudo 2nd order models for both single and mixed metals system but 2nd order is better than 1st order
Better fit of pseudo second-order suggested that chemical process may be the rate-limiting step in the adsorption
Kinetic experiment (mixture) Pb Cd Cu Zn Cr
Zeo
Qe exp.
5.57
4.30
3.61
3.96
2.42 Qe
4.70
3.70
3.50
3.30
2.40
ICZ
6.03
4.81
4.18
5.36
3.55
5.10
4.10
3.80
3.20

15. results
Zeolite
ICZ
Shoud be opposite side: metal order should be in the order of adsorption capacity
Kinetic experiments for single and mixed metals at pH 6.5

16. Breakthrough adsorption capacities and Thomas model parameters
results
Column experiment
Breakthrough adsorption capacities and Thomas model parameters HM
Individual metal
Metal mixture Qe Qo R2
Zeolite Pb
1.67
1.61
0.924
0.63
0.61
0.899 Cd
1.32
1.29
0.894
0.52
0.876 Cu
1.15
1.14
0.949
0.48
0.49
0.879 Zn
1.19
1.10
0.959
0.45
0.41
0.917 Cr
0.81
0.74
0.945
0.35
0.32
ICZ
2.28
2.03
1.03
0.95
0.954
1.89
1.82
0.933
0.93
0.86
0.940
1.70
0.948
0.89
0.83
0.946
1.66
0.919
0.75
1.17
1.08
0.76
0.67
0.957
Qe: Breakthrough adsorption capacity (mg/g)
Qo: Thomas adsorption capacity

17. results Single adsorption for all metals Adsorption capacity :
ICZ > Zeolite:
Pb > Cd > Cu > Zn > Cr

18. results Mixed HMs Adsorption capacity :
Breakthrough time for ICZ longer than for zeolite
For both zeolite and ICZ, HMs adsorption order: Pb > Cd > Cu > Zn > Cr

19. Mechanism of heavy metal adsorption on adsorbents
results
Mechanism of heavy metal adsorption on adsorbents
Ligand exchange
M(OH)2: precipitation
Low pH
High pH
Electrostatic induction is a redistribution of electrical charge in an object, caused by the influence of nearby charges
Precipitation

20. CONCLUSIONs
Equilibrium adsorption data sastisfactorily fitted to Langmuir model for all single and mixed HMs
Langmuir adsorption capacities of HMs: Pb > Cu > Cd > Zn, Cr for single metal ( mg/g) and for mixed metals solution ( mg/g).
The kinetic adsorption data fitted reasonably well to the pseudo-second-order
Batch adsorption shows better for zeolite and ICZ

21. CONCLUSIONs
Breakthrough adsorption capacity for single and mixed HMs in zeolite and ICZ column
Pb > Cd > Cu > Zn > Cr
Langmuir > Freudlich
Pseudo first-order > Pseudo second-order
All column breakthrough data fitted satisfactorily by Thomas model
Both the batch and column adsorption data showed that ICZ had higher metal adsorption capacity than zeolite
ICZ is a potential adsorbent for removing heavy metals from water

22. ACKNOWLEDGEMENT
Thanks so much my supervisors Prof. Vigneswaran, Dr Loganathan and Dr Tien Vinh Nguyen for their great academic supports
We would like to thank the Faculty of Engineering and IT, and Faculty of Science, UTS for technical support
This study was funded by Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) (project number )

23. Thank you for your attention !