Potentiostatic Anodization for Resource Recovery and · PDF file · 2015-10-10Laboratory (EML) Nanotube ... Detergent Cleaner Fertilizer Soap Polisher Dyestuffs Various ... Photocatalytic

Jong-Oh Kim
Department of Civil and Environmental Engineering Hanyang University, Republic of Korea
October 5, 2015
Environmental Materials Laboratory (EML)
Potentiostatic Anodization for Resource Recovery and Purification in Water
The 12th U.S.-Korea Forum on Nanotechnology

Iron Oxide Nanotubes for Phosphate
Recovery in Water.
Photocatalytic Metal Membrane with
Self-organized Reactive TiO2 Nanotubes.
01
02

Anodization
Nanotube Formation Useful method for modifying
the surface structure to obtain
nanoporous array.
The surface of valve metal is
instantaneously covered with
a native oxide film when these
metals are exposed to oxygen
containing environment. High surface area. Short solid-state diffusion path for catalysis and energy application. Fabrications are simple and cost effective.

Iron Oxide Nanotubes for Phosphate Recovery in Water

Phosphorus
Phosphorus is an essential component for food production and industrial growth.
The global supply of this non-renewable resource is limited.
Most researches were focused on the removal not recovery.
Recovered phosphate can be reused at various demands. Environmental Materials Laboratory (EML)
Detergent
Cleaner
Fertilizer
Soap
Polisher
Dyestuffs
Various Demand
Others: Lithium Ion Battery, Developer, Ceramics, Cosmetics, Cement, Artificial teeth etc.
Dees Lijmbach (Chris Thornton) "Phosphate removl and phosphate recovery: towards sustainable development" COPPERAS-November 2000

Fe0
Fe0
Fe2O3 (hematite), Fe3O4 (magnetite)
Schematic diagram of Iron Oxide Nanotubes

Power Supply
Circulator
Reactor
An anodization apparatus A lab-scale column for continuous adsorption
Device for desorption

40 V & 60 min 40 V & 90 min 60 V & 60 min 60 V & 90 min
20 V & 5 min 20 V & 30 min 20 V & 60 min 20 V & 90 min
1M Na2SO4 + 0.5 wt% NH4F
Ethylene glycol + 3.0 wt% NH4F
FE-SEM images of INTs The 12th U.S.-Korea Forum on Nanotechnology

AFM 2D and 3D images
(a) Fe foil (b) INTs
2D
3D

2 Theta (degree)
20 30 40 50 60 70
Inte
nsity
3.0 wt% NH4F (60 min)
1.5 wt% NH4F (60 min)
1.0 wt% NH4F (60 min)
Fe Foil
Magnetite
Hematite
Iron
XRD pattern The 12th U.S.-Korea Forum on Nanotechnology

(a) Pseudo first-order model
(b) Pseudo second-order model (c) Elovich model
Kinetic Model Analyses for Adsorption
(a)
(c)
(b)

(b) Repeated adsorption and desorption for reusability.
(a) (b)
(a) Desorption efficiency of phosphate- adsorbed INTs depending on various concentrations of NaOH.
Desorption and Reusability

Binding energy (eV)
0 200 400 600 800 1000 1200
Cou
nts/
s
0.0
5.0e+4
1.0e+5
1.5e+5
2.0e+5
2.5e+5
3.0e+5
3.5e+5
Before adsorptionAfter adsorptionAfter desorption
Atomic fraction (%) Fe O P
Before adsorption 23.6 74.8 -
After adsorption 10.5 78.8 10.7
After desorption 12.9 86.2 0.4
X-ray Photoelectron Spectroscopy (XPS) of INTs

Photocatalytic Metal Membrane
with Self-Organized Reactive
TiO2 Nanotubes.

Water and wastewater treatment systems using TiO2 photocatalytic reaction have been widely developed. - High oxidation-reduction potential for refractory organics decomposition. - Reduction of excess sludge. - Low cost & Non-toxic. Problem : Separation between TiO2 particles and purified water. Requires post-TiO2 particles recovery process. Causes engineering difficulties in automatic operation.
Organics H2O, CO2
TiO2

Although several immobilization methods were tried to improve the treatment performance, there are not satisfied aspects due to TiO2 particle exfoliation and activity decrease in long-term operation.

TiO2 nanotube
Permeate
. . .
. . . . . . . . .
. . .
. . . . .
. . . . . . . . .
Feed
Ti membrane anodization
Characteristics of proposed technology
Ti membrane
- No requirement of catalyst separation process
- Enhancement of adsorption
- Long retention time for photocatalytic reaction
Nanostructured photocatalytic TiO2 membrane
Minimize membrane fouling & Maximize degradation efficiency of contaminants

FE-SEM images
,
Stable TiO2
Soluble TiO2
pH vs. pF curve in various electrolyte Environmental Materials Laboratory (EML)

Before anodization After anodization L 150 mm D 15 mm

Pure Ti membrane TiO2 membrane embedded with nano tube
Energy Dispersive X-ray spectroscopy (EDX)
Oxygen content 9 wt% Oxygen content 41 wt%

X-ray diffraction (XRD) patterns
(a) Anodization and annealing (b) Untreated Ti membrane
TEM analysis
Crystal fringe distance : 3.51 corresponding to spacing of (101) of the anatase phase TiO2
(a) cross section (b) a part of nano tube
(c) Crystal fringe distance
b

0
10
20
30
40
50
0 30 60 90 120
Time (minute) Ln
(C0/C
t, CO
D cr b
ase)
0
10
20
30
40
50
0 30 60 90 120
Time (minute)
Ln (C
0/Ct,
TOC
base
)
With anodization/UV on With anodization/UV off Without anodization/UV on
Photocatalytic activities
Organics removal
Rate constants : TiO2 membrane with UV > TiO2 membrane without UV
> without anodization with UV . Environmental Materials Laboratory (EML)

0
0.2
0.4
0.6
0.8
1
0 30 60 90 120
J/J 0
Time (minute)
Distilled water Humic acid + UV on
Humic acid + UV off
Permeation flux ratio (J/J0) of anodized TiO2 metal membrane
Permeation flux ratio with UV-on showed about 8 times higher value than that of UV-off at 2 hrs filtration.

Disinfection Oxidation
Filtration
Anodization enabled the fabricated nano-structured TiO2 metal filter with dual functions of filtration and oxidation, at the same time.
With this new technology combined with NT and ET, we are hoping for a marked improvement on phosphate recovery and treatment efficiency compared to the conventional methods.
The use of nanomaterials in water and wastewater treatment has attracted a growing amount of attention due to the excellent electrical, magnetic, and catalytic properties of nanomaterials.
In phosphate recovery, INTs are useful to recover phosphates in wastewater because additional collection of adsorbents is unnecessary and industrial byproducts can be used as raw materials to prepare INTs.
Conclusion

Acknowledgements This work was supported by Basic Science Research Program through National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2013R1A2A1A09007252).

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Potentiostatic Anodization for Resource Recovery and · PDF file · 2015-10-10Laboratory (EML) Nanotube ... Detergent Cleaner Fertilizer Soap Polisher Dyestuffs Various ... Photocatalytic