Potentiostatic Anodization for Resource Recovery and Purification in - - PowerPoint PPT Presentation

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.

Environmental Materials Laboratory (EML)

01 02

The 12th U.S.-Korea Forum on Nanotechnology

Anodization

Environmental Materials Laboratory (EML)

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.

The 12th U.S.-Korea Forum on Nanotechnology

Environmental Materials Laboratory (EML)

Iron Oxide Nanotubes for Phosphate Recovery in Water

The 12th U.S.-Korea Forum on Nanotechnology

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

The 12th U.S.-Korea Forum on Nanotechnology

Fe0 Fe0 Fe2O3 (hematite), Fe3O4 (magnetite)

Schematic diagram of Iron Oxide Nanotubes

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

Power Supply Circulator Reactor

An anodization apparatus

A lab-scale column for continuous adsorption Device for desorption

The 12th U.S.-Korea Forum on Nanotechnology

Environmental Materials Laboratory (EML)

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

Environmental Materials Laboratory (EML)

AFM 2D and 3D images

(a) Fe foil (b) INTs

2D 3D

The 12th U.S.-Korea Forum on Nanotechnology

Environmental Materials Laboratory (EML)

2 Theta (degree)

20 30 40 50 60 70

Intensity

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

Environmental Materials Laboratory (EML)

(a) Pseudo first-order model (b) Pseudo second-order model (c) Elovich model

Kinetic Model Analyses for Adsorption

(a) (c) (b)

The 12th U.S.-Korea Forum on Nanotechnology

Environmental Materials Laboratory (EML)

(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

Environmental Materials Laboratory (EML)

Binding energy (eV)

200 400 600 800 1000 1200

Counts/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 adsorption After adsorption After 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

The 12th U.S.-Korea Forum on Nanotechnology

Environmental Materials Laboratory (EML)

Photocatalytic Metal Membrane with Self-Organized Reactive TiO2 Nanotubes.

The 12th U.S.-Korea Forum on Nanotechnology

▪ 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

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

▪ 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.

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

TiO iO2 na nano notub ube

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

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

FE-SEM images , Stable TiO2 Soluble TiO2 pH vs. pF curve in various electrolyte

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

Before anodization After anodization

L 150 mm D 15 mm

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

Pure Ti membrane TiO2 membrane embedded with nano tube

Energy Dispersive X-ray spectroscopy (EDX)

Oxygen content 9 wt% Oxygen content 41 wt%

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

X-ray diffraction (XRD) patterns

(a) Anodization and annealing (b) Untreated Ti membrane

TEM analysis

Crystal fringe distance : 3.51 Å corresponding to spacing of (101) of the anatase phase TiO2

(a) cross section (b) a part of nano tube (c) Crystal fringe distance

b

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

10 20 30 40 50 30 60 90 120 Time (minute) Ln (C0/Ct, CODcr base) 10 20 30 40 50 30 60 90 120 Time (minute) Ln (C0/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)

The 12th U.S.-Korea Forum on Nanotechnology

0.2 0.4 0.6 0.8 1 30 60 90 120

J/ J0

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.

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology

Environmental Materials Laboratory (EML)

Disinfection Oxidation Filtration Anodization enabled the fabricated nano-structured TiO2 metal filter with dual functions of filtration and

• xidation, 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

■ ■ ■ ■

The 12th U.S.-Korea Forum on Nanotechnology

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).

Environmental Materials Laboratory (EML)

The 12th U.S.-Korea Forum on Nanotechnology