Sustainable Extraction of Critical Metals from Industrial Wastewater: Opportunities and

Challenges

ACS Presidential Symposium

Tuesday August 21, 2012

Philadelphia, PA, USA

Mamadou Diallo Associate Professor and Director of the Laboratory of Advanced Materials and Systems for Water Sustainability, Graduate School of Energy, Environment, Water and Sustainability (EEWS), KAIST Visiting Faculty in Environmental Science and Engineering, Division of Engineering and Applied Science, Caltech Chief Technology Officer and Founder of AquaNano, LLC

Outline

• A. Industrial Wastewater as Sources of Critical Materials • B. Extraction of Critical Materials from Industrial Wastewater:

Overview of Recent Advances • C. Concluding Remarks • D. Acknowledgments

Sustainable Supply of Critical Materials: Sources, Extraction, Recovery and Purification

Computer Circuit Boards as Sources of Critical Materials (Johnson et al. Environ. Sci. Technol. 2007, 41, 1759-1765)

Wastes as Sources of Critical Materials: The Metals-Specific Sherwood Plot

David Allen. Adapted from Johnson et al. Environ. Sci. Technol. 2007, 41, 1759-1765)

Metal prices (2004) as a function of dilution (1/concentration) of metals in commercial ores. This Sherwood plot illustrates the concept that the more dilute a material is in its native ore, the more expensive it will be to purify into a commodity material.

Industrial Wastewater as Source of Critical Materials

David Allen, MRS Bulletin, March 1992

• Metal Products and Machinery Industry (63,000 sites) • Metal Finishing Industry (44,000 facilities) • Metal Molding and Casting Industry ( > 700 facilities) • Mineral Mining and Processing • Nonferrous Metals Manufacturing • Semiconductor Industry

Examples of Industrial Discharges of Wastewater Containing Metals

These industries are all subject to the effluent guidelines promulgated by EPA, under '40 CFR’ of the Code of Federal Regulations (CFR).

Extraction of Critical Materials from Wastewater: Scientific Grand Challenges

• Design and synthesize high capacity, recyclable

and robust separation materials (e.g. chelating ligands, ion exchange media and sorbents) that can – Selectively extract critical materials from complex

aqueous solutions (e.g., highly acid and/or saline media)

– Be seamlessly integrated with existing separation equipment including (i) packed bed reactors, (ii) pressure vessels, (iii) clarifiers and (iii) membrane modules and systems.

Dendritic Macromolecules as High Capacity, Selective and Recyclable Chelating for Cu(II) and Ag(I)

G4-NH2 PAMAM Dendrimer

Selectivity versus Capacity

Dendritic Macromolecules as High Capacity, Selective and Recyclable Chelating for Cu(II) and Ag(I) [Cont]

160

140

120

100

80

60

40

20

0

160140120100806040200Metal-Ion Dendrimer Loading (mole/mole)

G4-NH2 pH 7 replicate 1 G4-NH2 pH 7 replicate 2 G4-NH2 pH 7 replicate 3 G4-NH2 pH 9 G4-NH2 pH 5

EOBmax1=12.0

EOBmax2=74.0

Diallo et al. Langmuir. 2004, 20, 2640-2651

At pH 9.0, the G4-NH2 PAMAM dendrimer binds more than 100 Cu(II) Ions at pH 9.0. At pH 5.0, we observe no binding of Cu(II) to the G4-NH2 PAMAM dendrimer.

Extraction of Cu(II) and Ag(I) from Solutions Using Dendrimer Enhanced Ultrafiltration

Highly branched and water-soluble macromolecules with tunable ion binding sites

• Large size allows for low pressure membrane (MF/UF) separation

• Easily integrated into existing treatment systems

• Scalable – for small and large scale applications

Diallo, M.S. Water Treatment by Dendrimer-Enhanced Filtration (US Patent 7,470,369)

Case Study: Recovery of Cu(II) from Aqueous Solutions by Crossflow Dendrimer Enhanced Filtration

Diallo et al. Environ. Sci. Technol. 2005, 39, 1366-1377.

Crossflow GE Osmonics Sepa Cell

Prototype of First Generation Dendrimer Enhanced Filtration System (AquaNano, LLC)

UF 1: IMT Multibore Ultrafiltration Membrane: Membrane: Bore Size: 0.9 mm Chemistry: Modified PES MWCO: 100 to 150 kD Active Area: 0.5 m2

Operation: Nominal Flow: 40 L/hr Flux: 75 L/m2/hr UF 2: X-Flow Tubular Ultrafiltration Membrane: Membrane: Bore Size: 8.0 mm Chemistry: Modified PES MWCO: 100 to 150 kD Active Area: 0.3 m2

Operation: Nominal Flow: 17 L/hr Flux: 55 L/m2/hr

Could achieve large water recovery (> 95%) and concentration factor (> 4000)

Acknowledgments ( US:Caltech, AquaNano, etc ) Team) Program)

• Senior Collaborators: Prof. William A. Goddard III (Caltech), James H. Johnson (Howard U), Prof. Jean Frechet (UC-Berkeley), Prof. Donald Tomalia (Central Michigan University) and Dr. Glenn Waychunas (Lawrence Berkeley National Laboratory)

• Staff Scientists and Post Doctoral Research Associates : Dr. Vyacheslav Bryantsev (Caltech), Dr. Tapan Shah (Caltech), Dr. Joytsnendu Giri (Caltech), Dr. Yi Liu (Caltech), Dr. CJ Yu (AquaNano), Dr. Emine Boz (UC-Berkeley), Dr. Samuel Webb (Stanford Synchrotron Radiation Laboratory) and Dr. Pirabalina Swaminathan (Howard U)

• Graduate and Undergraduate Students: Simone Christie (Howard U), Sa’Nia Carasquero (Howard U), Kwesi Falconer (Howard U), Mary Maneno (Howard U), Elijah George (Howard U), Margaret Barris-Milman (Caltech) and John Howard (Caltech)

• US National Science Foundation (Funding) • US EPA STAR Program (Funding) • Aqua Nanotechnologies (Funding) • Stanford Synchrotron Radiation Laboratory (EXFAS and XANES Experiments) • Advanced Light Source of Lawrence Berkeley National Laboratory (NEXAFS

Experiments)

Acknowledgments (Korea: KAIST) • Senior Collaborators: Prof. Yousung Jung (KAIST Graduate School of EEWS) and

Prof. William A. Goddard III (KAIST Graduate School of EEWS) • Staff Scientists and Post Doctoral Research Associates : Dr. Seongjik Park (KAIST) and

Dr. Chidralaravi Kumar (KAIST) • Graduate Students: Man-Ki Cho (KAIST), Doyeon Lee (KAIST), Dennis Chen (KAIST)

and Sang Lee (KAIST) • KAIST EEWS Initiative (Funding) •