Nanocomposite Membranes for Water Purification

Nanocomposite Membranes for Water Purification Sebastián Hernández Minghui Gui Douglas Davenport Lindell Ormsbee, PhD Dibakar Bhattacharyya, PhD Department of Chemical and Materials Engineering University of Kentucky, Lexington, KY – 40506

An Equal Opportunity University

Outline •

Background – Chlorinated contaminants. – Microfiltration membranes. – Hydrogel for nanoparticle synthesis. • Detoxification reactions. • Applications. • Objectives. • Nanoparticle characteristics • Dechlorination studies – Thin flat sheet membranes – Thick flat sheet and Hollow Fiber – Chloride/TCE Ratio Membrane used: PVDF flat sheet (650 nm pore size and 125 mm thickness); Full-Scale Membrane Development with Sepro Membranes (Oceanside, CA)


Chlorinated Organics Background

Superfund Site in Paducah, KY

Soil and ground water contain VOCs, PAHs, PCBs and TCE

Status (Oct. 2014) Proposed Sites Final Sites Deleted Sites http://en.wikipedia.org/wiki/List_of_Superfund_sites_in_the_United_States http://www.as.uky.edu/sites/default/files/spotlight-superfund1.jpg An Equal Opportunity University

Non-Federal (General) 45 1165 367

Federal 4 157 17

Total 49 1322 384

Microfiltration Membrane for NP Systems •

• •

•

• •

•

Open structure and large pore size (200-800 nm). Based in sizeexclusion. Different materials (PVDF, PS, PC, Cellulose, etc.) Porosity up to 70% with operational pressures higher than 10 bar. Highly efficient utilization of available sites Easy accessibility to immobilized nanoparticles inside. Functionalize the membrane pores to obtain special separation and reaction characteristics Membrane used: PVDF flat sheet (650 nm pore size and 125 mm thickness)


50 mm

500 mm

Thin Membrane

Hollow Fiber

100 mm Thick Membrane

Membrane Module

http://ulturawater.com/ http://www.yamit-f.com/english/Article.aspx?Item=651

Hydrogels for Metallic Nanoparticle (NP) Synthesis • • •

•

Functional polymers make responsive hydrogels. Change the reactivity Porous network prevents aggregation and loss. Uniform distribution. Control of separation by environmental changes and tunable size of NPs

-

-

-

- -

-

-

∆pH/ ∆T

-

-


• Swelling is affected by: – Change in Temperature → Hydrophilicty/ Hydrophobicity – Degree of ionization – Nature of the counterions in the fluid. • Ionic content ↑, then repulsive forces ↑ and hydrophilicity ↑

Adapted from Zhang, Xu and Kumacheva. Polymer Microgels: Reactors for Semiconductor, Metal, and Magnetic Nanoparticles. J. AM. CHEM. SOC. 9 VOL. 126, NO. 25 (2004) Adapted from Lowman AM, Smart Pharmaceuticals, www.gatewaycoalition.org/files/NewEH/htmls/lowman.doc, 7 September 2008.

Detoxification Using Metallic Nanoparticles by Reductive/Oxidative Pathway Pollutant Toxicity

High

Low

Reductive pathway 3

2

2'

3'

4 (Cl)n

Very low

5

6

6'

5'

Fe/Pd 4' (Cl)n Membrane

PCBs

OH Nontoxic products H2O2

Biphenyl

Oxidative pathway Very low

Fe2+ 0 Fe

High

Low

Fe2+

Single metal e-/H+

TCE

e-/H+





R  Cl  2e  H  R  H  Cl 

2 H  2e  H 2  Gui et al. J. Membr. Sci. Submitted (2015) Xu, J. & Bhattacharyya, D. Environ Prog 24, 358-366 (2005). He F and Zhao D. Applied Catalysis B: Environmental 84 (2008) 533–540. An Equal Opportunity University

H2

H*

e-/H+

Pd/Ni

Fe0  Fe2   2e  

Bimetallic nanoparticle

e-

0 Fe

e-/H+

Water Solubility

Fe  Fe2   2e  0



2 H 2O  2e   2 H *  2OH  2H *  H 2 Ni R  Cl  e   H * Pd /  R  H  Cl 

Applications Fe2O3

Water Remediation with Nano-structured Materials

Fe

Underground:

Aboveground:

Ex-Situ Remediation In-Situ Remediation • Direct injection (environment • Batch treatment (aggregation • Continuous process → Need of • Supported •injection→ NeedNPs of in different Immobilized and separation issue) immobilized NPs in a suitable immobilized NPs in a suitable supports, e.g. Permeable reacti • Immobilized NPs in membranes support (membrane separation support (hydrogel/membrane hydrodynamic flow system) andwith full-scale development system) barrier, membranes…

Lab scale

Si Membrane

Hydrogel

Commercial scale Membrane module Industrial scale JointLab work scale with Sepro Membrane Inc. An Equal Opportunity University

Hydrogel

Functionalized membrane

Fun sili

Objectives Redox - Thermal polymerization - Strong oxidant - Temp./ Metal accelerant (Fe2+)

Responsive Hydrogel

Ion Exchange with metallic salts

Na+

Fe2+

Metallic reduction NPs formation

Functionalized Microfiltration Membrane

Functionalized Hydrogel

TCE/ PCBs Dechlorination Reductive/ Oxidative pathway with Fe/Pd NPs


Nanoparticle synthesis NPs size Φav = 55 nm

Area of flat sheet membranes = 13.2 cm2

Fe NPs

200 nm

(a)

− 𝟎 + 𝑭𝒆𝟑+ + 𝟑𝑩𝑯− 𝟒 + 𝟗𝑯𝟐 𝑶 → 𝑭𝒆 + 𝟑𝑯𝟐 𝑩𝑶𝟑 + 𝟏𝟐𝑯 + 𝟔𝑯𝟐 𝟎 𝑭𝒆𝟐+ + 𝟐𝑩𝑯− 𝟒 + 𝟔𝑯𝟐 𝑶 → 𝑭𝒆 + 𝟐𝑩 𝑶𝑯 𝟑 + 𝟕𝑯𝟐 − 𝑩𝑯− 𝟒 + 𝟐𝑯𝟐 𝑶 → 𝑩𝑶𝟐 + 𝟒𝑯𝟐

Fe NPs

Thin Flat Sheet Membrane 2.5 mm

𝑷𝒅𝟐+ + 𝑭𝒆𝟎 → 𝑭𝒆𝟐+ + 𝑷𝒅𝟎 (b)

1mm Hollow Fiber Membrane

NPs size Φav = 131 nm

1 mm

Thick Flat Sheet Membrane

NPs size Φav = 233 nm

1mm Hernández S, Papp, J. K. and Bhattacharyya, D. I&EC Research, Nov. 2013

1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

ksa = 0.10 L/(m2∙h)

Pseudo first-order reaction

𝑑𝐶 − = 𝑘𝑜𝑏𝑠 𝐶 = 𝑘𝑠𝑎 𝑎𝑠 𝜌𝑚 𝐶 𝑑𝑡

ksa = 0.11 L/(m2∙h)

ksa = 0.13 L/(m2∙h)

0

1.4 mg Fe (3.4% wt Pd) 2.3 mg Fe (3.5% wt Pd) 9.1 mg Fe (3.4% wt Pd) Blank PVDF-PAA

2

4

6

Time (h) 1

0.9

0.9

0.8

0.8

0.7

0.7

0.6

0.6

0.5

0.5

0.4

2-Chlorobiphenyl

0.4

0.3

Biphenyl

0.3

0.2

Carbon balance

0.2

0.1

0.1

0

0 0

0.5

1

1.5

Reaction Time (h)

2

2.5

[Biphenyl]/[Biphenyl]max

[PCB]/[PCB]0

1

[TCE]t/[TCE]0

[TCE]t/[TCE]0

Dechlorination Studies

1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

ksa = 3.39 L/(m2h)

ksa = 6.19 L/(m2h) Thick Membrane 0.8 mg Fe (1.1% wt Pd) Hollow Fiber 1.1 mg Fe (0.75 %wt. Pd)

0

1

2

Time (h)

3

TCE Dechlorination and Chloride 0.6 0.5

[Cl-]formed(mM)

0.4

Theoretical Flat Sheet PVDF-PAA membrane Hollow Fiber PVDF-PAA membrane PAA Hydrogel

0.3

0.2 0.1 0

Cl /TCE ≈ 2.78 7.5% difference error

0 reduction0.05 0.1 0.15 production. 0.2 TCE batch by Fe/Pd nanoparticles and Chloride TCE concentration = 0.21 [TCE] mM. Volume 0.02L. pH ≈ 6.0. T = 22 °C consumed=(mM) An Equal Opportunity University

Hernández S, Papp, J. K. and Bhattacharyya, D. I&EC Research, Nov. 2013

Summary and Future Work • Nano-structured metal composite material can be used for chloroorganic detoxification. • Iron nanoparticles can be directly synthesized in the PAA or PNIPAAM hydrogel, showing no agglomeration. • Complete degradation of TCE/PCBs with no presence of chlorinated byproducts. • Benefits of metal nanoparticle direct synthesis in hydrogel and hydrogel/membrane platforms. • Inverse relationship between the mesh size of the hydrogel and the pore size of the membrane. • Have successfully advanced membrane from lab-scale to fullscale by modification of polymerization procedures • Application to other types of membranes.


Acknowledgments Dr. D. Bhattacharyya Dr. L. Ormsbee Dr. M. Gui Dr. L Xiao Joe Papp Andrew Colburn Doug Davenport David Whitehead

Nanostone/Sepro Membranes

Environmental Research Training Laboratories at UK

This research is supported by NIEHSSRP at the University of Kentucky (P42ES007380)