Superwetting nanowire membranes for selective absorption

Authored by Jikang Yuan, Xiaogang Liu, Ozge Akbulut, Junqing Hu, Steven L. Suib, Jing Kong and Francesco Stellacci

Presented by Bryce Smith, Neal Mistry, Elliot Young, and Kyle Hamaker

Problem● Need new ways to combat water pollution

o Oil spillso Industrial pollutiono Water contaminants

Source: http://www.freedrinkingwater.com/images-new/education-page/image/algae-lake.jpg

PurposeConstruction method of nanoporous membranes for:

● Catalyst Supports● Filters for Biomolecule Purification● Seawater desalination

Construct a nanowire membrane that is:● thermally stable● controlled wetting behaviour ranging from

superhydrophilic to superhydrophobic

What has been done?BP Oil Spill - Chemical Dispersants

● Breaks down oil into smaller dropletsMagnets and Nanotechnology

● water-repellent nanoparticles that contain ironCloth Coated with Chemical Polymer

● both hydrophilic and oleophobic

http://upload.wikimedia.org/wikipedia/commons/6/61/C-130_support_oil_spill_cleanup.jpg

Image: Yuan, J., Laubernds, K., Villegas, J., Gomez, S. & Suib, S. L. Spontaneous formation of inorganic paper-like materials. Adv. Mater. 16, 1729–1732 (2004).

● 3D porous nanostructures○ capillary action

● Oleophobic● Cryptomelane pore size = 10nm, 44 m2 g-1

Procedure

1:2:1

● Manganese OxideAutoclavemanganese sulfate,potassium sulfate,potassium persulfateDI water

Teflon

Procedure● Coating of silane = superhydrophobic

o Vapor depositionPolydimethysiloxane (PDMS)Cooling 234°C, 30minHeating 390°CSilicone coating

Image: Barron, Andrew R. "Chemical Vapor Deposition." OpenStax CNX. Rice University, n.d. Web. 21 Sept. 2014.

Non-Coated Membranea) Optical image of

membraneb) SEM image of

cross-sectional areac) SEM image of

surface morphology of membrane

d) SEM image of nanowire networks

e) Close up SEM of nanowire bundle

f) TEM of single cryptomelane nanowire

g) Close-up view of f)h) Wetting time vs. #

water droplets deposited over a time interval

Figure adapted from reference 1.

Water contact angle

Figure adapted from http://www.funsci.com/fun3_en/exper2/exper2.htm

Silane-coated membrane

Figure adapted from reference 1

a) Water contact angle b) SEM image of nanowires coated in

siliconec) TEM image of modified nanowiresd) High-magnification TEM image of

silicone coating on nanowiree) EDS spectrum

Cryptomelane: K(Mn4+,Mn2+)8O16

PDMS: (C2H6OSi)n

Surface wetting switchability

Figure adapted from reference 1

a) Representation of reversible wettability

b) Contact angle and hysteresis measurements taken after each transition cycle

Wettability

a) Absorption capacities for different organic solvents and oils

b,c) Layer of blue-dyed gasoline being removed by membrane

Figure adapted from reference 1

Analysis● Wettability is highly switchable● Mechanically robust - resists repeated

ultrasonic treatment● Silane coating not the only reason for

superhydrophobic behavior● Highly effective selective superabsorbance● Reusable

Applications1. Removal of oil from water in case of oil spills2. Detection of solutes with similar polarities in

a solution

http://www.safety4sea.com/ship-execs-in-trouble-over-oil-spill-13790

Oil Spill● Absorbs oil while leaving water behind● Using ultrasonic washing, the membrane

releases the oil and allows for reuse of both oil and material

ChromatographyThe massive surface area of the nanotube membrane magnifies the difference in polarity of similar solutes in a solution Leads to better detection of pollutants

Example SolutesTOLUENE

BENZENE

http://iaspub.epa.gov/tdb/pages/contaminant/contaminantOverview.do?contaminantId=10140http://commons.wikimedia.org/wiki/File:Toluene.png

Chromatography Data

Figure adapted from Reference 1

References1. Yuan, Jikang, Xiaogang Liu, Ozge Akbulut, Junqing Hu, Steven L. Suib, Jing Kong, and Francesco Stellacci.

Superwetting Nanowire Membranes for Selective Absorption (2008): 332-36. Web. 19 Sept. 2014.2. Barron, Andrew R. "Chemical Vapor Deposition." OpenStax CNX. Rice University, n.d. Web. 21 Sept. 2014.

3. Levitt, Tom. "Cleaning up Oil Spills with Nanotechnology and Magnets." CNN. CNN, 21 Sept. 2012. Web. 21 Sept. 2014.

4. Rutherglen, Chris, Dheeraj Jain, and Peter Burke. "Nanotube Electronics for Radiofrequency Applications."

Nature.com. Nature Publishing Group, 29 Nov. 2009. Web. 19 Sept. 2014.

5. "Seven Technologies Used to Clean the Gulf Oil Spill." CBSNews. CBS Interactive, 5 May 2010. Web. 21 Sept. 2014.