superwetting nanowire membranes for selective absorption authored by jikang yuan, xiaogang liu, ozge...
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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.