Phase change materials (PCM) are used in many energy storage applications. Energy is stored (latent heat of fusion) by melting the PCM and is released during resolidification. Dispersing highly conductive nanoparticles into the PCM enhances the effective thermal conductivity of the PCM, which in turn significantly improves the energy storage capability of the PCM. The resulting colloidal mixture with the nanoparticles in suspension is referred to as nanostructure enhanced phase change materials (NEPCM). A commonly used PCM for energy storage application is the family of paraffin (CnH2n+2). Mixing copper oxide (CuO) nanoparticles in the paraffin produces an effective and highly efficient NEPCM for energy storage. However, after long term application cycles, the efficiency of the NEPCM may deteriorate and it may need replacement with fresh supply. Disposal of the used NEPCM containing the nanoparticles is a matter of concern. Used NEPCM containing nanoparticles cannot be discarded directly into the environment because of various short term health hazards for humans and all living beings and unidentified long term environmental and health hazards due to nanoparticles. This problem will be considerable when widespread use of NEPCM will be practiced. It is thus important to develop technologies to separate the nanoparticles before the disposal of the NEPCM. The primary objective of this research work is to develop methods for the separation and reclamation of the nanoparticles from the NEPCM before its disposal. The goal is to find, design, test, and evaluate separation methods which are simple, safe, and economical. The specific NEPCM considered in this study is a colloidal mixture of dodecane (C12H26) and CuO nanoparticles (1–5% mass fraction and 5–15 nm size distribution). The nanoparticles are coated with a surfactant or stabilizing ligands for suspension stability in the mixture for a long period of time. Various methods for separating the nanoparticles from the NEPCM are explored. The identified methods include: (i) distillation under atmospheric and reduced pressure, (ii) mixing with alcohol mixture solvent, and (iii) high speed centrifugation. These different nanoparticle separation methods have been pursued and tested, and the results are analyzed and presented in this article.

References

References
1.
Nomura
,
T.
,
Okinaka
,
N.
, and
Akiyama
,
T.
,
2009
, “
Impregnation of Porous Material With Phase Change Material for Thermal Energy Storage
,”
Mater. Chem. Phys.
,
115
(
2–3
), pp.
846
850
.10.1016/j.matchemphys.2009.02.045
2.
Kuznik
,
F.
,
David
,
D.
,
Johannes
,
K.
, and
Roux
,
J.
,
2011
A Review on Phase Change Materials Integrated in Building Walls
,”
Renewable Sustainable Energy Rev.
,
15
(
1
), pp.
379
391
.10.1016/j.rser.2010.08.019
3.
Meng
,
Q.
, and
Hu
,
J.
,
2008
, “
A Poly(Ethylene Glycol)-Based Smart Phase Change Material
,”
Sol. Energy Mater. Sol. Cells
,
92
(
10
), pp.
1260
1268
.10.1016/j.solmat.2008.04.026
4.
Liu
,
M.
,
Saman
,
W.
, and
Bruno
F.
,
2012
, “
Review on Storage Materials and Thermal Performance Enhancement Techniques for High Temperature Phase Change Thermal Storage Systems
,”
Renewable Sustainable Energy Rev.
,
16
(
4
), pp.
2118
2132
.10.1016/j.rser.2012.01.020
5.
Khodadadi
,
J. M.
,
Fan
,
L.
, and
Babaei
,
H.
,
2013
, “
Thermal Conductivity Enhancement of Nanostructure-Based Colloidal Suspensions Utilized as Phase Change Materials for Thermal Energy Storage: A Review
,”
Renewable Sustainable Energy Rev.
,
24
, pp.
418
444
.10.1016/j.rser.2013.03.031
6.
Fan
,
L.
, and
Khodadadi
,
J. M.
,
2011
, “
Thermal Conductivity Enhancement of Phase Change Materials for Thermal Energy Storage: A Review
,”
Renewable Sustainable Energy Rev.
,
15
(
1
), pp.
24
46
.10.1016/j.rser.2010.08.007
7.
Gunawan
C.
,
Teoh
,
W. Y.
,
Marquis
,
C. P.
, and
Amal
,
R.
,
2011
, “
Cytotoxic Origin of Copper(II) Oxide Nanoparticles: Comparative Studies With Micron-Sized Particles, Leachate, and Metal Salts
,”
ACS Nano
,
5
(
9
), pp.
7214
7225
.10.1021/nn2020248
8.
Heinlaan
,
M.
,
Kahru
,
A.
,
Kasemets
,
K.
,
Arbeille
,
B.
,
Prensier
,
G.
, and
Dubourguier
,
H.
,
2011
, “
Changes in the Daphnia Magna Midgut Upon Ingestion of Copper Oxide Nanoparticles: A Transmission Electron Microscopy Study
,”
Water Res.
,
45
(
1
), pp.
179
190
.10.1016/j.watres.2010.08.026
9.
Manusadžianas
,
L.
,
Caillet
,
C.
,
Fachetti
,
L.
,
Gylytė
,
B.
,
Grigutytė
,
R.
,
Jurkonienė
,
S.
,
Karitonas
,
R.
,
Sadauskas
,
K.
,
Thomas
F.
,
Vitkus
,
R.
, and
Férard
,
J. F.
,
2012
, “
Toxicity of Copper Oxide Nanoparticle Suspensions to Aquatic Biota
,”
Environ. Toxicol. Chem.
,
31
(
1
), pp.
108
114
.10.1002/etc.715
10.
Wang
,
Z.
,
Li
,
N.
,
Zhao
,
J.
,
White
,
J. C.
,
Qu
,
P.
, and
B.
Xing
,
2012
, “
CuO Nanoparticle Interaction With Human Epithelial Cells: Cellular Uptake, Location, Export, and Genotoxicity
,”
Chem. Res. Toxicol.
,
25
(
7
), pp.
1512
1521
.10.1021/tx3002093
11.
Liu
,
F. K.
,
Ko
,
F. H.
,
Huang
,
P. W.
,
Wu
,
C. H.
, and
Chu
,
T. C.
,
2005
, “
Studying the Size/Shape Separation and Optical Properties of Silver Nanoparticles by Capillary Electrophoresis
,”
J. Chromatogr., A
,
1062
(
1
), pp.
139
145
.10.1016/j.chroma.2004.11.010
12.
Lam
,
K. F.
,
Sorensen
,
E.
, and
Gavriilidis
,
A.
,
2011
, “
Towards an Understanding of the Effects of Operating Conditions on Separation by Microfluidic Distillation
,”
Chem. Eng. Sci.
,
66
(
10
), pp.
2098
2106
.10.1016/j.ces.2011.02.013
13.
Xiong
,
B.
,
Cheng
,
J.
,
Qiao
,
Y.
,
Zhou
,
R.
,
He
,
Y.
, and
Yeung
,
E. S.
,
2011
, “
Separation of Nanorods by Density Gradient Centrifugation
,”
J. Chromatogr., A
,
1218
(
25
), pp.
3823
3829
.10.1016/j.chroma.2011.04.038
14.
Chen
,
H.
,
Kaminski
,
M. D.
,
Ebner
,
A. D.
,
Ritter
,
J. A.
, and
Rosengart
,
A. J.
,
2007
, “
Theoretical Analysis of a Simple Yet Efficient Portable Magnetic Separator Design for Separation of Magnetic Nano/Micro-Carriers From Human Blood Flow
,”
J. Magn. Magn. Mater.
,
313
(
1
), pp.
127
134
.10.1016/j.jmmm.2006.12.015
15.
Liu
,
F.
,
2009
, “
Using Micellar Electrokinetic Chromatography for the Highly Efficient Preconcentration and Separation of Gold Nanoparticles
,”
J. Chromatogr., A
,
1216
(
12
), pp.
2554
2559
.10.1016/j.chroma.2009.01.004
16.
Van der Bruggen
,
B.
,
Mänttäri
,
M.
, and
Nyström
,
M.
,
2008
, “
Drawbacks of Applying Nanofiltration and How to Avoid Them: A Review
,”
Sep. Purif. Technol.
,
63
(
2
), pp.
251
263
.10.1016/j.seppur.2008.05.010
17.
Vertellus,
2005
, “
Material Safety Data
,” http://www.vertellus.com/Documents/MSDS/N-Dodecane%20English.pdf
18.
Clary
,
D. R.
, and
Mills
,
G.
,
2011
, “
Preparation and Thermal Properties of CuO Particles
,”
J. Phys. Chem., C
,
115
(
5
), pp.
1767
1775
.10.1021/jp110102r
19.
Coker
,
A. K.
,
2010
, “
Distillation: Part 1: Distillation Process Performance
,”
Ludwig's Applied Process Design for Chemical and Petrochemical Plants
,
4th ed.
, Vol.
2
,
Gulf Professional Publishing
,
Boston
, MA, pp.
1
268
.
20.
Yang
,
D.
,
Martinez
,
R.
,
Fayyaz-Najafi
,
B.
, and
Wright
,
R.
,
2010
, “
Light Hydrocarbon Distillation Using Hollow Fibers as Structured Packings
,”
J. Membr. Sci.
,
362
(
1–2
), pp.
86
96
.10.1016/j.memsci.2010.06.019
21.
Sánchez
,
L. M. G.
,
Meindersma
,
G. W.
, and
Haan
,
A. B.
,
2009
, “
Potential of Silver-Based Room-Temperature Ionic Liquids for Ethylene/Ethane Separation
,”
Ind. Eng. Chem. Res.
,
48
(
23
), pp.
10650
10656
.10.1021/ie9010244
22.
Shi-Chang
,
W.
,
1987
, “
Ten Years' Development on Distillation in China
,”
Desalination
,
64
, pp.
211
215
.10.1016/0011-9164(87)90097-X
You do not currently have access to this content.