Nanomaterials, carbon based and inorganic nanomaterials, are being employed in consumer and industrial products. Many end product applications include polymer composites, drug delivery systems, coatings and films, military applications, electronics, cosmetics, healthcare, and others. The most important characteristic of a nanoparticle is the large surface area to weight ratio that enables “designer” functionality to be added to nano-surfaces. Depending on the nano-application, complex functionalities are being added to the surfaces of the nanomaterial for nanocomposites to drug delivery systems, to cosmetics, and even clothing. It is during this process of coating that characterization is important. Characterization is essential for reproducible manufacturing processes. Not surprising, environmental scientists are also interested in nano-coating characterization as these functionalized nanomaterials enter our environment. This paper discusses the characterization of nanomaterial coatings by TGA-GC-MS. Originally presented at Pittconn.

1. Characterizing Interaction of Nanoparticles with Organic Pollutants Using Coupling Thermal Analysis
with Spectroscopic Techniques
E. Sahle-Demessie, Amy Zhao, U.S. Environmental Protection Agency Cincinnati, Ohio;
Andrew W. Salamon, PerkinElmer Corp., Shelton, Connecticut
1 Introduction TGA Curves for Octano-Water-TiO2
partitioning of Phenathrene
100
There are more than a thousand products claiming containing Engineered Neat TiO2
Nanoparticles (ENP) in biomedical, chemical, clothing, cosmetics, electronics, 95 wet TiO2 Control
energy, environmental, food, materials and optical products. The effects of ENP on
Weight percent, %
90 Run 4, w / light
the environmental and human health are strongly related to their large surface-to-
mass ratio and surface properties. Although the influence of natural colloids on the 85
environment is well documented, we have limited understanding of fate, transport, 80
Run 5, w / Light
toxicity and pollutant interaction of ENP. The tools to study these interactions are
75
being develop. Run 4, No ligjt
70
2 Pollutants-Colloid Interaction 65
Run 5, No light
0 100 200 300 400 500 600
Many nanoparticles suspended in natural water come in contact with
Temperature, oC
pollutants and proteinaceous materials. The unique properties and behaviors of Figure 8. Absence of light made the nanoparticles less hydrophilic and increased
ENP are strongly influenced by their physical-chemical characteristics, including the distribution to the organic phase.
their high surface area relative to their volume, high interface energy and high
surface-to-charge ratio density.
The partitioning and phase distribution of hazardous organic compounds
5 Summary
Figure 2. Figure 4. Photographs of PerkinElmer TGA-GC-M System
(HOC) can influence in the fate and bioavailability of the contaminants in aquatic • TGA-GC-MS a useful technique to study nanoparticle influence on adsorption
systems and aquatic microorganisms significantly. There are a wide range of The physico-chemical properties relating to the environmental behavior of and partitioning PAHs
organic and inorganic pollutants that become associated with partitioning of HOC to hydrophobic organic compounds are mainly affected by the aqueous solubility and
octanol-water partition coefficient. Aqueous solubility (Sw) is the equilibrium • Presence of nano-TiO2 increased the partitioning of PAHs to water phase.
the particles. This partitioning has been shown to be inversely proportional to log
solubility of HOC and the log of particle concentration. Dynamics of nanoparticle- distribution of a solute between water and solute phases. In other words it is the • Nanoparticles resulted in increased partitioning of PAHs; six to ten times than
water partitioning can significantly influence the speciation, and hence, maximum solute concentration possible at equilibrium, and it can function as a in water-octanol equilibrium conditions
understanding their fate, transport and toxicological impact of POPs such as PAHs, limiting factor in concentration dependent (for example, kinetic) processes The
octanol-water partition coefficient is the ratio of the concentration of a chemical in • Naphthalene and phenanthrene have low water solubility but differing
PCBs and is critical. The fate of organic pollutants in aquatic environment depends partitioning .
largely on their partitioning behavior to nanoparticles and colloids. octanol and in water at equilibrium. Octanol is an organic solvent that is used as a
surrogate for natural organic matter. This parameter is used in many • Partitioning influence increased at higher pH.
environmental studies to help determine the fate of chemicals in the environment,
such as to predict the extent a contaminant will bioaccumulate in fish. The octanol- • Absence of light made the nanoparticles less hydrophilic and increased the
7 distribution to the organic phase.
water partition coefficient has been correlated to water solubility; therefore, the
6
Hexachlorobiphenyl
. water solubility of a substance can be used to estimate its octanol-water partition
Andrew W. Salamon, PerkinElmer Corp., Shelton, Connecticut; • Study suggested that the environmental risk of NP should include their
Tetracene coefficient. The presence of nano-particles can influence the octanol-water Figure 5. Thermal Analysis of nano-TiO2, a) conOrganic pollutants adsorbed on transformation and influence in the transport of other pollutants.
partitioning of hydrophobic organic water contaminants. nanoparticles: O-W Partitioning
5 Pyrene Methoxychlor
Abundanc e
9-Methylanthracene
Log Koc
Anthracene
4
S c a n 1 7 9 7 (1 5 .6 2 2 min ): D 7 E xt# 5 b .D d a ta .ms
4 Phenanthrene Measurement Techniques 12000
10000
178
2-Methylnaphthalene 8000
We selected low molecular weight poly aromatic hydrocabons (PAHs) for this study 100
6000
3 including anthracene, naphthalene and phenanthrene as probe molecules to study
98 4000
2000 56 6976 84
Naphthalene 96
49 97 111 1926 139
1
1 151
163 70
1 185 197
the fate and transport of hydrophobic organic pollutants in water streams 94
Abundance
0
4 0 5 0 6 0 7 0 8 0 9 0 1 0 01 1 01 2 01 3 01 4 01 5 01 6 01 7 01 8 01 9 0
m/Tz-->D 7 E x t # 5 b . D d a t a . m s
IC :
2 nanoparticles. The experimental procedure for this study involved the addition of 0-
2200000
92 2000000
B
1800000
Benzene 90
20 mg/l of PAHs in 200 ml of octanol to 900 ml of DI water containing different 88
1600000
1400000
1200000
1 concentrations of nanoparticles (ranging from 0-20 mg/l) in Erlenmeyer flask. After 86
1000000
800000
600000
1 2 3 4 5 6 7 stirring the flasks for 5 days the mixture was allowed to settle for 3 hours and then 84
400000
200000
the aqueous and octanol layers were separated. The aqueous suspensions were 82 A T im e -->
9 .5 0 1 0 .0 0 1 0 .5 0 1 1 .0 0 1 1 .5 0 1 2 .0 0
Log Kow 80
Additional Reading:
divided into three portions. One portion will be extracted with equal volumes of 0 200 400 600 800
Temperature, oC
Figure1. Suspended solid-Organic Carbon Partitioning Coefficient Versus Kow for methylene chloride (MC) and hexane. The mixture will be centrifuged and the PerkinElmer, Nanotechnology and Engineered Nanomaterials – A
PolyCyclic Aromatic Hydrocarbons and Their Derivatives (Karickhoff et al, Water supernatant organic phase will be collected and injected into GC. The concentrations Primer, www.perkinelmer.com/nano
Figure 6. TGA of phenatherene adsorption on nano-TiO2 at pH of 10 (curve A)
Res., 241 (1979) of PAHs in MC and hexane and water were measured by Gas chromatography
and 6.6 (Curve B)
analysis. The second portion will be centrifuged at 10,000 rpm for 30 min. The PerkinElmer, Nanomaterials Reference Library
3 Pollutants sorbed on engineered nanoparticles mixture will be decanted and the settled nanoparticles will be put in crucible to dry in www.perkinelmer.com/nano
oven (105 oC) for 8 hr. The mass fraction of the adsorbed organics on dried particles
The sorption of pollutants on to nanoparticles in water phase will be the
was analyzed using thermal gravimetric analyzer (PerkinElmer) and FTIR or TOC.
result of three phase partitioning of pollutants between organic phase, water and
suspended solids.
References:
Octanol-Water Partition Coefficient (KOW) - "A coefficient representing the ratio of
the solubility of a compound in octanol (a non-polar solvent) to its solubility in water 1. Bom, D., Andrews, R., Jacques, D., Anthony, J., Chen, B., Meier, M. S.,
(a polar solvent). The higher to KOW, the more non-polar the compound. Kd is the Selegue, J. P., Thermogravimetric Analysis of the Oxidation of Multiwalled
GC MS
ration of pollutant attached onto the particle and in the water phase. Phenanthrene
Carbon Nanotubes: Evidence for the Role of Defects Sites in Carbon
Naphthalene
Nanotube Chemistry, NanoLetters, 2002, 2, 6, 615-619.
Anthracene 2. Pinault, M, Mayne-L’Hermite, M., Reynaud, C., Beynaud, C., Beyssac,
O.,Rouzaud, J.N., Clinard, C., Carbon nanotube produced by aerosol
pyrolysis: growth mechanisms and post-annealing effects, (2004) 13, 1266-
1269
Where Co, Cw and Cp are concentration of the pollutant organic compounds in the
Figure 7. TGA –GC-MS Data with SEM image
non-polar organic phase, in an equal weight of water, and concentration pollutants 3. Penn SG, He L and Natan MJ. Nanoparticles for bioanalysis. Current
attached on per mass of particles. Ideally these ratios are equilibrium partitioning of
Figure 3. Schematic PerkinElmer TGA-GC-MS set-up with heated transfer capillary Opinion in Chemical Biology 2003, 7, 609-615
pollutants between organic phase, dissolved in water phase and particulate phases.
line.
PerkinElmer, Inc., 940 Winter Street, Waltham, MA USA (800) 762-4000 or (+1) 203 925-4602 www.perkinelmer.com