1) Thermogravimetric analysis (TGA) measures the weight changes of a material as it is heated in different atmospheres. It can be used to analyze inorganic materials, metals, polymers, ceramics, and composites. 2) The document describes using TGA to analyze the thermal decomposition of calcium oxalate monohydrate. Calcium oxalate monohydrate decomposes in three steps as it is heated. 3) The measured mass losses at each step of decomposition closely matched the theoretical predictions, validating the predicted thermal decomposition reactions of calcium oxalate monohydrate.

1. D.Kalpana
Assistant professor,
Department of chemistry
Bon secours college for women
Thanjavur

2.  TGA analysis measures the amount of weight
change of a material, either as a function of
increasing temperature.
 Thermal gravimetric analysis can be interfaced
with a mass spectrometer RGA to identify and
measure the vapors generated, though there is much
greater sensitivity. when the mass spectroscopy
heating is performed in an ultrahigh vacuum system
Inorganic materials, metals, polymers and
plastics, ceramics, glasses, and composite materials
can be analyzed.

3.  Temperature range from 25°C to 900°C routinely. The
maximum temperature is 1000°C on our instrument. The
maximum heating rate is greater than 100°C/min. We have
access to an instrument with an upper temperature limit of
1500°C when you need it.
 Sample weight can range from 1 mg to 150 mg. Sample
weights of more than 10 mg are preferred, but excellent results
are sometimes obtainable on 1 mg of material.
 Weight change sensitivity of 0.01 mg.
 Samples can be analyzed in the form of powder or small pieces
so the interior sample temperature remains close to the
measured gas temperature.

4. Applications of TGA Analysis or
Thermogravimetry
Determines temperature and weight change of decomposition
reactions, which often allows quantitative composition
analysis.
May be used to determine water content or the residual
solvents in a material.
Allows analysis of reactions with air, oxygen, or other
reactive gases
Can be used to measure evaporation rates as a function of
temperature, such as to measure the volatile emissions of
liquid mixtures.

5.  Helps to identify plastics and organic materials by
measuring the temperature of bond scissions in inert
atmospheres or of oxidation in air or oxygen.
 Used to measure the weight of fiberglass and
inorganic fill materials in plastics, laminates, paints,
primers, and composite materials by burning off the
polymer resin. The fill material can then be identified
by XPS and/or microscopy. The fill material may be
carbon black, TiO2, CaCO3, MgCO3, Al2O3, Al(OH)3,
Mg(OH)2, talc, Kaolin clay, or silica, for instance.

6.  Allows determination of Curie temperatures of
magnetic transitions by measuring the temperature at
which the force exerted by a nearby magnet
disappears on heating or reappears on cooling.
 Can measure the fill materials added to some foods, such
as silica gels, cellulose, calcium carbonate, and titanium
dioxide.
 Can determine the purity of a mineral, inorganic
compound, or organic material.
 Distinguishes different mineral compositions from broad
mineral types, such as borax, boric acid, and silica gels.

7. Thermogravimetric Analysis of
Calcium Oxalate
 Thermogravimetric analysis (TGA) is a type of analysis
that determines the mass change of a sample over time as
it is heated.
 This analysis requires that the test instrument be able to
accurately measure mass, temperature, and temperature
change.
 Typically, samples are analyzed in an inert atmosphere
although an oxidizing or reducing atmosphere can be used
when necessary. TGA is widely employed in research and
development, testing and characterization of all kinds of
materials from metals and alloys to polymeric and ceramic
composites.

8.  Typical applications of TGA may include determination of
polymer degradation and decomposition temperatures,
moisture content of materials, oxidation resistance and
dynamics, volatile and nonvolatile components, thermal
stability, etc.
 Thermal decomposition is the process in which a
substance decomposes due to the application of heat.

9.  The phenomenon is common to most organic substances
and occurs in many inorganic substances as well.
 Using thermogravimetry, the decomposition temperature
and mass loss of each reaction can be determined.

11.  Calcium Oxalate Monohydrate, CaC2O4•H2O, is a useful
industrial compound used to make oxalic acid, organic
oxalates, and glazes.
 Thermal decomposition data for CaC2O4•H2O was
obtained using a Simultaneous TG-DTA/DSC Apparatus
STA 449 F3 Jupiter (Netszch, Germany).

12.  Thermal decomposition of CaC2O4•H2O occurs in
three distinct steps
 Figure 1. The theoretical mass loss during each step
can be calculated using the molar masses of the
individual components.

13. Table 1
Table 1 shows the decomposition reactions that occur at each
step as well as the theoretical and measured mass loss for each
step.

14.  The measured mass losses during steps 1 to 3 closely
match the predicted mass losses, which verify the
theoretical predictions of the thermal decomposition for
the calcium oxalate monohydrate.
 It is interesting to note the slight difference in the mass
loss between theoretical calculation and actual
measurement for decomposition

15.  According to research, this is most likely due to
disproportionation (a type of redox reaction during which
a reactant is simultaneously oxidized and reduced, thus
forming two different products) of CO into CO2 and
carbon
 This disproportionation is highly dependent on the
impurities within the sample as well as the cleanliness and
material of the sample holder.