TGA can be used for proximate analysis. However, the samples generally used are raw polymers such as tire chips and so on (Menczel and Bruce Prime, 2009).
I need to carry out proximate analysis on below samples, where there is no paper/reference on such analysis:
(1) char
(2) crude pyrolysis oil (CPO)
Should the TGA environment be inert/ oxidising/ reducing?
Dear Teo,
TGA is used to determine the content of moisture, volatiles and ash. TGA with N2 (temperature upto 1000C) is performed to determine the content of moisture and volatiles (or organic) compounds. TGA with air should give you the inorganic content present the material. Thus the choice of the gas in TGA depends on the information one has to seek from the analysis.
Dear Kakasaheb,
I need to determine the % of fixed carbon, ash, moisture and volatile matters. So, it is best i use air as the medium, correct? since Chakraborty's paper (2011) mentioned:
" Under nitrogen atmosphere, the low-volatile processing aids (volatile material) and polymers were thermally degraded. However, the carbon black remained unchanged because of its inertness under nitrogen atmosphere. As soon as the atmosphere was changed to oxygen, the carbon black (and carbonaceous material, if any) was burnt out leaving behind inorganic residue or ash. "
Choosing of gas in TGA instrument depends on the aim of a study like degradation, adsorption, desorption..etc.To avoid oxidation, inert atmosphere is a good choice because that nitrogen and argon gases does not interfere with sample during thermal treatment. Under oxygen atmosphere, black carbon starts burning at above 300 oC , CO and CO2 are produced which cause more lose weight (1).At higher temperature, black carbon be easily burning and more weight loss is expected which due to availability of pyrolysis conditions.
1-https://www.researchgate.net/publication/236835631_A_study_of_TiO2carbon_black_composition_as_counter_electrode_materials_for_dye-sensitized_solar_cells/figures?lo=1
In " HANDBOOK OF COAL ANALYSIS 2nd Ed." by JAMES G. SPEIGHT (2015), he stated that
" thermogravimetric analysis cover determinations of volatile matter (as well as determination of moisture and ash) by pyrolyzing the samples in oxygen and air and the weight loss at prescribed temperatures was measured by using a thermobalance."
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