According to the ASTM D2867-09 1 g of activated carbon should be heated up to ca. 150 deg C for 3 h. However in most of the papers I checked out the usual conditions reported are 105 degrees C for few hours (1-3 h). Am I not interpreting the standard correctly?
Hi Prakash, I know about TGA but I have been told that loss on ignition methods are more suitable for the determination of moisture, volatiles and ashes.
Dear Antonio Salituro, the procedure 150 deg C for 3 h is correct in my view. Generally ACs have same surface functional groups which are involved in chemisorption of water molecules, which is very hard to remove at 105 deg C. if you record the TGA of ACs at 105, 125 and 150 deg C isothermally you will get more clarity on the topic.
Dear Antonio,
following up to Atul’s comment please remember that ACs will not only adsorb moisture but also other small molecules from the environment. Isothermal TGA will give you a total volatiles content but that may not all be water.
If you are only interested in moisture, I would suggest to heat the sample to 150 °C under a stream of dry nitrogen and moisture analysis in the gas using coulometric Karl Fischer titration.
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