I want to analyze surface area of Iron ore fine particle by BET analysis. What will be the degassing temperature and degassing time of gas and number of points to be considered ??
Hi
Test to start with 150-200 C for 3 hours. Go up in temperature to 200-250 C an use the same time. Then prolong degassing time to 4 hours for both temperatures. Run BET analyses and compare reults. Most likely You can use even higher temperatures.
The IUPAC recommendation is 180 °C for three hours in general. Can you check the pressure change during degassing? You would see the pressure as constant as your sample is degassed properly. If you have Quantachrome analyser, there can be useful deltaPressure function.
For temperature determination: think about the stability of your sample, you can run a DTA/TG to check when changes happens (like water dessorption, or phase transitions..). If you don't know anything about your sample stability, you can even make XRD and infrared before and after degassing at any temperature.
For the time, some equipments has a degassing test as sugested by Jaroslav Kastyl , if your equipment doesn't have this test, I advise you to take longer times (from 6 to 8 hours, depending on how porous is your material, and if you are at low temperatures,
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