i am trying to find the amount of hydrogen stored by my sample with changing pressure in an IGA instrument, there is effect of buoyancy causing the decrement in sample mass after increased pressure. Can anyone please explain me how to do these calculations?
https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/49_1_Anaheim_03-04_0985.pdf
http://lem.ch.unito.it/didattica/infochimica/Idrogeno_2005/documenti/Review_Zuettel_2004.pdf
https://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/bestpractices_h2_storage_materials.pdf
https://pdfs.semanticscholar.org/1f58/a9e744beba97039e2a6fc8fecb820317f118.pdf
https://www.hzg.de/imperia/md/content/hzg/zentrale_einrichtungen/bibliothek/berichte/hzg_reports_2014/hzg_report_2014_2.pdf
IGA is doing that calculation for you. You have to:
1. correctly define the gas (hydrogen) and sample density during loading procedure, so the instrument knows the parameters of the gas and sample you use (you also can do densitometry measurement if you do not know density of your material),
2. find the mass of of your sample in the degassed state (dry mass),
3. do your sorption / desorption experiment and
4. when re-plotting PCI data select "wt%" instead "weight". That will do both, changing weight gain (lost) into wt% and correction for buoyancy.
The calculation itself is just subtracting the weight of the gas volume that is taken by the sample from sample weight. The more tricky is to find the gas density at given temperature and pressure. This can be read from one of the relevant databases (e.g. NIST http://webbook.nist.gov/cgi/fluid.cgi?ID=C1333740&Action=Page )
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