I treated activated carbon with HNO3 and Air drying. Compared with the untreated as supplied activated carbon. I don't see any sharp absorption. I am looking for -OH groups on the surface. I used N2 in FTIR. Can anyone help?
Good day, Naharin Jannath!
The only options for uncertainty is a) preparation of AC, b) methodology of treatment, c) problem with FTIR apparatus. Please, check the following methodology:
Article Antibacterial properties of AgNO3-activated carbon composite...
Such a low differences in spectra may occur due to the limited oxidation of activated carbon by conc. HNO3. Here is the reference:
Article Notes Surface functionalities of nitric acid treated carbon ...
Best of luck in your research!
Yours sincerely,
M. Sc. Vadym Chibrikov
Department of Microstructure and Mechanics of Biomaterials
Institute of Agrophysics, Polish Academy of Sciences
This is not noise, these are gas phase absorption peaks from CO2 and especially from H2O.
You have a severe problem with water vapour (and CO2). This does not necessarily mean your levels are too high, but that your levels change *a lot* when you switch from background to sample. This could either mean your N2 purging is insufficient, or that your chamber is not tightly sealed. In a similar situation, I found that increasing the flow from 1 l/min to 8L/min helped, but this is expensive and can even be dangerous in a small lab.
Another option is a super-long waiting time after exchanging background/sample. For me, this did not help. What did help a little bit was the opposite, very fast switch, but then you also need to limit the number of scans, e.g. to only 50.
The very best option would be a chamber, and inside a mechanism to switch from background to sample *without opening*.
On another note, what is your background? I found this a tough question for carbon. We resolved for the ugly case of "activated carbon" by using no background (i.e. N2) in ATR with a Si prism. This gives hugely different sample and background spectra, so the difference looks weird, with a sloping background, which we did *not* correct, to avoid artefacts. But this method was reproducible, so finally we also were confident to publish the spectra. They show possibly some features that you, too, would expect:
A.M. Bittner; M. Zhu; Y. Yang; H.F. Waibel; M. Konuma; U. Starke; C.J. Weber
J. Power Sources 203 (2012) 262-273
“Ageing of electrochemical double layer capacitors”
M. Zhu, C.J. Weber, Y. Yang, M. Konuma U. Starke, K. Kern, A.M. Bittner
Carbon 46 (2008) 1829-1840
“Chemical and electrochemical ageing of carbon materials used in supercapacitor electrodes”
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