We screened biochar into three fractions.We found that the size < 1 mm fraction had less transmission than the coarser fractions,1-2 and 2-4 mm.What does this mean, Does it mean that fraction < 1 mm fraction is different compositionally.. The peaks are similar. See attachment
It sounds like you measured transmission spectra. If so, what happened to the bulk density?
Thanks very much for your response,The bulk density is higher in the fine fraction. Is that the information you wanted.We used ATR.
Hi Munoo Prasad I had a look at your FTIR spectra of bamboo biochar. Looking at the values of the y-axis it seems that the data are on absorbance basis not transmission. Knowing the correct data type affects the identification of the peaks. Can you confirm please?
Assuming that the FTIR spectra are on absorbance basis following tentative peaks have been identified (see also attached figure):
1578 cm-1: Aromatic ring vibration
876 cm-1: lone aryl CH wag 1
794 cm-1: aromatic CH wag 2
753 cm-1: aromatic CH wag 3
Sharma et al. (2004) Article Characterization of chars from pyrolysis of lignin
was referred to when assigning the groups. Sharma et al. (2004) pyrolyzed lignin and observed a shift in the CH wag bands towards higher wavenumbers suggesting that this indicates the formation of fused ring systems also found in substituted naphthalene, anthracene and phenanthrene.
Hi Robert Bachmann,
I really appreciate your effort . Yes it is absorbance. I will look at the paper of Sharma et al.I am abroad at the moment and travelling.Your comments have really helped me. I may come back with some questions!!
It's weird since you can see negative peaks at 2850 and 2915 cm-1 associated with C-H absorption from methylene moieties. Why should that be negative if these spectra are measured in transmission and displayed in absorbance unit?
Are those single beam spectra? How did you measure the spectra?
To me, it looks your spectra are too distorted to be representative of the real composition of your sample.
Millimeter sized particles would be mostly opaque in the mid IR. Plants are generally sectioned to 15-25µm thickness for IR measurement (often loosing cell content).
I would recommend either:
- performing measurements in ATR mode
- sectioning the sample to something like 15-25µm thickness
- or crushing them in a compression anvil to make them thin enough.
depending on what's available to you. ATR measurement is probably the easiest and most accessible way to measure your powder.
Hi Munoo Prasad, have you managed to complete the interpretation of your FTIR spectra?
No, I have had little time.But I will be doing it soon.
Thanks very much for your interest
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