In the production of bio-oil from sawdust using fast pyrolysis the Fourier Transform-Infra red analysis was performed. Can the results obtained from the FT-IR analysis of the sawdust say something about the characteristics of the Bio-oil to be produced? Many thanks
FT-IR data of bio oil can tell you the functional groups present in the bio oil which will lead you to the information related to the reaction process. For example you may compare the FT-IR results of final product with that of raw material and see how the bonds have been broken or bent or rejoined or expanded to form new structure and it may help you to understand the reaction mechanism.
FT-IR gives information about microscopic CHARACTERIZATION. FOR e,g you can predict hydroxycinnamic acids , nitrogen and alkali index by partial least squares
regression.
not sure what you mean exactly - are you looking at the IR of the sawdust before pyrolysis? If so, it will give you some info about what is there. How much is debatable - certainly broadly the polysaccharides and lignin should show up, but how specific you can be about exact (sub) structures is hard to decide. there is quite a lot of literature about most of this, so a good search of IR data for the obvious generic components (cellulose, hemicellulose and lignin) should help to unravel a fair bit. As the oil will contain some similar components (e.g. monosaccharides are often present, along with anhydrosugars such as levoglucosan (by IR very similar) then these should be identifiable at a generic level rather than as specific individual sugars (unless you are very lucky), but the main components are likely to be significantly degraded and wont retain many of the IR features. Monomeric phenolics will look probably quite similar to the lignin itself and to oligomeric fractions.
As a predictive tool, you would need to use it in conjunction with known degradation pathways of the individual components under thermal conditions (bearing in mind that real biomass will have other stuff in there, eg inorganics, that can influence the processes. Such inorganics wont be present in the typically pure individual components that are often used for such studies. Likewise the major components will influence each other once one starts to break down.
Not an easy task, except at a very generic level
You can only be sure of the functional groups present. But you cannot quantify then. Unless you are sure of the decomposition mechanism you can't say that you have one compound or other. But you can say if the bio-oil is more or less oxidized for example. And if you do a aqueous extraction you can see if you have a lot of sugars or not because sugars have a typical fingerprint. But as someone already said, is only in theory because that are lots of vibration that overlap. Bur you can see if you have more esters, acids, ethers, hydroxyl...but only qualitatively. You'll have to perform further analyses.
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