Characterization of Residual Lignin in Cellulose Isolated by the Diglyme Method from Three Pinus Species by IR Spectroscopy and Analytical Pyrolysis

Abstract Quantitative determination of cellulose content by means of diglyme [bis(2-methoxyethyl) ether] isolation is useful for rapid screening experiments. However, diglyme isolation from softwoods results in a certain amount of residual lignin in the cellulose. In this paper, the lignin content (L) in diglyme cellulose of three pine species (Pinus halepensis Miller, Pinus sylvestris L. and Pinus pinaster Aiton) was analysed by ATR-FTIR spectroscopy and analytical pyrolysis (Py). Py allowed lignin quantification. The influence of wood milling on cellulose yield was also analyzed and it was shown that a particle size between 10 and 60 mesh did not noticeably influence the cellulose yield or L; however, ball-milling to powder did cause a cellulose loss of around 37%. The diglyme method is only reproducible if the experimental parameters are standardized and meticulously followed.