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ESCA study of the solid residues of supercritical extraction of Populus tremuloïdes in methanol
Author(s) -
Ahmed A.,
Adnot A.,
Kaliaguine S.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070340129
Subject(s) - supercritical fluid , supercritical fluid extraction , extraction (chemistry) , residue (chemistry) , chemical composition , chemistry , polymer , fraction (chemistry) , analytical chemistry (journal) , carbon fibers , methanol , materials science , chromatography , organic chemistry , composite material , composite number
A systematic ESCA study of the solid residues of supercritical critical extraction of Populus tremuloïdes prepared in various conditions has been performed. Reference materials also examined by ESCA included the initial wood, Whatman no. 1 paper, and two lignins prepared by different procedures. Interest has been focused on the C ls and O ls spectra and on the determination of surface O/C atomic ratio. A difference between bulk O/C values measured by chemical analysis and surface O/C ratios obtained from ESCA data is considered diagnostic of a difference in chemical composition of the bulk and the surface. In the C ls peaks of wood and its constitutive polymers, the usual components peaks C 1 , C 2 , and C 3 were observed. For the solid residues, however, a fourth peak designated as C 0 appears, the importance of which increases steadily when the temperature of extraction is raised from 250 to 350°C. The component C 0 was ascribed to polyaromatic constituants. Its proportion is correlated with the fraction of the carbon in the residue comprised in the recondensed material and determined independently. The O ls peak shows also a complex structure with three components in the wood‐derived reference materials and four in some of the solid residues. These structures have not been discussed previously in the literature and a tentative assignment for the component peaks is proposed.