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Title
Fractional and structural characterization of alkaline lignins from Carex Meyeriana Kunth
Authors
J. Z. MAO L. M. ZHANG and F. XU
Received
November 21, 2011
Published
Volume 46, Issue 3-4 March-April
Keywords
Carex meyeriana Kunth, alkaline lignin, fractionation, ?-O-4 aryl ether linkages
Abstract
Successive extractions with distilled water, 0.25% NaOH-95% ethanol solution, 0.5%, 1%, 1.5% and 2% NaOH aqueous solutions at a solid-liquid ratio of 1:25 (g mL-1) at 80 °C for 3 h from Carex meyeriana Kunth released 4.4%, 6.9%, 10.9%, 13.2%, 7.9% and 4.9% of the original lignin, respectively. The physico-chemical properties and structural features of these lignin fractions were comprehensively characterized by HPLC, GPC, NMR spectroscopy, and TGA. The alkali concentration increment had a positive influence on the purity of the lignin fractions, but a negative influence on the average molecular weight and thermal stability. The FT-IR spectra showed that the lignin fractions had similar structural features with those of HGS lignin. The 1H, 13C and 2D NMR spectra illustrated that typical lignin fractions had predominantly ?-O-4 aryl ether linkages followed by ?-? and ?-5’ ones.
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