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Okko Ringena, Bodo Saake, Ralph Lehnen
Isolation and fractionation of lignosulfonates by amine extraction and ultrafiltration: A comparative study
Keywords: amine extraction, lignosulfonates, molar mass, molecular weight distribution, size exclusion chromatography, spent sulfite liquor, Ultrafiltration
Spent sulfite liquors (SSLs) were fractionated by two common separation techniques: amine extraction and ultrafiltration. The lignin fractions obtained were characterized with respect to their elemental composition, functional groups and molecular weight distribution. The results of size exclusion chromatography indicate a broad molecular weight distribution of the lignosulfonates (LS). Irrespective of the separation technique used, a small LS fraction with high molecular mass and low degree of sulfonation was obtained, while most of the lignosulfonates have much lower molar masses and a much higher degree of sulfonation. Both separation methods offer the opportunity to extract high-purity LS fractions; however, compared to amine extraction, ultrafiltration provides additional information about the molecular weight distribution of the SSL components without application of other analytical techniques.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 59, 07/2005
Pages: 405 - 412