Characterization of Non-wood Lignin Precipitated with Sulphuric Acid of Various Concentrations

• Main Authors: Igor Šurina, Michal Jablonský, Aleš Ház, Alexandra Sladková, Anna Briškárová, František Kačík, Jozef Šima
• Format: Article
• Language: English
• Published: North Carolina State University 2015-01-01
• Series: BioResources
• Subjects: Selectively precipitated lignin; Renewable raw materials; Sulphuric acid; Black liquor
• Online Access: http://ojs.cnr.ncsu.edu/index.php/BioRes/article/view/BioRes_10_1_1408_Surina_Non_Wood_Lignin_Precipitated_Sulphuric_Acid

Lignin is an attractive, renewable raw material provided by all types of agricultural and silvicultural vegetation. The precipitation of lignin fractions through acidification of the black liquor was performed and the products characterized for the following parameters: C, H, N, and S elemental composition; zeta potential; electrophoretic mobility; heating value; molecular weight; content of non-conjugated, conjugated, and total phenolic hydroxyl groups; and total yield of oxidation products. Lignin was isolated from black liquor by adding sulphuric acid at four levels of concentration (5, 25, 50, and 72 wt%) and subsequently adjusting the pH to 5. A comparison study of the physico-chemical and surface properties was also performed. The acid concentration influenced the yield of precipitated lignin and had an effect on the properties of precipitated lignin and the content of non-conjugated, conjugated, and total amount of phenolic hydroxyl groups. However, the concentration of acid had no relevant effect on the heating value, molecular weight, polydispersity, total yield of oxidation products, or the elemental composition of isolated lignin.