Studies on the Utilization of Alkali Lignin (Part 1)

Recovery of Lignin from Black Liquor of Soda-pulp Process.

Abstract

In this paper was described an experimental study of recovery method of lignin and NaOH from black liquor.
Crude lignin was precipitated from black liquor by CO₂ at pH 7.5 and centrifugated. The yield of the deposit was 43% of wood. The lignin content of the deposit, when purified 72% H₂SO₄ was found to be 45.2%. From the supernatant liquor which contains 7% Na₂CO₃, NaOH was recovered by CaO. The yield was 18.5% per Na₂O of black liquor :
Elementary analysis, infrared spectrum, DTA, and TGA-DTA-GC of the alkali lignin and of HCl process lignin did not show marked difference.