THE SEMICHEMICAL PULP

Abstract

The lignin content of the red pine wood extracted with alcohol-benzene solvent and of the pulps prepared from the extracted red pine wood by neutral sulfite process, are determined by sulfuric acid in several concentrations. Then their methoxyl and sulfur contents are determined, and the following chief results are obtained:1. To determine the lignin content of red pine wood, using 72% optimum concentration of sulfuric acid it requires 4 hrs at 20°C2. The methoxyl contents of the prepared lignin from red pine pulps are always smaller than that from red pine wood, and the higher the degree of pulping the smaller methoxyl content of the prepared lignin is obtained.3. It is estimated that the measured methoxyl amounts of red pine wood or pulps are not all due to their lignin contents, but some to their carbohydrate parts.4. On the process of lignin determination of sulfite pulps by 72% sulfuric acid, considerable amounts of sulfonic radical of lignosulfonic acid in the pulps are splited.5. The higher the degree of pulping the more strongly the concentration of sulfuric a_??_id effects on the analysed lignin value.