Effect of raw material and Kraft Pulping Conditions on Characteristics of Dissolved Lignin
Year: 2014
Type: dissertation
Abstract: Lignin is one of the main components in wood and during the chemical pulping processes it is degraded and dissolved into the cooking liquor. The current challenge is to meet the need for energy and raw materials, and reform to a more environmentally sustainable society, so there is a great interest in using kraft lignin as a raw material for energy, materials and as source of chemicals. ) To meet this goal, it is essential to obtain kraft lignin with desirable properties. The overall goal of this master thesis project was to understand the relationship between kraft process conditions and the structure and properties of the dissolved lignin. Wood chips of pine, spruce and eucalyptus were pulped with the kraft process at constant temperature and similar alkali charge and sulphidity to different cooking times. From the collected black liquor, the dissolved kraft lignin was precipitated by acidification with sulphuric acid. It was observed that longer cooking time yields more precipitated material, where pine gave the highest yield. There was a significant difference in colour of the precipitated between eucalyptus and the softwood samples. Some the characteristic properties of the collected samples were investigated. Results from the Klason lignin and ionic chromatography showed variation in lignin and carbohydrate composition depending on raw material and cooking time. This was also indicated by results lignin carbohydrate ratio from analytical pyrolysis. However, the analytical pyrolysis data showed that the relative composition of lignin and carbohydrates was similar independent on pulping time and raw material. The sulphur content was higher for eucalyptus lignin compared to the softwood lignin. Pine lignin with the longest pulping time had the highest total phenolic content. Spruce lignin with the longest cooking time had the highest glass transition temperature.
Author: Antonia Svärd
Language: English
Topic: Lignin and Wood Chemistry
Subfield: Process Chemistry and Technology
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2148390602