Description of the thesis:
In all research and development on lignocellulose and in all activities involving forest industries and biorefineries, analysis of the raw material composition is a central technique. The development in the area also means that the industry is interested in new types of raw materials and that the raw material undergoes treatments that have not previously been relevant. Therefore, there is a need to investigate certain fundamental issues that concern the analytical technique for different kinds of raw materials and different substances that are found in the raw materials from the beginning or which are formed when the raw materials are converted.
The proposed degree projects will be carried out at MoRe Research in close collaboration with Umeå University, Sekab E-Technology and RISE Processum. All of these organizations are active in Domsjö's development area in Örnsköldsvik.
Degree Project - Lignin (30p)
Lignin is one of the major constituents of lignocellulose and is built up in a complex manner by phenylpropane units derived from the three building blocks 4-cumaryl alcohol, coniferyl alcohol and sinapyl alcohol. The structure of the Lignin also differs for different kinds of raw materials.
The traditional way of analyzing lignin is to treat a lignocellulosic sample with strong acid (sulfuric acid) and thereby dissolve and remove hemicellulose and cellulose. The weighted residue is considered to be lignin and is called Klason lignin. One can also measure acid-soluble lignin with UV spectroscopy. Both of these methods have drawbacks in quantifying lignin in different types of raw materials and process streams because the methods are not specific to lignin. Everything that does not dissolve after acid treatment is considered Klason lignin and anything that absorbs at a certain wavelength is considered as acid soluble lignin.
In this thesis, an analysis method based on thioacidolysis will first be set up and evaluated for quantitative determination of lignin in various raw materials and modified raw materials. The result of the thioacidolysis will be compared to Klason lignin and acid soluble lignin from known raw materials. Pyrolysis GC/MS will also be used to compare different lignin characterization methods. Different types of lignin will be characterized; precipitated sulfate lignin, hydrolysis lignin, lignocellulose (eg wood), enzymatically treated lignocellulose, lignosulfonate and organosolvine lignin.
After the analysis methodology has been developed, it will be applied to a scientific issue. Few microorganisms are capable of mineralizing lignin (breaking down lignin into carbon dioxide), but there are some kinds of fungi, white rot fungi, which can cause extensive mineralization of lignin. The details of how the degradation occurs, however, are still largely unclear. Some white rot fungi, e.g. shamrock and oyster slice, are also good food fungi grown on an industrial scale. By analyzing the lignin composition before, during and after the fungal cultivation, one should be able to get information on how the initial steps of the lignin decomposition go to. The issue has both scientific and applied value, since the cultivation of mushrooms on wood substrate gives a pretreatment of lignocellulose which means that the residues from fungi can then be used for further processing of the remaining lignocellulose into green chemicals and propellants. The lignin degradation is believed to play a key role in this, which, however, needs to be investigated more closely to understand how the process works.
Start: Autumn 2019
Contact: Robert Selling, +4670-522 73 99, E-mail