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Microwave-assisted modification of lignin

Master thesis project – 30 p


Explore and evaluate sustainable methods for modification of kraft lignin 


Due to increased environmental concern, there is a strong wish to decrease the world’s dependence on petrochemicals. A corner stone in a sustainable economy is the development of processes and products from renewable raw materials such as those originating from the forestry. 

Lignin is one of the major macromolecules in wood with a broad molecular mass distribution. It is also structurally heterogeneous composed of guaiacyl and syringyl units, connected with different types of ether and carbon-carbon bonds. During kraft pulping for paper production, the wood lignin is partly degraded and about 90 % is dissolved into the black liquor, making kraft lignin the main organic molecule in the side streams of the kraft pulping process, conventionally used as an energy source in the mill. 

The increasing competiveness and decreasing profit for traditional products has boost the interest to expand their product portfolio to include kraft lignin. More profitable utilisation of kraft lignin has so far been restricted partly due to its heterogeneity and partly due to inferior properties compared to today’s raw materials used in e.g. the production of adhesives. Thus, to increase the competitiveness of kraft lignin in higher-value applications, its properties must be more even and predictable.


In this MTh project, you will explore efficient modification methods considering sustainable issues as specified by the Principles of Green Chemistry e.g. energy utilization, choice of solvents and reagents. In this context microwave induced synthesis will be applied using environmental benign solvents as well as reagents, the latter in form of organic carbonates. By exploring the limits of the reaction conditions, optimised conditions for at least one type of modification/ lignin product will be settled. The method will be evaluated with respect to efficiency (conversion to desired product) and the product will be evaluated with respect to thermal properties and solubility. The project involves a brief literature survey, to be executed in parallel with the experimental tasks.

You will use techniques such as microwave irradiation, differential scanning chromatography (DSC), nuclear magnetic resonance spectroscopy (NMR) and eventually evaluate the atom economy of selected conditions. At the end of the project you will write a report and give a presentation in English.

The project will give you an understanding in how to design methods based on the principles of Green Chemistry and how it can be applied to kraft lignin. A suitable background is theoretical knowledge in organic chemistry/wood chemistry. An interest in experimental work is vital. 


January-May 2017 (20 weeks)


Elisabeth Sjöholm



Elisabeth Sjöholm
08 676 7448
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