Doctor of Technology Elina Warsta In his doctoral dissertation, he studied the reactions of neutral sodium sulfite solutions with wood, wood pulps and their chemical components – lignin, cellulose and hemicelluloses.
“Neutral sulfite chemistry and related processes are only used to a limited extent on an industrial scale, and therefore there is little research on the topic,” he says.
“However, universities and research institutes can also explore side paths where it is possible to find something new and valuable.”
Rapid analysis method
The study developed a new analytical method for measuring phenolic hydroxyl groups in lignin using UV resonance Raman spectroscopy.
“The method allows for rapid measurement of large quantities of different samples without chemical separation of lignin or time-consuming steps that change the lignin structures. The samples can be, for example, wood, pulp or lignin solution, and by quickly adjusting the pH, the reactivity of the lignin can be analyzed. This in turn provides information on how successful different treatments have been. Although it is only an analytical process, it is important for the development of new products.”
Possible applications
As part of the research, laboratory experiments were conducted in which neutral sulfite treatment was tested on kraft pulps. The result was the formation of microcrystalline cellulose, which was a surprise.
"Microcrystalline cellulose already has many applications: it is used in cosmetics, for example. In addition, under the conditions in which we conducted the experiments, sulfonated cellulose is also presumably formed, which can be used as a solid acid catalyst in the chemical industry, for example in the production of biodiesel."
The catalyst could replace traditional chemical catalysts.
"Current catalysts cause corrosion, which is challenging for equipment. Being toxic, they also require neutralization of waste sludge. Therefore, such a harmless alternative would be necessary."
The research also tested the production of softwood pulp in neutral sulfite cooking, which resulted in high-yield pulp and strongly charged fibers.
“Such materials could be utilized, for example, in packaging requiring multilayer solutions to replace plastic.”
However, Warsta emphasizes that the experiments were conducted from a purely chemical perspective.
“For example, we did not assess whether such applications would be economically feasible.”
Elina Warsta's doctoral dissertation
Reactions of neutral sodium sulphite solutions with chemical components of wood and wood pulps, Aalto University School of Chemical Engineering, Department of Bioproducts and Biotechnology. Aalto University publication series Doctoral Theses, 27/2026.
