The kinetics of lignin extraction in oxygen delignification.

The current and future environmental challenges call for improved and more sustainable processes in the pulp industry. To contribute to a sustainable and competitive Swedish bioeconomy the pulp industry needs to increase efficiency without increasing the use of hazardous chemicals. Oxygen delignification is a unit process that has been used in pulp mill fiberlines between the cooking step and bleaching steps since it was introduced in the 1970´s. Oxygen lignification is a way to significantly reduce and extract the lignin content from the fibers in an environmentally friendly way, which gives the possibility to minimize the requirement for chemicals in later bleaching steps and give the possibility to fractionate the lignin molecules for energy or materials production. The aim of this project is to provide fundamental understanding of the mass transport within the extraction of lignin molecules from the fiber wall during oxygen delignification in order to comprehend the full delignifying potential of this stage in the fiber line.