A LASER-INDUCED FLUORESCENCE (LIF) METHOD FOR MONITORING OXYGEN–ALKALI DELIGNIFICATION OF SOFTWOOD KRAFT PULP

ABSTRACT

A laser-induced fluorescence (LIF) method for monitoring the oxygen–alkali delignification of pine (Pinus sylvestris) kraft pulp was tested. The fluorescence intensity of the effluent was found to increase systematically during treatment as the lignin content of the pulp decreased. This emission method, compared, for example, to a UV/Vis absorption method, seems to have potential for large-scale applications. Owing both to the complex chemical nature of the effluent from oxygen–alkali delignification and to the complex nature of the fluorescence method, further work on this method is needed before it can be used for industrial purposes.

Keywords:

• Fluorescence emission
• LIF
• Absorption spectroscopy
• Oxygen delignification
• Kraft pulp
• Pine wood
• Lignin content

ACKNOWLEDGMENTS

This study was supported by the Natural Scientific Foundation, Kajaani Electronics Ltd., and the Jenny and Antti Wihuri Foundation.