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Proceedings Paper

Laser Induced Fluorescence For Measurement Of Lignin Concentrations In Pulping Liquors
Author(s): J. J. Horvath; H. G. Semerjian; K. L. Biasca; R. Attala
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Paper Abstract

Laser excited fluorescence of pulping liquors was investigated for use in the pulp and paper industry for process measurement and control applications. Liquors from both mill and laboratory cooks were studied. A Nd-YAG pumped dye laser was used to generate the excitation wavelength of 280 nm; measurements were also performed using a commercially available fluorometer. Measurements on mill pulping liquors gave strong signals and showed changes in the fluorescence intensity during the cook. Absorption spectra of diluted mill liquor samples showed large changes during the cook. Samples from well controlled and characterized laboratory cooks showed fluorescence to be linear with concentration over two decades with an upper limit of approximately 1000 ppm dissolved lignin. At the end of these cooks a possible chemical change was indicated by an increase in the observed fluorescence intensity. Results indicate that lignin concentrations in pulping liquors can be accurately determined with fluorescence in the linear optical region over a greater dynamic range than absorption spectroscopy. Laser induced fluorescence may also provide an indication of chemical changes occurring in the lignin structure during a cook.

Paper Details

Date Published: 29 November 1988
PDF: 10 pages
Proc. SPIE 0961, Industrial Optical Sensing, (29 November 1988); doi: 10.1117/12.947860
Show Author Affiliations
J. J. Horvath, National Bureau of Standards (United States)
H. G. Semerjian, National Bureau of Standards (United States)
K. L. Biasca, Institute of Paper Chemistry (United States)
R. Attala, Institute of Paper Chemistry (United States)

Published in SPIE Proceedings Vol. 0961:
Industrial Optical Sensing
James Carney; Ernie Stelzer, Editor(s)

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