METHOD FOR QUANTITATIVE DETERMINATION OF INDIVIDUAL POLYSULPHIDE SPECIES IN OXIDIZED WHITE LIQUORS BY MEANS OF RAMAN SPECTROSCOPY

摘要

A direct monitoring method is provided for the online measurement of the concentration of individual polysulphide species, e.g. trisulphide, tetrasulphide and inactive polysulphide, in process liquors used in the production of kraft pulp. The method eliminates the need for frequent sampling and manual analysis technique and the need for frequent equipment maintenance. The method includes the steps of: (1) withdrawing a sample from the process liquors, (2) subjecting the sample to a monochromatic light source of predetermined wavelength, (3) collecting the scattered Raman intensity over a predetermined wave number region so as to produce a Raman-scattered peak-intensity spectrum, (4) recording peak-intensity measurements for individual polysulphide species, (5) correlating by univariate or multivariate calibration the relationship between the peak-intensity measurements of the sample with the concentration of individual polysulphide species to determine polysulphide concentration in the samples, and controlling at least one process parameter to obtain optimum polysulphide of the liquor generated from such processes, but not limited to, as oxidative process and electrolysis with or without the presence of catalysis such as manganese, lime mud, and wet-proofed agent.