Determination of the Total Sulfur Content in Black Liquor By X-Ray Fluorescence, 2004 International Chemical Recovery Conference

The general methods for determining the total sulfur content of black liquor include ion chromatographic, titrimetric, and gravimetric analyses. A common prerequisite for these methods is the need to oxidize different sulfurcontaining compounds, e.g., sulfide, thiosulfate, and sulfite, to sulfate prior to performing the measurements. However, oxidation is time-consuming and there is also a real possibility of losing part of the sample by evaporation or other means during the multistage sample treatments. In this study, a method for analyzing the total sulfur content of black liquors without any preoxidation by means of an energy dispersive X-ray fluorescence (EDXRF) spectrometer was developed. This method was evaluated by comparing the results with those obtained by other known methods. The results agreed well with those of other methods and their reproducibility proved to be better than, or at least equal to, that of other methods. Simplicity of use, absence of need for multistage sample treatment, stability of calibration, and rapidity of measurement were considered to be the major benefits of the EDXRF.