Rapid determination of the reactivity of dissolving pulps by reaction-based headspace gas chromatography

This paper reports on a headspace gas chromatographic (HS-GC) method for rapid determining the reactivity of dissolving pulps. After xanthation process, the viscose solution was acidified and degassed, and the dissolved cellulose in the viscose solution was regenerated and then oxidized by potassium dichromate in a strong-acidic solution in a sealed headspace vial. It showed that the cellulose can be completely converted to CO2 at the given reaction conditions (temperature = 100 °C, time = 60 min, K2Cr2O7 = 33.5 μmol, H2SO4 = 9000 μmol). By quantifying CO2 using HS-GC, the pulp reactivity of the sample can be indirectly determined. The result showed that the present method has a good repeatability (with a relative standard deviation (RSD) less than 3.7%) and a good accuracy (the differences were less than 5.0% compared to the reference method). The limit of quantitation (LOQ) of the method was 8.78%. In summary, the present method is rapid, simple, and suitable for determining the reactivity of dissolving pulps in both laboratory or industrial applications.