XPS in combination with mercurization - incorporation of mercury into different morphological parts of an unbleached softwood kraft pulp

摘要

In this study the rate and extent of mercury incorporation into different morphological fractions, i.e., fibers, mechanically peeled fibers, primary and secondary fines, of an unbleached softwood kraft pulp were evaluated. In addition, the surface coverage of the different morphological pulp fractions by lignin was quantified using XPS in combination with mercurization. Incorporation of approximately one mole of mercury per mole of lignin (C_9-unit) was obtained for the different morphological parts after a 10-h reaction. Extractives inhibit the mercurization reaction; however, this effect decreases as the mercurization procedure proceeds and disappears after approximately 10 h. XPS analysis showed that the amount of lignin on the pulp fiber surfaces was approximately twice as high as in the rest of the fibers and that mechanical peeling in a disintegrator removed lignin-rich material from fiber surfaces. The amount of surface lignin on primary and secondary fines was 3.5- and 6.5-fold higher than in the bulk, respectively. The mercurization technique in combination with XPS is well suited for verification of the amount of surface lignin.