ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Displacement washing of soda rapeseed pulp

František Potůček and Kateřina Hájková

Institute of Chemistry and Technology of Macromolecular Materials, Faculty of Chemical Technology, University of Pardubice, Studentská 95, 532 10 Pardubice, Czech Republic

E-mail: frantisek.potucek@upce.cz

Abstract: The paper deals with the displacement washing of unbleached pulp cooked from rapeseed straw by soda pulping under laboratory conditions. Pulp fibres were characterised by their average length, as well as by effective specific volume and surface. Using the step function input change method, the washing breakthrough curves measured for alkali lignin as a tracer were described by the dispersed plug flow model containing a dimensionless criterion, the Péclet number. Besides the wash yield, the dispersion coefficient as well as the mean residence time and space time were evaluated. Preliminary results obtained for soda rapeseed pulp were compared with those for kraft hardwood (beech) and softwood (spruce, pine) pulps published earlier. The wash yield measured for soda pulp was found to be lower than that for hardwood and softwood pulps which manifested lower hydraulic resistance. The presence of silique valves in rapeseed straw resulted in lower mean residence time of lignin removed from the pulp bed in comparison with pulp manufactured from stalks only.

Keywords: displacement washing – soda pulp – rapeseed straw

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0106

Chemical Papers 69 (8) 1067–1074 (2015)