Analysis of impurities ocurring in a totally chlorine free-bleached Kraft pulp

Instituto de Recursos Naturales y Agrobiología de Sevilla, Consejo Superior de Investigaciones Científicas, P.O. Box 1052, 41080-Seville, Spain; Corresponding author (J.C. del Río): e-mail: delrio@irnase.csic.es
A set of impurities (specks) occurring in a TCF (Totally chlorine free)-bleached Kraft pulp of Eucalyptus globulus wood was studied. The impurities were Soxhlet extracted with acetone, and the extracts subsequently analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) using high temperature capillary columns. The lipophilic fraction isolated from E. globulus wood extractives was also analyzed for comparison. The composition of the acetone extracts was very similar to that of E. globulus wood. Fatty acids, steroid hydrocarbons, sterols, steroid ketones and sterol esters, arising from E. globulus wood extractives survived the cooking and bleaching processes and accumulated in the pulp. On the other hand, the residue left after acetone extraction was studied by pyrolysis-GC-MS. The results indicated that it was composed of small particles of polyisoprene rubber. In conclusion, the speck impurities studied here seems to be composed of two different moieties, a lipophilic part arising from wood extractives and a core of small particles of synthetic polymers (polyisoprene rubber).
This research has been carried out with financial support from the Commission of the European Communities, Agriculture and Fisheries (FAIR) specific RTD Programme, CT95-0560, "Wood Extractives in Pulp and Paper Manufacture: Technical and Environmental Implications and Biological Removal".