Impact of kraft process modifications on Eucalyptus globulus pulping performance and polysaccharide retention

The impact of effective alkali (EA) splitting and anthraquinone (AQ) addition on Eucalyptus globulus kraft pulping yield and pulp quality was investigated. AQ addition to kraft pulping enhances the rate of delignification, leading to alkali saving and reducing time at maximum temperature. A 1.9% total yield increase was observed, assigned to the enhancement of both cellulose and xylan retention but also due an increase of rejects content. Contrary to results described in the literature for other woods, the use of an even effective alkali concentration profile throughout the cook of E. globulus did not affect pulp yield or carbohydrate composition of screened pulp. However, EA profiling resulted in a higher pulp viscosity, indicating a lower degradation of cellulose chains along the pulping. Such results were interpreted taking into account the peculiar chemical structure of E. globulus wood components.