Optimization of Treatments for the Conversion of Eucalyptus Kraft Pulp to Dissolving Pulp

Abstract

Eucalyptus wood is known worldwide for its use in the production of kraft pulps and dissolving pulps. In our previous study, the feasibility of using a eucalyptus kraft pulp as a dissolving pulp was investigated. It was demonstrated that a kraft pulp subjected to a sequence of treatments that included enzymatic treatments using a xylanase and a monocomponent endoglucanase and, an alkali extraction, accomplished the requirements of a commercial dissolving pulp in terms of cellulose reactivity and hemicellulose content. Nevertheless, the low degree of polymerization and the presence of cellulose II showed that the combination of treatments had to be optimized. As a result, the parameters involved in the sequence of treatments were examined as well as their influence in the production of dissolving pulps. Furthermore, new sequences were tested. It was noticed that by decreasing the concentration of alkali in the alkali extraction stage, no cellulose II formed at short reaction times (10 min.) and that the degree of polymerization was increased. On the other hand, the cellulose reactivity and the hemicellulose content were barely affected. Moreover, a high pulp consistency (10%) led to an inhomogeneous mixture and the stirring effect was slightly noticeable.