Effect of eucalyptus wood chips pretreatment with sodium xylenesulphonate (SXS) in the kraft cellulosic pulp quality

Abstract

This study aimed to evaluate the effect of sodium xylenesulphonate (SXS) application as a pretreatment in wood chips of Eucalyptus grandis x Eucalyptus urophylla in the kraft cellulosic pulp quality. First the wood chemical characterization was made; subsequently the chips underwent a pretreatment in the following conditions: 12 hours, 30% concentration of SXS and temperature of 130°C. After the pretreatment the yield parameters and lignin content remaining in the chips were determined. The pretreated and normal chips (control) were subjected to the kraft pulping process for obtaining a pulp with kappa number 15 ± 0.5; for analyzing the pretreatment effect on the pulp quality. From the results obtained, it was possible to observe that the pretreatment with SXS allowed the extraction of 39.12% of lignin from wood chips, compared with the normal wood. Regarding the pulping process, the pulp yield values obtained from the wood chips pretreated with SXS were lower than the normal chips, but on the other hand showed a high degree of delignification, allowing to obtain pulp with the same kappa number (15 ± 0.5) with active alkali loads 34.8 and 37.6% lower, without and with anthraquinone, respectively, when compared with the normal chips. The addition of anthraquinone increased the screened yield and intensified the pulp delignification rate for the normal chips, not featuring notorious effect for the pretreated chips. The pretreatment with SXS considerably reduced the hexenuronic acids content, and increased the cellulosic pulp viscosity. By analyzing the results obtained from the materials pretreated with sodium xylenesulphonate, it is inferred that the concerned compound is an alternative to the cellulosic industry, because it combines its beneficial characteristics (biodegradable, odorless, non-incrustant, non-corrosive, low volatility, low flammability, easy recovery and high selectivity), to a reduction of reagents consumption in the pulping process, with an improvement in the cellulosic pulp quality.