Hot water pre-extraction of Barley straw and its effect on soda and monoethanolamine pulps properties

In this study, hot water pre-extraction of barley straw followed with soda and monoethanolamine pulping was investigated. Pre-extraction that resulted in removal of 28 % of barley straw hemicelluloses and pre-extraction yield of 72.7 % was selected as the optimum pre-extraction treatment. The pulping results show that among the pulps from pre-extracted barley straw and barley straw without pre-extraction, monoethanolamine pulps have the highest yields. Also, the yields of pulps were drastically dropped after hot water pre-extraction. At the same pulping conditions, the kappa numbers of pulps that produced from pre-extracted barley straw were decreased more than that of from barley straw without pre-extraction in soda pulping, but this effect is not seen in the case of monoethanoleamine pulps. Pre-extraction of barley straw followed with soda pulping resulted in pulps with higher tensile, burst and tear indices in comparison to untreated samples. In the case of monoethanoleamine pulp the similar trend can be seen in except of tensile index. The brightness of pulps from pre-extracted barley straw is decreased while the pre-extraction has no effect on pulp opacities.