Influence of Sodium Borohydride on Kraft Pulping of European Black Pine as a Digester Additive

Abstract

In this study, the effects of sodium borohydride (NaBH4) on properties of kraft pulp and paper obtained from European black pine (Pinus nigra Arn.) were investigated. Kraft−NaBH4 cookings were done under fixed cooking conditions by adding NaBH4 in the amounts of 0.5%, 1%, 1.5%, and 2% (oven-dried wood) to the cooking liquor. NaBH4-free kraft cooking was carried out as control. The results indicated that addition of NaBH4 to cooking liquor increased the pulp yield. However, the kappa number of pulp and beating time decreased. The brightness of kraft−NaBH4 papers was found to be higher than that of control papers. Addition of NaBH4 significantly decreased pulp viscosity and slightly decreased strength properties of papers.

Effects of cationic starch addition and pulp beating on strength properties of softwood kraft pulp

“…The increase of the beating degree from 15 °SR (CS‐free) to 20, 25, and 30 °SR led to increments in the tensile index of 150, 218, and 236%, respectively. Similar results have been reported in other studies . This rise in the tensile index could be ascribed to the increase in the bonded area of the fibers owing to the internal and external fibrillation that occurs during beating .…”

“…The increase of the pulp beating degree from 15°SR to 20, 25, and 30°SR increased the burst index by 100, 122, and 129%, respectively. Several investigations reported that beating results in an increase in the burst index [21,32]. However, addition of 0.75, 1.5, and 2.25% CS to the 15°SR pulp increased the burst index as 177%, 262%, and 278%, respectively.…”

The effect of increased pulp yield using additives in the softwood kraft cook on the physical properties of lowgrammage handsheets

“…Yield-increasing additives to stabilise glucomannan (Rydholm 1965) can be either reducing or oxidizing chemicals. A reducing additive is sodium borohydride (NaBH 4 ), which yields stable alcohol groups (Rydholm 1965;Gulsoy, Eroglu 2011) and sodium borate according to the reaction (Rydholm 1965), Eq 1. 4RCHO+NaBH 4 +2NaOH+H 2 O 4RCH 2 OH+Na 3 BO 3 [1] At the same time a side reaction occurs, Eq 2.…”

“…4RCHO+NaBH 4 +2NaOH+H 2 O 4RCH 2 OH+Na 3 BO 3 [1] At the same time a side reaction occurs, Eq 2. NaBH 4 +2NaOH+H 2 O 4H 2 +Na 3 BO 3 [2] The most important advantage of using NaBH 4 is the significant yield increase, but there are other advantages such as energy savings during refining and an increase in pulp brightness (Gulsoy, Eroglu 2011). An oxidizing chemical additive is polysulfide which can be produced by adding elemental sulfur to white liquor (Rydholm1965; Lindgren, Lindström 1995), when the following reaction takes place already at 70°C, Eq 3.…”

Chemical Composition, Fiber Morphology, and Kraft Pulping of Bracken Stalks (Pteridium aquilinum (L.) Kuhn)

“…Higher hemicellulose content results in an increase of pulp strength. Gulsoy and Eroglu (2011) noted that tensile index increased in European black pine kraft pulp, and Gümüşkaya et al, (2011) noted that it increased in stone pine AS-AQ pulp with NaBH 4 addition. On the contrary, some authors noted that NaBH 4 had a negative effect on tensile index of handsheets (Akgül et al, 2007;Çöpür ve Tozluoğlu, 2008;Istek and Özkan, 2008).…”