Effect of sodium borohydride and hydrogen peroxide pretreatments on soda pulping of sugar maple (Acer saccharum)

Abstract

For recovering value-added wood-based organic material prior to delignification, sodium borohydride (NaBH₄) and hydrogen peroxide (H₂O₂) pretreatments under alkaline conditions were performed before soda pulping of sugar maple (Acer saccharum) chips with sodium hydroxide (NaOH). In this investigation, it was determined whether the pulp yield could be increased by partly stabilizing the hemicelluloses by these pretreatments, and simultaneously obtains lower pulp kappa numbers. The results indicated that when aiming to the same kappa numbers (i.e., kappa numbers 14.3-20.5), roughly 3% higher pulp yield could be achieved if the chips were pretreated with alkaline 0.5% NaBH₄ solutions, compared to those produced without such pretreatment or pretreated only with NaOH (i.e., without NaBH₄). In contrast, pretreatments conducted with alkaline 2.5% H₂O₂ did clearly lower pulp yields at the same kappa number range (14.0-22.7) when compared to the reference cooks conducted with NaOH pretreated materials. However, an increase in the H₂O₂ charge of the pretreatment from 2.5% to 5.0% had a clearly beneficial effect, as the pulp yield and kappa numbers after pulping of 5.0% H₂O₂ pretreated pulps were comparable to the reference cooks.

Keywords:

• Hydrogen peroxide
• pretreatment
• soda cooking
• sodium borohydride
• sugar maple

Additional information

Funding

The Foundations’ Post Doc Pool and The Finnish Cultural Foundation are gratefully acknowledged for providing funding for the research project.