Enhancing Kraft based dissolving pulp production by integrating green liquor neutralization

Abstract

A pre-hydrolysis Kraft pulping (PHK) process that was used to make dissolving pulp was enhanced by replacing conventional white liquor (WL) neutralization with green liquor (GL) neutralization prior to Kraft pulping. This resulted in a 10% increase in dissolving pulp production, and significant chemical savings, without compromising pulp reactivity. When the possible influence of the alkaline charge on fibre properties was assessed using methods such as viscosity, Simon's stain, Size Exclusion Chromatography (SEC) and SEM, it was apparent that stronger alkaline treatments (WL) resulted increased cellulose degradation, a lower cellulose DP and a slightly larger surface area. When these methods were complemented with an assay based on the selective binding of site-specific carbohydrate-binding modules (CBMs), it was apparent that green liquor (GL) neutralization resulted in an increase in less-ordered cellulose being exposed. This likely contributed to its higher reactivity despite its lower overall surface area.

Keywords

• Pre-hydrolysis and Kraft pulping process
• Green liquor
• Yield
• Surface characterization
• Carbohydrate-binding modules
• Reactivity