Kraft Green Liquor Pretreatment of Softwood Chips. Part Ⅱ: Chemical Effect on Pulp Carbohydrates

摘要

The quantitative and structural changes in wood carbohydrate sugars that occur as a result of kraft green liquor (GL) pretreatment of wood chips before conventional kraft pulping were analyzed by means of high-performance anion-exchange chromatography with a pulsed ampemmetric detector. The results clearly demonstrated that GL pretreatment preserved a greater amount of carbohydrate sugars compared to conventional kraft pulping. The higher carbohydrate yield was derived mainly from a preservation of glucan. Additional approaches to improving yield such as using surfactants, poly sulphide (PS) and anthraquinone (AQ) were attempted in conjunction with GL impregnation for purposes of comparison and contrast. It was found that a judicious choice of the proper surfactant used during pretreatment was able to improve further carbohydrates preservation. GL pretreatment combined with PS and AQ additives improves the rate of delignification, yet it provides no clear influence on total carbohydrate yield.