Reinforcement of Alkaline Pulping Processes with Organic Solvents. Part II. Screening of Suitable Solvents

The effects on the delignification process by adding different organic solvents to soda, soda-anthraquinone and kraft processes were studied. Eleven solvents were selected via a principal component analysis of 103 solvents and 9 solvent descriptors, to cover a wide range of physical properties of the solvents. The results show that many of the added solvents have a positive effect on the pulping selectivity i.e give a high pulp viscosity at a given lignin content. The most promising solvents were found in a rather narrow polarity range. The effect of adding a solvent, with regard to both delignification and carbohydrate degradation, is similar in the three alkaline pulping processes studied.