Effect on the Temperature in Hot Alkaline Refining of Pulp

Abstract

As noted in the previous paper (J. Japan Wood Res. Soc., 1957, 31), a sodium hydroxide solution has a stronger refining power than a sodium carbonate solution for the pulp and this difference can be attributed almost to the difference of hydroxyl ion concentration. In this paper, the refining of prechlorinated sulphite pulp with a sodium hydroxide or a sodium carbonate solution were studied for the various temperature between 95°C and 160°C, and the following results were obtained :(1) The temperature is less effective in the refining with a sodium hydroxide solution. With a lower pH solution such as a sodium carbonate solution, however, the refining power varies with the temperature (Fig. 1-3)(2) As a sodium carbonate solution attacks the pulp slowly, it needs a longer time treatment or a higher temperature treatment for the preparation of pulp containing high alpha-cellulose.(3) So far as a sodium hydroxide or sodium carbonate solution is used as the refining agent, the yield of pulp with equal alpha-cellulose content is almost same under any temperature or pH within a range of experiments (Fig. 6).