Improvement of alkali efficiency for purification of dissolving pulp by a modified cold caustic extraction process.

In this study, a reutilization of caustic lye during cold caustic extraction (i.e., CCE) process to produce high-purity dissolving pulp and high-concentrated hemicellulose solution was proposed. The results showed that the lye can be reused about 12 times for producing high-purity dissolving pulps. With the number of CCE stages of 12, the hemicellulose in the lye can be auto-concentrated to about 37g/L. The alkali efficiency of the modified CCE process was about 6 (or 3) times better than the traditional CCE process with low- (or middle-) consistency of pulps. Therefore, the present process is feasible to be used for the purification of dissolving pulps with a cost-effective manner.