In order to elucidate the characteristics of the waste liquor from semichemical pulping, experiments were made on three subjects as summarized below on comparing the color intensity and COD of various spent liquors with each others.
1. Contribution of the wood components to color and COD of spent liquor from NSSCP cooking : More than 50% of the color intensity come from the extractives, and lignin also contributes about 45% of it. Besides, hemicellulose and cellulose show negligible contribution to the color. Hemicellulose registers extensive contribution to COD (50%) of spent liquor. Other components contribute in the following order; lignin 15-30%, cellulose 15%, extractives 5-15%.
2. Progressive features of color and COD during NSSCP cooking : The color intensity based on the dissolved organic matters is constant during NSSCP cooking, but COD increases along the lapse with cooking. Because the dissolution of the hemicellulose is increasingly observed in the later stages of the cooking, COD of the spent liquor based on the dissolved organic matters changes during NSSCP cooking. On the other hand, as the organic matters themselves were deepened their coloration during the high temperature cooking, the apparent color intensity based on the dissolved organic matters reach a constant level.
3. Variation of color and COD of spent liquors from some pulping methods : The color intensity is proportional to the pH-value of the cooking liquor and the spent liquor, accordingly the method employing high pH cooking liquor deepens the color of the spent liquor. Contrary to this, the effect of the species variation of pulping timbers and pulping methods on COD of the spent liquor is considerably small, that is to say, under the usual pulp yield 65-70% there are no great differences in COD.

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This paper is to present some of the properties of pulp obtained by the new process using “Monoethanol Amine” (MEA) which is the basic organic solvent for lignin. This process is used to investigate the fundamental information for development of the High Yield Pulping method which uses as little water as possible.
Several species of soft and hardwoods were heated with MEA, under atmospheric pressure and also in autoclave under the conditions cited in Tab. 2.
Investigations of the fundamental pulp properties indicated the following conclusions. :
1) This method was found to be more suitable to hardwoods than soft woods.
2) Better Pulps qualities were obtained in cooking under atmospheric pressure than in autoclave.
3) In the cooking process only that amount of MEA sufficient to saturate the wood was necessary.
4) The experience was carried out re-using the waste liquor under the condition cited in Tab. 3-2. The result was that the same quality of pulp was obtained until the fifth operation.
5) In the case of Buna-wood (Beech), the refluxing with MEA for 3 hours under atmospheric pressure yielded a pulp of 65% which contained 5% of Klason-Lignin (namely the degree of delignification was more than 70%, ) about 16% pentosan and 95% holocellulose. The higher viscosities of holocellulose in the cuprammonium method but lower brightness by the Hunter method (23-27% GE) were shown in comparison with those found in ordinary pulp.

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Beech, oak, lauan, and pine woods were made into chips of 1.5-3.0 mm in thickness, and the chips were cooked with NaOH and O₂ using a rotating autoclave under the conditions shown in Table 2. Pine and lauan chips consumed more O₂ than did beech and oak chips. The partially-delignified chips were then defiberized mechanically to make the oxygen-alkali method semichemical pulp (OSCP). The chips were possible to be defiberized mechanically without breaking of fibers.
The yield, Kappa number, brightness, and C. I. E color scales of OSCP were compared with those of the neutral sulfite method semichemical pulp (NSSCP) and the kraft method semichemical pulp (cf. Table 3, 4, and 5). OSCP was high in yield and tan or yellowish white colored.
The test sheets were made of OSCP and NSSCP, and studied for their breaking length, burst factor, and tear factor. OSCP were comparable to NSSCP on the strength of the sheet (cf. Table 6).
The test fibreboards were made of OSCP, NSSCP, and refiner ground wood pulp, and studied for their specific gravity and bending strength. On the bending strength, the fibreboard made of OSCP was almost on a level with the fibreboard made of NSSCP and was on much higher level than that made of refiner ground wood pulp (cf. Table 7).

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