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Mixed southern hardwood chips were extracted with an alkaline wood pulping solution called kraft green liquor. This aqueous solution containing mainly sodium carbonate and sodium sulfide was applied at different alkali charges (expressed as Na 2 O) of 0, 2, 4, and 6% on dry wood weight. The extractions were performed at 160 °C for effective times ranging from about 1-2 h to determine the effect of extraction severity on pulp yield and composition of the extracted liquor. The severity of hemicellulose extraction time and alkaline charge controls the concentration of acetic acid and monosaccharide sugars available for downstream processing, the accumulation of degradation products such as organic acids and furans in the extract, and the pulp yield attainable for the extracted wood chips. As the alkali charge was increased, the amount of acetate side chains on the hemicelluloses and the dissolved lignin in the extract increased but the carbohydrate and sugars in the extract decreased appreciably. Water extraction (0% alkali addition) released the greatest amount of carbohydrates, up to 30 g/L measured as component sugars, but resulted in the greatest decrease in pulp yield, dropping from 47% to 35%. Extraction with 2% green liquor increased the pulp yield to 51% while greatly reducing the component sugars to 8 g/L. Data obtained in this work will allow selection of optimum hemicellulose extraction conditions for integrating the extraction operation into the Kraft pulping process.

Reactions involving methyl b-cellobioside and several oxygen species were used to investigate cleavage of glycosidic linkages in cellulose by reaction with photochemical hydroxyl radicals. The intent is not to reproduce delignification conditions, but rather to study the specific behavior of carbohydrate models toward hydroxyl radical. Experiments show that hydroxyl radicals are responsible for the degradation of glycosidic linkages in methyl b-cellobioside by substitution reactions displacing cellobiose, D-glucose, methyl b-D-glucoside, and methanol. Once the glycosidic linkages are broken, the reducing carbohydrates undergo a series of reactions forming 67

The P-p-T-x relationships of the propane-n-octane and the n-butane-n-octane systems are determined. The experimental results cover a range from about 150 lb/in.2 abs and room temperature to the highest pressure and temperature at which liquid and vapor can coexist. The data are presented in tabular form. P-T-x, p-T-x, and isobanc T-x diagrams are given.This paper presents the P-p-T-x relationships of the binary systems of propane-n-octane and n-butane-n-octane. It is the third of a series (5, 6) in a study of the effect of the relative size of the molecules on the phase diagram of mixtures of n-alkanes.

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The selectivity of kraft pulping versus the oxygen delignification processes over the range of kappa nos. 25–90 was compared. Kraft pulping was found to be more selective than oxygen delignification for removing lignin from southern softwood kraft pulps. The greater selectivity is thought to be related to hydroxyl radicals that form in the oxygen delignification process that are not present in the kraft process. The hydroxyl radicals attack the carbohydrates and randomly cleave the polymeric chains, causing a significant decrease in the degree of carbohydrate polymerization and thus a loss of viscosity. Kraft pulping generates hydrosulfide ions that are highly selective and attack the lignin. Carbohydrate degradation occurs mainly from peeling reactions, which do not appreciably reduce the degree of polymerization of the cellulose and thus there is less viscosity loss. At low lignin content (i.e., low kappa number), the remaining lignin is likely bound covalently to the carbohydrate portion in both processes. Therefore, removal of the lignin results in significant degradation of the carbohydrates.

The PVT-x diagrams of five binary systems composed of the Isomers of hexane with perfluoromethylcyclohexane as the common component were determined In the critical region. All of these systems form positive azeotropes and exhibit a minimum temperature point In their critical locus curves.The measured critical points In these systems and their correlation and prediction using an extended corresponding states principle are reported In this paper.i The Ohio State University.

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