Influence of the oxidative thermochemical treatment on the chemical composition of hardwood kraft black liquor.Application:This alternative for black liquor Black liquor is a byproduct of the Kraft process, (also known as Kraft pulping or sulfate process) during the production of paper pulp. Wood is decomposed into cellulose fibers (from which paper is made), hemicellulose and lignin fragments. processing in modern pulp mills can reduce viscosity and have other beneficial effects on black liquor evaporation evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at a rate that depends on the amount of surface exposed, the humidity and combustion. Black liquor exhibits a significant increase in viscosity as a function of its dry solids content. For this reason, viscosity is the limiting lector in raising the dry solids content of black liquor at the mill. The greater the dry solids content, the more energy efficient the recovery process and the fewer sulfur dioxide sulfur dioxide, chemical compound, SO2, a colorless gas with a pungent, suffocating odor. It is readily soluble in cold water, sparingly soluble in hot water, and soluble in alcohol, acetic acid, and sulfuric acid. emissions. This study focused on influences of oxidative thermochemical treatment on the physical and chemical properties of hardwood kraft black liquor. We treated hardwood kraft black liquor thermochemically to reduce its viscosity without and with NaOH addition. All black liquors were analyzed with respect to viscosity. We also characterized selected liquors for residual effective alkali, molecular-mass distribution of lignin lignin (lĭg`nĭn), a highly polymerized and complex chemical compound especially common in woody plants. The cellulose walls of the wood become impregnated with lignin, a process called lignification, which greatly increases the strength and , and chemical composition of aliphatic aliphatic /al·i·phat·ic/ (al?i-fat´ik) pertaining to any member of one of the two major groups of organic compounds, those with a straight or branched chain structure. al·i·phat·ic adj. carboxylic acids, and determined total content of lignin, aliphatic carboxylic acids, and polysaccharides. The results indicated that the heat treatment under oxidative alkaline conditions with the presence of excess alkali decreased significantly the viscosity of hardwood kraft black liquor: In this study, degradation of the high-molecule-mass fraction (M> 10,000 De) of lignin was one of the main reasons for viscosity decrease. However, a clear relationship between the viscosity and the chemical composition of black liquor could not be easily seen. These findings indicated that other teeters, such as changes in physical properties of black liquor during the treatments, might have an important role in viscosity reduction. Louhelainen is research scientist and Alen is professor at the University of Jyvaskyla, Department of Chemistry, Laboratory of Applied Chemistry, P.O. Box 35, FIN-40014 University of Jyvaskyla, Finland; Zielinski is manager, North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. wet oxidation Wet oxidation is a form of hydrothermal treatment. It is the oxidation of dissolved or suspended components in water using oxygen as the oxidizer. It is referred to as "Wet Air Oxidation" (WAO) when air is used. , with Air Products and Chemicals, Inc., 7201 Hamilton Boulevard, Allentown, PA 18195-1501, USA; email Louhelainen at jarmo.louhelainen@jyu.fi |
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