BEHAVIOUR OF CARBOHYDRATE-BASED MATERIAL IN BLACK LIQUOR DURING HEATING

Abstract

One industrial softwood kraft black liquor was heat-treated (at 175 ?C and 190 ?C for 15?60 min) together with laboratory-made soda-AQ (wheat straw and reed canary grass) and kraft (reed canary grass) black liquors (at 190 ?C for 30 min). The feedstock black liquors were characterised with respect to their polysaccharide (mainly xylan) and aliphatic carboxylic acid contents before and after the heat treatments. It was noted that, due to the higher amount of polysaccharides in the nonwood black liquors (8.2-16.6 % of d.s.) compared to that in the softwood black liquor (1.4 % of d.s.), the heat treatment in the former case resulted in a 5-30 % increase in the amount of aliphatic acids formed by various alkali-catalysed degradation reactions of the liquor polysaccharides. In addition, in each case detailed gas chromatographic studies revealed that as a general trend the content of higher-molecular-mass acids decreased on heating with the subsequent increase in the content of lower-molecular-mass acids.

Keywords

Dates

  • Submission Date2004-05-17
  • Revision Date2004-08-27
  • Acceptance Date2004-09-16

References

  1. [1] Sj?str?m, E., Wood Chemistry - Fundamentals and Applications, 2nd ed., Academic Press, San Diego, USA, 1993
  5. [2] Clayton, D., Easty, D., Einspahr, D., Lonsky, W., Malcolm, E., McDonough, T., Schroeder, L., Thompson, N., Part I. Chemistry of Alkaline Pulping, in: Pulp and Paper Manufacture ? vol. 5. Alkaline Pulping, 3rd ed. (Eds. T.M. Grace and E.W. Malcolm), The Joint Textbook Committee of the Paper Industry, Montreal, Canada, 1989, pp. 1-128
  7. [3] Al鮬 R., Basic Chemistry of Wood Delignification, in: Papermaking Science and Technology - Vol. 3, Forest Products Chemistry (Ed. P. Stenius), Fapet Oy, Helsinki, Finland, 2000, pp. 58-104
  9. [4] Lindberg, B., Alkaline Hydrolysis of Glycosidic Linkages, Svensk Papperstidning., 59 (1956), pp. 531-534
  11. [5] Mutton, D. B., Cellulose Chemistry, Pulp & Paper Magazine of Canada, 65 (1964), pp. T41-T51
  13. [6] Biermann, C. J., Essentials of Pulping and Papermaking, Academic Press, San Diego, USA, 1993
  15. [7] Malinen, R., Sj?str?m, E., The Formation of Carboxylic Acids from Wood Polysaccharides during Kraft Pulping, Paperi ja Puu, 57 (1975), No. 11., pp. 728-730, 735-736
  17. [8] Simonson, R. Hemicellulose in the Sulfate Pulping Process, Svensk Papperstidning, 74 (1971), No. 21., pp. 691-700
  19. [9] Kiiskil䬠E., Virkola, N.-E., Method of Decreasing Black Liquor Viscosity, PCT Int. Appl. WO 87/03315, (1987)
  21. [10] Louhelainen, J. Changes in the Chemical Composition and Physical Properties of Wood and Nonwood Black Liquors during Heating, Ph.D. Thesis, University of Jyv䳫yl䬠Laboratory of Applied Chemistry, Finland, 2003
  23. [11] S?derhjelm, L., S姦ors, P.-E., Kiiskil䬠E., Factors Influencing Heat Treatment of Black Liquor, Proceedings, 1998 Int. Chem. Recov. Conf., Tampa, USA, June 1-4, 1998, vol. 1, pp. 169-183
  25. [12] Feng, Z., Alkaline Pulping of Non-Wood Feedstocks and Characterization of Black Liquors, Ph.D. Thesis, University of Jyv䳫yl䬠Laboratory of Applied Chemistry, Finland, 2001
  27. [13] Al鮬 R., Niemel䬠K., Sj?str?m, E., Gas-Liquid Chromatographic Separation of Hydroxy Monocarboxylic Acids and Dicarboxylic Acids on a Fused-Silica Capillary Column, Journal of Chromatography, 301 (1984), No. 1., pp. 273-276
  29. [14] Al鮬 R., J䮮䲩, P., Sj?str?m, E., Gas-Liquid Chromatographic Determination of Volatile Fatty Acids C1-C6, and Lactic Acid as their Benzyl Esters on a Fused-Silica Capillary Column, Finnish Chemical Letters, (1985), No. 5., pp. 190-192
  31. [15] Gierer, J., W䮮str?m, S., Formation of Ether Bonds Between Lignins and Carbohydrates during Alkaline Pulping Processes, Holzforschung, 40 (1986), No. 6., pp. 347-352
  32. [16] Karlsson, O., Westermark, U., The Significance of Glucomannan for the Condensation of Cellulose and Lignin under Kraft Pulping Conditions, Nordic Pulp and Paper Research Journal, 12 (1997), No. 2., pp. 90-93
  34. [17] Holmbom, B., Research on Production and Use of Agro-Fibers in Finland, Proceedings, Int. Symp. Vegetal (Non-Wood) Biomass as a Source of Fibrous Materials and Organic Products, Guangzhou, China, 1996, pp. 30-35
  36. [18] Li, Z., Further Discussion on the Basic Behavior of the Pulping of Grasses, China Pulp and Paper, 7 (1988), No. 5., pp. 53-59
  38. [19] Al鮬 R., Oasmaa, A., Conversion of Glucoisosaccharinic Acid by Heating under Pressure, Acta Chemica Scandinavica, B42 (1988), No. 8., pp. 563-566
  40. [20] Al鮬 R., Oasmaa, A., Thermochemical Conversion of Hydroxy Carboxylic Acids in the Liquid Phase, Holzforschung, 43 (1989) No. 3., pp. 155-158
Volume 8, Issue 2, Pages81 -92