Abstract
Cellulose can be directly dissolved in cold alkali without derivatization. However, this requires low cellulose molecular weight, i. e. low pulp viscosity, preferably below 300 mL g−1. This can be achieved by for example acid or enzymatic hydrolysis of the dissolving pulp. However, it would be beneficial to manufacture pulp with sufficiently low viscosity without an additional treatment stage prior to dissolution. Unit processes in pulping can be operated in such a way as to reduce the molecular weight of cellulose. The approach of the study was to modify the conditions in unit pulping processes in order to obtain a low pulp viscosity of fully bleached prehydrolysis kraft pulp. A high charge of alkali in the oxygen delignification reduced the cellulose molecular weight significantly. Increased temperature, 120 °C compared to 98 °C, had also a significant effect on viscosity. By performing peroxide bleaching at acidic pH, the viscosity could be sufficiently reduced even when oxygen delignification was performed at lower temperature. However, for high brightness, a chlorine dioxide stage is needed.
Funding source: Horizon 2020 Framework Programme
Award Identifier / Grant number: 720729
Funding statement: The study was funded by European Union’s Horizon 2020 research and innovation programme under grant agreement No 720729.
Acknowledgments
Magnus Paulsson is thanked for valuable comments on the manuscript.
Conflict of interest: The authors declare no conflicts of interest.
References
Bergnor, E., Axegård, P., Larsson, T., Karlström, K. (2017) USA Patent No. US 2017/0314197 A1.Search in Google Scholar
Budtova, T., Navard, P. (2016) Cellulose in NaOH-water based solvents: a review. Cellulose 23(1):5–55.10.1007/s10570-015-0779-8Search in Google Scholar
Cai, J., Zhang, L. (2006) Unique gelation behavior in NaOH/urea aqueous solution. Biomacromolecules 7:183–189.10.1021/bm0505585Search in Google Scholar PubMed
Chirat, C., Lachenal, D. (1997) Effect of hydroxyl radicals on cellulose and pulp and their occurrence during ozone bleaching. Holzforschung 51(2):147–154.10.1515/hfsg.1997.51.2.147Search in Google Scholar
Chunilall, V., Bush, T., Larsson, T., Iversen, T., Kindness, A. (2010) A CP/MAS 13C-NMR study of cellulose fibril aggregation in eucalyptus dissolving pulps during drying and the correlation between aggregate dimensions and chemical reactivity. Holzforschung 64:693–698.10.1515/hf.2010.097Search in Google Scholar
da Silva Perez, D., van Heiningen, A. (2015) Prediction of alkaline pulping yield: equation derivation and validation. Cellulose 22(6):3967–3979.10.1007/s10570-015-0735-7Search in Google Scholar
Daňhelka, J., Kössler, I., Boháčková, V. (1976) Determination of molecular weight distribution of cellulose by conversion into tricarbanilate and fractionation. J. Polym. Sci., Part A, Polym. Chem. 14(2):287–298.10.1002/pol.1976.170140202Search in Google Scholar
Egal, M., Budtova, T., Navard, P. (2007) Structure of aqueous solutions of microcrystalline cellulose/sodium hydroxide below 0 °C and the limit of cellulose dissolution. Biomacromolecules 8:2282–2287.10.1021/bm0702399Search in Google Scholar PubMed
Gierer, J. (1997) Formation and involvement of superoxide (O2-/HO2·) and hydroxyl (OH·) radicals in TCF bleaching processes: A review. Holzforschung 51(1):34–46.10.1515/hfsg.1997.51.1.34Search in Google Scholar
Grönqvist, S., Hakala, T., Kamppuri, T., Vehviläinen, M., Hänninen, T., Liitiä, T., Suurnäkki, A. (2014) Fibre porosity development of dissolving pulp during mechanical and enzymatic processing. Cellulose 21(5):3667–3676.10.1007/s10570-014-0352-xSearch in Google Scholar
Hartler, N., Norrström, H., Rydin, S. (1970) Oxygen alkali bleaching of sulfate pulp. Sven. Papp.tidn. 69(6):52–60.Search in Google Scholar
Hellström, P., Heijnesson-Hultén, A., Paulsson, M., Håkansson, H., Germgård, U. (2014) The effect of Fenton chemistry on the properties of microfibrillated cellulose. Cellulose 21(3):1489–1503.10.1007/s10570-014-0243-1Search in Google Scholar
Jafari, V., Nieminen, K., Sixta, H., van Heiningen, A. (2015) Delignification and cellulose degradation kinetics models for high lignin content kraft pulp during flow-through oxygen delignification. Cellulose 22(3):2055–2066.10.1007/s10570-015-0593-3Search in Google Scholar
Kihlman, M., Medronho, B., Romano, A., Germgård, U., Lindman, B. (2013) Cellulose dissolution in an alkali based solvent: Influence of additives and prettreatments. J. Braz. Chem. Soc. 24(2):295–303.10.5935/0103-5053.20130038Search in Google Scholar
Kontturi, E., Vehmaa, J., Vuorinen, T. (2005) Quantification method for hydrogen peroxide formation during oxygen delignification of kraft pulp. Nord. Pulp Pap. Res. J. 20(4):490–495.10.3183/npprj-2005-20-04-p490-495Search in Google Scholar
Larsson, P.T., Svensson, A., Wågberg, L. (2013) A new, robust method for measuring average fibre wall pore sizes in cellulose I rich plant fibre walls. Cellulose 20(2):623–631.10.1007/s10570-012-9850-xSearch in Google Scholar
Larsson, T., Wickholm, K., Iversen, T. (1997) A CP/MAS[loc=pre]13C NMR investigation of molecular ordering in celluloses. Carbohydr. Res. 302(1-2):19–25.10.1016/S0008-6215(97)00130-4Search in Google Scholar
Liebergott, N., van Lierop, B., Teodorescu, G., Kubes, G. (1985) Comparison between low and high consistency oxygen delignification of kraft pulps. Pulping Conference. TAPPI, Hollywood. pp. 213–.Search in Google Scholar
Lovikka, V., Khanjani, P., Väisänen, S., Vuorinen, T., Maloney, T.C. (2016) Porosity of wood pulp fibers in the wet and highly open dry state. Microporous Mesoporous Mater. 234:326–335.10.1016/j.micromeso.2016.07.032Search in Google Scholar
Palme, A., Aldaeus, F., Larsson, T., Hasani, M., Theliander, H., Brelid, H. (2019) Differences in swelling of chemical pulp fibers and cotton fibers–effect of the supramolecular structure. BioResources 14(3):5698–5715.10.15376/biores.14.3.5698-5715Search in Google Scholar
Pouyet, F., Chirat, C., Lachenal, D. (2013) On the origin of cellulose depolymerization during ozone treatment of hardwood kraft pulp. BioResources 8(4):5289–5298.10.15376/biores.8.4.5289-5298Search in Google Scholar
Pönni, R., Kontturi, E., Vuorinen, T. (2013) Accessibility of cellulose: structural changes and their reversibility in aqueous media. Carbohydr. Polym. 93(2):424–429.10.1016/j.carbpol.2012.12.025Search in Google Scholar
Stone, J., Scallan, A. (1967) The effect of component removal upon the porous structure of the cell wall in wood. II. Swelling in water and the fiber saturation point. Tappi J. 50(10):496–501.10.32964/TJ50.10.496Search in Google Scholar
Vehviläinen, M., Kamppuri, T., Nousiainen, P., Kallioinen, A., Siika-Aho, M., Elg Christoffersson, C., Janicki, J. (2010) Effect of acid and enzymatic treatments of TCF dissolving pulp on the properties of wet spun cellulosic fibers. Cellul. Chem. Technol. 44(4-6):147–151.Search in Google Scholar
Virtanen, T., Penttilä, P.A., Maloney, T.C., Grönqvist, S., Kamppuri, T., Vehviläinen, M., Maunu, S.L. (2015) Impact of mechanical and enzymatic pretreatments on softwood pulp fiber wall structure studied with NMR spectroscopy and X-ray scattering. Cellulose 22(3):1565–1576.10.1007/s10570-015-0619-xSearch in Google Scholar
Wickholm, K., Larsson, T., Iversen, T. (1998) Assignement of non-crystalline forms in cellulose I by CP/MAS 13C NMR spectroscopy. Carbohydr. Res. 312:123–129.10.1016/S0008-6215(98)00236-5Search in Google Scholar
Yang, Q., Qi, H., Lue, A., Hu, K., Cheng, G., Zhang, L. (2011) Role of sodium zincate on cellulose dissolution in NaOH/urea aqueous solution at low temperature. Carbohydr. Polym. 83(3):1185–1191.10.1016/j.carbpol.2010.09.020Search in Google Scholar
© 2020 Walter de Gruyter GmbH, Berlin/Boston
