Journal of Polymers and the Environment, Vol. 11, No. 2, April 2003 (© 2003) 1566-2543/03/0400-0039/0 © 2003 Plenum Publishing Corporation 39 1 Swedwood Latvia Ltd., Planupes iela 24, LV-2141 Incukalns, Latvia. 2 Man-Technology-Environment Research Centre, Örebro University, SE-701 82 Örebro, Sweden. 3 IFM-Department of Chemistry, University of Linköping, Linköping, Sweden. 4 To whom all correspondence should be addressed. E-mail: jessika. hagberg@nat.oru.se Alkaline Degradation of Cellulose: Mechanisms and Kinetics Ivars Pavasars, 1 Jessika Hagberg, 2,4 Hans Borén, 3 and Bert Allard 2 Cellulose powder and softwood sawdust were subjected to alkaline degradation under condi- tions representative of a cementitious environment for periods of 7 and 3 years, respectively. During the first 3 years, sampling was frequent, and data on the degradation of cellulose and production of isosaccharinic acid was used for establishing long-term prediction models. Samples after an additional period of 4 years were compared to the predicted values. The total rate of degradation was measured as the increase in total organic carbon (TOC) in corresponding so- lutions. A previously published theoretical model of degradation kinetics gave a good approxi- mation of the present experimental data. Peeling-off, stopping, and alkaline hydrolysis reaction rate constants were obtained as model parameters, and the results suggested that the transfor- mation of the glucose end group is the rate-limiting step in the cellulose peeling-off reaction and also determines the pH dependence of that reaction. After 3 years, isosaccharinic (ISA) acid represented 70–85% of all degradation products as quantified by capillary zone electrophore- sis. The long-term prediction model indicated that all of the cellulose would be degraded after only 150–550 years. The control sampling after 7 years points toward a lower degradation of cellulose and production of ISA than predicted by the model, reflecting either a degradation of ISA that was faster than the production or a termination of the ISA production. KEY WORDS: Alkaline degradation of cellulose; isosaccharinic acid; prediction models. INTRODUCTION Cellulose loses weight upon reaction with alkali, which is a phenomenon that is well known from pulp- ing and textile industries [1, 2]. Alkaline degradation of cellulose has also been studied in relation to trans- formation of biomass to various low-molecular-weight products [3, 4]. Thus examinations of alkaline degra- dation of cellulose have been focused on conditions that are pertinent for the relevant technological processes, particularly elevated temperatures. Alkaline degradation of cellulose is a process of potential importance in the design and performance assessment of facilities for long-term disposal of radio- active waste [5, 6]. Substantial amounts of organic mat- ter, including cellulose materials such as wood and paper, can be present in low- and intermediate-level radioactive wastes [7]. Cementitious facilities have been proposed for storage of such waste. The highly alkaline cement pore water in such an environment would eventually lead to a partial degradation of any cellulose present. This would lead to a production of water-soluble, low-molecular-weight species with metal complexing properties leading to higher solubil- ity and possibly enhanced mobility of radionuclides in the deposit.