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Alkaline degradation of cellulose: mechanisms and kinetics
Örebro University, Department of Natural Sciences.ORCID iD: 0000-0003-4128-8226
Örebro University, Department of Natural Sciences.ORCID iD: 0000-0002-2104-4593
2003 (English)In: Journal of polymers and the environment, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 11, no 2, p. 39-47Article in journal (Refereed) Published
Abstract [en]

Cellulose powder and softwood sawdust were subjected to alkaline degradation under conditions 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 solutions. A previously published theoretical model of degradation kinetics gave a good approximation 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 transformation 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 electrophoresis. 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.

Place, publisher, year, edition, pages
2003. Vol. 11, no 2, p. 39-47
Keywords [en]
alkaline degradation of cellulose, isosaccharinic acid, prediction models
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:oru:diva-15872DOI: 10.1023/A:1024267704794ISI: 000183563800002OAI: oai:DiVA.org:oru-15872DiVA, id: diva2:422527
Available from: 2011-06-13 Created: 2011-06-13 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Capillary zone electrophoresis for the analysis of low molecular weight organic acids in environmental systems
Open this publication in new window or tab >>Capillary zone electrophoresis for the analysis of low molecular weight organic acids in environmental systems
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Capillary zone electrophoretic (CZE) methods were developed to identify and quantify low molecular weight (LMW) organic acids in environmental samples. Sensitivity and selectivity were optimised by adapting the background electrolyte to the characteristics of analytes, and by using different modes of detection and injection. Electrokinetic injection mode in combination with an isotachophoretic state increased the sensitivity remarkably for LMW organic acids using UV detection. Calcium ions were added to the background electrolyte, inducing an on-column complexation between acids and calcium ions, which gave good separation of the acids. Mass spectrometric detection (compared to UV detection) increased the sensitivity when using hydrodynamic injection mode during analysis, and selectivity was improved by mass identification. A CZE method for determination of the dissociation constants of LMW organic acids in the pKa range of 3.54.5 was also developed.

The developed procedures were applied to different areas where LMW organic acids play an important environmental role:

Low molecular weight organic acids were analysed in rainwater and soil water in the low μg/l range, within ten minutes after sampling. Rapid analysis and high sensitivity are essential when studying samples with rapid turnover due to microbial activity and photodegradation.

The use of CZE-ESI-MS proved to be a robust analytical tool for determining LMW organic acids in samples rich in interfering ions. Organic acids excreted by soil fungi as response to metal exposure was easily and rapidly quantified with CZE-ESI-MS compared to HPLC and CZE-UV analysis.

Dissociation constants for isosaccharinic acid (ISA) and gluconic acid were determined by CZE to 3.87 and 3.64, respectively. The ability to make the determinations in the presence of impurities as well as not having to know the exact concentration of analyte were identified as the major benefits of CZE.

Isosaccharinic acid was identified as the main degradation product from alkaline degradation of cellulose by CZE analysis. Long-term predictions on both cellulose degradation and ISA production were made based on three years of sampling data. A control sampling after seven years indicated that the degradation of cellulose and the production of ISA were lower than predicted.

Place, publisher, year, edition, pages
Örebro: Örebro universitetsbibliotek, 2003. p. 59
Series
Örebro Studies in Chemistry, ISSN 1651-4270 ; 2
Keywords
capillary zone electrophoresis, capillary zone electrophoresis-electrospray ionization-mass spectrometry, low molecular weight organic acids, pKa
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:oru:diva-42 (URN)91-7668-323-0 (ISBN)
Public defence
2003-01-10, Hörsal Bio, Örebro universitet, Örebro, 10:15
Opponent
Supervisors
Available from: 2003-01-10 Created: 2003-01-10 Last updated: 2017-10-18Bibliographically approved

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Hagberg, JessikaAllard, Bert

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