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首页> 外文期刊>Journal of Polymers and the Environment >Alkaline Degradation of Cellulose: Mechanisms and Kinetics
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Alkaline Degradation of Cellulose: Mechanisms and Kinetics

机译：纤维素碱性降解：机理和动力学

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摘要

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.
机译：纤维素粉和软木锯末分别在代表胶结环境的条件下经受了7年和3年的碱降解。在最初的三年中，采样很频繁，并且使用了纤维素降解和异糖精酸生产的数据来建立长期预测模型。再经过4年后，将样本与预测值进行比较。将总降解速率测量为相应溶液中总有机碳（TOC）的增加。先前发布的降解动力学理论模型可以很好地近似本实验数据。获得了剥离，终止和碱性水解反应速率常数作为模型参数，结果表明葡萄糖端基的转化是纤维素剥离反应中的限速步骤，并且还决定了pH对pH的依赖性。那反应。 3年后，通过毛细管区带电泳定量，异糖精酸（ISA）占所有降解产物的70-85％。长期预测模型表明，仅在150-550年后，所有纤维素都会降解。 7年后的对照抽样表明，纤维素的降解和ISA的产生比模型预测的要低，这反映了ISA的降解快于生产或终止了ISA的生产。

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