Analysis And Prediction Of Cellulose Hydrolysis Model In Organic Acid System

The recycling of waste textiles is a matter of environment, resources and energy. In waste textiles, cotton textiles is in a large proportion. So the recycle of waste cotton fiber is also an important contents of recycling and utilization of waste textiles. The effective degradation of cotton fiber to glucose is the main way of cotton fiber regeneration. As more than 90% of the cotton fiber is cellulose, the effective degradation of cotton fiber can be simplified as the degradation of cellulose. And the degradation of cellulose was achieved by hydrolysis, analyzing the behavior of cellulose hydrolysis. Cellulose degradation kinetics model was established, laying the theoretical foundation for the effective recycling of cotton fiber and utilization. Prediction is always a difficult problem to the chemical industry. To establish the forecast model of cellulose hydrolysis is helpful to guide the cellulose hydrolysis reaction process conditions optimization, and promote the promotion and development of the prediction model in the field of chemical industry.The main work of this thesis is to study microcrystalline cellulose hydrolysis behavior in organic acid system. It analyzes the microcrystallinecellulose in oxalic acid-hydrochloric acid system and acetic acid hydrochloric acid system. And the effects of different process factors on the hydrolysis of cellulose were discussed. The optimum technological conditions for the hydrolysis of microcrystalline cellulose in oxalic acid-hydrochloric acid system are:oxalic acid 25g/L, hydrochloric acid 1g/L, temperature 90 C, time 9h. The influence of temperature on the hydrolysis reaction is more significant. Hydrolysis is accelerated with the temperature increasing. The high temperature will lead to rapid degradation of glucose produced by hydrolysis. Glucose concentration with the passage of time gradually become larger. When arrived at certain concentration range of glucose concentration, it is no longer increased but decreased. With the increase of concentration of oxalic acid, the concentration of glucose increases first and then decreasing. Along with the increase of the mass concentration of HC1, the mass concentration of glucose decreased gradually. The optimal process conditions for the hydrolysis of microcrystalline cellulose in acetic acid-hydrochloric acid system are:acetic acid 750g/L, hydrochloric acid 3g/L, temperature 80 C, time 5h. Hydrolysis rate was accelerated with increasing temperature; with the increasing concentration of acetic acid, glucose concentration showed a decreasing trend; with the increasing concentration of hydrochloric acid, glucose concentration showed a trend of first increased and then decreased.According to the Seaman model, the kinetics model of cellulose hydrolysis and glucose degradation was established, and the apparent activation energy of cellulose hydrolysis and glucose degradation were 58.02 kJ/mol and 144.2 kJ/mol, respectively. At 80 ℃,85℃,90℃ ,95℃ temperature conditions, the reaction of cellulose hydrolysis rate constant ki were 0.0838,0.1219,0.1508, and 0.1578 h-1, the corresponding temperature under the condition of glucose degradation reaction rate constant k2 were 0.3596,0.7765,1.6455, and 1.6008b-1.Using the artificial neural network model and grey prediction model, thehydrolysis behavior of cellulose in oxalic acid and hydrochloric acid system was predicted, and the feasibility of the two prediction models were analyzed and evaluated. The relative error of the GM (1,1) model is less than 0.1, and the magnitude of the deviation is less than 0.1, which indicates that the model has higher precision. The relative error of the BP neural network model is less than 0.02, and the global error is 0.00023, which shows that the model is very accurate. The two models can predict the hydrolysis of cellulose in oxalic acid system.The spherical carbon materials were obtained by the high temperature treatment of the hydrolysis pretreatment of oxalic acid and hydrochloric acid system, and the morphology and structure of the products were analyzed. The results showed that the size of the product decreased with the increase of the concentration of hydrochloric acid, and the size of the product was very good at the same time.