Anaerobic digestion and acid hydrolysis of nitrocellulose

摘要

In this investigation, studies were conducted to evaluate the biodegradation of nitrocellulose in anaerobic batch reactors with and without the supplemental carbon inducers, such as cellulose, cellobiose, and lactose. Results from the anaerobic study show that degradation of nitrocellulose alone is difficult and that nitrocellulose degradative enzymes could be induced by the three inducers tested. As high as 48.91% conversion could be obtained at Cellulose/Nitrocellulose ratio of 1 to 1. Studies also indicated that type 20 and 50 celluloses would be more effective and optimum pH was about 6.4 in biodegradation of nitrocellulose. Three testing systems, namely, single-stage, two-stage, and staged-feed anaerobic treatment were utilized in the biodegradation study. Results from this study showed that a two-stage anaerobic treatment did not clearly enhance biodegradation. Stage-feed system had a higher rate of gas production; unfortunately, the system sometimes was not stable. Experiments indicated that nitrocellulose affected the biodegradation of cellulose and decreased gas production at cellulose/nitrocellulose ratios lower than 1/1. Analysis of the data shows that the inhibitory effect of nitrocellulose on cellulose degradation behaved like competitive inhibition. This inhibitory effect can be overcome at higher cellulose concentrations.;In the second part of this study acid hydrolysis of nitrocellulose was conducted by using concentrated hydrochloric acid at intermediate temperatures. Results showed that the end products from acid hydrolysis were mainly glucose and small molecular weight organic acids. Glucose yields ranged from 45 to 85 percent depending on acid concentration, acid/solid ratio, reaction time, and heating temperature. It was found that the higher the acid concentration and temperature, the faster the hydrolysis reaction. Nitrogen dioxide gas was the dominant species of nitrogen formed during the hydrolysis reaction. From a kinetics study of nitrocellulose hydrolysis and glucose degradation, it was found that the rate of the reaction is related to acid concentration, acid/solid ratio, and temperature.;A complete treatment system, including acid hydrolysis process to decompose nitrocellulose, electrodialysis system to recover the hydrochloric acid used in the acid hydrolysis process, and fermentation to finally convert glucose into ethanol, proved to be a technically feasible alternative to convert waste nitrocellulose into useful products.