REVISITING THE NITRATION TECHNOLOGY OF CELLULOSE FROM ALTERNATIVE FEEDSTOCK
The present work outlines the results of the study on nitration technology of cellulose isolated by the nitric-acid method in pilot production from a non-woody feedstock – agro-industrial residues – oat hulls, by using mixed acid. Experimental statistical models based on a range of experiments have been built that enable basic physicochemical properties of cellulose nitrates to be predicted from treatment parameters and mixed acid properties. The initial water content and the mixed acid-to-solid mass ratio were found to be key parameters for the production of cellulose nitrates soluble in the alcohol-ester mixture. The physicochemical properties were established to be almost independent on nitration temperature and time. The findings are of fundamental importance: the possibility of replacing cotton cellulose with an alternative source has theoretically been justified. Optimum nitration conditions for the synthesis of cellulose nitrates soluble in the alcohol-ester mixture have been identified: water content of 14 % in the mixed acid, temperature of 30–40 °С, nitration time of 30–60 min, and mixed acid-to-solid mass ratio of 1:25 assure the synthesis of cellulose nitrates with over 90 % solubility. The practical significance of the study is that the obtained regularities can be applied to the development of nitration technology of cellulose from alternative raw materials.