Preparation Methods for Nanocrystalline Cellulose - Acid hydrolysis and various cellulose sources

The aim of this project has been to prepare nanocrystalline cellulose (CNC) from hydrochloric acid hydrolysis and optimise the process. CNC was also prepared from sulphuric acid hydrolysis to use as a reference. The starting material in both these processes was microcrystalline cellulose (MCC), therefore another cellulose source was used to try and prepare CNC from. The cellulose was extracted from barley husk in another project performed in the same division which is usually considered a waste product. Four different procedures were performed using hydrochloric acid, where the first three procedures followed various studies in literature and the parameters of the fourth procedure was determined after evaluating the results from the first three. After analysing the samples with atomic force microscopy (AFM) it was found that no clear CNC had been obtained. Preparing CNC from sulphuric acid hydrolysis was shown to be an optimised process with successful results. Characteristic rod-like crystals were obtained and could be seen after using AFM. Therefore this process was used in the attempt of preparing CNC from cellulose that was extracted from barley husk. Two different procedures were evaluated, one starting with wet cellulose and one with dry cellulose. It was found that preparing CNC from dry cellulose with sulphuric acid hydrolysis was possible. The AFM picture showed that some of the crystals seemed to be a bit too long to be nanosize which implies that the process needs to be evaluated and adjusted. The conclusions of this project is that further studies must be performed on preparing CNC from hydrochloric acid hydrolysis to obtain an optimised process. It is possible to prepare crystals from cellulose extracted from barley husk although the process must be further evaluated to obtain parameters that accommodates the cellulose source. It has been shown that preparing CNC from sulphuric acid hydrolysis is an optimised and established process.