The York Research Database

The present work describes a quick and efficient method for the production of lignin from rapeseed meal using a microwave-assisted hydrothermal process. Specifically, the following operating conditions were used for the isolation of high purity lignin from this material: a temperature of 190 °C, a reaction time of 10 minutes, a concentration of sulphuric acid of 0.2 mol/L and a biomass/water mass ratio (m/m) of 3/10. The isolated lignin was thoroughly characterised and a comparison was established between the original biomass and the lignin produced. The experimental results revealed that this microwave assisted hydrothermal process is a quick and efficient method for the production of high purity lignin (>90%) from rapeseed meal with an experimental yield (15.84±0.37%) very close to the theoretical lignin content of this biomass (19 wt.%). The comparison between the characterisation results for the original biomass and the isolated lignin showed an increase in the proportion of C together with a decrease in the relative amounts of O and N, the proportion of H being less affected. The STA analysis revealed a greater thermal stability of lignin than that of the original biomass, which is in agreement with the information obtained from the solid-state ¹³C NMR spectra that showed an increase in the proportion of aromatics due to the elimination of cellulose and hemicellulose. In addition, the FTIR spectra also displayed a decrease in the CO-H region for lignin. These developments are in agreement with the Py-GC/MS experiments where an increase in the proportions of phenols along with a decrease in the relative amount of hydrocarbons was noticed for the isolated lignin in comparison with the results obtained for the original material.