alkaline pulping and oxygen delignification of rapeseed fibers to a low kappa number
DESCRIPTION
The 6th International Symposium on ADVANCED TECHNOLOGIES FOR THE PULP AND PAPER INDUSTRY - Braila, ROMANIA, 6-9 September 2011.available on-line at http://ceprohart.ro/documente/Volum%20lucrari.pdfABSTRACT. The aim of this study was to investigate the use of rapeseed (Brassica napus) stalks as a source of cellulosic fibers with low lignin content by means of alkaline pulping followed by oxygen delignification. Chemical pulping was carried out by sulphate and soda-anthraquinone method under varying conditions. Time to achieve maximum temperature (60 minutes), maximum temperature (170°C), reaction time at maximum temperature (60 minutes), solid-to-liquid ratio (1:5) were kept constant in all experiments. The influence of active alkali (18, 20 and 22% sodium hydroxide on oven-dried stalks) on pulp yield, screening reject, lignin residual content and intrinsic viscosity was studied. Results indicated that alkali charge was an important parameter on yield and kappa number of the pulps. Addition of 0.1% anthraquinone (on oven-dried stalks) to the alkaline liquor as an additive in soda pulping determines a significant reduction of kappa number. The total pulp yields and kappa number was decreased with increasing the alkali charge ratio. It was found that kappa number values in soda-anthraquinone pulp samples were lower than sulphate pulps at similar pulping condition. The residual lignin left in the pulp was subsequently removed in a bleaching stage, with oxygen treatment in a pressurized vessel at elevated temperature and in an alkaline environment. Results showed that rapeseed pulps were delignified to a low Kappa number without significant loss in viscosity. It is concluded that the rapeseed stalk have the potential for being used for obtaining cellulosic pulp.TRANSCRIPT
