Nanofibrillated cellulose from Soda/Ethanol-Oxygen pulp of pine sawdust by oxidant treatments and mechanical fibrillation

EHMAN, N.; AREA M.C.; FELISSIA, F. E.; IMLAUER, C.

Montevideo

Workshop; I&S WORKSHOP. Insights and strategies towards a bio-based economy; 2016

Universidad de la República; I+D+i . Technological Laboratory of Uruguay (LATU); Instituto Nacional de Investigación Agropecuaria (INIA). Uruguay - VTT - Technical Research Centre of Finland; Faculty of Chemistry and Engineering. Åbo Akademi University. F

Nanofibrillated cellulose (NFC) from Soda/Ethanol-Oxygen pulps of pine sawdust has been prepared by a combination of chemical treatment and mechanical fibrillation. Soda/Ethanol-Oxygen pulps of pine sawdust were obtained in previous experiences using Soda/Ethanol treatment at different conditions and two oxygen stages at 10 % consistency, 100°C, and 60 minutes. Three pulps with different chemical composition were used to evaluate the effect of hemicelluloses and lignin contents on the production of NFC. The initial kappa number of the tested pulps was 8.2, 25.2, and 9.6, and hemicelluloses content was 6.19%, 7.99%, and 5.30%, respectively.Pulps were subjected to an ozone treatment stage, followed by a hydrogen peroxide stage and TEMPO oxidation. TEMPO-oxidized pulps were fibrillated by means of a high speed blender. Ozone treatment was performed at 2.5% consistency, during 60 minutes at 20°C. Two pH conditions were assessed: acidic medium (pH 2.3) and neutral medium (pH 7). Previous to the TEMPO oxidation, a hydrogen peroxide stage was applied to evaluate its effect on the nanofibrillation yield. This stage was carried out at 10% consistency and 4% H2O2 over dry pulp, during 120 minutes at 80°C. TEMPO-Oxidation treatment was performed with 5 mmols NaClO over dry pulp at room temperature and pH 10, under continuous stirring conditions, and these pulps at 1% consistency were mechanically treated in a high speed blender, at 35.000 rpm during 18 minutes. Carboxyl rate and cationic demand were assessed. Finally, NFC specific surface and diameters were determined applying mathematical models from those values. Transmittance of NFC was also The estimated specific surfaces of the obtained particles varied from 199 to 441 m2/g, and the average diameters ranged between 6.0 nanometers and 13.4 nanometers. Lowest NFC diameters where obtained when using the pulp with the lowest hemicelluloses content, obtained with ozone application in both acidic and neutral conditions. Highest NFC diameters were attained when the hydrogen peroxide stage was not included. High kappa number pulps require acidic ozone conditions to obtain particles of similar diameters than the other pulps.Specific surface and diameters of NFC were similar to those obtained by the application of 5 mmols NaClO on over dry pulp and fibrillation using homogenization equipment. This indicates the feasibility of using the high speed blender to obtain NFC.All transmittances exceeded 90%, showing high nanofibrillation yields.