Soda/ethanol-oxygen delignification of pine sawdust for a biorefinery

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

Concepción

Congreso; 3er Congreso Iberoamericano sobre Biorrefinerías (CIAB), 4to Congreso Latinoamericano sobre Biorrefinerías, y 2do Simposio Internacional sobre Materiales Lignocelulósicos; 2015

CIADEB-RIADICYP-PROVALOR-BIOREN- Centro de Biotecnología UdeC- Unidad de Desarrollo Tecnológico (UDT)- VTT

Thegeneration of large amounts of sawdust and other waste is a specific problem ofthe primary processing of wood. The objective of this work is to study an environmentallyfriendly delignifying strategy for a sequential fractionation, following abiorefinery concept. A Pinus elliotti and Pinus taeda sawdust mix fromMisiones, Argentina, was tested as raw material for a soda-ethanol pulping.Three different conditions were performed in a 7 L pressurized reactor, with indirectheating. Cooking conditions were: liquor to wood ratio 5:1, maximum temperature170ºC, time to maximum temperature 40 min, and time at maximum temperature 140min. Experiences were performed as follows: 1) NaOH load of 27.6% w/w and a35/65 ethanol to water ratio (%v/v). 2) NaOH load of 19.0% w/w and a 35/65ethanol to water ratio (%v/v). 3) NaOH load of 27.6% w/w and a 10/90 ethanol towater ratio (%v/v). Pulping yields and Kappa number were assessed in eachexperience. Pulps obtained from the different experiences showed the followingresults of total yield and Kappa number: 1) 41.4% and 25.74; 2) 47.24% and59.40; and 3) 40.58% and 32.40. These pulps were subsequently subjected to atwo-stage oxygen treatment, carried out in a multipurpose reactor withmechanical stirring and a glycerin-jacket heating. Oxygen treatments wereperformed at 10% consistency, 100°C of maximum temperature, 6 kg/ cm2 of oxygenpressure, NaOH load of 2% w/w, and 60 min of time at maximum temperature. MgSO4(0.1% w/w) was added in the first stage. Pulps were washed before eachtreatment. Kappa number dropped to 13.4, 38.8 and 15.4, for experiences 1, 2,and 3, respectively. Final Kappa numbers after the second oxygen stage were8.2, 25.2 and 9.6. The highest drop in the Kappa number between oxygen stagescorresponded to experience 2. Pulp viscosity was measured to evaluate theprocess selectivity. Pulp from experience 1 showed higher selectivity than theothers. Yields of the two-stage oxygen treatment were 95.73%, 86.74% and 91.35%for experiences 1, 2 and 3, respectively. Finally, pulps were refined at 500rpm in a laboratory pulp refiner (PFI). The highest difference between theinitial and final ºSR was observed for experience 1.