Using Undigested Biomass Solid Leftovers from the Saccharification Process to Integrate Lignosulfonate Production in a Sugarcane Bagasse Biorefinery

10 páginas.- 5 figuras.- 2 tablas.- 50 referencias.- The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acssuschemeng.2c01274
Innovative schemes for lignocellulosic biomass refining could optimize the chemical use and biomass conversion efficiency, providing diversified biorefinery products. A new biorefinery scheme used mild alkaline-sulfite chemithermomechanical processing to pretreat sugarcane bagasse, producing highly digestible solids and diluted lignosulfonates in the black pretreatment liquor. Most of the glucan and xylan contained in the pretreated solids were converted into monosaccharides by saccharification with commercial enzymes. The undigested biomass solids remaining from the saccharification process were recycled with the existing alkaline-sulfite black pretreatment liquor. The optimized reaction conditions (159 degrees C and 13% NaOH amendment in the liquor) enhanced the lignosulfonate concentration from 7.1 +/- 0.3 to 33.5 +/- 0.7 g/L. Mass balance for the process indicates that most of the original sugarcane bagasse lignin were split into lignosulfonates contained in the resulfonation liquor (57.3%) and in the enzymatic hydrolysate (16.2%). 2D-NMR analysis of a lignosulfonate fraction recovered by ultrafiltration confirmed that approximately 9-10% of all beta-O-4' alkyl-aryl ether substructures were alpha-sulfonated. The combined chemical characteristics of the prepared lignosulfonate suggested its suitability for use in several lignosulfonate applications.
This work was supported by FAPESP (grant number 2019/25867-3), CNPq (grant number 308570/2017-0), and Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior-Brasil (CAPES)-Finance Code 001. J.R. and J.C.d.R. were funded by MCIN/AEI/10.13039/501100011033, by "ERDF A way of making Europe" (project PID2020-118968RB-I00), and by the Regional Andalusian Government, Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades/FEDER (project P20-00017).