Organosolv delignification of birch wood (Betula pendula): DMSO/water pulping optimization

Abstract

Abstract Improving the quality of cellulose semi-finished products for subsequent chemical processing in combination with the “green” concept is an important technical challenge. The article investigated a number of organic solvents as a delignifying agent. It has been shown that DMSO usage is the most efficient organosolv way to obtain cellulose from birch wood (B. pendula). The influence of the concentration of the organic solvent in the cooking liquid, the concentration of the acid catalyst, the duration and temperature of the process has been studied. The conditions for maximum process desirability at which the highest yield of cellulosic semi-finished product (CSP) and degree of delignification were as follows: 2 h treatment time at 156 °C, DMSO/water 75–95% solvent system with solid to liquid ratio of 1:10. At a concentration of DMSO in the cooking liquor of 85–90%, the degree of wood delignification was about 95%. The mechanical properties of the experimental DMSO pulp were similar to those of kraft pulp. DMSO lignin was characterized by Pyr-GC/MS. More than 65% of monomer fragments of phenolic compounds were S-unit derivatives. The results show that organosolv delignification with DMSO/Water can be proposed as an eco-friendly alternative process to the kraft pulping.