Characterization of isolated lignin from eucalyptus wood chip obtained by liquid hot water process

Abstract

In this study, we propose a novel optimization for lignin isolation from the eucalyptus wood chip (EWC) under hydrothermal liquid hot water (LWH) process in the presence of alkaline catalyst (NaOH). The optimal conditions were obtained employing response surface methodology (RSM). The optimal condition was 160°C for 30 min in the presence of alkaline catalyst of 0.020 M. This condition demonstrated the highest lignin extraction with solid fraction of 77.3% and 76.1%. In addition, the physicochemical structure of isolated lignin was characterized with diverse techniques. The lignin recovery from liquid phase’s GPC analysis illustrated a high average Mw/Mn (17500/7450 g/mol) while polydispersity index (2.34) was lower in comparison with the commercial organosolv lignin. The TGA analysis showed the maximum decomposition of lignin recovery at 140 to 350oC. Furthermore, the Py/GCMS analysis showed a predominance of 57.63% of syringyl units (S) over 37.37% of guaiacyl units (G) under optimal conditions. The results revealed that the integrated process was a potential approach to add more value in the employment of the agricultural waste material.