Isolation of lignin by organosolv process from different varieties of rice husk: Understanding their physical and chemical properties

- Organosolv method used to isolate lignin from 3 rice husk to understand properties.
- XRD analysis proves extracted lignin is not contaminated with polysaccharides.
- ATR and NMR revealed presence of H, G, S & T substructures in varying concentrations.

The aim of this work was to study the difference in properties of lignins, those (organosolv lignins (ORGLs, 12 ± 3% yield and 93 ± 5% mass balance) were isolated from diverse rice husk (RH) substrates using organosolv procedure (water:ethanol, H2SO4) carried out at 180 °C for 1 h. To identify the possible alterations in lignin structures several bulk and molecular level advanced characterization tools were employed. Even though lignins were extracted using common isolation procedure from three varieties of similar species of RH; from XRD, GPC, and elemental analysis it was found that those have comparable properties on bulk level. But molecular level analysis conducted using UV-vis, ATR, 1D/2D HSQC NMR techniques could help disclose that isolated lignins have varying concentrations of G, H, S and T substructures. Additionally, the double bond equivalence of 4.4-4.7 reveals that few of the aromatic rings are devoid of substituent.

Organosolv lignin from 3 rice husks were isolated and studied for their physico-chemical properties.304