Fractionation and physicochemical characterization of lignin from waste jute bags: Effect of process parameters on yield and thermal degradation

•Extracted high purity lignin from waste jute bags with cost effective separation technique of ethanol evaporation•Effect of alkali concentration and pH on yield, purity, structure and thermal degradation were studied•Decrease in pH resulted in lignin with highest yield and purity whereas increase in alkali concentration beyond 8% resulted in lignin with low yield and purity.•Lignin obtained at 8%alkali concentration with pH 2 had the highest yield and purity with higher cross linked structure and thermal stability.

In this work lignin was extracted from waste jute bags using soda cooking method and effect of varying alkali concentration and pH on yield, purity, structure and thermal degradation of lignin were studied. The Lignin yield, chemical composition and purity were assessed using TAPPI method and UV-vis spectroscopy. Yield and purity of lignin ranged from 27 to 58% and 50-94%, respectively for all the samples and was maximum for 8% alkali concentration and at pH 2 giving higher thermal stability. Chemical structure, thermal stability and elementary analysis of lignin were studied using FTIR, HNMR, thermo gravimetric analysis (TGA) and Elemental analyzer. FTIR and HNMR results showed that core structure of lignin starts breaking beyond 10% alkali concentration. S/G ratio shows the dominance of Syringyl unit over guaiacyl unit.

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