Stepwise Ethanol-Water Fractionation of Enzymatic Hydrolysis Lignin to Improve Its Performance as a Cationic Dye Adsorbent

Stepwise Ethanol-Water Fractionation of Enzymatic Hydrolysis Lignin to Improve Its Performance as a Cationic Dye Adsorbent

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In this work, lignin fractionation is proposed as an effective approach to reduce the heterogeneity Bosch KAN93VIFPG Serie 4 91cm Frost Free American Fridge Freezer Stainless of lignin and improve the adsorption and recycle performances of lignin as a cationic dye adsorbent.By stepwise dissolution of enzymatic hydrolysis lignin in 95% and 80% ethanol solutions, three lignin subdivisions (95% ethanol-soluble subdivision, 80% ethanol-soluble subdivision, and 80% ethanol-insoluble subdivision) were obtained.The three lignin subdivisions were characterized by gel permeation chromatography (GPC), FTIR, 2D-NMR and scanning electron microscopy (SEM), and their adsorption capacities for methylene blue were compared.The results showed that the 80% ethanol-insoluble subdivision exhibited the highest adsorption capacity and its value (396.

85 mg/g) was over 0.4 times higher than that of the unfractionated lignin (281.54 mg/g).The increased adsorption capacity was caused by the enhancement of both specific surface area and negative Zeta potential.

The maximum monolayer adsorption capacity of 80% ethanol-insoluble subdivision by adsorption kinetics and isotherm studies was found to be 431.1 mg/g, which was much higher than most of reported lignin-based adsorbents.Moreover, the 80% Media Tower ethanol-insoluble subdivision had much higher regeneration yield (over 90% after 5 recycles) compared with the other two subdivisions.Consequently, the proposed fractionation method is proved to be a novel and efficient non-chemical modification approach that significantly improves adsorption capacity and recyclability of lignin.