Acid hydrotropic fractionation of switchgrass at atmospheric pressure using maleic acid in comparison with p-TsOH: Advantages of lignin esterification

Chen Su; Kolby Hirth; Zhulan Liu; Yunfeng Cao; Junyong Zhu

doi:10.1016/j.indcrop.2020.113017

Treesearch

Acid hydrotropic fractionation of switchgrass at atmospheric pressure using maleic acid in comparison with p-TsOH: Advantages of lignin esterification

Formally Refereed

Authors:

Chen Su, Kolby Hirth, Zhulan Liu, Yunfeng Cao, Junyong Zhu

Year:

2021

Type:

Scientific Journal

Station:

Forest Products Laboratory

DOI:

https://doi.org/10.1016/j.indcrop.2020.113017

Source:

Industrial Crops and Products

Download (PDF 7.13 MB)

Download (PDF 7.13 MB): https://research.fs.usda.gov/download/treesearch/62177.pdf

Abstract

Switchgrass was fractionated using maleic acid (MA) as an acid hydrotrope in comparison with p-toluenesulfonic acid (p-TsOH) at atmospheric pressure. MA achieved more rapid and greater maximal dissolution of lignin and hemicelluloses (88 % and 63 %, respectively) than did p-TsOH (73 % and 55 %, respectively). MA esterified (carboxylated) the dissolved acid hydrotropic lignin (AHL) as evidenced by 2D 1 H-13C HSQC NMR analysis, which improved AHL antioxidant ability compared with AHL from p-TsOH that is not carboxylated. MA also carboxylated the lignin and cellulose in the fractionated cellulosic water-insoluble solids (WIS), which significantly improved WIS enzymatic digestiblity for sugar production than did p-TsOH with the same level of delignification. It also improved the lignin lubrication effect to facilitate mechanical fibrillation of WIS into lignocellulosic nanofibrils. MA is an FDA-approved indirect food additive (21CFR175-177) with lower acidity and solubility than p-TsOH, which substantially benefits recycling and decreasing environmental impacts to achieve sustainability.

Keywords

Maleic acid fractionation, lignin esterification, lignin-containing cellulose nanofibrils (LCNFs), antioxidant activity, structural characteristic

Citation

Su, Chen; Hirth, Kolby; Liu, Zhulan; Cao, Yunfeng; Zhu, J.Y. 2021. Acid hydrotropic fractionation of switchgrass at atmospheric pressure using maleic acid in comparison with p-TsOH: Advantages of lignin esterification. Industrial Crops and Products. 159(6): 113017. https://doi.org/10.1016/j.indcrop.2020.113017.