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Individual Highlight

Scientists discover rapid and near-complete dissolution of wood lignin by a recyclable acid hydrotrope

Photo of Fig. 1  General experimental flow diagram of p-TsOH fractionation of wood for producing fibers, cellulose nanofibrils (LCNF), lignin nanoparticles (LNP), sugar/biofuel, and furfural. JY Zhu, USDA Forest Service
Fig. 2 Application p-TsOH fractionation for producing lignin containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNP). 
Fig. 1 General experimental flow diagram of p-TsOH fractionation of wood for producing fibers, cellulose nanofibrils (LCNF), lignin nanoparticles (LNP), sugar/biofuel, and furfural. JY Zhu, USDA Forest Service Fig. 2 Application p-TsOH fractionation for producing lignin containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNP). Snapshot : A low-temperature (below water boiling point) wood fractionation process has the potential for developing disrupting technologies for sustainable and economic production of wood pulp, wood-based nanomaterials, and biochemicals.

Principal Investigators(s) :
Zhu, J.Y. 
Research Location : Madison, WI, Forest Products Laboratory
Research Station : Forest Products Laboratory (FPL)
Year : 2017
Highlight ID : 1287

Summary

Forest Service researchers report the discovery of the hydrotropic properties of a recyclable aromatic acid, p-toluenesulfonic acid (p-TsOH), for potentially low-cost and efficient fractionation of wood through rapid and near-complete dissolution of lignin. Approximately 90 percent of poplar wood lignin can be dissolved at 80 degrees Celsius (176 degrees Fahrenheit) in 20 minutes. Equivalent delignification using known hydrotropes such as aromatic salts can be achieved only at 150 degrees Celsius (302 degrees Fahrenheit) or higher for over 10 hours, or at 150 degrees Celsius for 2 hours with alkaline pulping. p-TsOH fractionated wood is divided into two fractions: (1) a primarily cellulose-rich water-insoluble solid fraction that can be used for production of high-value building blocks, such as dissolving pulp fibers and lignocellulosic nanomaterials, and/or sugars through subsequent enzymatic hydrolysis, and (2) a spent acid liquor stream containing mainly dissolved lignin that can be easily precipitated as lignin nanoparticles simply by diluting the spent acid liquor to below the minimal hydrotrope concentration. Forest Service scientists’ analyses of the dissolved lignin revealed that p-TsOH can depolymerize lignin via ether bond cleavage and separate carbohydrate-free lignin from the wood. p-TsOH has a relatively low water solubility, which can facilitate efficient recovery simply using commercially proven crystallization technology by cooling the concentrated spent acid solution to ambient temperatures to achieve environmental sustainability through recycling of p-TsOH. Therefore, the p-TsOH fractionation process has potential for developing disrupting technologies for sustainable and economic production of wood pulp, wood-based nanomaterials, and biochemicals.

Forest Service Partners

External Partners

 
  • Aalto University, Helsinki, Finland University of Wisconsin-Madison