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Keywords: Biofuels, Lignin

Market Overview

This renewable solvent system consisting of hot acetic acid-water mixtures can simultaneously purify, fractionate, and solvate lignins. This approach to purifying and controlling the molecular weight of lignin improves the pulping process and its output. Previous processes can be expensive and have poorly controlled molecular or chemical properties. Using traditional methods, less than 0.2 percent of the 50 million tons/yr of Kraft lignin is recovered for use in value-added products because of high ash content and poorly controlled molecular and chemical properties. Clemson University researchers have developed a hot acetic-water solvent system that can obtain ultra-pure lignin (UPL). This unique, multifunctional method for solvation will enables direct processing of lignin into microstructure-controlled, high performance carbon fibers and coatings. This form of ultra-pure lignin has potential to replace petroleum-derived polymers in a wide variety of applications.


Carbon fibers, Industrial and Food additives, Biofuels

Technical Summary:

This approach uses a renewable solvent system that can simultaneously purify, fractionate and solvate lignins. The process operates at an elevated temperature in the presence of the hot acetic acid-water mixture, making the formation of a liquefied lignin phase. A key element of this process is tuning the compositions of the solvent system so as to split the lignin into two phases, a solvent-rich and a lignin-rich phase. This phase split is the key to the highly versatile purification, fractionation/molecular weight control, and solvation of the lignin. The ultra-pure lignins produced have broad potential use as carbon fiber. 


  • Utilizes a continuous process that can be significantly scaled up, resulting in a cost effective and easily commercialized product
  • Allows adjustment of the solvent composition (i.e., the AcOH/H2O ratio), enabling one to isolate lignin fractions from each of the liquid phases with the desired molecular weight, chemical functionality, and ash/metals purity

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Technology Overview

State of Development


Patent Type

Issued U.S. Patent


Advanced Materials

Serial Number


CURF Reference No.



Mark Theis, Adam Klett, David Bruce

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