EPA Helps Fund Research on New Hemp-Pulping Method in California

Microscopes in Lab
  • The Environmental Protection Agency is providing funding for a research project in California that is developing new, clean hemp-pulping methods.
  • The new methods are intended to eliminate the by-product known as “black liquor,” which is known to be devastating to aquatic ecosystems.
  • The new round of funding from the EPA runs through 2022.

The process of extracting cellulose fibers from hemp typically leaves behind a mixture of toxic chemicals that is commonly referred to as “black liquor.” This dark by-product has often been dumped in waters near extraction plants, damaging the aquatic wildlife and leaving a caramel color in the water.

In an attempt to combat this issue, the U.S. Environmental Protection Agency (EPA) is helping to fund a research project at the University of California, Riverside, that is focused on developing new hemp-pulping methods that will not leave behind black liquor.

Charles Cai, research engineer and adjunct professor at UC Riverside, is credited with the development of a new process that delignifies hemp stalks and only leaves behind mineral ash. In 2019, Cai won a grant from the EPA’s People, Prosperity, and the Planet Program for his pulping method.

The new method, called Co-solvent Enhanced Lignocellulosic Fractionation (CELF), uses a renewable and recyclable solvent that does not generate any harmful emissions. The only waste from the process is a small heap of mineral ash that can then be used to amend the soil.

CELF was originally created to create biofuels out of plant waste but was later revered for its unmatched ability to deconstruct plant matter.

UC Riverside announced that the EPA has also awarded Cai an additional $74,822 to study commercial applications for the process.

Cai’s green chemistry approach to hemp pulping, which he calls the “one-pot” method, separates hemp stalks into:

  • Sugars
  • Lignin
  • Extracts
  • Pulped fiber

EPA funding for the project runs through the end of 2022.

Research Partners

UC Riverside plans on working with hemp companies in an attempt to commercialize the method by creating renewable fiber that can be used to create things such as hempcrete blocks for construction. Their partners so far include:

  • The Hurd Co.
  • Hempire USA
  • InnovaCan.
  • Match Patch Pro.



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