Researchers at the University of Arkansas have found an innovative and eco-friendly use for lignin, a common byproduct of the pulp and paper industry, turning it into a powerful material for removing toxic textile dyes from wastewater.
The study, led by chemical engineering Ph.D. candidate David Chem, addresses a long-standing challenge in the textile industry: the treatment of azo dyes such as Congo red and methyl orange. Widely used in fabrics for their bright colors and durability, these dyes are notoriously difficult to degrade and can pose carcinogenic and environmental risks once they enter water systems.
Azo dyes account for 60–70% of commercial textile production and often end up in wastewater from both garment manufacturing and household laundry. Chem’s team saw potential in lignin, an underutilized biopolymer found in plant cell walls and produced in vast quantities by the pulp and paper industry—up to 70 million tons per year, most of which is discarded.
“Lignin extraction is hard to process. It has a complex structure,” Chem explained. “It is underutilized as a biopolymer.”
To make lignin more reactive, researchers first treated it with phenol, then added amino groups to give the material a positive charge, allowing it to attract and bond with the negatively charged dye molecules. This dual-functionalization process, previously explored for removing heavy metals, was used for the first time to target harmful dyes.
The results were striking: in lab tests, the modified lignin removed 96% of Congo red and 81% of methyl orange from contaminated water. Both the dyes and the lignin could then be recovered and reused.
“The process is really scalable. It’s a relatively green process. And it is highly effective,” Chem said.
The findings, published in the Journal of Polymers and the Environment, were co-authored by Professor Keisha Bishop Walters, Chem’s doctoral supervisor and chair of the Ralph E. Martin Department of Chemical Engineering, postdoctoral fellow Fatema Tarannum, and Samantha Glidewell, an undergraduate researcher.
The University of Arkansas is a leading research institution known for its innovation in engineering, materials science, and environmental sustainability. The university’s Ralph E. Martin Department of Chemical Engineering focuses on developing sustainable technologies that transform industrial byproducts into valuable resources, advancing circular economy principles.
