Dyes like Congo red and methyl orange create brightly hued shirts, sweaters and dresses. But these commonly used azo dyes can be toxic, carcinogenic and are hard to remove from wastewater. David Chem, a University of Arkansas Ph.D. candidate, developed an environmentally friendly solution to remove these dyes using a common byproduct of the pulp and paper industry. Azo dyes are used in 60%–70% of commercial textile production. The dyes dissolve easily in water and resist biodegradation, which makes them an environmental hazard. …To remove azo dyes from water, Chem started with lignin, a low-cost, widely available biopolymer derived from plant cell walls. …The modified lignin removed 96% of the Congo red dye and 81% of the methyl orange dye. With this method, both the dyes and the lignin can be reused. “The process is really scalable. It’s a relatively green process. And it is highly effective,” Chem said.