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Polymer can remove dyes from wastewater

Swatches | November 27, 2022 | By:

The left vial shows dye solution in water (blue) and the right vial shows clear water after the dye was removed from the solution by the polymer. Photo: Januka Budhathoki-Uprety

North Carolina State University researchers have demonstrated that a synthetic polymer can remove certain dyes from water and that the polymer can be recovered and reused. The results offer a new method for cleaning wastewater after use by textiles, cosmetics or other industries.

“Dyes are used everywhere, including in the textile industry, as well as in pharmaceuticals, cosmetics, paper, leather and even in medicines,” says Januka Budhathoki-Uprety, lead researcher on the work and an assistant professor of textile engineering, chemistry and science at NC State. “If these contaminants aren’t properly removed from wastewater after dyeing and finishing, they can be a significant source of environmental pollution and pose risks for human health.”

Researchers made a synthetic polymer and tested its ability to clean wastewater, first by dissolving it in a solvent, and then mixing it with water contaminated with dyes. They tested the polymer solution against a series of 20 anionic dyes, also called acid dyes, which are used in the textile industry. 

“The polymer part of the solution grabs onto the dyes,” Budhathoki-Uprety says. “Then we were able to easily separate the clean water from the contaminated solution mixture.” The polymer solution removed all but four of the 20 acid dyes tested. In addition, researchers found it was easy to recover the polymer to use again. 

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