New Hydrogel Effectively Removes Toxic Dyes from Industrial Wastewater

Researchers at the Indian Institute of Technology Gandhinagar (IITGN) have developed a new hydrogel capable of removing toxic dyes from industrial wastewater. This advanced material, called CAPA, acts like a microscopic sponge. It effectively traps common dyes such as methylene blue, crystal violet, and rhodamine B, even when multiple dyes are present in the same water solution.

Industrial wastewater often contains various dyes. Billions of tons of dye-containing wastewater enter water systems annually. Much of this water is released untreated or used for irrigation, particularly in low- and middle-income nations. These dyes can harm aquatic life and pose health risks to humans and animals.

The CAPA hydrogel is made from carboxymethyl cellulose (CMC), a biodegradable material, and acrylic acid. Adjusting the amount of acrylic acid allowed researchers to fine-tune the hydrogel's structure and adsorption capabilities. One version, CAPA-2, demonstrated a 99.6% removal rate for methylene blue dye. Its adsorption capacity of approximately 475 milligrams of dye per gram of hydrogel is among the highest reported for CMC-based hydrogels.

The hydrogels work by attracting positively charged dye molecules to their negatively charged sites. They also contain tiny pores, about 25 nanometers in diameter, which effectively trap dye molecules that are one to two nanometers in size. CAPA-2 maintained its effectiveness across various pH levels, from acidic to alkaline environments. The material also proved durable, showing only a slight decrease in performance after four reuse cycles.

This development offers a promising solution for treating industrial wastewater. The researchers emphasize the importance of evaluating the hydrogels' performance in real-world conditions. This innovation could help protect water resources and ecosystems, contributing to a more sustainable future.