New sugar-based polymer could help remove heavy metals from water

Researchers at the University of Texas at Austin have developed a new solution to purify water.

They have created a sugar-derived polymer that can effectively trap and remove heavy metals from polluted water.

Heavy metals, like lead and mercury, pose a persistent threat to water resources and can have devastating effects on both human health and marine dwellers.

These heavy metals can enter the water supply through various sources, including industrial waste and agricultural runoff.

Traditional water purification methods, while effective, often face challenges such as high energy consumption and clogging of filtration membranes.

Plant-derived solution

Plants have a protective barrier composed of polysaccharides, which are macromolecules composed of repeating sugar units. This barrier traps metal ions, defending the plant cells.

Several such plant-based sugar polymers have been made earlier. While most of them can purify water by trapping heavy metals, they need a helping hand. For instance, these require additional substances to improve their stability or solubility.

A previous study utilized sticky polysaccharide extracts from okra and aloe to eliminate microplastics from wastewater. However, some of these natural cleaners dissolved in water, necessitating additional support.

In this new study, researchers created a sugar-like polymer to purify water without relying on additional chemicals.

Interestingly, this newly created single material has a sugar-like structure with adjustable water solubility. This allows for specific removal of heavy metals from water.

Shows promise in cleaning polluted water

This innovative polymer is designed with a water-insoluble backbone and water-soluble carbohydrate “charms” that attract and bind heavy metal ions.

“The team constructed several polymers, each having a water-insoluble backbone with different water-soluble carbohydrates dangling from the repeating units like charms on a bracelet,” the press release explained.

For this, the researchers experimented with different carbohydrate structures to find the most effective one for capturing ionic cadmium. They discovered that a carboxylic acid group was particularly effective at attracting and binding this metal ion.

Subsequently, they tested a polymer with this carboxylic acid group in water contaminated with ionic cadmium. The polymer formed visible clumps within three minutes, which could be readily filtered out of the water. The clumps can be redissolved to release the captured metals. The researchers repeated this process three times to assess the polymer’s durability.

“After three cycles of binding, clumping, and redissolving, the polymer maintained the same metal-trapping efficiency, demonstrating its potential as a recyclable material,” they mentioned in the press release.

Testing for validation

To demonstrate its effectiveness, the carbohydrate-containing polymer was tested on Colorado River water contaminated with ionic cadmium and lead.

Within 24 hours, the polymer was able to capture up to 20% of the added cadmium and 45% of the added lead from the Colorado River water sample. The polymer’s unique structure allows it to selectively capture heavy metal ions while minimizing the capture of other, less harmful ions.

Compared to other methods, the sugar-derived polymer offers several advantages, including higher efficiency, reusability, and selectivity.

“The researchers say their new material is a promising step towards more efficient, reusable, and selective materials for water purification,” the press release stated.

The findings were published in the journal ACS Central Science.