A hydrogel formulated by North Carolina State University researchers effectively filters phosphorus from contaminated surface waters, drinking water supplies or wastewater streams. The highly selective hydrogel offers a relatively low-cost means of reducing phosphorus pollution that can also release the nutrient for future agricultural and industrial applications.

The reusable hydrogel combines two commercially available materials: polyethyleneimine (PEI), which is anAerial view of a wastewater treatment plant. Source: Ivan Bandura inexpensive polymer whose molecular structure allows it to capture phosphorus as water passes through the material, and poly(methyl vinyl ether-co-maleic anhydride) (PMVEMA), which is also an inexpensive polymer that bonds with the PEI to form a robust gel that allows water to pass through while maintaining its structural integrity.

Tests described in the journal Langmuir confirm that the PEI/PMVEMA hydrogel was extremely efficient at removing phosphorus from contaminated water as it flowed through the material at room temperature. It also efficiently released the captured phosphorus at room temperature using mild bases.

“Our experiments suggest the hydrogel would be able to remove well over 90% of the phosphorus from wastewater or contaminated surface waters,” noted the researchers. “We also demonstrated that we can reclaim up to 99% of that phosphorus for reuse. We also showed that the hydrogel can then be reused with minimal decline in performance. For example, after being used three times, we could still reuse 97.5% of the phosphorus.”