Natural Plant Extract Removes up to 90% of Microplastics From Water

Okra and fenugreek extracts can remove up to 90% of microplastics from water, offering a safer, biodegradable alternative to synthetic polymers. Credit: Shutterstock

Researchers found that natural polymers derived from okra and fenugreek are highly effective at removing microplastics from water.

The same sticky substances that make okra slimy and give fenugreek its gel-like texture could help clean our water in a big way. Scientists have discovered that these natural plant extracts are surprisingly good at trapping microplastics, tiny plastic particles that pollute oceans, rivers, and even our drinking water.

In fact, researchers found that extracts from okra and fenugreek can remove up to 90 percent of microplastics from ocean water, freshwater, and groundwater. These results were recently published in the journal ACS Omega.

Rajani Srinivasan and her research team have been searching for safe, plant-based ways to remove pollutants from water. In earlier lab experiments, they tested extracts from okra, fenugreek, and tamarind. They found that these natural polymers grab onto microplastics, causing them to clump together and sink to the bottom, making it much easier to separate the plastics from the water.

Srinivasan spoke about successful demonstrations of the plant extracts in freshwater and ocean water at ACS Spring 2022, a meeting of the American Chemical Society. In this next stage of the research, they have optimized the process for okra and fenugreek extracts in various types of water.

To extract the sticky plant polymers, the team soaked sliced okra pods and blended fenugreek seeds in separate containers of water overnight. Then, researchers removed the dissolved extracts from each solution and dried them into powders. Analyses showed that the powdered extracts contained polysaccharides, which are natural polymers.

Lab Tests Show High Efficiency of Natural Powders

Initial tests in pure water spiked with microplastics showed that:

• One gram of either powder in a quart (one liter) of water trapped microplastics the most effectively.
• Dried okra and fenugreek extracts removed 67% and 93%, respectively, of the plastic in an hour.
• A mixture of equal parts okra and fenugreek powder reached maximum removal efficiency (70%) within 30 minutes.
• The natural polymers performed significantly better than the synthetic, commercially available polyacrylamide polymer used in wastewater treatment.

Then the researchers tested the plant extracts on real microplastic-polluted water. They collected samples from waterbodies around Texas and brought them to the lab. The plant extract removal efficiency changed depending on the original water source: Okra worked best in ocean water (80%), fenugreek in groundwater (80-90%), and the 1:1 combination of okra and fenugreek in freshwater (77%). The researchers hypothesize that the natural polymers had different efficiencies because each water sample had different types, sizes, and shapes of microplastics.

Polyacrylamide is currently used to remove contaminants during wastewater treatment, but the researchers say that okra and fenugreek extracts could serve as biodegradable and nontoxic alternatives.

“Utilizing these plant-based extracts in water treatment will remove microplastics and other pollutants without introducing additional toxic substances to the treated water,” says Srinivasan, “thus reducing long-term health risks to the population.”

Reference: “Fenugreek and Okra Polymers as Treatment Agents for the Removal of Microplastics from Water Sources” by Rajani Srinivasan, Rajita Bhuju, Victoria Chraibi, Mihaela C. Stefan, Nguyen Hien, Damla Ustundag, Jeri La Neice Gill, Nikolas Rasmussen, Blake Saurenmann, Joe Bracerra, Michael Fowler, Hailey White and Marconi Azadah, 10 April 2025, ACS Omega.

DOI: 10.1021/acsomega.4c07476

The authors acknowledge funding from the U.S. Department of Energy; Tarleton State University; High Plains Water District located in Lubbock, Texas; the Burnaby Munson Endowed Research Professorship; the National Science Foundation Research Experiences for Undergraduates program; and the Welch Foundation.

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