Okra Can Be Used to Remove Plastic Waste From Water

Okra Can Be Used to Remove Plastic Waste From Water

Dr. Rajani Srinivasan of Tarleton State University in Texas led a team of researchers in investigating the uses of gooey plant extracts, such as those from okra, aloe vera, and various cacti, for wastewater cleanup. Having previously studied the plant extract-aided removal of textile-based pollutants and microorganisms from wastewater, Srinivasan thought to explore using those same extracts to wrangle microplastics, which have been the subject of increasing global concern in recent years.

While some floating microplastics can be skimmed off the surface of water during treatment, others are too heavy or too small to be effectively removed this way. Those remaining are often captured by flocculants, a class of sticky chemical made to attract plastics and clump together. These clumps sink to the bottom of the water, making collection far easier. But Srinivasan noted many flocculants themselves are toxic, which defeats the purpose of treating the water in the first place—with the removal of one pollutant, another is added in its place.

Meanwhile, okra, aloe, cacti, fenugreek, and psyllium contain polysaccharide extracts seemingly capable of doing a commercial flocculant’s job. The researchers added polysaccharide compounds from the plants into water samples polluted with microplastics, then examined microscope images of the clumped microplastics before and after each addition. A combination of okra and fenugreek compounds proved most effective in ocean water, while okra and tamarind paired best during freshwater cleanups. All of the plants’ polysaccharide compounds worked just as well as the commercial-grade flocculants typically used to remove microplastics, while some worked even better.

Though Srinivasan and her team plan on continuing to experiment with various combinations of plant-derived flocculants in microplastic removal, they hope to scale their process and implement it in real-world settings and even on an industrial scale. The researchers say no additional equipment is needed to begin using plant-based flocculants like okra polysaccharide in wastewater treatment. “The whole treatment method with the nontoxic materials uses the same infrastructure,” Srinivasan said while presenting her team’s findings Wednesday at the spring meeting of the American Chemical Society (ACS). “We don’t have to build something new to incorporate these materials for water treatment purposes.”

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