AmericaCompounds extracted from okra and some mollusks can remove harmful microplastics from water sources, scientists say.
Slime from okra can absorb microplastics in water. Photo: Healthy life
New research presented at the American Chemical Society’s spring meeting on March 22 offers an alternative to synthetic chemicals that may pose health risks to those used in wastewater treatment plants.
“To further remove microplastics or other materials, we must use natural, non-toxic materials,” said lead researcher Rajani Srinivasan of Tarleton State University.
Okra is used as a thickener in many dishes, such as Gumbo, a Louisiana stew. It is also a main dish in South Asia called bhindi.
Srinivasan’s previous research looked at how slime from okra and several other plants can remove textile contaminants from water and even microorganisms, and he wanted to see if this could help. Would the same be true for microplastics?
Microplastics – pieces of plastic less than or equal to 5 mm in diameter – have been shown to harm fish in a number of ways, from disrupting the reproductive system to stunted growth and liver damage. .
It is estimated that around 8 billion tonnes of plastic have been produced since the 1950s, but less than 10% is recycled. The rest is eventually broken down into microplastics and is currently found in every corner of the world, from oceans and waterways to air and soil, and our food.
Microplastics when they enter the human body can have health effects. Many worry that they increase the risk of cancer and DNA mutations, although more research is needed to verify.
There may be more plastic waste than fish by 2050. Video: CNN
The traditional wastewater treatment process filters microplastics in two steps. First, remove the floating part from the water. However, these substances make up only a small part. The remainder is filtered off using flocculants, or adhesive chemicals, to attract the microplastics, forming larger clumps. These blocks sink to the bottom and are then removed from the water.
The problem is that synthetic adhesives, such as polyacrylamide, can break down into harmful chemicals. So Srinivasan and his colleagues set out to study how natural adhesives from okra, aloe, cactus, fenugreek, tamarind, and psyllium purchased at the supermarket would work.
They tested the carbohydrate chains, called polysaccharides, from each plant, as well as in combination, with various sources of water contaminated with microplastics, examining before and after microscopic images to determine how many seeds were removed.
They found that okra polysaccharides combined with fenugreek polysaccharides were the best at removing microplastics from seawater, while okra polysaccharides combined with acid performed best in freshwater samples.
In general, polysaccharides work well, some even better than polyacrylamide. Importantly, the plant-based compounds are non-toxic and can be used in existing processing plants.
Srinivasan hopes to scale up and commercialize the process, giving more people access to safer and cleaner water.
Doan Duong (Based on AFP)
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