Microplastics — tiny particles less than 5 mm in size that originate from
the breakdown of larger plastics and textiles such as polyester,
nylon
and
fleece
— are now a worldwide concern: A 2023 study estimated 171 trillion
microplastic
particles
are now floating in the world's waterways, from oceanic gyres to freshwater
lakes.
While researchers continue to study their effects on human, animal and
environmental health, microplastics can breach the body’s natural defenses;
serve as a substrate for other contaminants; accumulate in vital organs; and
potentially trigger inflammation, toxicity and chronic diseases. A 2019 WWF
study
estimated the average human is consuming roughly 5 grams of plastic every week,
which is approximately the equivalent of a credit card. And a study published
in PLOS
Water in
January revealed that France’s drinking water is saturated with
microplastics smaller than 20 micrometers (µm) — which falls below the threshold
of the EU’s current detection methodology, pointing to an urgent need for
updated water-safety protocols.
A number of emerging innovations show promise in cleaning up
the small but mighty menace,
but they remain notoriously difficult to collect and remove from the environment
— and conventional wastewater treatment using inorganic and organic polymeric
flocculants is nonbiodegradable and can be toxic to
ecosystems. A widely used
solution uses polyacrylamide — a
water-soluble polymer derived from acrylamide monomers. While polyacrylamide is
generally considered safe and is used in everything from cosmetics and water
treatment to soil conditioning, the residual acrylamide monomer is a primary
focus of safety assessments.
Dr. Rajani Srinivasan
and her colleagues at Texas’ Tarleton State
University have been working to address this by
exploring non-toxic, plant-based solutions for attracting and removing
contaminants from water.
In a new study recently
published in the journal, ACS Omega, the team found that polymers from
okra, fenugreek and tamarind extracts stick to microplastics —
clumping together and sinking for easy separation from water.
“Utilizing these plant-based extracts in water treatment will remove
microplastics and other pollutants without introducing additional toxic
substances to the treated water, thus reducing long-term health risks to the
population,” said Dr. Srinivasan — who in 2020 was awarded a
patent
for an invention related to the use of polymers from plant-based extracts to
separate solids, pathogens and both organic and inorganic pollutants from water.
To extract the sticky plant polymers, the researchers soaked sliced okra pods
and blended fenugreek seeds in separate containers of water overnight. They then
removed the dissolved extracts from each solution and dried them into powders.
Their analyses showed that the powdered extracts contained
polysaccharides, which are
natural polymers.
Initial tests in pure water spiked with microplastics showed that:
-
one gram of either powder in a quart of water trapped microplastics the most
effectively
-
dried okra and fenugreek extracts removed 67 percent and 93 percent,
respectively, of the plastics in an hour
-
a mixture of equal parts okra and fenugreek powder reached maximum removal
efficiency (70 percent) within 30 minutes
-
both natural polymers performed significantly better than the synthetic,
commercially available
polyacrylamide conventionally used
in wastewater treatment.
Effects on polluted waterways
The researchers then tested the plant extracts on real microplastic-polluted
water — collecting samples from water bodies around Texas — and found that the
removal efficiency of each plant extract changed, depending on the original
water source:
-
okra worked best in ocean water (80 percent)
-
fenugreek in groundwater (80-90 percent)
-
a 1:1 combination of okra and fenugreek was most effective (77 percent) in
freshwater.
The scientists hypothesize that the difference in efficiencies is due to the
different types, sizes and shapes of microplastics in each water sample.
Regardless of water source, they conclude that okra and fenugreek extracts could be viable as
biodegradable and nontoxic alternatives to polymers such as polyacrylamide in
wastewater treatment and filtration.
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Sustainable Brands Staff
Published May 30, 2025 2pm EDT / 11am PDT / 7pm BST / 8pm CEST