They develop a hydrogel to extract microplastics

Scientists at the Indian Institute of Science (IISc) have developed an eco-friendly hydrogel to remove microplastics, a new global pollutant, from water.

These small plastic waste can enter our body through the water we drink and increase the risk of enfermedades. They also pose a threat to the the environment, are found even in remote areas, such as polar ice caps and deep ocean trenches, and pose a threat to aquatic and terrestrial life.

On the seabed alone, the amount of microplastics has tripled in the last two decades, says a team of researchers from the Institute of Environmental Science and Technology of the Autonomous University of Barcelona (ICTA-UAB) and the Department of Built Environment of Aalborg University.

This is how hydrogel works

This material has a unique interlocking polymer network that can bind contaminants and decompose them under the influence of ultraviolet rays. The research was published in the journal Nanoscale.

Scientists have previously tried using membrane filters to remove microplastics. However, the membranes can become clogged with these small particles, making them unstable. Instead, the IISc team led by Suryasarathy Bose, professor in the department of materials science and engineering, decided to turn to 3D hydrogels.

The new hydrogel developed by the research team consists of three different polymer layers (chitosan, polyvinyl alcohol and polyaniline) intertwined to form an interpenetrating polymer network (IPN) structure.
The team filled this array with nanoclusters of a material called copper-substituted polyoxometalate (Cu-POM).

These nanoclusters are catalysts that can use ultraviolet light to break down microplastics.
By combining polymers and nanoclusters, a durable hydrogel was created capable of adsorbing and degrading large amounts of microplastics.


Laboratory tests

Most microplastics are the result of incomplete degradation of household plastics and fibers. To simulate this in the lab, the team cut lids from food containers and other everyday plastic products to create the two most common types of microplastics found in nature: polyvinyl chloride and polypropylene.

"In addition to cleaning or eliminating microplastics, another important issue is their detection. As these are very small particles, they cannot be seen with the naked eye.", explains in a statement Sumi Dutta, first author of the study and SERB national postdoctoral fellow in the Department of Materials Science and Engineering.

To solve this problem, the researchers added fluorescent dyes to the microplastics to monitor how much the hydrogel absorbed and degraded under different conditions. "We test the removal of microplastics at different water pH levels, different temperatures and different concentrations of microplastics"explains Dutta.

The hydrogel was found to be very effective as it could remove approximately 95% and 93% of two different types of microplastics from water at a near-neutral pH (approximately 6,5). The team also conducted several experiments to test the strength and durability of the material. They found that the combination of three polymers provided stability at different temperatures.

Hydrogel, an ecological and reusable material

"We wanted to create a material that was more ecological and reusable"explains Bose. The hydrogel withstands up to five microplastic removal cycles without significant loss of effectiveness.

Additionally, Bose notes, once the hydrogel is deactivated, it can be reused as carbon nanomaterials that can remove heavy metals like hexavalent chromium from contaminated water.

In the future, the researchers plan to collaborate with colleagues to develop a device that can be used on a large scale to clean microplastics from various water sources.

With information of:

With information of: