Magnetic material mops up microplastics in water

Researchers at RMIT University have found an innovative way to rapidly remove hazardous microplastics from water using magnets.

Lead researcher Professor Nicky Eshtiaghi said existing methods could take days to remove microplastics from water, while their cheap and sustainable invention achieves better results in just one hour.

The team says they have developed adsorbents, in the form of a powder, that remove microplastics 1,000 times smaller than those currently detectable by existing wastewater treatment plants.

The researchers have successfully tested the adsorbents in the lab, and they plan to engage with industry to further develop the innovation to remove microplastics from waterways.

The research results are published in the Chemical Engineering Journal.

Dr Nasir Mahmood, PhD candidate Muhammad Haris and Professor Nicky Eshtiaghi (left to right) with a sample of water with microplastics and a vial of clean water following its treatment with their innovation. Credit: RMIT University

“The nano-pillar structure we’ve engineered to remove this pollution, which is impossible to see but very harmful to the environment, is recycled from waste and can be used multiple times,” said Eshtiaghi from the School of Engineering.

“This is a big win for the environment and the circular economy.”

A magnet attracts the material that the team used to make adsorbents that remove microplastics and dissolved pollutants from water. Credit: RMIT University

How does this innovation work?

The researchers have developed an adsorbent using nanomaterials that they can mix into water to attract microplastics and dissolved pollutants.

Muhammad Haris, the first author and PhD candidate from the School of Engineering, said the nanomaterials contained iron, which enabled the team to use magnets to easily separate the microplastics and pollutants from the water.

“This whole process takes one hour, compared to other inventions taking days,” he said.

Co-lead researcher Dr Nasir Mahmood said the nano-pillar structured material was designed to attract microplastics without creating any secondary pollutants or carbon footprints.

“The adsorbent is prepared with special surface properties so that it can effectively and simultaneously remove both microplastics and dissolved pollutants from water,” said Mahmood from the School of Science.

“Microplastics smaller than 5 millimetres, which can take up to 450 years to degrade, are not detectable and removable through conventional treatment systems, resulting in millions of tonnes being released into the sea every year. This is not only harmful for aquatic life, but also has significant negative impacts on human health.”

The team received scientific and technical support from the Microscopy and Microanalysis Facility and the Micro Nano Research Facility, part of RMIT’s newly expanded Advanced Manufacturing Precinct, to complete their research.

PhD candidate Muhammad Haris and Professor Nicky Eshtiaghi (left to right) with the magnetic material that they developed into adsorbents that remove microplastics and dissolved pollutants from water. Credit: RMIT University

What are the next steps?

Developing a cost-effective way to overcome these significant challenges posed by microplastics was critical, Eshtiaghi said.

“Our powder additive can remove microplastics that are 1,000 times smaller than those that are currently detectable by existing wastewater treatment plants,” she said.

“We are looking for industrial collaborators to take our invention to the next steps, where we will be looking at its application in wastewater treatment plants.”

Eshtiaghi and her colleagues have worked with various water utilities across Australia, including with Melbourne Water and Water Corporation in Perth on a recent Australian Research Council Linkage project to optimise sludge pumping systems.

‘Self-assembly of C@FeO nanopillars on 2D-MOF for Simultaneous Removal of Microplastic and Dissolved Contaminants from Water’ is published in the Chemical Engineering Journal (DOI: 10.1016/j.cej.2022.140390).

The co-authors are Muhammad Haris, Muhammad Waqas Khan, Ali Zavabeti, Nasir Mahmood and Nicky Eshtiaghi. Further questions and enquiries can be directed to nicky.eshtiaghi@rmit.edu.au

Story: Will Wright

Science

Society and Environment

Technology

30 November 2022

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30 November 2022

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RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business - Artwork 'Luwaytini' by Mark Cleaver, Palawa.

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Magnetic material mops up microplastics in water