In recent years, microplastics have garnered significant attention due to their detection in tap and bottled water, as well as in rivers, lakes, and oceans.
Conventional filtering technologies for water treatment have difficulty effectively filtering out microplastics of various sizes and shapes and are prone to clogging. Additionally, recovering small particles requires extremely fine filter meshes, which increases pressure and drastically reduces filter efficiency.
Furthermore, they are not effective in open spaces such as lakes, rivers, or oceans, where microplastic pollution is increasing.
Dr. Seong Jin Kim and Myoung-Woon Moon of the Center for Extreme Materials Research at the Korea Institute of Science and Technology (KIST) have developed a new level of microplastic removal technology, offering a promising solution to this growing problem. They have developed a floating drone equipped with hydrophilic tooth structures that leverage surface tension to skim microplastics.
The research is published in the journal Advanced Science.
The core of the team’s approach is the hydrophilic ratchet structure. This design forms a water bridge that forms between the teeth due to its affinity for water, which maximizes the surface tension of the water to adhere the microplastics to the teeth.
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Prototypes of toothed drums for different types of MP recovery. (A) The experimental image shows the MP skimming process using a toothed structure drum with P = H = 6 mm and a drum diameter of 60 mm. The drum skims millimeter-sized PE pellets and micrometer-sized PE particles. (B) Shows how the toothed drum removes all MPs located on the right side of the bath, and then releases them to the left, regardless of whether the MPs are i) PE pellets with a size of 2β4 mm, or ii) PE particles in the range of 1β2000 ΞΌm (C). (D) The recovery seen by the toothed drum at three different drum rotation speeds for five different MPs. Credit: Korea Institute of Science and Technology
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Prototype of a floating drone with hydrophilic ratchet technology (marine robotic cleaner). The successive images depict a lab-scale prototype equipped with a ratchet-structured drum, skimming microplastics of various sizes as it moves forward. The left image shows a floating drone designed for cleaning open waters, while the right image features a handheld, portable version for manual cleaning in marinas or near shorelines. Credit: Korea Institute of Science and Technology
This approach enables the removal of microplastics ranging in size from 1 micrometer (ΞΌm) to 4 millimeters, addressing the challenges traditional filtering technologies face with size and shape variability. It also ensures reliable operation without the risk of clogging.
The technology has achieved over 80% recovery efficiency for various types of microplastics, including expanded polystyrene, polypropylene, and polyethylene.
In particular, the hydrophilic ratchet structure of the floating drone can be used to remove microplastics in real-time in large bodies of water such as oceans, lakes, and rivers. The drone can move autonomously and purify water quality like a household robot vacuum cleaner, showing its versatility beyond the limitations of existing fixed systems
“This technology can be applied not only to floating drones, but also to stationary systems such as water treatment filters in aquaculture farms,” said Dr. Moon. “It can also be expanded into a home water treatment filter device that individuals can use in their daily lives.”
