A team of researchers at North Carolina State University has unveiled an innovative proof of concept for a system that actively removes microplastics from water in just one cycle. The groundbreaking findings, published in the journal Advanced Functional Materials, offer promising potential for improving efforts to cleanse oceans and other water bodies from harmful microplastics that pose a risk to both human health and the environment.
The research, led by Orlin Velev, S. Frank and Doris Culberson Distinguished Professor of Chemical and Biomolecular Engineering at NC State, aims to address the growing issue of microplastic contamination in water. Velev and his team have designed a system that utilizes soft, self-dispersing particles that can actively capture and remove microplastics from water. The concept works by allowing the particles to sink, trap the microplastics, and then rise to the surface, where the contaminants can be easily collected.
“The idea behind this work is: Can we make the cleaning materials in the form of soft particles that self-disperse in water, capture microplastics as they sink, and then return to the surface with the captured microplastic contaminants?” Velev said. “We demonstrated how multiple principles can be integrated into a system that works in a single cycle.”
The breakthrough begins with the use of soft dendritic colloids—unique, hierarchically branched particles with remarkable properties, including the ability to adhere to almost any surface. These particles are created from various polymers and, in this case, are made from chitosan, a biodegradable polymer derived from chitin, which is found in processed shellfish waste.
The sticky nature of these dendritic colloids allows them to attract and capture microplastics, even under challenging conditions like the wet and salty environment of the ocean. This makes the process not only effective but also sustainable, using materials that are already naturally abundant in marine environments.
“These cleansing particles are made from chitosan, which comes from shellfish waste, an environmentally safe material that makes the process more sustainable,” explained Velev. “We’re essentially turning waste from the sea into a resource for cleaning the sea.”
The particles, when dried, take the form of small pellets suspended over a water-repellent surface. Once dropped into water, the pellets break apart, allowing the individual particles to spread out and actively seek out microplastics. To help the particles move efficiently through the water, the researchers infuse the pellets with eugenol, a plant-based oil that acts as a dispersant.
This oil reduces the surface tension on one side of the pellet, driving it forward by creating the so-called “camphor boat effect.” This effect propels the microcleaners across a large area, enabling them to capture microplastics as they descend through the water.
The real ingenuity, however, lies in how the particles make their way back to the water’s surface after capturing the microplastics. To facilitate this, the particles are infused with small amounts of magnesium, which reacts with water to create bubbles, helping the particles rise to the surface.
To control the timing of this rise, the researchers coat the magnesium with a layer of environmentally safe gelatin. This coating delays the magnesium’s reaction with water, allowing the particles more time to collect microplastics as they swirl and descend. As the gelatin dissolves, the magnesium generates bubbles, causing the particles to float to the surface, where they carry with them the captured microplastics.
The system has proven to be effective for up to 30 minutes, with the microcleaners successfully collecting microplastics during that time. Once they rise to the surface, the microplastic-laden particles can be collected using skimming techniques. According to Velev, the collected scum—which contains the captured plastics—can potentially be bioprocessed back into more chitosan, creating a self-sustaining cycle to produce more microcleaners and continue removing microplastics.
“Potentially, the collected scum can be bioprocessed into more chitosan, which can then be used to create more microcleaners in order to capture more microplastics,” Velev said, hinting at a circular process that could help scale up efforts for cleaner oceans and water bodies.
The researchers note that while this proof of concept is promising, further investigations will be required to scale up the process and refine its application in real-world conditions. However, the initial results suggest a significant breakthrough in the ongoing battle to address microplastic pollution in our water systems.
This innovative system represents a promising step forward in the fight against microplastic pollution. By using biodegradable, sustainable materials and employing a system that can capture microplastics in a single cycle, the researchers at North Carolina State University have taken a significant leap toward developing more effective and environmentally friendly water cleaning technologies. As further research and development take place, this technology may hold the key to revolutionizing how we cleanse our oceans, lakes, and rivers of the growing threat posed by microplastics.
By Impact Lab
