New water micro cleaner is floating to capture and remove microplastics, which is different from the self

In a new paper, researchers at North Carolina State University provide proof of concept of a system that actively removes microplastics from water in a single cycle.

The findings listed in the Journal Advanced Functional Materials hold the potential for advances in purifying small plastic water bodies and other water bodies that can be harmful to human health and the environment.

“The idea behind this work is to make cleaning materials in the form of soft particles that self-disperse in water, trap microplastics when sinking, then return to the surface with the captured microplastic contaminants?” Orlin Velev. He is a noted Frank and Doris Calverson, a professor of NC chemistry and biomolecular engineering, and is the author of the corresponding paper.

“We have demonstrated how to integrate multiple principles into a system that functions in a single cycle.”

This study begins with soft dendritic colloids with different, hierarchically branched soft particles, including the ability to stick to almost any surface, which can be created from a variety of polymers.

Student Haleen Hong, the first author of Velev and Ph.D. Paper, says the sticky nature of these particles can attract microplastics and grab them.

“The cleansing particles in this study are made from chitosan, a biodegradable polymer derived from chitin, derived from processed shellfish waste,” says Velev. He adds that using environmentally safe materials already coming from the ocean will make the process more sustainable.

Soft dendritic colloids form small pellets when dried in droplets suspended on a water-repellent surface. When dropped into the water, the pellet particles separate and spread to hunt microplastics. But first, the researchers inject a small amount of eugenol, a plant-based oil, into one section of the pellet, as a dispersant.

“The oil moves the pellet underwater through the so-called “camp-brain boat effect,” reducing the surface tension on one side of the pellet and driving it forward. This allows the microcleaner to spread across larger areas, trapping microplastics as they move and descend,” Hong said.

To provide water return to the surface, the microcleaner also contains small particles of magnesium, which bubbles up and rises to the surface when it reacts with water.

To delay this return trip, researchers coat magnesium with an environmentally safe gelatin layer that blocks reaction with water. Essentially, a thick coat of gelatin allows particles to delay from rising to surfaces, and as the microcleaner swirls and descends underwater, you can pick up more microplastics.

“When gelatin dissolves, magnesium produces foam, causing the microcleaner to rise, bringing plastic particles captured by the densely packed mixture of scamis to the surface,” Hon said.

This paper shows that particles can “swim” for up to 30 minutes and collect microplastics. Microcleaners containing microplastics that have risen to the surface can be collected by skimming.

“Potentially, the collected scum could be bioprocessed into more chitosan, which could be used to create more microcleaners to capture more microplastics,” Velev says. Researchers say further research is needed to expand the process.

Rachel Van, a former NC PhD student, co-authored thesis along with her current NC PhD. Student Lucille’s Burster.