Microplastics are everywhere, from the clouds to the deepest reaches of the sea. Photo: Sören Funk//Unsplash
Sponges are very useful things. The ones we have sitting in our sinks are modeled after nature’s sponges, of course, which is nice for the animals, but we made synthetic ones for a reason: a sponge is very good at absorbing stuff. Over the last few years, researchers have found another thing they’re good at sucking up: microplastics. That’s a good thing, because we are absolutely filling our world with them.
Back in August, a group of Chinese researchers published a study about a synthetic sponges they’d created to battle the ever-increasing amount of microplastics we’re finding all over the world, from the clouds to our blood and the falling snow.
“In tests, the researchers show that when a specially prepared plastic-filled solution is pushed through one of their sponges, the sponge can remove both microplastics and even smaller nanoplastics from the liquid,” wrote Chris Baraniuk for Hakai magazine. “These particles typically become trapped in the sponge’s many pores.”
As with anything, just how well the sponges worked depended on a variety of factors. “Though the sponges’ effectiveness varied in experiments,” Baraniuk continued, “in part depending on the concentration of plastic and the acidity and saltiness of the liquid, optimal conditions allowed the researchers to remove as much as 90 percent of the microplastics. They tried it in everything from tap water and seawater to – why not – soup from a local takeout spot.”
The new sponges are made predominantly from gelatin and starch. They look a bit like marshmallows, but likely don’t taste as good. They weigh almost nothing because the insides are mostly empty space, save for a few bits of shape-keeping structures.
A materials chemist named Guoqing Wang, who is a co-author of the paper, said that they’re able to make the sponges more or less porous depending on what size particles they’re looking to clean up. This is done through a relatively simple process of changing the temperatures of the gelatin and starch as they’re being mixed together. With any luck and a bit more R&D, Wang believes that the sponges will be extraordinarily useful in places like wastewater treatment plants or in food production facilities.
According to the Smithsonian, they could potentially also be used to great benefit in washing machines, which are notoriously bad for pulling microplastics from our synthetic clothing and sending them down the drain and into the environment. “You could place such a sponge inside the drum,” Christian Adlhart, a chemist at Zurich University of Applied Sciences in Switzerland, explained. “I think it would absorb a large fraction of the fibers.”
Despite the good intentions of the new sponges’ creators, some researchers believe that there are simply far too many microplastics hitting the sea every day for them to make any real difference. “I don’t think there is anything we can do on a large enough scale that will have any impact,” said Alice Horton at the United Kingdom’s National Oceanography Center. “We have to stop it getting there in the first place.”
