Sponges have been our go-to for countless tasks throughout our lives and not just for cleaning stuff. It’s all thanks to their ability to capture tiny particles in their pores.
Knowing this, scientists have developed and found a new use for these things. It all came from a simple question: can we make sponges that absorb microplastics?
In a recent study from China, researchers introduced a synthetic sponge designed to get microscopic plastic debris.
In their experiments, the researchers prepared a solution laden with plastic particles. When it flows through one of these sponges, it efficiently snags microplastics and smaller nanoplastics—trapping them in the pores.
Of course, no plastics are the same, so the effectiveness of these sponges varied. It all depends on factors like plastic concentration, liquid acidity, and saltiness.
But under optimal conditions, they managed to remove up to 90% of the microplastics.
This study tested the sponge in a range of liquids. Researchers did it in tap water, seawater, and even a serving of takeout soup, just for good measure.
The researchers made these plastic-eating sponges from starch and gelatin. They don’t look like regular washing sponges, but rather like oversized, lightweight marshmallows.
When we take a good look at these sponges, they have a complex structure filled with tiny bubble-like cavities.
Per the researchers, the materials needed to make these sponges are biodegradable. That makes them easier to transport and cost-effective.
Co-author of the study Guoqing Wang said that the formula to make these sponges is adjustable.
According to the Ocean University of China chemist, it’s done by tweaking the temperature. When it’s done during the mixing of the compounds, it results in the ability to control the sponge’s porosity.
Therefore, the researchers can adjust how absorbent to particles that the sponges will be. More porous sponges have a lot of smaller pores, which is good to trap the tiniest of particles.
These sponges, if mass produced, could prove to be useful in a lot of applications. They can filter microplastics in wastewater treatment plants or decontaminate water in the food production sector.
They might also find their place in washing machines. Capturing microplastics caused by synthetic fabrics during laundry would be easier than ever.
What sorcery is this?
The secret to these sponges’ success lies in a combination of mechanisms.
So, when water is actively pushed through them (like when we squeeze sponges), microplastics get caught in the sponge’s pores.
At the same time, although the sponge just floats around in still water, there’s electrostatic forces. These attract plastic particles to its surface.
Unfortunately, despite the boon, there are some things that the researchers take into consideration.
For one, starch and gelatin are staple ingredients in the food industry. So, this could lead to competition for these resources in the future. Other natural materials that are just as biodegradable can be substitutes, like chitosan, a sugar derived from crustacean shells.
Secondly, the process developed by the researchers to make these sponges relies on formaldehyde, a highly toxic compound. Although the researchers were careful during the making of these sponges, there were small traces of it in them.
Due to these limitations, the researchers plan to find an eco-friendlier alternative in the future.
Can these sponges really improve the pollution?
Now, we all know by now that microplastics have been a persistent issue in our environment, especially in waters.
And it’s not just the oceans which have been plagued by this problem. In fact, a study has found that plastics in some lakes are higher than in the most contaminated parts of oceans.
The researchers of this study sampled 38 lakes and reservoirs around the world. They include lakes in Australia, the United States, United Kingdom and Europe.
Additionally, they used fine plankton nets for plastic debris sampling to draw comparisons between lakes.
And well, they found both plastics and microplastics at every site, including very remote locations.
This is not-so-good-news, as many lakes right now are already suffering from other issues. We’ve now got algal blooms, deoxygenation, over-extraction and drying, and contamination adds another threat to these highly stressed ecosystems.
How did this happen?
Plastic pollution in freshwater ecosystems often happens when plastics are washed into lakes from nearby land areas. When plastics make their way into the environment, they can break down into smaller, more minuscule pieces.
These plastics then accumulate in lake water, and it can remain stagnant for a long time.
The researchers found that concentrations of plastic debris varied widely among the lakes. Approximately, 21 lakes had low concentrations, measuring below one particle per cubic meter (m³).
One of the study sites, Forest Lake in Brisbane, Australia contained three plastic particles per cubic meter. Known for recreational use, the lake ranks the sixth most contaminated among the 38 lakes.
The most heavily polluted lakes in the study were Lake Lugano, Lake Maggiore (Italy), and Lake Tahoe (United States).
According to the study, the colors of plastic particles were black (30%), transparent (24%), blue (18%), and white (13%).
They found less bright-colored particles, such as red. The researchers concluded that the more visible plastics may be mistaken by aquatic organisms as food and ingested.
Here and there, everywhere
Thanks to this lake study, we’ve become aware that plastic concentrations in freshwater ecosystems are just as bad. The researchers said that this highlights the urgent need to mitigate plastic pollution in lakes.
Because, when that happens, we can help prevent plastics from entering waterways and eventually reaching marine life.
The study also underscores that there should be more understanding of how much plastic debris enters our water supplies.
For example, up until now, we haven’t fully understood the full extent of the impact of microplastics on filter-feeding organisms. We don’t know how mussels, clams, and zooplankton adapt to the pollution.
Furthermore, there’s been considerable attention to plastic debris in marine ecosystems. But at the same time, those in lakes and reservoirs are often overlooked due to a lack of data.
Making a dent with sponges?
For what it’s worth, the researchers in the lake study expressed regret because no lake can be considered pristine now.
In the face of plastic pollution, all bodies of water now serve as a reminder of our lasting impact on nature.
Therefore, what needs to happen now is to prevent such pollution from happening in the first place.
Treating wastewater treatment plants can be a good start to do it. When we apply existing technologies like sand or activated carbon filters, that may remove plastic from water efficiently.
Current sponge-based technologies to remove pollution from water are still met with skepticism for now. As mentioned, there are still some limitations when it comes to large-scale use.
Although, employing Guoqing Wang’s sponges in smaller-scale applications like households may help making a dent, albeit not much.
Nonetheless, sponge technologies are not widely available to us yet. So what we can focus on now is prevention.