Scientists have created biodegradable sponges capable of removing up to 90 percent of microplastics from tap water and seawater.
Beijing, China, October 11, 2023: Sponges, a household item used for cleaning and various other purposes, have found an extraordinary new application. Researchers in China have introduced a synthetic sponge that excels at removing microscopic plastic debris, including microplastics and even smaller nanoplastics. These tiny plastic particles, which pose a significant threat to the environment, can become trapped within the sponge’s numerous pores.
The effectiveness of these plastic-absorbing sponges varies depending on factors such as the plastic concentration, liquid acidity, and saltiness. In ideal conditions, these sponges can eliminate as much as 90 percent of microplastics. The researchers conducted tests using various liquids, including tap water, seawater, and even soup from a local takeout spot.
These innovative sponges are primarily composed of starch and gelatin, making them biodegradable. Their lightweight and low cost make them an appealing solution for various applications. Their internal structure, characterized by numerous small pores, enables them to capture tiny particles effectively.
Guoqing Wang, a materials chemist at Ocean University of China, mentions that the sponge’s formula can be adjusted by modifying the temperature when mixing the two compounds. This adjustability impacts the size of the particles collected, with highly porous sponges being ideal for capturing very small particles.
The potential applications of these sponges are broad. They could be used in wastewater treatment plants to filter microplastics from the water or in food production facilities to decontaminate water. Another intriguing application is in washing machines, where they could capture microplastics shed by synthetic fabrics during washing.
These sponges operate through a combination of mechanisms. When water is actively driven through them, microplastic particles get trapped in the sponge’s pores. Even in still water, electrostatic interactions cause some plastic particles to cling to the sponge.
However, there are challenges to the widespread adoption of these sponges. Starch and gelatin, key ingredients in their composition, are important in the food industry, potentially leading to competition for these resources. Nevertheless, similar sponges can be crafted using alternative materials, like chitosan, which is derived from crustacean shells.
Chitosan, starch, and gelatin are all biodegradable, but the process to make these sponges currently involves using formaldehyde, a toxic compound. Efforts are underway to develop an environmentally friendly alternative.
Addressing microplastic pollution in the ocean remains a significant challenge, and one of the key approaches is to prevent microplastics from entering waterways in the first place. This involves targeting wastewater treatment plants that lack technologies to remove plastic effectively.
While there is a need for further proof of the cost-effectiveness and scalability of sponge-based technologies, they hold promise for smaller-scale applications, such as removing microplastics from household water supplies.
Alice Horton, a scientist at the United Kingdom’s National Oceanography Center, emphasizes that prevention is vital in the fight against microplastic pollution, as large-scale removal efforts once these particles reach the ocean are likely to be insufficient.