Scientists are just beginning to understand the range of these tiny particles and their effects on organisms from marine life to humans, and are acknowledging that microplastics pose an ever-increasing threat to ecosystems and health. It’s not debatable. A 2019 study revealed that we ingest about 5 grams of microplastics, the weight of a credit card, each week.
However, the current challenge is to find ways to successfully remove microplastics (MPs) from water and air. When these tiny pieces of plastic are just 1 micrometer to 5 millimeters in size, it’s no easy task.
To achieve that, a team of scientists from Shinshu University turned to sound, experimenting with acoustic filtering to push MPs into the central channel and a water-filled branch section without MPs.
“Our proposed microfluidic device is designed on the basis of a hydroelectric analogy, with three 1.5 mm wide microchannels connected via four continuous 0.7 mm wide trigeminal junctions. “Shinshu University, Faculty of Textile Science, Department of Robotics. “MPs are centered in the central microchannel using a bulk acoustic wave with a resonant frequency of 500 kHz. As a result, a 3.2-fold enrichment of MPs must occur at each junction and the gives a 105-fold enrichment at
In other words, ultrasound travels through the water, pushing MPs into the center of the fluid flow and collecting or filtering MPs as MP-free water is filtered into branches away from the main central pathway of the device. can. Traditionally, MPs were collected by mesh filters, which were prone to clogging and the size of the mesh limited what could be collected.
This device uses microfluidic technology instead. This is the new science of manipulating water behavior in micro-level channels. When individual experiments were performed with grouped MPs, recoveries for MPs of sizes 10 µm, 15 µm, 25 µm, 50 µm and 200 µm were greater than 90%. Further testing with mixed particle sizes (25-200 μm and 10-25 μm) showed recoveries of approximately 80%.
This is not the first acoustic filtering model developed by scientists, but a device previously built and tested for laundry wastewater. The team believes the progress so far indicates that the device has even broader applications, such as filtering wastewater from industrial-scale production before it is sent to sewers.
“This proposed microfluidic device based on acoustic focusing can efficiently, rapidly, and continuously collect 10–200 μm MPs without recirculation after prefiltration of larger MPs through a mesh.” says Akiyama. “It can be installed in washing machines, factories and other sources of MPs to efficiently concentrate and remove MPs of various sizes from laundry and industrial wastewater. will be possible.”
The device had issues, such as some MPs slowing down and clogging the walls of the microchannels, which the researchers solved by fine-tuning the prefiltration process and 2D focusing. I think we can.
The study was published in a journal Separation and purification technology.
Source: Shinshu University
