Specialised magnetic powder could remove microplastics from drinking water: Study

Durban: Microplastics are the crumbs of our plastic world, tiny pieces that come from bigger items breaking apart or from products like synthetic clothing and packaging.

They’re now everywhere. Scientists estimate there are about 51 trillion of these particles floating in the world’s surface waters, and low levels have even been found in South African tap water.

That’s worrying because these particles can carry chemicals and bad bacteria, get eaten by fish and other wildlife, and may end up in our bodies.

We’re water scientists who are looking for ways to solve this problem. In a recent study, we tested a practical fix: two “magnetic cleaning powders” that can attach onto microplastics in water; the combined clumps can then be pulled out using a magnet.

These materials are called magnetic nanocomposites (think: very fine powders with special surfaces).

The idea is simple: mix a small dose of powder into the water, let it attract and attach to microplastics, and then use a strong magnet to remove the powder-plastic clusters, leaving cleaner water behind.

Around the world, researchers have tried many different methods to capture microplastics, but our study is among the first to show that magnetic nanocomposites can work effectively not only under laboratory conditions but also in real-world samples, including municipal wastewater and drinking water.

This is the first study to use these specific nanomaterials for microplastic removal, proving both their high efficiency and their practical potential. Most existing filters struggle to catch the smallest plastics, the ones most harmful to health and the environment. The next step is to test these powders on a larger scale and develop simple, affordable systems that households and water treatment plants can use.

In our research we found that the powders were able to remove up to 96 per cent of small polyethylene and 92 per cent of polystyrene particles from purified water.

When we tried the same approach in both drinking water and water coming out of a municipal wastewater treatment plant, the results were just as strong.

In drinking water the removal was about 94 per cent and in treated wastewater the removal was up to 92 per cent.

Another finding from this study is that the size of the plastic particles matters. The smaller the microplastic, the easier it is for the powders to attach to it, because tiny particles can reach more of the powder’s special

“sticky” surface.