Arguably, everyone has heard about microplastics by now: They’re the microscopically small plastic particles to the surfaces of which toxic substances can be bound and ultimately enter the human body in that way. But plastic particles can be even smaller than that. Even less visible. Imagine a microplastic particle as a football and place it next to a pinhead. Nanoplastic particles are about 1,000 times smaller than their “big brothers,” microplastics. That’s hard to imagine and conventional purging methods (filtration, oxidation) don’t stand a chance against them. But a game changer is just around the corner, says a German team of research scientists.

Magnets collect lumps of plastics

Scientists at Friedrich-Alexander University Erlangen-Nürnberg (FAU), a cooperation partner of the Schaeffler Group in nearby Herzogenaurach, have shown how plastic particles of various materials (polyethylene, polystyrene, polyvinylchloride, Teflon, etc.) and dimensions – including nano-sized ones – can be removed from water. The principle: Like a type of glue, non-toxic, specially coated iron oxide nanoparticles called SPIONs (superparamagnetic iron oxide nanoparticles) clump together with the plastics to form larger agglomerates that can subsequently be magnetically collected very easily due to the iron oxide content. The team headed by Professor Marcus Halik refers to this bonded material as “smart rust.” A more efficient method is not currently known, according to Halik.

Our innovation is the only one that can remove nano-sized plastic particles from water

Professor Marcus Halik

The scientists’ plan is to use the SPIONS even before the plastics can pollute the oceans: in a container through which river water is conducted. It’s equipped with a metering and mixing unit, a magnetic separator, and analytics. Optimally, the system would operate directly at a water treatment plant as the final purification stage before releasing the water “into the wild.”

Alternative methods promise similar success

The principle developed by Fionn Ferreira, a student and winner of the 2019 Google Science Fair, works in similar ways. Ferreira extracted microplastics from water using a “magnetic liquid” invented by NASA. This so-called ferro fluid combines with microplastics in water. The method achieved an 87-percent success rate in 1,000 tests.

The German green-tech start-up Wasser 3.0 pursues a different strategy, where the contaminated water is mixed with non-toxic hybrid silica gels. Stirring causes the tiny particles to clump together, forming a popcorn-like entity that floats to the surface, where it can be skimmed off for further use. Initial research projects are said to have shown very good suitability as an insulation and construction material.

Facts and figures

Biodegradable plastics

Substituting the plastics that survive in nature “for eternity” is another alternative idea. US scientists have developed a plastic material that becomes biodegradable and recyclable within the space of a few months. A team at Yale decomposed wood powder, a common waste product at lumber mills, using a solvent to create a slurry of organic polymers and cellulose that was then suitable for casting as a bioplastic. Research scientists at Cambridge, on the other hand, created a plastic material from plant proteins by adding nanoparticles. In this way, the structure of the substance can be controlled for creating flexible films – a material that looks like spider silk on the molecular level.

Albeit: “There’s no major sense of suffering and pressure yet to massively combat the microplastics problem,” Professor Halik is sorry to say, “because no limits have been established for microplastics in water.” In view of the steadily growing volumes and the inestimable risks to humans if plastic particles enter the bloodstream this can be expected to change in the near future.