Plastic waste in the form of nano and microparticles has been detected in recent years in practically every corner of the planet, from the most remote natural spaces to commonly used substances such as drinking water; including organs and fluids in the human body.
In the case of water for human consumption, recent research shows the presence of nano- and microplastics (NMP) in both bottled water and tap water. Improving filtration systems can reduce this potential risk, but so far no solution has been implemented that can be considered fully effective.
A scientific team led by researchers from Guangzhou Medical University (China) and the Center for Environmental Studies on Microplastics at Jinan University (China) now presents a remedy that its authors consider “simple and effective”, as summarized in the article. presentation of results published (February 28) in the journal Environmental Science
“While many creative strategies have been tried to get rid of these pieces of plastic, an unexpectedly effective solution for cleaning drinking water, specifically, could be as simple as making a cup of tea or coffee,” states the information note published by the ACS in the Eurekalert scientific news service.
The Chinese experts point out in their study that their proposal “could help eliminate almost 90% of the nanoplastics and microplastics present in tap water”, although they point out that these results would be applicable in supplies with hard (calcareous) water, that is, , waters with a hardness (salt content) greater than 120 mg/L CaCO₃.
The contamination of water supplies with nano- and microplastics (particles between a thousandth of a millimeter and 5 millimeters) is spreading and, although their effects on human health have not yet been determined, there are indications that their ingestion could affect negatively, for example, to the intestinal microbiome.
Some advanced drinking water filtration systems capture NMP, but simple and inexpensive methods are needed to substantially help reduce human consumption of plastic, says the team led by Zhanjun Li, Eddy Zeng, author of the new study.
The researchers collected tap water samples from Guangzhou, China, with salt contents that place them in the hard water group, and added them with different amounts of NMP. The samples were boiled for five minutes and allowed to cool. The team then measured the free-floating plastic content.
The authors explain that boiling hard water, which is rich in minerals, naturally forms a calcareous substance known as lime or calcium carbonate (CaCO₃). The results of these experiments indicated that as the water temperature increased, CaCO₃ formed foulants or crystalline structures that encapsulated the plastic particles.
Eddy Zeng details that over time, these encrustants would accumulate like typical lime, at which point they could be eliminated to drag plastic waste with it. This expert, a professor at Jinan University’s School of Environment, suggests that any remaining foulant floating in the water could be removed by pouring it through a simple filter, such as a coffee filter.
In tests, the encapsulation effect was more pronounced in harder water: in a sample containing 300 milligrams of CaCO₃ per liter of water, up to 90% of free-floating NMP particles were removed after boiling. However, even in soft water samples (less than 60 milligrams of CaCO₃ per liter), boiling still removed about 25% of the NMPs. The researchers say this work could provide a simple but effective method to reduce NMP intake although it is not clear that its large-scale application is as simple as their explanations seem to indicate.