Magnetic Removal of Micro- and Nanoplastics from Water-from 100nm to 100µm Debris Size.

Abstract

Clean water is one of the most important resources of the planet but human-made contamination with diverse pollutants increases continuously. Microplastics (<5mm diameter) which can have severe impacts on the environment, are present worldwide. Degradation processes lead to nanoplastics (<1µm), which are potentially even more dangerous due to their increased bioavailability. State-of-the-art wastewater treatment plants show a deficit in effectively eliminating micro- and nanoplastics (MNP) from water, particularly in the case of nanoplastics. In this work, the magnetic removal of three different MNP types across three orders of magnitude in size (100nm-100µm) is investigated systematically. Superparamagnetic iron oxide nanoparticles (SPIONs) tend to attract oppositely charged MNPs and form aggregates that can be easily collected by a magnet. It shows that especially the smallest fractions (100-300nm) can be separated in ordinary high numbers (1013 mg-1 SPION) while the highest mass is removed for MNP between 2.5 and 5µm. The universal trend for all three types of MNP can be fitted with a derived model, which can make predictions for optimizing SPIONs for specific size ranges in the future.