Analysis of the capture of microplastics with hydrophobic metallic particles

One of the main environmental problems is related to the generation of micro- and nanoplastics. This study aims to analyze the viability of an innovative method consisting of the adsorption of microplastics using hydrophobic metal particles, which require their functionalization. A laboratory protocol (of the adsorption process) and analysis (of the particles and the adsorption efficiency) were designed. For the production of the metal particles (of micrometric size), the ball milling technique was used. Also, milling equipment operating with liquid nitrogen was used to generate the microplastics. For morphological characterization, electron microscopy was used; for structural X-ray diffraction to analyze the composition, X-ray dispersion spectroscopy was used; and to monitor the functionalization, Fourier transform infrared spectroscopy was used. The functionalization was carried out in a 1M solution of lauric acid. The metallic particles are nanocrystalline (crystallite size range of 12-44 nm) and the crystallographic phase is the bcc-Fe. It was found that the adsorption of microplastics is more efficient when the size of the metal particles is smaller. The correct functionalization of the metal particles prevents their oxidation in aqueous media. Regarding the efficiency in the capture of microplastics, the highest value found is close to 90%, depending on the metallic particle production conditions. Additional studies are needed to optimize the efficiency of microplastic capture, probably by increasing the surface/volume ratio of metal particles.