Binary solvent extraction of microplastics from a complex environmental matrix

Abstract

Separating microplastics (MPs) (smaller particle size, < 1 mm) from complex environmental samples such as particulate organic matter (POM) is challenging, particularly for polyethylene and polypropylene, which are buoyant like POM. It is often done using a time-consuming procedure, often with hazardous waste generation. We developed a simple, low-cost procedure using a binary solvent mixture (ethanol–water) followed by water solvation to separate MPs from estuarine POM and surface water. The isolated MPs were quantified and characterized using μFT-IR and scanning electron microscopy, with particle sizes ranging from 30 to 2500 μm and percentage mass from 2.62–21.3% wt/wt in POM and 0.04–0.42% wt/vol for surface water, respectively. Different polymer types, colors, and shapes were observed. Method recovery assessed using spiking yielded 89–93.1% and the method was validated by visual sorting with dye staining. This method is low-cost, simple, and aligns with Green Chemistry approaches while efficiently separating plastics of various particle sizes, shapes, and compositions. Furthermore, this low-cost approach and the near-universal availability of ethanol make this method more accessible in research and education throughout regions of the world where plastic debris is a major challenge but resources to study the problem are limited.