Green production of bioinspired reusable PP fluff for true-to-life microplastics removal from water

Abstract

Microplastic pollution is one of the most discussed environmental concerns. However, predicting the real behaviour of microplastics and producing environmentally friendly systems for their removal is still challenging. To address this, we propose an innovative and solvent-free method for producing reusable 3D fibrous fluff, specifically designed to remove microplastics from water. Fluff morphology is bioinspired by the natural structure of Posidonia Oceanica Egagropiles, since they are able to trap microplastics from water. Polypropylene (PP) PP fluff has been produced by combining a melt spinning process and a vortex motion field generated in distilled water. True-to-life microplastics were obtained by subjecting PP pasta bags to accelerated weathering and mechanical fragmentation. This protocol enables the generation of microplastics with properties that closely resemble real-world microplastics, in terms of chemical and physical characteristics. To better understand their settling behaviour in water and, therefore, to facilitate their removal, fluidodynamic modeling have been adopted, considering the real properties of the particles before and after photo-oxidation. The proposed PP fluff was finally used to filter the true-to-life microplastics, undergoing up to 10 cycles of use with almost unaltered performance. It ensured high removal efficiency, especially for larger particles, while a detailed analysis of smaller particles fraction was performed, by comparing ponderal and numerical removal efficiency.