Rapid, In Situ and Non-Destructive Analysis for the Evaluation of Microplastics Degradation in Water Via Haze Measurement

The presence of microplastics (MPs) in water represents a current problem for marine life and a future serious issue for human health. This is pushing towards new approaches for the removal of MPs and, hence, their characterization and evaluation, which up to now has represented a limit for tentative procedures for their degradation. Herein, we reported on a new facile, in situ and non-destructive approach for the qualitative analysis of polystyrene and polymethylmethacrylate MPs in water and their evaluation in photocatalytic degradation with the use of Co₃O₄@Co(OH)₂ heterostructures. The use of haze measurements allows to see the changes in light scattering of the MPs aqueous dispersions during the photocatalytic degradation and to know in situ the degradation of the MPs in the catalytic process. Significant changes in haze values were found in photocatalysis with Co₃O₄@Co(OH)₂, in contrast to no variations in control test using Co(OH)₂ and Co₃O₄. Synchrotron-radiation based scanning transmission x-ray spectroscopy further denotes strong interactions between the heterostructures with MPs and oxidization of the latter. The possible comparison of different techniques suggests that haze measurements could be a valid and cost-efficient methodology for the future evaluation of photocatalytic degradation of MPs in water.