Desempenho de diferentes metodologias utilizadas para extração e quantificação de microplásticos de poliestireno em matriz de solo e sedimentos

Abstract

Microplastics (MP) are polymeric debris (<5mm) that have become ubiquitous in the environment. Different methodologies have been applied for PM extraction, however, the proposed methods have not yet been standardized. The methodologies are composed of collection, density extraction (SPD), organic matter degradation (DMO), filtration and identification. In this study, expanded polystyrene (EPS) was selected for the application of four methods commonly used in the SPD step (H2O, NaCl, NaI and ZnCl2) and four methods in the DMO step (HNO3, H2O2, KOH and K2Cr2O7). To validate the ideal methodology, samples of PM and solids were submitted to the aforementioned treatments. Initially, the treatments were evaluated individually, where the PM extraction efficiency and the morphological modifications of the polymer were verified. Subsequently, the treatments selected from the SPD step were combined with the DMO treatments. In the first phase, only the D4 treatment (K2Cr2O7) was excluded, as it altered the dimensions of the polymers and did not obtain acceptable PM extraction rates (>95%). In the second phase, twelve combinations were evaluated, and the combination of KOH + NaI provided the highest PM extraction rate (98.84%), inhibited approximately 99% of the flotation of solids present in the samples and did not degrade the polymer. On the other hand, combinations between NaI + HNO3 and ZnCl2 + KOH should be avoided, as the reaction between treatments generates by-products that reduce the extraction efficiency.