Pomelo peel-graphene aerogel/filter membrane with confocal Raman spectroscopy for rapid separation and identification of microplastics

Microplastics (MPs) are ubiquitously distributed and pose a potential threat to marine ecosystems and human health. Although the lipophilicity of MPs permits efficient separation and enrichment via oil extraction, residual oil adhering to the MPs can interfere with their identification. To resolve this issue, a new strategy that an aerogel-filter membrane composite integrates with Raman spectroscopy was developed for the rapid separation and accurate identification of MPs. The aerogel-filter membrane composites were fabricated by combining pomelo peel-graphene aerogel (PGA) with filter membranes: polyethersulfone (1 and 3 μm PES), polytetrafluoroethylene (0.22, 2, and 3 μm PTFE), polyvinylidene difluoride (1 and 3 μm PVDF), and stainless steel mesh (2 and 3 μm SSM). Using tributyl phosphate as the oil extractant, results show that PGA@2 μm PTFE demonstrates the highest MPs recovery efficiency, with average rates of 90.81 ± 2.83 % for single-type MPs and 90.57 ± 5.42 % for mixed MPs. These results confirm that PGA@2 μm PTFE is an ideal composite for the separation and detection of MPs. After 20 cycles, PGA@2 μm PTFE maintains a high MPs recovery rate of 89.76 ± 4.31 %, demonstrating its excellent reusability. The proposed method was also successfully deployed for analysis of MPs in seawater, marine sediment, and beach sand. Moreover, this work provides a novel method for precisely assessing MPs in the marine environment.