Characterization of ship paint-derived microplastics by Fourier transform infrared spectroscopy (FTIR), energy...

This study presents a comprehensive characterization of ship paint-derived microplastics by integrating Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), and density analysis. FTIR identified characteristic absorption peaks in the fingerprint region (1500-600 cm⁻¹) across six paint types: acrylate, rosin, polydimethylsiloxane, epoxy, urethane, and alkyd. While four paint types showed high spectral match with their original polymers, acrylate- and rosin-based types, exhibited significant spectral similarity with alkyd- and urethane-based polymers, suggesting potential misclassification when relying solely on spectral libraries. EDS revealed the presence of elements including C, O, Mg, Si, S, Cl, Ca, Ti, Fe, Cu, Zn, and Ba in varying proportions, reflecting the compositions of pigments and biocidal additives. Density of the particles ranged from 1.177 to 2.615 g/cm³ , with high-density antifouling particles exceeding conventional microplastic separation thresholds (∼1.6 g/cm³), thereby increasing the likelihood of their underestimation in environmental monitoring. The combined use of FTIR spectral interpretation, elemental analysis, and density profiling offers a robust approach for distinguishing paint-microplastics from other microplastic types and provides critical reference data for improved identification and quantification. These findings underscore the need to refine current analytical methods to more accurately evaluate the contribution of paint particles to marine microplastic pollution.