A Resilient In Situ Raman-Based Framework for Identifying Thermally Aged Microplastics: Validation in Waste-to-Energy...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Waste-to-energy (WtE) incineration is a growing source of environmental microplastics (MPs).
• Identifying MPs from incineration is difficult due to high-temperature alterations affecting spectral data.
• Existing reference libraries are inadequate for classifying thermally aged MPs.

Purpose of the Study:

• To develop a reliable method for identifying microplastics from WtE incineration.
• To create a spectral library for thermally aged MPs.
• To assess the contribution of WtE to atmospheric MP pollution.

Main Methods:

• Utilized in situ Raman spectroscopy to analyze real-time spectral changes in plastics during thermal transformation.
• Established a comprehensive spectral library for aged MPs.
• Developed an open-access identification framework incorporating the concept of "MP derivatives".

Main Results:

• The new identification scheme significantly improved spectral matching (47% to 91%) and reduced unassigned spectra (by 76%).
• Over 89% of MPs in flue gas samples showed signatures of thermal transformation, primarily from polypropylene.
• An industrial WtE incinerator was estimated to emit 3.7 × 10¹² atmospheric MPs annually.

Conclusions:

• The study provides a robust framework for identifying aged MPs from incineration.
• WtE incineration is a significant source of atmospheric MPs, posing potential environmental and health risks.
• Addressing microplastic pollution from incineration is crucial.