Detection and quantification of biodegradable nano and microplastics in biowaste compost | Détection et quantification des nano et microplastiques biodégradables dans les composés de déchets biologiques

International audience

Inglés. With the mandatory separation of bio-waste at source compostable packaging could be treated in industrial composting stations be get out of their waste status and be converted in a valuable product, a compost used as soil fertilizer. However, compost can be considered as a potential source of soil contamination with nano and microplastics. To date, there is no standardized method for detecting and quantifying nano and microplastics in compost. The objective is to develop an efficient and non- destructive extraction protocol to identify and quantify biodegradable and conventional nano and microplastics present in compost by FTIR and Raman microspectroscopies, and thermal analysis (Pyr‐ GC-MS).The micro and nanoplastics were first extracted from the inorganic compounds present in the Compost complex matrix using the density difference using CaCl2 (d=1.4). The organic compounds present in the compost were eliminated by oxidative digestion using hydrogen peroxide H2O2 at 30%. Depending on their chemical fingerprint and after optimization microplastics were identified and quantified by number and mass (estimation by calculation using area, volume and density) by FTIR microspectroscopy and nanoplastics by Raman microspectroscopy. Pyr-GC-MS was used to quantify the polymer type in plastic.A method to extract microplastics from compost was optimized and validated with a recovery rate greater than 92% which proves extraction efficiency without significantly affecting the physical and chemical integrity of microplastics. Biodegradable nano and microplastics were analyzed well identified from a compost sample with a correlation coefficient at least greater than 70% compared to the internal library containing reference spectra of known materials and the analysis time is relatively short (4 hours per sample for FTIR) similar to that found by other authors and much longer for Raman.In this study, for the first time, a simple and efficient method for extracting biodegradable microplastics from compost was optimized and validated. Comparison of several analytical approaches using IR and Raman micro spectroscopy and thermal analysis was also proposed for identification and quantification.