Introduction: Plastic, predominantly derived from fossil fuels, is an essential material that degrades into microplastic particles under various environmental conditions, including radiation and microbial activity. These microplastics and plastic additives present risks to the environment, plants, animals, and humans. Consequently, alternative biodegradable plastics have been introduced to the market. Under certain conditions, biodegradable plastics break down into carbon dioxide, water, and biomass. Purpose of the research was: To optimize the extraction method for biodegradable microplastics from agricultural soil, apply this method to real samples, and determine differences in the spectra of plastic mulches of different chronological ages using an FTIR spectrometer. Methods: After sampling, the samples were prepared for laboratory extraction of microplastics by sieving, crushing, and separating larger plastic particles. Microplastic particles were separated based on density separation method using saturated solution of zinc chloride. Following extraction, artificially aged plastic film, naturally aged plastic film, and unused plastic film were analyzed with an FTIR spectrometer. Results and Discussion: The highest average mass of microplastic particles was extracted from samples where the foil contained cellulose and additives, followed by samples with PBAT, PLA, and additives, samples with TPS and additives, and the lowest from samples with polyethylene foil. In the FTIR analysis of different chronological types of plastic foil, we observed the stretching of C=O and O-H functional groups, which are characteristic of the degradation process of plastic materials. Conclusion: With the optimized density-based separation method, we can successfully extract biodegradable microplastics from real soil samples and compare the degradation processes of various commercial foils used in agriculture.
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