A method for extracting soil microplastics through circulation of sodium bromide solutions

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastics (MP) are increasingly detected in soil environments.
• High concentrations of MP may pose ecological risks.
• Efficient methods for soil MP extraction and analysis are crucial.

Purpose of the Study:

• To develop and validate a novel method for extracting microplastics from soil.
• To evaluate the efficiency of sodium bromide (NaBr) solution circulation for MP separation.
• To assess the impact of the extraction method on microplastic integrity.

Main Methods:

• Development of a device for circular extraction of soil MP, including separation, vacuum filtration, and solution recovery.
• Testing of NaBr, NaCl, and CaCl2 solutions for MP separation efficiency across various polymer types, sizes, and shapes.
• Analysis of extracted MP using hydrogen peroxide (H2O2) treatment and micro-Fourier transform infrared spectroscopy (micro-FTIR).

Main Results:

• Sodium bromide (NaBr) solution demonstrated the highest microplastic recovery rates, ranging from 85% to 100%.
• The developed extraction method did not significantly alter the integrity of microplastics.
• Analysis of Shanghai soils revealed microplastic abundances between 136.6-256.7 items kg-1, with Polypropylene (PP) and Polyethylene (PE) being the most prevalent.

Conclusions:

• The proposed NaBr solution circulation method offers an efficient and reliable alternative for soil microplastic extraction.
• This method is suitable for analyzing microplastic contamination in diverse soil types.
• The findings contribute to a better understanding of microplastic pollution in terrestrial ecosystems.