A rapid staged protocol for efficient recovery of microplastics from soil and sediment matrices based on hydrophobic separation

Microplastics (MPs) in soil and sediment (SS) matrices are emerging pollution hazards to ecosystems and humans. To mitigate MP pollution, suitable extractors and associated extracting solutions are required to efficiently separate MPs from SS matrices. In this study, we introduced a four-stage microplastic extractor (ME) device and investigated the fractional separation efficiencies of three extracting solutions (ultrapure water, saturated NaCl, and corn oil-in-NaCl) plus aeration, magnetic stirring, and electric stirring for three kinds of SS matrices (loam soil, sandy sediment, and muddy sediment) with four types of virgin MP pellets (acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polypropylene, and polystyrene). In addition, fragments of these four types of post-consumer MPs were also tested by the ME device. The mean recovery efficiencies of these MPs in the three SS matrices were 88.3 %-100 %. Oil-in-NaCl further improved the recovery efficiencies for the denser ABS and PC up to 40 % based on NaCl extraction.

Automated summary

Microplastics in soil and sediment matrices pose a pollution hazard to ecosystems and humans. In this study, a four-stage microplastic extractor device was introduced to efficiently separate microplastics from soil and sediment. The fractional separation efficiencies of three extracting solutions and different stirring methods were tested for different types of soil and sediment matrices and virgin microplastic pellets. The results showed that the oil-in-NaCl solution improved the recovery efficiency for denser microplastics.