Evaluation of Electrostatic Separation of Microplastics From Mineral-Rich Environmental Samples

Reliable, easy, cost-effective and reproducible ways of extracting microplastics (MP) from environmental samples remains an important requirement for MP research. In this context, electrostatic separation is a new proposition, especially for extracting MP from mineral-rich samples and large sample volumes. However, there is little research evaluating the reliability of the technique. This study has evaluated the effectiveness of the Korona-Walzen-Scheider (KWS) system; a small-scale version of larger machines designed to sort recycling materials. Recovery rates of a variety of sizes of MP, spiked in beach sediments, were found to be highly dependent on the MP size. MP ≥ 2 mm achieved 99 - 100% recovery (with the exception of fibres: ~80%), MP of 63 – 450 µm achieved ~60 – 95% recovery and MP of 20 µm achieved ~ 45% recovery. For particle-based analysis, additional density separation is still inevitable for the analysis of small MP after KWS separation and further reduces the overall recovery rates. Mass reduction rates of beach and commercial reference sand greatly differed, 93% and 17%, respectively. Mineral analysis using SEM-EDX suggested that lower reduction rates found in commercial sand was due to high presence of small ( 450 µm, electrostatic separation is a reliable and fast approach for MP extraction from the environment.