The challenge in preparing particle suspensions for aquatic microplastic research

Area of Science:

• Environmental Science
• Materials Science
• Polymer Chemistry

Background:

• Microplastics (MP) are prevalent in aquatic environments, necessitating standardized particles for research.
• Existing MP research often uses spherical particles, which may not accurately represent environmental conditions.
• Effective preparation and handling methods for microplastic particles are crucial for reliable scientific investigation.

Purpose of the Study:

• To develop and optimize methods for preparing defined microplastic particles for research.
• To investigate the behavior and dispersion of microplastic particles in aquatic media.
• To assess methods for stabilizing microplastic suspensions for toxicological studies.

Main Methods:

• Polystyrene (PS) was cryogenically milled to produce microplastic particles (1-200 µm).
• Particle yield was optimized by adjusting pre-cooling and milling durations.
• Ozone treatment was applied to stabilize microplastic suspensions and evaluate dispersion effects.

Main Results:

• Cryogenic ball milling effectively produced microplastic particles within the desired size range.
• Particle yield increased with longer pre-cooling and milling times.
• Ozone treatment reduced particle aggregation on glass surfaces but altered particle size distribution and increased dissolved organic carbon.

Conclusions:

• Cryogenic milling is a viable method for producing microplastic model particles.
• Microplastic particle behavior in water, including aggregation and dispersion, requires careful consideration.
• Ozone treatment shows potential for stabilizing microplastic suspensions but necessitates further research due to observed side effects.