Adsorption of silver on virgin and aged microplastics

When microplastics enter aquatic ecosystems they are submitted to environmental aging which change their properties. Especially colonization by microorganisms alter their properties in term of density and adsorption properties. Hence the aim of the study was to evaluate the adsorption and leaching properties of virgin and aged microplastics. Silver (in form of silver nitrate) was selected as a model metal used for adsorption study. Results showed that silver is quickly adsorbed on both types of microplastics while aged microplastics adsorbed significantly more silver than virgin ones. However, also leaching of silver from aged particles proceeds much faster - after 48 hours in Steinberg medium (pH = 5.8), only 23.7% of silver was leached out from virgin microplastics in comparison to 45.6% leached out from aged microplastics. In OECD medium (pH = 7.3) leaching was minimal. Our results showed that aging of microplastics and development of biofilm can significantly alter their properties and thus it is necessary to enhance our knowledge about microplastics’ aging in the aquatic environment, which is still far from well-understood.