Capturing colloidal nano- and microplastics with plant-based nanocellulose networks

Nanoplastic particles in aqueous environments are challenging to quantify and characterize due to a lack of methods to capture and analyze them. Here the authors demonstrate that nanocellulose networks can be used to capture colloidal plastics and quantify them through their fluorescence and adsorption, providing kinetic information on their uptake. Microplastics accumulate in various aquatic organisms causing serious health issues, and have raised concerns about human health by entering our food chain. The recovery techniques for the most challenging colloidal fraction are limited, even for analytical purposes. Here we show how a hygroscopic nanocellulose network acts as an ideal capturing material even for the tiniest nanoplastic particles. We reveal that the entrapment of particles from aqueous environment is primarily a result of the network's hygroscopic nature - a feature which is further intensified with the high surface area of nanocellulose. We broaden the understanding of the mechanism for particle capture by investigating the influence of pH and ionic strength on the adsorption behaviour. We determine the nanoplastic binding mechanisms using surface sensitive methods, and interpret the results with the random sequential adsorption (RSA) model. These findings hold potential for the explicit quantification of the colloidal nano- and microplastics from different aqueous environments, and eventually, provide solutions to collect them directly on-site where they are produced.

Automated summary

This study demonstrates that nanocellulose networks can be used to capture and quantify colloidal plastics in aqueous environments, providing kinetic information on their uptake. The findings contribute to understanding the mechanism of particle capture and offer possibilities for quantifying nano- and microplastics in different water environments.