Physical & Chemical Characterization of Nanoplastic Aerosol

Nanoplastics in aerosolized state are of increasing concern both in health and environmental aspects. At such small sizes the high specific surface area increasingly gains importance for sorption processes of organic pollutants and toxic heavy metals. The submicron size range features increased Brownian motion which reflects in long range atmospheric transport and deposition of nanoplastics in remote regions. Extended atmospheric life time may well lead to cloud processing of nanoplastic aerosol. However, knowledge of phase transition processes on nanoplastics is largely lacking and detection of plastic particles between few nm and 100 nm is merely impossible with existing technology. The underlying hypothesis of this project is the efficient production of nanoplastic particles at high concentration from gas-to-particle conversion. Macroplastics under thermal stress have been shown to produce nanoparticles likely orders of magnitude more efficient than mechanical breakdown from larger plastic entities. We therefore aim at process level studies under defined laboratory conditions to chemically and physically characterize nanoplastic particles. Both, chemical and physical characterization experiments will involve a stable source of nanoplastic aerosol where specific types of macroplastics will be exposed to elevated temperatures in a tube furnace. The resulting particles will then be size selected by electrical mobility analysis and passed into the corresponding analyzers. For the chemical characterization experiments we will employ an atmospheric pressure interface time-of-flight mass spectrometer (MS) covering both polarities simultaneously. The MS will be equipped with a new inlet to allow for thermal decomposition of particles and subsequent ionization. Besides sizing of nanoplastic particles physical characterization experiments will focus on the heterogeneous nucleation of vapors with varying polarity. Corresponding experiments will be performed in an expansion type size analyzing nuclei counter (SANC) providing quantitative measurements of particle number concentration as a function of saturation ratio. The flexibility of SANC with respect to working fluid will be complemented by an extended range of nucleation temperatures providing an additional means of in-depth analysis of heterogeneous nucleation. Thorough characterization of particles formed from macroplastics under thermal stress offers tremendous application potential for indoor air quality assessment. Innovation potential is further given by estimating the influence of nanoplastic particles on cloud formation and potential use of condensation methods for their detection. Project work will be distributed in a team of researchers involving primarily the PI Dr. Paul Winkler, an experienced researcher on postdoc level (Dr. Peter Wlasits) and an early stage researcher.