Computational analysis of an electrostatic separator design for removal of volatile organic compounds from indoor air

ABSTRACT

Concentrations of volatile organic compounds (VOCs) in air can be reduced in electrostatic separators where VOCs are ionized using ion-molecule reactions, extracted using electric fields, and eliminated in a waste flow. Embodiments for such separator technology have been explored in only a few studies, despite the possible advantage of purification without adsorbent filters. In one design, based on ionization of VOCs in positive polarity with hydrated protons as reactant ions, efficiencies for removal were measured as 30–40% . The results were fitted to a one-dimensional convective diffusion model requiring an unexpectedly high production rate of reactant ions to match both the model and data. A realistic rate of reactant ion production was used in finite element method simulations (COMSOL) and demonstrated that low removal efficiency could be attributed to non-uniform patterns of sample flow and to incomplete mixing of VOCs with reactant ions. In analysis of complex systems, such as this model, even limited computational modeling can outperform a pure analytical approach and bring insights into limiting factors or system bottlenecks.

Implications: In this work, we applied modern computational methods to understand the performance of an air purifier based on electrostatics and ionized volatile organic compounds (VOCs). These were described in the publication early 2000s. The model presented was one-dimensional and did not account for the effects of flow. In our multiphysics finite element models, the efficiency and operation of the filter is better explained by the patterns of flow and flow influences on ion distributions in electric fields. In general, this work helps using and applying computational modelling to understand and improve the performance bottlenecks in air purification system designs.

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethical statement

All authors declare that the manuscript has been written solely by authors and no Artificial Intelligence (AI) has been used.

Data availability statement

The COMSOL models that support the findings of this study are available from the corresponding author, upon reasonable request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/10962247.2023.2265329

Additional information

Funding

The work was supported by the European Union’s Horizon 2020 FET Open [899261].

Notes on contributors

Osmo Anttalainen

Osmo Anttalainen is a Ph.D. student at VERIFIN, University of Helsinki, specializing in chemical separation of atmospheric pressure ions. He earned M.Sc. (E.E.) from the University of Lappeenranta in 1992. He has more than 20 years of experience in instrumentation and applications of ion mobility spectrometry.

Elie Lattouf

Elie Lattouf, Ph.D., is a Physicist and former Associate Professor at the Faculty of Science, Lebanese University, and postdoctoral researcher at the University of Helsinki, and is currently joining ETH in Zürich to contribute to mid-IR spectroscopy and device benchmark in the Vocorder project.

Paula Vanninen

Paula Vanninen, Ph.D., professor, is a Director of the Finnish Institute for Verification of the Chemical Weapons Convention (VERIFIN) at the University of Helsinki. She works to support, execute and guide activities that belong to activities of VERIFIN, as well implements the strategic plan.

Hanna Hakulinen

Hanna Hakulinen, Ph.D., is the Research Director of the Finnish Institute for Verification of the Chemical Weapons Convention (VERIFN) at the University of Helsinki. She specializes on verification analysis and chemical forensics research to support the chemical weapons convention, and engages is versatile laboratory capacity building training activities.

Tapio Kotiaho

Tapio Kotiaho is a professor at the University of Helsinki.

Gary Eiceman

Gary Eiceman is Research Professor at New Mexico State University in Las Cruces, NM, where he has been on faculty since 1980. Recently, he has been a Director of Research at University Helsinki (2020-2023). His research interests include gas phase ion-molecule reactions at ambient pressure, technology for measuring the mobility of ions in electric fields, and applications with portable ion mobility spectrometers. These include the detection of explosives in aviation security, other hazardous substances in airborne vapors, and volatile organic compounds in indoor air of residential and commercial buildings and in confined places such as spacecraft. He is co-author of Ion Mobility Spectrometry which is in a third edition. He assisted in the launch of Sionex Corp in 2000 and Gas Phase Ionics, LLC, in 2021 and has been a consultant to small and large companies for chemical instrumentation.