Collection of nanoparticles by electrostatic precipitation operating over a wide range of electric fields

ABSTRACT

In the electrostatic precipitation of microparticles, it is common to evaluate the voltages between the corona onset voltage and the breakdown point. However, the charging of particles in the nanoscale size range mainly occurs by diffusion, suggesting the possibility of its occurrence, even at low values. This paper investigates the implications of a wide range of electric fields applied in the collection of nanoparticles (6.15–241.4 nm). Two electrostatic precipitators (P.I. and P.II.), both with plates 10 cm high and 30 cm long, but with different plate spacings (4 and 6.5 cm), were tested using three air velocities (1.9, 2.9, and 3.9 cm/s) and 36 electric fields (0.0 − 5.0 kV/cm). Under the highest electric fields, both precipitators showed efficiencies above 99.9%. Furthermore, nanoparticles were collected before the corona onset voltage, with efficiencies of around 28% (P.I.) and 35% (P.II.). Even though no current was detected by the high voltage source, charges on the particles were measured in electric fields lower than 3.0 kV/cm. The higher the applied voltage, the higher the residual charge of the particles at the precipitator outlet. It is expected that the findings of this work should contribute to the technological development of electrostatic processes for air treatment.

KEYWORDS:

• Electrostatic precipitation
• nanoparticles
• air pollution
• low voltage
• collection efficiency

Acknowledgments

This research was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico – Brazil (CNPq, grant 132752/2019-0) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil (CAPES, Finance Code 001). The authors would also like to thank the Environmental Control Laboratory of the Federal University of São Carlos (LCA-UFSCar) for support of this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Contributions

All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Felipe de Aquino Lima and Vádila Giovana Guerra. The first draft of the manuscript was written by Felipe de Aquino Lima. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Additional information

Funding

The work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico [132752/2019-0]; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [Finance Code 001].