Can bubble columns be an alternative to fibrous filters for nanoparticles collection?

• Published in: Journal of hazardous materials 2011-11, Vol.195, p.432-439
• Main Authors: Charvet, A., Bardin-Monnier, N., Thomas, D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Bubble column; Bubble columns; Bubbling; Chemical and Process Engineering; Chemical engineering; cleaning; Collection; Diffusion; Electrostatics; Engineering Sciences; Exact sciences and technology; filters; Filters (fluid); Hydrodynamics of contact apparatus; Media; Nanoparticles; particle size; Pollution; Pressure drop
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.08.064

► Bubble columns as an alternative to fibrous filters for nanoparticles collection. ► Efficiency improvement for low bubbling orifice diameters and high liquid height. ► Presence of a most penetrating particle size between 10 and 30 nm. ► Efficiency increase for charged particles. ► Good agreement between modelling and experimental data in the diffusional regime. The most effective and widely used dedusting techniques to separate nanoparticles of a carrier fluid are fibrous media. The main problem is the clogging of the filter that induces a pressure drop increase over time and thus requires a regular cleaning of the media (or its replacement). Following these observations, this study proposes to investigate the potential of bubble columns for nanoparticles collection. Despite collection efficiencies lower than those of fibrous filters, experimental results show that bubble columns present likely performances for the collection of nanoparticles and have collection efficiency even more important when the liquid height is high and bubbling orifices have low diameters. Experiments have also revealed the presence of a most penetrating particle size for a particle diameter range between 10 and 30 nm. The model developed in this article highlights a good agreement between the theoretical collection efficiency by Brownian diffusion and experimental collection efficiencies for particles lower than 20 nm. Nevertheless, the modelling may be extended to other collection mechanisms in order to explain the collection efficiency increase for particles higher than 20 nm and to confirm or infirm that electrostatic effects can be the cause of this efficiency increase.