AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Nanometer-rated Liquid Filter Evaluation using the TSI Nanoparticle Nebulizer
TSZ YAN LING, Axel Zerrath, David Pui, University of Minnesota
Abstract Number: 338 Working Group: Control Technology
Abstract State-of-the-art liquid particle counters have a detection limit of about 50 nm. This causes challenges in experimental evaluation of nanometer-rated liquid filters, which are used in industries requiring high-purity water and chemicals. It is commonly agreed that air-borne nanoparticle generation, classification and detection methods are more sensitive compared to the liquid-borne nanoparticle counterparts. Therefore, by properly dispersing the liquid-borne nanoparticles into air-borne form and having them measured by appropriate aerosol instruments, namely the Scanning Mobility Particle Sizer (SMPS), the sensitivity of the current liquid-borne nanoparticle characterization methods can be greatly enhanced. A major concern of using a conventional atomizer as a nanoparticle dispersion tool is the interference of residue particles, which are particles that are dried from droplets containing no solid particles. It is necessary that residue particles are controlled to be as small as possible to avoid them from overlapping with the solid particles as shown in a size distribution measurement.
TSI Inc. has newly developed the Nanoparticle Nebulizer, which can nebulize much smaller droplets compared to conventional atomizers, and therefore the residue problem encountered can be avoided. In this study, we applied the Nanoparticle Nebulizer to study the performance of nanometer-rated liquid filters using the aerosolization technique. Gold and PSL particles of sizes 80, 50 and 30 nm were used to challenge the filters. Hydrosols upstream and downstream of the filters were collected and the nanoparticle concentrations were measured using the Nanoparticle Nebulizer/SMPS system. Efficiency of the liquid filters as a function of particle size was obtained and compared with measurements made with another hydrosol analyzer, the Nanoparticle Tracking Analyzer. Both methods show results comparable with each other.