Production of Residue-Free Nanoparticles by Atomization of Aqueous Solutions

Abstract

It has been difficult to produce physically and chemically pure nanoparticles from a particle solution in deionized (DI) water by atomization due to residue from impurities in the DI water. In this study, we show that further purification of DI water by reverse osmosis (RO) membrane filtration under high pressure (900 psi) substantially reduces solvent impurities when submicrometer and nanosized particles are atomized. Comparison of size distributions among several types of DI water showed that the production of residual particles significantly decreased by a factor of ∼11 (by number) after the RO filtration of regular DI water from commercially available DI water. Mixing states of aerosolized particles produced from particle solutions were examined by using the hygroscopicity tandem differential mobility analyzer technique and transmission electron microscopy/energy dispersive spectroscopy. We found that residual particles were externally mixed with particles of interest during the aerosolization and drying process and that impurities in DI water can beadded onto the target particles (i.e., internally mixed). By removing impurities in DI water by the RO filtration, the effect of impurities for the production of clean nanoparticles was significantly reduced, suggesting that the atomization method can still be a promising tool to produce pure nanoparticles in a simple and inexpensive way.

A spectrometer for measuring particle size distributions in the range of 3 nm to 10 μm

“…The small peak near~182 nm is caused by the doubly charged 300 nm PSL. Again, the peak near 25 nm is caused by impurities in ultrapure water used for the PSL solutions [41].…”

“…Please note that the second peak in the size distribution corresponds to 50 nm PSL, while the first peak (~18 nm) is due to impurities in the ultrapure water. This impurity peak remains even when reverse osmosis processed deionized water were used [41]. 3.2 Comparing the RSMPS and the APS Before comparing particle size distributions measured by the RSMPS and APS, the size precision of the APS was verified by measuring monodisperse PSLs with nominal diameters of 900 nm, 1 μm, 1.6 μm, 2 μm, and 2.5 μm, respectively.…”

Ultrafine Particle Generation through Atomization Technique: The Influence of the Solution

“…Amongst these, one of the most reliable, repeatable, flexible, and cheap techniques is based on the atomization of a properly prepared solution and the consequent evaporation of the solvent from the solution droplets (Liu and Lee, 1975;Park et al, 2012).…”

“…The comparison of particle number distributions and concentrations obtained through the different salts was performed using equal molar concentration of the solution; in particular, four different molar concentrations were considered for each solution: 2 × 10 -3 M, 2 × 10 -4 M, 2 × 10 -5 M, and 2 × 10 -6 M. 2 × 10 -3 M solutions were prepared by weighing the corresponding salt mass (molar mass and density data are reported in Table 1) and, then, dissolving it in deionized water, produced through the Human Power I Plus, up to final solution volume equal to 1 L. Deionized water was produced through a reverse osmosis technique in order to guarantee lower residual particle number than commercially available one (Park et al, 2012). In order to avoid errors in salts weighing, the hydrated forms were used for hygroscopic salts operation weighing.…”

Standard source of atmospheric black carbon aerosol generated from ultrasonic spray of BC suspension

“…It has a great advantage of producing high particle number concentrations, but the interference of impurities in the solvent is the main limitation of this method (Biskos et al, 2008;Tiwari et al, 2013). An aerosol generator of high stability using syringe pump to provide a constant liquid flow is introduced (Liu and Lee, 1975) and it has been developed and widely used to generate aerosols (Park et al, 2012;Stabile et al, 2013). Vibrating orifice aerosol generator (VOAG) is a kind of ultrasonic nozzle used for generating aerosols (Berglund and Liu, 1973).…”