Mathematical modeling of monodisperse nanoparticle production in aerosols using separation in an electric field

The wide range of applications of particulate materials in the modern industry, as well as growing concerns about their potential risks to human health and the environment, has boosted studies related to the production, control, and classification of nanoparticles. Differential mobility analyzers (DMAs) are one of the main technologies used to characterize the size distribution of nanoparticles in aerosols. However, the high price and complexity of this equipment have been limiting factors for its use. Thus, the purpose of this study was to evaluate the performance of a Long-DMA, designed and built with its own technology and to propose and solve an inverse problem to determine the monodisperse aerosol concentration distribution. The polydisperse aerosols were generated by atomization of NaCl solutions with 0.1, 0.5, and 1.0 g L−1 concentrations. In order to estimate the theoretical nanoparticle size distributions of monodisperse aerosols, a new mobility balance was proposed. This was based on the Wiedensohler charge distribution associated with a loss parameter, obtained considering a formulation and solution of an optimization problem by using the differential evolution algorithm. The Long-DMA was able to produce monodisperse aerosols for all the saline concentrations evaluated, showing evidence of its potential for classifying nanoparticles. Comparisons between the experimental and theoretical results showed that the proposed mobility balance was able to satisfactorily describe the distributions related to monodisperse aerosols. The proposed methodology was able to estimate the monodisperse aerosol distribution in intermediate solution concentration using only the data about the highest and lowest concentrations. It is worth mentioning that the cost of the designed equipment was approximately 10% of the commercial equipment value.