Avaliação do desempenho de um analisador eletrostático de baixo custo para classificação de tamanhos de nanopartículas

Abstract

There is a lot of speak about nanotechnology, and this science has a range of applications, such as electronics, pharmaceutical, air filters, among others, besides its importance when if comes to environmental issues. For production and quality control of nanometer-sized particles, there is the Nano-DMA (Differential Mobility Analyzer). Similar equipment, but with a lower cost, was designed and built in the FEQUI / UFU NanoAerosol Technology Laboratory to separate nanometric particles from a polydisperse aerosol in order to classify them according to their size distribution, producing a monodisperse current. This electric mobility analyzer consists of two concentric cylindrical electrodes, where a voltage is applied to inner cylinder, while the outer cylinder is grounded, establishing an electric field between them. The polydispersed aerosol is passed between the spacing of the cylinders and, through a particle counter, the concentration of the particles passing through the apparatus is determined, passing through the classification slot and leaving the monodisperse aerosol. Using a commercial atomizer to generate a polydisperse aerosol of NaCl nanoparticles, it can be seen that the designed equipment was capable of producing a monodisperse aerosol stream and it was observed that the particles concentration present in the aerosols formed, increased with increasing saline concentration. It was performed tests in the Department of Chemical Engineering from the Federal University of São Carlos (DEQ / UFSCar), using a commercial analyzer (SMPS) of rand TSI. These tests allowed the comparison of the experimental results with the theoretical ones, resulting from the balance of load distribution, showing the efficiency of the Nano-DMA projected in FEQUI / UFU. It was verified the possibility of using this equipment for the same functionalities of a commercial SMPS, such as: indoor air quality measurement; vehicles exhaustion; and, in researches with bioaerosols. It is worth mentioning that the cost of the designed equipment was approximately 22% the value of the commercial equipment, which represents a great advantage for its use. It was also verified the representativeness of mobility balance for the nanoparticles classification, based on the charges distributions, for the inlet (except for particles smaller than 20 nm due to Brownian effect), monodisperse and excess aerosols.