Aerosol analysis of residual and nanoparticle fractions from spray pyrolysis of poorly volatile precursors

The quality of aerosol-produced nanopowders can be impaired by micron-sized particles formed due to non-uniform process conditions. Methods to evaluate the quality reliably and fast, preferably on-line, are important at industrial scales. Here, aerosol analysis methods are used to determine the fractions of nanoparticles and micron-sized residuals from poorly volatile precursors. This is accomplished using aerosol instruments to measure the number and mass size distributions of Liquid Flame Spray-generated alumina and silver particles produced from metal nitrates dissolved in ethanol and 2-ethylhexanoic acid (EHA). The addition of EHA had no effect on silver, whereas, 5% EHA concentration was enough to shift the alumina mass from the residuals to nanoparticles. The size-resolved aerosol analysis proved to be an effective method for determining the product quality. Moreover, the used on-line techniques alone can be used to evaluate the process output when producing nanopowders, reducing the need for tedious off-line analyses. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 881-892, 2017