M. Kurz et al., UV-broadband light scattering measurements during metallic particle formation in a combustion-like environment, PART PART S, 16(2), 1999, pp. 77-84
The thermal evolution of aqueous solution droplets of lead and nickel nitra
te was studied experimentally in a drop-tube furnace operated up to 1300 K.
Dimensions and physico-chemical properties of the droplets/particles were
obtained by coupling the analysis of the spectra of ultraviolet light scatt
ered by the produced aerosol with scanning electron microscopy and numerica
l simulation of the scattering spectra by Mie theory. Lead nitrate forms so
lid hollow particles with sizes of the order of the original droplets durin
g the drying process, whereas at higher temperature it decomposes, forming
spherical micrometer-sized particles of lead oxide and even submicrometer-s
ized particles of pure lead.
Nickel nitrate never forms solid particles owing to its high solubility in
water but precipitates as nickel hydroxide particles in the temperature ran
ge where this intermediate decomposition product is formed. At higher tempe
ratures the decomposition of nickel hydroxide and the formation of oxide pa
rticles in the micrometer size range is observed.
The mutual interaction of the salt properties were analyzed by studying the
behavior of a lead-nickel nitrate mixture in the drop-tube reactor. The ma
in peculiarity of the mixture evolution is the formation of composite parti
cles of lead nitrate in a nickel hydroxide shell.
The combined use of in situ ultraviolet spectral scattering and ex-situ sca
nning electron microscopy, along with the simulations of the scattering spe
ctra by Mie theory, allows us to compile a database of scattering spectra a
ttributed to specific droplets or particles of given chemical properties an
d size which may be useful for the continuous detection and speciation of m
etallic aerosols at the exit of real plants.