Morphological characterization of water-based nanolime dispersions

Abstract

This paper studies the morphological characteristics of calcium hydroxide nanoparticles in water based dispersions, produced following the main bottom-up (CaCl2/NaOH replacement reaction) and top-down methodologies. The work focuses on the effect of three different surfactants (TritonX-100, n-octylamine and amylamine) on the morphological characteristics of the resulting Ca(OH)2 nanoparticles and compares them with the ones produced in a mixture of water and 2-propanol. Moreover, in an attempt to approach the compatibility enhancement with siliceous stones, a calcium hydroxide—TEOS composite was also studied. The morphological, chemical and the mineralogical characterization of the nanoparticles produced were carried out by electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). It is shown that the modifications induced by the production methodologies limited the agglomeration phenomena and altered the morphological characteristics of nanoparticles, when compared to the results obtained by the original bottom-up method, resulting in the synthesis of hexagonal, plate-like, rounded and angular portlandite nanoparticles. The size range of the nanoparticles extended from 60 to 350 nm.