The finite size effect on the surface structure and thermal properties of nanostructured natural pumice

Abstract

ABSTRACT Natural pumice materials have attracted wide attention owing to their unique physical and chemical properties that are suitable for various applications. This study investigated the finite size effect on the surface, crystal structure and thermal properties of nanostructured pumice. For this, nanostructured pumice samples were prepared using high-energy ball milling for different durations (0, 1, 2, 3, and 7 h), which reduced the particle size from 1117 nm to 100 nm and increased the surface area from 0.83 to 18 m2/gm (i.e. by more than 21 times). All the nano pumice samples have the same chemical composition and crystal structure. However, the crystallisation of the samples decreased with decrease in the particle size. The thermogravimetric analysis revealed an increase in weight loss from 1% to 12% with decreasing particle size, owing to humidity resulting from the porosity of the samples. While the differential scanning calorimetry results revealed thermal stability of the samples with the decrease in particle size, no changes in the melting point or oxidation of the samples with temperature were observed. Thus, nanostructured pumice can be concluded to be an excellent natural thermally stable material with a large surface and mesoporous structure that would prove more promising than raw pumice in several industrial, economic, and nanotechnology applications, such as water purification and geopolymers.