Effect of physical, chemical and electro-kinetic properties of pumice samples on radiation shielding properties of pumice material

Thermoluminescence in pumice stone collected from the Mediterranean coast

Pumice is a low-density, light-coloured volcanic rock (igneous rock) formed when the magma from a volcanic eruption is suddenly cooled. It has a porous structure and can be different colours and have different densities. Pumice stone, unlike other rock, does not sink in water because it has a low density. In the present study, the thermoluminescent (TL) dosimetric characteristics, such as the dose-response, TL signal fading as a function of storage time, heating rate, and reusability of pumice collected on the Mediterranean coast were investigated. From this study, it was concluded that the pumice stone showed TL properties with a TL glow curve including an obviously wide peak at ∼200°C. A wide linear dose-response region up to 144 Gy, low fading of the TL signal when it was kept in a dark room for a long time, and poor reusability properties were observed for dosimetry use.

Pumice as a Novel Natural Heterogeneous Catalyst for the Designation of 3,4-Dihydropyrimidine-2-(1H)-ones/thiones under Solvent-Free Conditions

In this study, pumice is used as a novel natural heterogeneous catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones/thiones via the one-pot multi-component condensation of aromatic aldehydes, urea/thiourea, and ethyl acetoacetate or acetylacetone in excellent yields (up to 98%). The physical and chemical properties of the catalyst were studied. Their geochemical analysis revealed a basaltic composition. Furthermore, X-ray diffraction showed that it is composed of amorphous materials with clinoptilolite and heulandites zeolite minerals in its pores. Moreover, pumice has a porosity range from 78.2–83.9% (by volume) and is characterized by a mesoporous structure (pore size range from 21.1 to 64.5 nm). Additionally, it has a pore volume between 0.00531 and 0.00781 m²/g and a surface area between 0.053 and 1.47 m²/g. The latter facilitated the reaction to proceed in a short time frame as well as in excellent yields. It is worth noting that our strategy tolerates the use of readily available, cheap, non-toxic, and thermally stable pumice catalyst. The reactions proceeded smoothly under solvent-free conditions, and products were isolated without tedious workup procedures in good yields and high purity. Indeed, pumice can be reused for at least five reuse cycles without affecting its activity.