Sol-gel synthesis of zirconia-based nanoparticles from the side product of tin mining

Abstract

Indonesia has been one of the world’s primary source of tin since the early of 19th century. Bangka island has the largest tin abundant with a side product is zircon sand (ZrSiO₄). The existence of zircon (ZrSiO₄) is mostly associated with some of the valuable oxide compounds (VOC) and rare earth oxides (REO). The zirconia powders were synthesized from the zircon sand of PT. Timah Tbk by caustic fusion method followed by sol-gel method. The raw material zircon sand and as-synthesized zirconia were characterized through x-ray fluorescence (XRF), x-ray diffraction (XRD), surface area analysis and porositymeter, thermogravimetric and differential scanning calorimetry analysis (TG-DSC), fourier transform infra-red (FTIR) and scanning electron microscopy (SEM) techniques. The results show that zircon sand from PT Timah Tbk contains some of VOCs, such as ZrSiO₄, ZrO₂, HfO₂, SiO₂, Al₂O₃, TiO₂, Fe₂O₃ and some REOs, such as La₂O₃, Y₂O₃, Nb₂O₅. The fusion temperatures varied from 600 to 800 °C which resulted in an increase of the purity of ZrO₂ to 76% based on the XRF analysis. The surface area analysis and porositymeter results showed the significant change in specific surface area, pore size and pore volume of as-synthesized zirconia. The specific surface area increased dramatically from 0.28 m²/g to 173.97, 125.18, and 102.14 m²/g, at fusion temperatures of 600, 700, and 800 °C, respectively. The average particle size of as-synthesized zirconia showed the significant change from 21.31μm to 34.48 nm. The results of this work open new opportunities for the development of zirconia-based nanoparticles from the side product of tin mining.