The effect of NaOH, KOH and equimolar mixture of NaOH and KOH on the synthesis of zirconia from Indonesian natural zircon sand using alkali fusion method

Abstract

In this research, Indonesian natural zircon sand from Kereng Pangi, Central Kalimantan, was processed to determine the effect of NaOH, KOH and equimolar mixture of NaOH and KOH on the synthesis of zirconia using alkali fusion method. Synthesis of zirconia was started with initial preparation of zircon sand followed by alkali fusion with NaOH, KOH and equimolar mixture of NaOH and KOH. The fusion condition in this research was at 700 ° C for 3 hours with a zirkon:alkali wt. ratio of 1:4.8. The next step was leached with water, leached with HCl, precipitated with NH4OH, and calcined at 500 °C for 3 hours. Fusing zircon sand with KOH was most favorable to get 99% zircon decomposition. The products were characterized trough X-ray diffraction (XRD). The zirconia that was resulted by fusing with KOH has a tetragonal structure as same as fusing with NaOH, whereas fusing with equimolar mixture of NaOH and KOH produces amorphous structure. Refinement results showed that tetragonal zirconia that was produced from fusion with NaOH has a similar lattice parameter and crystal size estimation values to fusion with KOH, it is mean that there was no significant effect of using KOH or NaOH on alkali fusion method to the lattice parameter and the crystal size of the resulting zirconia.