Shortening synthesis process of zirconium hydroxide as a hydrolysis product of sodium zirconate

Abstract

This research was focusing on shortening the process of Zirconium hydroxide (Zr(OH)<sub>4</sub>) synthesis to get a more efficient process. In the earlier method, Zr(OH)<sub>4</sub> was produced through ZOC, which was the product of Na<sub>2</sub>ZrO<sub>3</sub> reacted with HCl. While this study offers a new method to synthesize Zr(OH)<sub>4</sub> through the hydrolysis process of sodium zirconate (Na<sub>2</sub>ZrO<sub>3</sub>), removing the leaching step of Na<sub>2</sub>ZrO<sub>3</sub> with HCl. The hydrolysis process of Na<sub>2</sub>ZrO<sub>3</sub> was carried out in a multistage stirred reactor at 70 °C. The multistage hydrolysis process occurred in 13 stages with 4000 grams of feed and 890 liters of water. This process produced 2500 grams of Zr(OH)<sub>4</sub>. Then the impurities analysis was done using UV-Vis and atomic absorption spectroscopy (SAA). The UV-Vis analysis was done to analyze Si concentration, while the atomic absorption spectroscopy (SAA) was done to analyze Na concentration. Si and Na concentrations could decrease to 23.98 µg/ml and 1.05 µg/ml, respectively. The Zr(OH)<sub>4</sub> contained in the residue was characterized using X-Ray Diffractometer (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Then, the calcination process of Zr(OH)<sub>4</sub> was done at 300 °C and 400 °C for 1 hour, and characterized using XRD. The XRD result shows crystals of zirconium titanium oxide or srilankite, and SiO<sub>2</sub> crystals that are separated from ZrO<sub>2</sub> or TiO<sub>2</sub> crystals. Surface analysis was done using Scanning Electron Microscope – Energy Dispersive X-Ray (SEM-EDX), the result shows that the hydrolysis process at the 3<sup>rd</sup>, 7<sup>th</sup>, and 13<sup>th</sup> stages have different amorphous crystals with bright colors. At the 13th hydrolysis stage, Zr concentration increased to 63.38%, and Si concentration decreased. Thus, the shorter process of Zr(OH)<sub>4</sub> synthesis has been done successfully.