*3.4. Production of Rubidium Carbonate and Cesium Carbonate*

In order to get stable compounds of rubidium and cesium, ammonium carbonate was added into rubidium hydroxide solutions and cesium hydroxide solutions to produce rubidium carbonate solutions and cesium carbonate solutions. The reaction situations were shown in Equations (5) and (6).

$$\text{(NH4)}\_{2}\text{CO}\_{3(s)} + \text{RbOH}\_{(aq)} \rightarrow \text{Rb}\_{2}\text{CO}\_{3(aq)} + \text{NH}\_{3(aq)} + \text{H}\_{2}\text{O}\_{(l)}\tag{5}$$

$$\text{(NH4)}\_{2}\text{CO}\_{3(s)} + \text{CsOH}\_{(aq)} \rightarrow \text{Cs}\_{2}\text{CO}\_{3(aq)} + \text{NH}\_{3(aq)} + \text{H}\_{2}\text{O}\_{(l)}\tag{6}$$

The rubidium carbonate solutions and cesium carbonate solutions were then put into rotary evaporators and evaporated under low pressure and temperature and precipitate the purity of 98.0% of rubidium carbonate and 98.9% of cesium carbonate. After chemical precipitation and solvent extraction, the ICP-OES analyses are shown in Table 7.

**Table 7.** ICP-OES analyses of rubidium carbonate and cesium carbonate


N.D.: Not-detected.
