2.2 Single-stage extraction procedures

The extraction experiments were conducted and duplicated in separatory funnels. At ambient temperature (293±1 K), a mixture containing a certain volume of the aqueous and organic phase was subjected to mechanical vibration at 300 r/min, and then let it stand until the two phases separated. Contact time was selected after preliminary extraction experiments, for a period of 10 min, which was found enough for equilibrium. Then, the aqueous and organic samples were collected for further analysis.
The organic solution used in all experiments was composed of 0.4 mol/L TMPD dissolved in CCl4, and the phase ratio was 1/1 (O/A), except when explicitly described otherwise. In order to investigate the effects of pH, the concentration of H3BO3 and the concentration of MgCl2 on boron extraction, three simulated brines (which are listed in Table 2) were prepared, respectively, while the filtered SL brine (given in Table 1) was used in the experiment of other factors, including the concentration of TMPD, the phase ratio (O/A) and the temperature. All single factor experiments were performed at room temperature, except when studying the effect of temperature, according to procedures described above.
Table 2. Main characteristics of the simulated brines.