Fig. 12. IR spectra of the organic
phases. The organic phase after extraction of (1)
H3BO3 dissolved in saturated magnesium
chloride, (2) H3BO3 dissolved in
deionized water; (3) The organic phase before extraction.
3.3 Three-stage continuous countercurrent
extraction
In order to completely extract H3BO3from brine, we performed an experiment using the three-stage continuous
countercurrent extraction (O/A=1) determined by the McCabe-Thiele method
(as shown in Fig. 13). SL brine presented in Table 1 was used as aqueous
phase. 0.4 mol/L TMPD dissolved in CCl4 was used as
organic phase. The experiment results are listed in Table 4. Finally,
the raffinate of 0.0253 g/L H3BO3 and
the organic containing 12.340 g/L H3BO3were obtained, which corresponds to an extraction efficiency of
H3BO3 of 99.79%. The results show that
the extraction efficiency of H3BO3 and
distribution ratio are significantly improved in three-stages
countercurrent extraction, and boric acid was almost extracted
completely.
Table 4. Comparison of single-stage and three-stage experiment results.