Fig. 13. McCabe–Thiele diagram of boron extraction using TMPD.
3.4 Study of stripping
process
Boron-loaded organics were stripped
by hydrochloric acid, deionized water and different concentrations of
sodium hydroxide solutions at a constant O/A of 2/1, respectively. As
shown in Table 5, it is evident that the stripping efficiency of boron
by NaOH is significantly higher than that of H2O and
HCl, which can indicate that the complex formed by boron and 1,3-diol
(TMPD) is more stable than that formed by monohydric alcohol. The
stripping efficiency of H3BO3 increased
with the increasing of NaOH concentration. however, emulsification
occurs when the NaOH concentration is greater than 0.4 mol/L, which is
not conducive to phase separation, and the
stripping efficiency decreases when
it continues to increase to 0.6 mol/L. Therefore, the concentration of
the stripping agent is selected to be 0.4 mol/L, which can achieve a
good stripping effect while avoiding the phenomenon of emulsification.
Table 5. Results of stripping H3BO3 with
different stripping agents