3. Results and Discussion
3.1 Effects of the extraction parameters on
H3BO3Extraction
3.1.1 Effect of Feed pH
The pH of the aqueous solution has
been considered as the crucial parameters affecting the
H3BO3 extraction
process[17,28]. To determine the effect of pH on
H3BO3 extraction, experiments were
performed at pH from 1 to 10
with
a constant O/A of 1/1. As shown in Fig. 2, at a condition of initial
aqueous pH value (abbreviated to pHini ) less than
7, the extraction efficiency reached a stable level of 85%, and
equilibrium aqueous pH value (abbreviated to
pHeq ) reduced obviously comparing to the
pHini . Meanwhile, the pHeqand ΔpH (pHini -pHeq )
increased with the increasing of pHini . The
extraction efficiency decreased sharply with the
pHini continuously increasing, and the
pHeq was slight higher than
pHini . It can be concluded that the extraction
efficiency and pHeq changed inversely, and a low
extraction efficiency obtained when the pHeqexceeded 9.4.
Boron is mainly present in natural water in the form of boric acid, and
it appears as weak Lewis acid after hydrolysis.: