In order to evaluate the effect of pH of the solution on the percentage
of dye extracted, a series of experiments were performed
and the dye solution was adjusted to the desired pH
by adding NaOH or HNO3 solutions. As shown from Fig. 2,
the percentage dye extracted increases from 20.2% to 100%
as the pH increases from 2 to 12. The changes in the behavior
of the dye could be attributed to the hydrolysis or aggregation
at these pH conditions [35]. The results reveal that the maximum
extraction of dye occurred in the pH range of 9–12.
For further studies, it was decided to maintain the extraction
at pH 11.