The experimental
procedures were performed as follows: (1) a series of solutions
of various NA concentrations were prepared; (2) the initial pH was
measured, and a defined amount of the HSANGs was then added to
the solutions; (3) these solutions were agitated on a magnetic
stirrer for a certain period of time, at room temperature; (4) at
defined points in time, a certain volume of the solution was
removed and immediately filtered to collect the supernatant; and
(5) the residual MB concentration in the supernatant using an
UV/Vis instrument at 370 nm.