Table 2.

Amount of HA needed to reach the changes in surface charge for the Fe₃O₄-APTES samples (pH ∼5 and KCl = 0.01 M).

HA Amount	Fe3O4	Fe3O4/APTES (Air)	Fe3O4/APTES (Ar)
for full neutralization of charge, g/g	0.01	0.0085	0.005
to reach −20 mV of zeta potential, g/g	0.016	0.038	0.014
to reach plateau, g/g	0.04	0.056	0.04