The difference is due to the adsorbed GA onto the surfaces of LDH platelets. The mole fractions of Al3+ (xAl), i.e. mole ratio of Al3+ to (Zn2+ + Al3+) that is an indication of the charge density of the inorganic LDH layers are 0.21 and 0.20, for ZAL and ZAG, respectively. In the ion-exchange process, it is not changed significantly [14].