For the pseudo-second-order model, the correlation coefficient
(R2 = 0.9989) was much higher than that of the pseudo-first-order
model, and no obvious difference occurred between the experimental
(75.5 mg g1) and the theoretical adsorbed masses
(74.6 mg g1) at equilibrium. The good coherence between the
experimental data and the pseudo-second-order kinetic model
indicated that the adsorption of ammonium on the ceramic adsorbent
was well described by the pseudo-second-order kinetic model.
As a result, this adsorption could be dominated by a chemical
process, primarily ion exchange, which was in accordance with
the results obtained by many other researches