The results investigating the effect of adsorbent dosage on
ammonium removal with an initial ammonium concentration of
5000 mg L1 are shown in Fig. 4 and revealed that the adsorption
capacity of ammonium ion by the ceramic adsorbent decreased
with an increase in adsorbent dosage. It reduced from 53.4 to
24.3 mg g1 with the increase of adsorbent dosages ranging from
5 g L1 to 40 g L1; however, the removal efficiency increased from
5.34% to 19.44%. This tendency was consistent with that observed
by many other studies [16,19,26,27]. It was obvious that the available
exchange sites were enlarged with increasing the adsorbent
dosage; thus, the adsorption amount of ammonium was increased,
and the removal efficiency was improved. The decrease of adsorption
capacity may be due to the fact that the intensity of the concentration
gradient for unit mass adsorbent dosage diminished
when the interface area expanded with the increase in adsorbent
dosage.