Based on the kinetic results shown in Table 2, the values for
adsorption capacity of ZnCl2/450-AC and CAC were obtained for the
batch system experiments, as shown in Table 8 (entries 4e5), with
multi-layer adsorption based on Freundlich model. The Table shows
value of adsorption capacity for nitrite onto ZnCl2/450-AC and CAC
samples, together with reported values for other materials (entries
1e5). The results indicate that ZnCl2/450-AC has much higher
adsorption capacity than the reported materials. An earlier report
(Ho and McKay) stated an adsorption capacity of up to 50 mg nitrite
per 1 g carbon cloth (which was pretreated with acidic media),
however the adsorption capacity described therein could not be
confirmed due to lack of description of experimental conditions.
Packed column flowadsorption experiments (entry 6) indicate that
the adsorption capacity for the ZnCl2/450-AC is also higher than for
other reported systems (entries 1e3 and 7). The lower adsorption
capacity values measured in packed column adsorption experiments
compared to the batch experiment systems are presumably
due to insufficient time allowed for equilibrium to be achieved. This
is because batch experiments were allowed to continue for more
than 1500 min (Fig. 5) whereas the column flow experiments were
only allowed for 130 min.