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chemical activation, while intermediate capacities were observed for the
thermally activated or the charred forms. This indicates that the activated
adsorbents are most likely to be efficacious for certain wastewater treatment
purposes, depending upon effluent requirements. It was noted that the
untreated adsorbents have almost identical isotherms for the three-phenol
system. The efficiency of ATW and ANL for phenol adsorption is also ascer-
tained by the rapid uptake of adsorbate within the first 1 h of adsorption.
The adsorption capacity in all the studied adsorbents showed the order
P<4-CP<4-NP.
8.7 MULTICOMPONENT ADSORPTION STUDIES
In practice, wastewater consists of a broad range of adsorbates with interac-
tion among the adsorbate molecules that even complicates the theoretical
study of multicomponent adsorption. Very little literature or information
is available on column performance of multicomponent systems. Some
recent reports on the multicomponent adsorption of toxic chemicals from
wastewater, which focuses on the removal of mixtures of metals
(Srivastava et al., 2008, 2009), metals with phenols (Aksu and Akpinar,
2000; Aksu and Yener, 2001; Quintelas et al., 2006), and mixtures of organic
compounds (Seidel and Gelbin, 1988; Sulaymon and Ahmed, 2008; Yang
et al., 2008), attempt to predict multisolute adsorption. However, interpre-
tation of the interactive influence of the solute components from experi-
mental data needs to be studied in the context of understanding the real
adsorption phenomena.
Binary solute adsorption ofmixtures of4-CPand 4-NP,phenol and 4-NP,
and phenol and 4-CP were studied. Also, the single component adsorption
was extended to binary study using an ANL adsorbent because ANL gave
the highest adsorption capacity. The stock solution of the binary system con-
sisted of equal mass concentrations of the two selected adsorbates under study
to make up a binary solute system having an initial concentration of
1
1000 mg L . This ratio was used and equilibration was carried out for 24 h.
It can be inferred from Table 8.6 that the adsorption capacity of 4-NP
and 4-CP decreased more during binary adsorption than in single compo-
nent adsorption. This shows the double antagonistic effect of 4-NP and
4-CP adsorption in the binary mixture of 4-NP and 4-CP. There is extreme
reduction in adsorption capacity in the case of 4-NP in the binary mixture
compared to that in the single system. The reduction in adsorption capacity
in the binary system may be explained because of the presence of strong