As it was noticed for the adsorption in
spiked solution that even at low pH values the adsorption of Zn2+
occurred. At pH 2, the removal efficiency was around 20%. This is a
relevant result to treat another acidic effluent containing Zn2+ since
electroplating wastewater containing Zn2+ had an initial wastewater
pH equal to 12 in relation to the majority of the materials tested
in the literature [30]. For an adsorbent concentration (Cad) of 1.2 g/L
in the wastewater, it was possible to obtain an adsorption efficiency
of 92% for ES and of 89% for EB. These results showed that even with
the presence of other metallic ions these materials exhibited a very
good efficiency for Zn2+ removal.
Fig.