The overall metal recovery also depends on the metal elution
efficiency of the adsorbed metals. Elution efficiency was defined
in this study, as the ratio of the mass desorbed from the resins to
the mass adsorbed onto the resins. Table 4 compares the elution
of nickel adsorbed on Purolite S950. The effects of variables
including the nature of the complexes, metal (100–2000 mg/L)
and acid concentrations (0.01 and 0.1 M) on metal elution were
considered in this investigation.