SELECTIVE SORPTION OF Pb(II) AND Cd(II) UNDER SALINITY CONDITIONS: PROSPECTS FOR Fe–Al–Si-BASED INORGANIC COMPOSITES
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The presence of Pb(II) and Cd(II) in saline wastewater is a significant environmental problem because dissolved salts and competing ions can affect heavy-metal sorption. This paper reviews the scientific basis for using Fe–Al–Si-based inorganic composites for the selective sorption of Pb(II) and Cd(II) under saline conditions. Previous studies have demonstrated that salinity and the composition of inorganic phases can substantially influence metal removal. For example, Fe-based electrocoagulation achieved 99.5% Cd(II) removal under optimized high-salinity conditions, while sulfate-containing iron phases showed stronger Cd(II) adsorption than chloride-containing phases. A silicon-supported Fe/Al/Mg composite prepared from biotite showed a maximum Cd(II) sorption capacity of 78.37 mg/g, with ion exchange and surface complexation identified as important mechanisms. Binary Pb(II)/Cd(II) experiments with an aluminosilicate adsorbent also demonstrated preferential Pb(II) uptake under specific conditions. These findings provide a basis for further experimental investigation of Fe–Al–Si composites in saline wastewater.
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