Adsorption of Pb (II) and Zn (II) ions from aqueous solutions by Red Earth.

This study was carried out to investigate Pb (II) and Zn (II) removal from aqueous solutions by Red Earth (RE) as a new local natural adsorbent in using the batch method. The chemical structure of RE adsorbent was characterized by XRF. Giles, Langmuir, and Freundlich isotherms were used to describe the adsorption data. The effect of metals concentration, initial pH, adsorbent dosage, and agitation time were studied. The results showed that RE contains of SiO2 (58 %) and Al2O3 (15.2 %) as major compounds. The equilibrium time was reached following 30 min and the maximum adsorption capacities (mg/g), based on Langmuir equation were 10.31 and 8.74 for Pb (II) and Zn (II), respectively. By increasing the initial metal ions concentration, the adsorption efficiencies were decreased and adsorption capacity of RE increased with an increase in the initial pH.