Removal of Pb(II) from aqueous solution by acid activated red mud

• HCl activated red mud was used to investigate the removal efficiency of Pb(II) from the aqueous solutions.
• The percentage removal was found to increase gradually with decrease of pH and maximum removal was achieved at pH 4.
• Kinetic studies indicated that the adsorption process was best described by pseudo-second-order kinetics.
• The adsorption data fitted well with Langmuir isotherm with R2 (correlation coefficient) > 0.99.

In this work, batch adsorption study was conducted to investigate the removal efficiency of Pb(II) from the aqueous solutions by using HCl activated red mud (ARM). Adsorption experiments were conducted as a function of adsorbent dose, equilibrium pH, contact time, initial lead concentration, kinetics and Langmuir isotherms. The characterization and mechanisms involved in adsorption of lead ions on ARM were studied by using instrumental technique like XRD, FTIR, SEM/EDX, TG-DSC and chemical methods. The percentage removal was found to increase gradually with decrease of pH and maximum removal was achieved at pH 4. The adsorption kinetic studies indicated that the overall adsorption process was best described by pseudo-second-order kinetics. The adsorption data were fitted to linearly transformed Langmuir isotherm with R2 (correlation coefficient) > 0.99. The results indicate that ARM can be used as an effective and low cost adsorbent for the treatment of wastewaters contaminated with Pb(II) ions.