Optimization of parameters for competitive adsorption of heavy metal ions (Pb+2, Ni+2, Cd+2) onto activated carbon

This study investigates optimization of various competitive adsorption parameters for removal of Cd(II), Ni(II) and Pb(II) from aqueous solutions by commercial activated carbon (AC) using the Taguchi method. Adsorption parameters such as initial metal concentration of each metal ion (C-0,C-i ), initial pH (pH(0)), adsorbent dosage (m) and contact time (t) in batch technique were studied to observe their effects on the total adsorption capacity of metals onto activated carbon (q (tot) ). The adsorbent dosage has been found to be the most significant parameter. Interactions between C-0,C-Cd xC(0,Ni) , C-0,C-Cd xC(0,Pb) and C-0,C-Ni xC(0,Pb) have been considered for simultaneous metal ions adsorption. The optimum condition for adsorption of metal ions were obtained with C-0,C-i =100 mg L-1, pH(0)=7, m=2 g L-1 and t=80 min. Finally, experimental results showed that a multi-staged adsorptive treatment would be necessary to reach the minimal discharge standards of metal ions in the effluent.