Removal of nickel (II) and lead (II) by adsorption method from waste waters

In this study, batch experiments were carried out for the adsorption of nickel (II) and lead (II) ions onto boron industry waste. The operating variables studied were initial metal concentration, initial solution pH, adsorbent dosage, contact time. Equilibrium adsorption data was fitted to Freundlich and Langmuir isotherms. Langmuir isotherm was found to be an optimum isotherm for two metals. The maximum adsorption capacity for nickel (II) and lead (II) ions were found to be 69.13 mg g-1 at optimum conditions of pH (7.0) and temperature (25oC) and 73.15 mg g-1 at optimum conditions of pH (6.0) and temperature (25oC), respectively. The equilibrium time for the removal of nickel (II) and lead (II) ions onto the adsorbent was reached within 90 min. Two simplified kinetics models were tested to investigate adsorption mechanisms in terms of the first order and the pseudo-second order rate equations. The adsorption rates of nickel and lead were found to be in consistent with the pseudo-second order model.