Removal of lead(II) from waste water on zeolite-NaX

In this work sorption of Pb(II) on zeolite-NaX was studied. Zeolites NaX is characterized by large surface area because of its highly porous nature. High surface area and ordered pore structure of zeolite-NaX result in adsorption of large quantities of adsorbate depending on adsorbate size, aperture size, temperature and surface acidity of zeolites. Therefore, equilibrium isotherms were obtained using batch study by varying operating parameters such as pH, initial concentration, temperature, adsorbent dosage and the contact time. The optimum condition thus obtained are: pH-6, concentration 10 mg/L and temperature of 303 K. The adsorption mechanism and the characterizing parameters were analyzed using two parameter (Dubinin–Radushkevich (DR), Temkin, Freundlich–Langmuir) and three parameter (Khan, Toth, Sips and Redlich–Peterson) isotherm models. Kinetics of the process was studied using Pseudo first order, Pseudo second order, First order reversible reaction, Elovich equation, intra-particle diffusion and Bangham equation. Dubinin–Radushkevich (DR) fitted the experimental data very well amongst the two parameter models. The three parameter isotherms show high determination coefficient compared to two parameter isotherms in the following order i.e., Sips > Toth > Pedlich–Peterson > Khan.The separation parameter, RL, values of less than 1.0 indicate that adsorption of Pb(II) on zeolite-NaX is favorable. The estimated values of thermodynamic parameters indicate the exothermic nature of adsorption of Pb(II) on zeolite-NaX. This study supports the view that zeolite-NaX could be an efficient adsorbent for removal of Pb(II) form aqueous solution.