Adsorptive removal of Pb(II) from aqueous solution using NaP zeolite synthesized from coal fly ash

Zeolite was prepared from coal fly ash obtained from power generation plant with sodium hydroxide in different concentration ratios at 550 °C with activation time of 12 hours by direct hydrothermal method. The synthesized zeolite was found to have greater removal capabilities for heavy metals than coal fly ash and natural zeolites. It was characterized by XRF, SEM, XRD and FTIR. Batch studies were performed to study the effect of different parameters like contact time, pH, amount of adsorbent, adsorbate concentration and temperature. The results revealed that the removal of lead was strongly pH dependent and maximum removal metal was observed at equilibrium pH of 5.0, optimum adsorbent dose and contact time were found to be 10 g/l and 120 minutes respectively. It was found that adsorption increased with increase in temperature thereby showing the process endothermic in nature. The experimental data were analyzed by Langmuir, Freundlich, Temkin and Dubnin isotherm models. The adsorption isotherm fitted the Freundlich rather than other isotherms. The maximum removal of Lead was found to be 89.7 % at 25 °C. The Kinetic studies were also investigated to know the mechanistic aspect using models pseudo-first-order, pseudo-second-order, Elovich and Intra particle diffusion.