Lead Adsorption onto Surface Modified Nano Titania: Kinetic and Thermodynamic Studies

The present work focused on the adsorption of Pb(II) from aqueous solutions by amino-functionalized nano titania in a batch system. Surface modification was based on immobilization of o-phosphoethanolamine on the surface. The effects of pH, adsorbent dose, contact time, initial metal concentration, and temperature on the adsorption process were examined. The maximum adsorption of Pb(II) was observed to occur at pH 6.0. Kinetic data showed that the adsorption process achieved equilibrium within 90 min and experimental data were fitted well by the pseudo-second-order model. According to the equilibrium data, Pb(II) adsorption was well described by the Langmuir isotherm model. According to the evaluated thermodynamic parameters at different temperatures, the adsorption was a spontaneous (Δ𝐺 0) and endothermic (Δ𝐻 0) process. The presence of Mg and Ca ions as interfering cations up to 150 mg/g caused no considerable lowering effect on the Pb(II) adsorption. In addition, the regeneration of the adsorbent was performed using HNO3 (0.1 mol/L). The obtained studies showed that amino-functionalized nano titania was successfully used as an efficient adsorbent for removal of the Pb(II) from aqueous solutions.