Lead sorption onto acrylamide modified titanium nanocomposite from aqueous media

The purpose of this study was to investigate the adsorption of lead (Pb(II)) onto acrylamide (AM) doped TiO2 nanocomposites (Ti-AM) using batch techniques for evaluation of isothermal and kinetic properties. Chemical, structural and textural characteristics of the material were determined by FTIR, XPS, XRD, SEM and EDAX analysis. XPS results showed that a change in oxidation state occurred due to lead adsorption. The adsorption conditions for the adsorbent were optimized by varying several experimental parameters, i.e., contact time, initial lead concentration, adsorbent dose, pH, and electrolyte amount of the solution. The adsorption data were modeled using both the Langmuir and Freundlich isotherms. The maximum adsorption capacity using Langmuir isotherm (q(max)) for the nanocomposite was found to be 476.19 mg g(-1). Adsorption showed pseudo-second-order kinetics with a rate constant of 8.7 x 10(-4) and 1.2 x 10(-4) g mg(-1)min(-1) at 100 and 500 mg L-1 initial Pb(II) concentrations, respectively. Acrylamide concentration in nanocomposite synthesis up to 1 g had greater influence on the sorption of lead. The most favorable pH for the adsorption was pH 5.5. With increasing concentrations of three electrolytes (NaCl, Na2SO4 and Na2CO3) from 0.01 to 1.0 M Pb(II), the lead removal decreases from 76.3 to 32.8 mg g(-1), from 97.4 to 68.7 mg g(-1), and from 98.8 to 72.5 mg g(-1), respectively. Further, the Ti-AM nanocomposite is amenable to efficient regeneration by a 0.05 N HCl solution for repeated (up to six cycles) use without any significant capacity loss, making this approach very economical. (C) 2013 Elsevier Ltd. All rights reserved.