Novel hyperbranched polyurethane resins for the removal of heavy metal ions from aqueous solution

Abstract

Novel polyurethane (PU) resin was studied for removal of Pb(II) and Ni(II) ions from aqueous solution. The resin was characterized by FT-IR, 1H NMR, 13C NMR, TGA, SEM, EDAX and DLS analysis. The optimization of experimental conditions and parameters including pH, adsorbent dosage, contact time, and initial metal ion concentration for the removal of heavy metal ion was evaluated. Batch adsorption kinetic studies were mathematically described, and it has been found that the adsorption of Pb(II) and Ni(II) ions onto the PU follow the pseudo-second order kinetic model. Adsorption isotherms have also been studied, and the data fitted well in the order of the Freundlich>Temkin>Sips>Langmuir isotherm models. The maximum adsorption capacities of PU for Pb(II) and Ni(II) ions were calculated from the Langmuir isotherm, 236.5 and 217.5mg/g respectively. Thermodynamic parameters such as, ΔH° and ΔG° suggest that the adsorption of Pb(II) and Ni(II) ions onto PU is exothermic and spontaneous in nature. The adsorption efficiency of the PU was retained even after five cycles. The PU has good adsorption efficiency for the removal of Pb(II) and Ni(II) ions compared to other adsorbents.