Preparation of zwitterionic hybrid polymer and its application for the removal of heavy metal ions from water

A series of zwitterionic hybrid polymers were prepared from the ring-opening polymerization of pyromellitic acid dianhydride (PMDA) and phenylaminomethyl trimethoxysilane (PAMTMS), and a subsequent sol-gel process. FTIR spectra confirmed the step products. TGA analysis showed that the thermal degradation temperature increased with an increase in PMDA content. As a typical example, sample B was used to separate Cu2+ and Pb2+ removal by adsorption. It was indicated that its adsorption for Cu2+. and Pb2+ followed Lagergren second-order kinetic model and Langmuir isotherm model, demonstrating that the adsorption process might be Langmuir monolayer adsorption. Meanwhile, it was found that the adsorption capacity of Pb2+ on sample B is beyond 12 times higher than that of Cu2+ in 0.1 mol dm(-3) aqueous solution, revealing that it has larger affinity for Pb2+. The desorption efficiency of Cu2+ and Pb2+ in 1 mol dm(-3) HNO3 solution reached up to 96 and 89%, respectively; indicating that they can be regenerated and recycled in industry. These findings suggest that they are promising adsorbents for the selective removal of Pb2+ from Pb2+/Cu2+ mixed aqueous solution, and can be applied to separate and recover the heavy metal ions from contaminated water and waste chemicals. (C) 2010 Elsevier B.V. All rights reserved.