Adsorption properties of Merrifield-bCCA chelating resins: a new alternative for Pb2+ removal from water

Abstract

In this work, five new chelating resins (MR_nBz) functionalized with N-benzyl bis(carbamoyl)carboxylic acid molecules (BzbCCA) on their surface were prepared to study the metal ion (Mⁿ⁺) adsorption properties in water. MR_nBz resins were characterized by FTIR, TGA, FESEM and EDS. The surface charge as a function of pH and the chemical adsorption of Mⁿ⁺ on the surface were evaluated through zeta potential (ζ) measurements. The Mⁿ⁺ adsorption capacity of MR_nBz resins was evaluated using Pb²⁺, Cu²⁺, Cd²⁺, and Ni²⁺ mixture model solutions at low concentrations. MR_nBz resins displayed selective adsorption of Pb²⁺ even in the presence of a molar excess of other cations, due to the intrinsic affinity and selectivity of BzbCCA molecules for this metal ion. The adsorption isotherms of Pb²⁺ showed that the adsorption capacity of MR_nBz resins was influenced by the spacer chain length. In addition, the resins were characterized by FTIR, TGA, FESEM and EDS after the Mⁿ⁺ adsorption process, confirming the Mⁿ⁺ loading on the resin surface.