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

In this work, five new chelating resins (MR Bz) functionalized with N-benzyl bis(carbamoyl)carboxylic acid molecules (BzbCCA) on their surface were prepared to study the metal ion (M ) adsorption properties in water. MR Bz resins were characterized by FTIR, TGA, FESEM and EDS. The surface charge as a function of pH and the chemical adsorption of M on the surface were evaluated through zeta potential (ζ) measurements. The M adsorption capacity of MR Bz resins was evaluated using Pb²⁺, Cu²⁺, Cd²⁺, and Ni²⁺ mixture model solutions at low concentrations. MR Bz 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 Bz resins was influenced by the spacer chain length. In addition, the resins were characterized by FTIR, TGA, FESEM and EDS after the M adsorption process, confirming the M loading on the resin surface.