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

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