Exploring the ion exchange and separation capabilities of thermally stable acrylamide zirconium(iv) sulphosalicylate (AaZrSs) composite material

Abstract

In this work, a hybrid composite material, acrylamide zirconium(IV) sulphosalicylate (AaZrSs) has been synthesized by intercalating acrylamide into zirconium(IV) sulphosalicylate. The synthetic conditions were varied to optimize the ion exchange properties of the material. The characterization of the material was done using SEM, IR, XRD and TGA so as to identify the various functional groups and ion exchange sites present in the material. The ion exchange capacities of some monovalent and divalent cations were investigated in order to know the working capacity of the composite material. Quantum chemical computations at B3LYP/LanL2DZ level were performed to substantiate the structural conclusions based on instrumental techniques. Investigations into the elution behavior, ion exchange reversibility and distribution capacities of the material towards some heavy metal ions were also performed. The distribution coefficients of certain metal ions were determined in different media and following order is observed; Cd(II) > Pb(II) > Zn(II) > Co(II) > Sn(II). Its selectivity was examined by achieving some important binary separations like Co(II)–Cd(II), Pb(II)–Cd(II), Zn(II)–Cd(II) and Sn(II)–Cd(II). The extent of Cd(II) removal was tested by varying the solution parameters like adsorbent dose, adsorbate concentration, pH of the solution, contact time and temperature. The adsorption process followed second order kinetics and adsorption data was best fitted to Langmuir isotherm with correlation coefficient of 0.994. The values of various thermodynamic parameters like ΔG°, ΔS° and ΔH° were also determined. Hence the composite material can be potentially applied to remove Cd(II) from polluted waters.