Preparation and characterization of modified anion exchange resin for uranium adsorption: estimation of nonlinear optimum isotherm, kinetic model parameters, error function analysis and thermodynamic studies

Abstract

In this study, a modified metal hydroxides on surface of Lewatit resin (HMO @LM500, where M indicates to Al, Fe, Mn or Zn) were designed and used as efficient adsorbents for uranium (U(VI)) ions capture from aqueous solution. The prepared materials were characterized by using transform infrared spectroscopy, scanning electron microscope, energetic dispersive x-ray techniques. Batch adsorption methods were done to investigate all factors affecting adsorption process such as the effect of pH, concentration, contact time and temperature. Optimum values of each parameter were calculated as pH of 1.8, temperature of 298 K (25 °C), contact time of 60 min for the removal of uranium ions. Analysis within the nonlinear isotherm models indicates that the Liu model offers the best description for the equilibrium data since it has the highest R 2 value and the lowest error analysis value when compared with the other models. The calculated adsorption capacity of Liu model is 217.06 mg g−1, whereas analysis within the nonlinear kinetic models indicate that pseudo-second-order behavior is involved. The thermodynamic examination of the equilibrium data proved that the adsorption process of U(VI) was found to be a spontaneous and exothermic process. The ΔH 0 and ΔS 0 parameters were calculated as −66.5827 kJ mol−1 and −0.2051 kJ mol−1 K−1, respectively. Therefore, the prepared adsorbent can be applied to capture of U(VI) ions from aqueous medium.