Kinetic, isotherm, and thermodynamic investigations of uranium(VI) adsorption on synthesized ion-exchange chelating resin and prediction with an artificial neural network

In this study, an amidoximated chelating ion-exchange resin was prepared using poly-acrylonitrile grafted potato starch. The resin characterizations such as specific surface area, pore volume, average pore radius, and Fourier transform infrared spectroscopy of the resin were defined. The effects of pH, contact time, adsorbent dosage, initial concentration of uranium, and temperature on adsorption of uranium ion from aqueous solutions were investigated. The equilibrium adsorption data are fitted Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Temkin isotherm models and the model parameters are evaluated. The results showed that the D-R model had the best agreement with experimental data. The maximum capacity of adsorption of uranium(VI) onto polyamidoxime resin was found 415.77mg/g using D-R equation. The kinetic data were well fitted by the pseudo-second-order kinetic model. Thermodynamic parameters including standard enthalpy change (H degrees), entropy change (S degrees), and Gibbs free energy (G degrees) were also determined to specify the type of adsorption reaction using equilibrium constant values at various temperatures. The evaluated H degrees and G degrees indicate the endothermic nature of adsorption and the process is spontaneous and favorable. The present study suggests that the prepared adsorbent has promising potential for the removal of uranium(VI) from wastewaters. Furthermore, an artificial neural network (ANN) model was applied to predict adsorption percent of uranium and final pH of solution (pH(f)). A good agreement between experimental data and predicted values of applied ANN model was observed.