Sorption Behavior and Mechanism of Simulated Radionuclide Nd(III) from Aqueous Solution by Bentonite

A local bentonite from Gaomiaozi county (Inner Mongolia province, China) was purified, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) were used for the characterization of the purified sample to determine its chemical constituents and microstructures. The sorption behavior of Nd(III) on bentonite was performed by batch technique, and the effects of contact time, clay dosage, pH, ionic strength and temperature were investigated. The results indicated that sorption of Nd(III) on bentonite was strongly dependent on pH values, suggesting that surface complexation was the main sorption mechanism in the sorption process. The sorption isotherm fitted well by Langmuir models. The thermodynamic parameters, such as, enthalpy ( increment H degrees), entropy (Delta S degrees), and Gibbs free energy (Delta G degrees) were calculated from the temperature dependent sorption data, and the results indicated that the sorption of Nd(III) on bentonite was a spontaneous process, and the sorption was endothermic.