Preparation, characterization and adsorptive study of rare earth ions using magnetic GMZ bentonite

The magnetic GMZ bentonite adsorbent was prepared by the co-precipitation method to study adsorption of rare earth elements (REE)(La3+,Eu3+ and Yb3+), especially Eu3+. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, magnetization measurement, N2 adsorption–desorption isotherms and zeta potential were used to characterize its structure, morphology, surface chemistry and magnetic properties. The removal of REE (%) was determined as a function of contact time, pH, and adsorbent and metal ion concentration in batch experiments. The optimal adsorption condition was pH 6.5 and adsorbent content of 1.0 g/L. Use of the Langmuir isotherm showed that maximum adsorption capacity was 18.4 mg/g for La (III), 26.1 mg/g for Eu (III) and 71.4 mg/g for Yb (III). Pseudo-second-order rare equation fit the data well and adsorption was found to occur via chemisorption. The magnetic composite could be regenerated with a 0.5 mol/L NaCl solution (pH 2.0) and reused for three times with limited magnetic loss.