In this study, Fe3O4/MnO2/FA nanocomposite was synthesized as a low cost adsorbent with high adsorption capacity, desorption efficiency and reusability for Sr(II) extraction from seawater. FT-IR, FESEM-EDS, XRD, VSM and BET experiments were used to characterize the composite. Sr(II) adsorption onto Fe3O4/MnO2/FA followed a pseudo-first-order kinetic model and was well fitted with the Langmuir isotherm model. Fe3O4/MnO2/FA has demonstrated an excellent adsorption capacity of 227.3 mg/g for Sr(II) ions at 25 °C and pH 8. The composite showed high selective uptake of Sr(II) in the presence of cations Na, Mg and Ca. However, Ca ions reduced the Sr (II) uptake from 49.1 to 41.0 mg/g at 600 mg/L Ca. Sr(II) desorption was performed using 0.1M HCl which showed an excellent desorption efficiency. In natural seawater containing 9.4 mg/L Sr(II), without changing the physicochemical conditions, Fe3O4/MnO2/FA composite showed 6.4 mg/g of Sr(II) adsorption, which leads to save time and energy consumption.
