Application of a novel adsorbent prepared using magnetized Spirulina platensis algae modified by potassium nickel hexacyanoferrate for removal of cesium, studied by response surface methodology

Abstract In this research, a new magnetized adsorbent was prepared by impregnation of Spirulina platensis (SP) with potassium nickel hexacyanoferrate (KNiFC). The synthesized biosorbent was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) N 2 adsorption-desorption, vibrating-sample magnetometry (VSM), and a thermal analysis method (themogavimetry-differential thermogravimetry, TG-DTG). The adsorption performance of the biosorbent was then evaluated for uptake of Cs + , and influencing variables were optimized by response surface methodology (RSM). An R 2 value of 0.9994 for the second-order polynomial indicated that the predicted data were in accordance with experimental data. The maximal adsorption capacity of 149 mg/g obtained for the synthesized adsorbent was superior to the values reported for previously studied adsorbents. The adsorption achieved at equilibration within 61.68 min, and the cesium uptake was selective in the presence of Na + and K + ions. The used sorbent was easily separated using a magnetic field and regenerated, keeping 85% of its initial capacity after five regeneration cycles. The adsorption data were well fitted to the Langmuir model, indicating a monolayer and homogeneous adsorption process.