Performance of novel adsorbent prepared by magnetic metal-organic framework (MOF) modified by potassium nickel hexacyanoferrate for removal of Cs + from aqueous solution

Abstract

Abstract In the current study on the basis of metal organic frameworks (MOFs) a new adsorbent is developed for efficient removal of Cs + from aqueous solutions. MOF, HKUST-1 prepared by a simple, rapid and efficient method was magnetized and the magnetized adsorbent was impregnated with potassium nickel hexacyanoferrate (KNiFC); a promising adsorbent for Cs + removal. The magnetic nanocomposite was characterized by X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR), Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), Energy Dispersive Analytical X-ray (EDAX), Vibrating sample magnetometer (VSM) and Thermogravimetry Analysis (TGA) techniques. MOF/KNiFC adsorbent exhibited high adsorption affinity (K d = 1.5 × 10 3 ), high adsorption capacity (153 mg·g −1 ). The selectivity of the adsorbent towards Cs + in the presence of Na + and K + ions was excellent. The removal process was kinetically fast and the equilibration was established within 45 min. The used adsorbent was efficiently separated from the solution by applying external magnetic field. The regenerated adsorbent retained 85% of its initial capacity after five regeneration cycle. The adsorption data analyzed by Langmuir and Freundlich models. The data best fitted to the Langmuir equation indicating that the adsorption process was monolayer and homogeneous. The positive values of ΔH° indicated the endothermic nature of the sorption process and suggested that chemisorption was the predominant mechanism. The negative value of ΔG° indicated that the sorption reaction was spontaneous and more favorable at higher temperature.