Preparation and characterization of core‐shell structured nanocomposite materials and their adsorption behavior on U (VI) from aqueous solutions

Abstract

Mixed metal hydroxide nanoparticles SnAlFe (OH)x (SAF) was prepared via a rapid coprecipitation method and used in coating two different cores MnO2 and TiO2 to form MnO2@SAF and TiO2@SAF. The prepared adsorbents were characterized carefully by scanning electron microscopy/energy dispersive X‐ray, transmission electron microscopy, atomic force microscope, X‐ray diffraction, and Fourier transformed infrared spectroscopy. The prepared core‐shell nanocomposites used as new adsorbents for U (VI) removal from aqueous solutions in a series of batch experiments. The effect of pH, contact time, initial U (VI) concentration, and temperature were investigated on U (VI) adsorption process. The results showed that the maximum adsorption capacities were 152.9 and 144.7 (mg/g) for MnO2@SAF and TiO2@SAF, respectively, with pH 7 and 293 K. The adsorption kinetics of U (VI) onto both prepared adsorbents followed pseudo‐second order and intra‐particle kinetic models. At the same time, the adsorption isotherms obeyed the Langmuir isotherm model. Thus, the kinetic and the isothermal data reveal the chemisorption of U (VI) on the prepared adsorbents. Thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were calculated from the temperature‐dependent adsorption data. The U (VI) adsorption process on the prepared adsorbents is endothermic and spontaneous. The results show that the adsorbent materials maintain removal efficiency during the first two cycles of the adsorption‐regeneration cycle and then decrease slightly in the third cycle. The results indicate that the prepared adsorbents are potential and suitable candidates for U (VI) adsorption from aqueous solutions.

Polyethyleneimine-functionalized β-cyclodextrin porous polymers for enhanced elimination of U(vi) from wastewater

“…One reason was that the proportion of (UO 2 ) 3 (OH) 7 − and UO 2 (OH) 3 − augmented with increasing pH, which led to a decrease in the concentration of U( vi ) which were exchanged with H + ions on the surface of PEI-PCDP. 47 The other reason was that CO 2 in the air could dissolve in water under relatively basic conditions, and then gradually form a negatively charged uranyl carbonate complex, which enhanced the migration rate of adsorbed U( vi ), was adverse to the fixation of U( vi ) and thus reduced the adsorption quantity. 48 Besides, the net surface charge density became more negative due to the increase in surface OH − ions.…”

Comparative study of synthesized Kaolinite supported-metal oxides for Th (IV) adsorption

“…From the data illustrated in Table 3, the positive value of ∆Hº and the negative value of ∆Gº indicates the adsorption of Th(IV) onto KZn and KCu was endothermic and spontaneous. The positive value of ∆Sº showed increased randomness at the solid-solution interface during the adsorption process [22].…”