One-pot synthesis of pyridine dicarboxamide derivative and its application for uranium separation from acidic medium

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One-pot synthesis of N 2 ,N 2 ,N 6 ,N 6 -tetrakis(2-ethylhexyl)pyridine-2,6-dicarboxamide (EHPyCA ligand) was done by condensation of pyridine-2,6-dicarboxylic acid and di-(2-ethyl-hexyl) amine using polyphosphoric acid (PPA) as catalyst. The EHPyCA ligand was impregnated on Amberlite XAD-7 to form a chelating EHPyCA-AXAD-7 resin that runs for U 6+ ions sorption from G.Gattar leachate solution, North Eastern Desert, Egypt. Experimental measurement parameters were optimized by a batch technique such as contact time, initial U 6+ ions concentration, EHPyCA-AXAD-7 dose, pH, interfering ions, and temperature. The maximum uptake of EHPyCA-AXAD-7 ligand was 76.92 mg·g −1 at pH 7. From the gained result, adsorption equilibrium followed well with the Langmuir isotherm model. The thermodynamic parameters (ΔS°, ΔH°, and ΔG°) were also assessed, and they elaborated that the adsorption process was endothermic and spontaneous in nature. The kinetic study clarified that the U 6+ ions adsorption on EHPyCA-AXAD-7 obeyed the pseudo-first-order kinetic mechanism. U 6+ ions were completely eluted from the loaded EHPyCA-AXAD-7 using 2 M H 2 SO 4 . Finally, the optimized parameters were applied for U 6+ ions recovery from G.Gattar leachate to prepare sodium diuranate concentrate (Na 2 U 2 O 7 ) with a uranium content of 69.88%. • The prepared adsorbent was characterized by SEM-EDX, BET, FTIR, and TGA. • The optimum uptake was realized to 75 mg·g −1 at pH 7 in citrate solution. • The optimum U 6+ ions elution from the U-adsorbent was obtained using 2 M H 2 SO 4 . • The adsorption equilibrium isotherm of the studied adsorbent fitted well for the Langmuir model. • The optimum adsorption parameters were applied on Gattar leachate for U 6+ ions separation.