Physico-Chemical Aspects on Uranium and Molybdenum Extraction from Aqueous Solution by Synthesized Phosphinimine Derivative Chelating Agent

To retain uranium and molybdenum ions from G.Gattar leach liquor (GI), North Eastern Desert, Egypt, a new fabricated chelating 3-mercapto-2-trioctyl phosphinimine propionic acid (MTPP), was functionalized. Specifications for MTPP chelating ligand were successfully completed by utilizing a variety of methods. Enhanced experimental factors controlling, namely; pH, shaking time, initial uranium and molybdenum conc., MTPP dosage, A/O phase ratio, temp. and stripping agents, have been achieved. At 25 °C, pH 2 for uranium and 3.5 for molybdenum, 30 min shaking for uranium and 40 for molybdenum and 4.08 × 10–3 mol/L, MTPP/kerosene has a maximum retention power of 135 and 173.5 mg/g for uranium and molybdenum respectively. From the stoichiometric calculations point of view, approximately 1 mol of MTPP can chelate 1 mol of uranium and 3 mol of MTPP can chelate 1 mol of molybdenum. According to kinetic aspects, pseudo-second order kinetic model well interpret the extraction of U6+ and Mo6+ by MTPP giving a retention power of 131.57 mg/g for uranium and 175.43 mg/g for molybdenum. The distribution isotherm (McCabe–Thiele), predicts three theoretical extraction stages necessary to extract nearly all the uranium and molybdenum ions at an A/O ratio of 1/2 for uranium and 1/1.7 for molybdenum ions respectively, while in stripping, four and three theoretical stripping stages are needed. Based on thermodynamic regards, the extraction process by MTPP was predicted as an exothermic with a -ΔH, spontaneous with a -ΔG, and advantageous extraction at low temperatures with a small –ΔS for uranium and molybdenum ions. Uranium and molybdenum ions may be stripped successfully from the loaded MTPP/kerosene by 2 M H2SO4 with 99% efficiency. The enhanced optimized variables were finally put to use to produce uranium and molybdenum concentrate (Na2U2O7, MoO3) with 65.23% uranium content and 87% purity and 60.37% molybdenum content and 90.53% purity.