A Novel Phosphonated Polyethyleneimine Composite for the Removal of Thorium(iv) and Uranium(vi) Ions from Aqueous Solutions: Kinetic, Isotherm, and Thermodynamic Studies

Hyperbranched polymers are one of the most promising, cost-effective, and important materials sorbents for wastewater treatment. In this study, a newly synthesized hyperbranched Polyethylene-Methylene Phosphine Oxide (PEMPO) was characterized and applied for individual retrieval of Thorium (IV) and Uranium (VI). The impact of the different adsorption parameters, namely interactions contact time, the measure of pH, ionic force, metallic concentration, and temperature additionally to metal adsorption kinetics, was studied using a batch adsorption process. Experimental results displayed that PEMPO had a bigger metal ion adsorption capacity for uranium (VI) than for thorium (IV) and pHint significantly affected the extraction yield, with an optimum yield of 5.8  for uranium (VI) and 3.6 for Thorium (IV). Moreover, the sorption kinetics exhibited successful adherence to a pseudo 2nd order. Langmuir’s pattern isotherm was well fitted to the adsorption equilibrium measurements for both metals compared to Temkin, Freundlich, and Dubinin Radushkevich isotherms. The sorption capacities of Uranium (VI) and Thorium (IV) ions were 200.1 and 28.6 mg/g respectively. Also, the addition of (KCl, KSCN) increased the extraction capacity, which showed the existence of a synergistic ionic force for the removal process. Thermodynamic analysis showed that the adsorption mechanism for both metals showed an endothermic nature and progressively became more spontaneous as the degree of freedom increased. The outcomes of the desorption study indicated that the best eluents for the recovery of thorium and uranium ions were sulphuric acid and hydrochloric acid, respectively. After three cycles, the PEMPO resin can be regenerated for reuse, with a desorption efficiency still above 85%. These results concluded that PEMPO could potentially be applied for the extraction of metals from water.