Removal of uranium(VI) and thorium(IV) from aqueous solution by Hedera helix leaves: kinetics and thermodynamic studies

In this research, Hedera helix leaves were evaluated for biosorption of uranium(VI) and thorium(IV) ions from aqueous solution. H. helix leaves were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and scanning electron microscope. Biosorption of uranium(VI) and thorium(IV) ions using a batch technique by H. helix leaves was evaluated as a function of metal concentration, adsorbent dose, contact time, pH and temperature. The results of biosorption kinetic show that biosorption of U(VI) and Th(IV) by H. helix leaves was well described by the pseudo-second-order kinetic model. Negative values of Gibbs free energy Delta G degrees indicate the spontaneity of the biosorption process on H. helix leaves, while the positive values of enthalpy Delta H degrees indicate the endothermic process. The biosorption isotherm was better fitted by Langmuir isotherm, with a maximum biosorption capacity of 3.86 and 5.16 mg/g for U(VI) and Th(IV) respectively. Desorption studies show that 75% of U(VI) was recovered using 0.1 M HNO3 after four cycles, while 87.7% of Th(IV) was recovered using 1.0 M HNO3 after four cycles.

Automated summary

This study investigated the biosorption of uranium and thorium ions using Hedera helix leaves. The biosorption process followed pseudo-second-order kinetics and Langmuir isotherm best described the biosorption isotherm. Desorption studies showed efficient recovery of uranium and thorium using nitric acid solutions after multiple cycles.