Simultaneous Adsorption of Th(IV) and U(VI) Ions from Aqueous Solutions by a Tannic-Acid-Modified Nanomagnetite Adsorbent

Abstract

Nuclear wastewater remediation provides an intriguing opportunity to successfully remove and recover radioactive elements, especially Th(IV) and U(VI) ions, since they play a crucial role as nuclear fuel and pose a significant threat to the sustainability of the environment. In the present investigation, magnetic nanoparticles were modified by a polyphenolic compound, tannic acid (TA), to develop a tannic acid@magnetite (TA@Fe 3 O 4 ) nanocomposite for effective adsorption of Th(IV) and U(VI) ions from wastewater. To more accurately predict the effective adsorption of the ions, adsorbents varying in the mass ratio of TA and Fe 3 O 4 were synthesized, and also the practical utility of the adsorbent was evaluated by employing batch adsorption studies under the conditions of pH, adsorbent dosage, contact time, and initial concentration. The maximum removal efficiency, i.e., 99.42% and 92.63% for Th(IV) and U(VI) ions, respectively, was obtained with a 1:2 ratio of TA@Fe 3 O 4 at pH 6 with 6 mg of absorbent dosage of 10 mL of 50 ppm thorium and uranium solution in 20 min. Further, the experimental data were attributed to the isotherms and kinetic models, corresponding the adsorption system with the Langmuir model of the isotherm and pseudo-second-order kinetics, thus revealing the monolayer chemisorption process of adsorption for both ions. The TA@Fe 3 O 4 nanocomposite exhibited high recyclability with seven adsorption–desorption cycles via magnetic separation, indicating its potential application in wastewater treatment. Hence, on the basis of facile, low-cost precursors for large-scale manufacturing and excellent recyclability, this work presents a potential and promising strategy of the TA@Fe 3 O 4 nanocomposite for enhanced removal of radionuclides for wastewater reclamation.