Synthesis of Porous Magnetic Ni_0.6Fe_2.4O₄ Nanorods for Highly Efficient Adsorption of U(VI)

Abstract

In this study, porous magnetic Ni0.6Fe2.4O4 nanorods (MNs) were successfully synthesized just by calcining the Ni0.6Fe2.4C2O4·2H2O precursor. MNs exhibited porous structure with disorderly nanorods based on the characterizations. Experimental results showed that the removal of U­(VI) by MNs can reach equilibrium within 150 min at 293 K with a maximal adsorption capacity of 57.7 mg/g. Besides, the adsorption performance was highly dependent on solution pH values, while ion strength and ion species had little influence. The U­(VI) adsorption onto the MNs was fitted better by the pseudo-second-order kinetic model, and the isothermal data can be better described by the Langmuir model, suggesting a monolayer adsorption process. Thermodynamic studies indicated the adsorption process to be spontaneous and endothermic. In addition, this magnetic material can achieve convenient separation using an external magnet. Hence, the MNs can be utilized as an effective candidate to enrich and separate U­(VI) from aqueous solutions.

Facile Synthesis of Phytic Acid Impregnated Polyaniline for Enhanced U(VI) Adsorption

“…The parameters calculated from the pseudo-first-order and the pseudo-second-order kinetic models are listed in Table . The adsorption process can be well described by the pseudo-second-order kinetic model equation according to the correlation coefficient ( R 2 = 0.997), implying that the adsorption is chemisorption. , And the calculated equilibrium adsorption capacity q e.cal is 55.6 mg/g which is consistent with the experimental value ( q e.exp = 49.4 mg/g).…”

“…Also, the theoretical maximum adsorption capacity is about 87.0, 106.7, 107.3, and 114.3 mg/g for PA-PANI-3 at 308, 318, 328, and 338 K, respectively. These results demonstrated that the adsorption capacity of PA-PANI-3 is higher than that of pure PANI and some other adsorbents, for example, the calcon carboxylic acid grafted polyacrylamide (18.8 mg/g, pH = 5.5), porous magnetic Ni 0.6 Fe 2.4 O 4 (57.7 mg/g, pH = 5.0), activated carbon (25.5 mg/g, pH = 3.0), graphene oxide (86.2 mg/g, pH = 3.0), reduced graphene oxide (74.1 mg/g, pH = 4.0), polypyrrole (87.7 mg/g, pH = 5.0), but is lower than some reported adsorbents, such as the PA-based adsorbent (PA/PANI/FeOOH, 555.8 mg/g, pH = 8.0) and Zeolitic Imidazolate Framework-67 (1683.8 mg/g, pH = 4.0) . Therefore, it is desired to improve the adsorptive capacity of this adsorbent by choosing suitable substrate material in which PA groups can act as a functional group in the future.…”

“…To obtain the adsorption process mechanism of U­(VI) onto PA-PANI-3, two adsorption kinetics models, namely, pseudo-first-order and pseudo-second-order kinetic models were used to fit the data. ,, The relevant equations are expressed as follows: where q t (mg/g) and q e are the adsorption capcities of U­(VI) at contact time t and at equilibrium time. k 1 (1/min) and k 2 (g/(mg/min)) are the rate constants of the pseudo-first-order and the pseudo-second-order kinetic models, respectively.…”

“…The Δ G values are calculated as approximately −20.5, −21.8, −23.0, and −25.4 kJ/mol at 298, 308, 318, and 338 K, respectively. The negative values of Δ G imply that the adsorption is a spontaneous process and at high temperature favors a more negative value of Δ G . , …”

“…Nowadays, energy crisis and environmental issue has become the crucial factor restricting the social development and economic growth. Uranium, has been considered as the dominant nuclear fuel to produce nuclear energy, but the toxicity of the heavy metal and radioactivity in nuclear waste that can result in groundwater contamination that threatens human health and ecosystem stability cannot be ignored. , Therefore, to develop a method or material for efficient removal of U­(VI) from radioactive wastewater is crucial.…”