Maghemite nanoparticles bearing di(amidoxime) groups for the extraction of uranium from wastewaters

Abstract

Polyamidoximes (pAMD) are known to have strong affinities for uranyl cations. Grafting pAMD onto the surface of functionalized maghemite nanoparticles (MNP) leads to a nanomaterial with high capacities in the extraction of uranium from wastewaters by magnetic sedimentation. A diamidoxime (dAMD) specifically synthesized for this purpose showed a strong affinity for uranyl: Ka = 105 M-1 as determined by Isothermal Titration Calorimetry (nano-ITC). The dAMD was grafted onto the surface of MNP and the obtained sorbent (MNP-dAMD) was characterized. The nanohybrids were afterward incubated with different concentrations of uranyl and the solid phase recovered by magnetic separation. This latter was characterized by zeta-potential measurements, X-Ray Photoelectron Spectroscopy (XPS) and X-Ray Fluorescence spectroscopy (XRF), whereas the supernatant was analyzed by Inductively Coupled Plasma coupled to Mass Spectrometry (ICP-MS). All the data fitted the models of Langmuir, Freundlich and Temkin isotherms very well. These isotherms allowed us to evaluate the efficiency of the adsorption of uranium by MNP-dAMD. The saturation sorption capacity (qmax) was determined. It indicates that MNP-dAMD is able to extract up to 120 mg of uranium per gram of sorbent. Spherical aberration (Cs)-corrected High-Resolution Scanning Transmission Electron Microscopy (HRSTEM) confirmed these results and clearly showed that uranium is confined at the surface of the sorbent. Thus, MNP-dAMD presents a strong potential for the extraction of uranium from wastewaters.

Improvement in Heavy Metal Removal from Wastewater Using an External Magnetic Inductor

“…The solids that are generated after the adsorption process can be separated from the aqueous solution by centrifugation or filtration, but this implies additional cost and time of cleaning treatments [7]. Adsorption with magnetic NPs has been of great interest in recent years [21,22,23,24,25]. Magnetic materials offer the possibility of being easily extracted from contaminated areas by means of a magnet.…”

Preparation of Mesoporous Carbon from Sodium Lignosulfonate by Hydrothermal and Template Method and Its Adsorption of Uranium(VI)

“…Uranium is one of the most widely used radioactive elements. However, uranium is highly toxic in all of its oxidation states, which has caused a potential environmental and health risk to the biosphere through water pollution. − Therefore, the removal and enrichment of uranium from wastewater are necessary in order to avoid environmental contamination and save uranium resources. At present, a variety of methods have been used in uranium­(VI) removal and enrichment process, including ion exchange, , coagulation sedimentation, and adsorption. , Among those methods, adsorption has attracted a great deal of attention from scientists because of its process simplicity, wide application range, and high removal efficiency without releasing harmful byproducts …”