Synthesis of Amidoxime-Grafted Activated Carbon Fibers for Efficient Recovery of Uranium(VI) from Aqueous Solution

Abstract

A novel fibrous sorbent, amidoxime-grafted activated carbon fibers (ACFs-AO), was prepared using a chemical grafting method and tested for the efficient removal of uranium from aqueous solution. The sorbent was characterized using X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, elemental analysis, thermogravimetric analysis, and Brunauer–Emmett–Teller. The effects of pH, contact time, initial concentration, and temperature on the sorption of U­(VI) were investigated. The sorption of U­(VI) on ACFs-AO obeyed the pseudo-second-order model and Langmuir isotherm. The sorption capacity of ACFs-AO for U­(VI) (about 191.6 mg/g) was much higher than that of activated carbon fibers (ACFs) (about 70.52 mg/g), which was mainly attributed to surface complexation between U­(VI) and the amidoxime group on ACFs-AO. Additionally, the thermodynamic parameter results showed that the sorption process of U­(VI) was spontaneous, feasible, and endothermic. Moreover, ACFs-AO adsorbed U­(VI) selectively in an aqueous solution containing competitive ions, and was regenerated and reused efficiently. The findings of this work indicate that ACFs-AO could be a promising sorbent for the effective removal of U­(VI) from aqueous solution.

Symbiotic Aerogel Fibers Made via In-Situ Gelation of Aramid Nanofibers with Polyamidoxime for Uranium Extraction

“…The first weight loss before 160 °C was ascribed to the evaporation of physically absorbed water. The second weight loss from 160 to 350 °C could be the decomposition of the amidoxime groups [26,41,42]. The third decomposition from 350–500 °C could be regarded to the decomposition of the main chain of PAO.…”

“…Besides, with regard to the practical application of various adsorbents in seawater, more active chelating sites, more feasible materials synthesis along with less cost are critical factors for the design of the optimal adsorbent towards high efficiency [23,24,25,26]. From this point, aerogels as highly porous materials with extremely high specific surface area (SSA) (~1000 m 2 ·g −1 ) and high porosities (~99%) satisfy the above requirements exactly [27,28,29,30,31].…”

Uranium(VI) and zirconium(IV) sorption on magnetic chitosan derivatives – effect of different functional groups on separation properties

“…The deprotonation of reactive groups (which facilitates the tautomerization effect), the progressive formation of neutral (for zirconium(IV)) or polynuclear species (for uranium(VI)) explains the progressive increase in sorption properties. This is consistent with the results reported for uranium(VI) sorption on amidoxime‐functionalized sorbents . In the case of seawater, uranium is negatively charged (being under the form of carbonate species) which can be readily sorbed by positively charged amidoxime‐functionalized polymers .…”

“…This is consistent with the results reported for uranium(VI) sorption on amidoxime-functionalized sorbents. 26,34 In the case of seawater, uranium is negatively charged (being under the form of carbonate species) which can be readily sorbed by positively charged amidoxime-functionalized polymers. 33 Wei et al 55 reported the interest of bi-functionality of polymer sorbents on the recovery of uranium from complex solutions: the presence of uranyl carbonate species may be bound by positively charged reactive groups while neutral species can be bound by chelation on amidoxime groups.…”

“…This intermediary product is chemically modified to produce an amidoxime derivative (AO‐AHC) and a hydrazinyl derivative (HZ‐AHC). These functional groups are recognized for their high affinity for metal ions: amidoxime reactive groups are highly selective for uranium (including in seawater), while hydrazinyl amine groups can bind metal cations or anions with high efficiency depending on metal speciation and pH of the solution . The two functional groups (and more generally the moieties grafted on epichlorohydrin‐activated magnetic chitosan (EPI‐MG‐CH) bear many O and N ligands with affinity for a broad range of metal ions.…”