Pore-Free Matrix with Cooperative Chelating of Hyperbranched Ligands for High-Performance Separation of Uranium

Abstract

A new strategy combining a pore-free matrix and cooperative chelating was proposed in the present paper in order to effectively avoid undesired nonselective physical adsorption and intraparticle diffusion caused by pores and voids in porous sorbents, and to greatly enhance uranium-chelating capability based on hyperbranched amidoxime ligands on the surface of nanodiamond particles. Thus, a pore-free, amidoxime-terminated hyperbranched nanodiamond (ND-AO) was designed and synthesized. The experimental results demonstrate that the strategy endows the as-synthesized ND-AO with the following expected features: (1) distinctively high uranium selectivity (S = q-U/q-tol × 100%) from over 80% to nearly 100% over the whole weak acidity range (pH < 4.5); especially, the S can reach up to unprecedented >91% at pH 4.5, more than 20% of selectivity increment over any analogous sorbent materials reported so far, with a uranium sorption capacity of 121 mg/g in simulated nuclear industry effluent samples containing 12 coexistent nuclide ions; (2) superfast equilibrium sorption time of <30 s; and (3) one of the highest distribution coefficients (K) of ∼3 × 10 mL/g for U(VI) as well as a fairly high sorption capacity of 212 mg/g at pH 4.5 in pure uranium solution. The strategy could also provide an optional approach for the design and fabrication of other new high-performance sorbing materials with prospective applications in selective separation of other interested metal ions.

Preparation of Porous Carbon Materials Derived from Hyper-Cross-Linked Asphalt/Coal Tar and Their High Desulfurization Performance

“…The adsorption rate of CHAS-1 is much faster than those of most kindred porous materials, whose equilibrium time ranges from tens of minutes to several days. 46 Hereafter, the influence of dosage of adsorbent, volume and concentration of model oil on adsorption kinetics behavior of CHAS-1 is further studied. As illustrated in Figures S13−S16, CHAS-1 can reach adsorption equilibrium in 5 min under chosen experimental conditions.…”

“…As shown in Figure , the curve of DBT uptake increases rapidly and reaches adsorption equilibrium in one minute. The adsorption rate of CHAS-1 is much faster than those of most kindred porous materials, whose equilibrium time ranges from tens of minutes to several days . Hereafter, the influence of dosage of adsorbent, volume and concentration of model oil on adsorption kinetics behavior of CHAS-1 is further studied.…”

Highly Efficient Removal of Uranium from Aqueous Solution Using a Magnetic Adsorbent Bearing Phosphine Oxide Ligand: A Combined Experimental and Density Functional Theory Study

“…However, most of these magnetic adsorbents often suffer from many drawbacks such as low adsorption capacity and poor selectivity. Generally, the removal efficiency and selectivity for uranium mainly depends on the functional groups of the adsorbents − Among the various organic ligands studied for the entrapment of uranium from aqueous media, phosphine oxide ligand has attracted extensive attention owing to its strong complexation with uranium. − Thus, the adsorbents functionalized with phosphine oxide ligand have been widely used for the removal of uranium, exhibiting excellent adsorption efficiency in uranium separation. − However, the traditional modification method to introduce phosphine oxide ligand onto the adsorbents was often by a wet-chemistry method, , which has many drawbacks including complexity, substrate dependency and a high speed of waste manufacture. Meanwhile, the amount of phosphine oxide groups introduced onto the adsorbents through a wet-chemistry method is also limited, due to a difficult and time-consuming surface activation is often required during the process of direct bonding of functional groups to the adsorbents matrix.…”

Preparation of Polyamidoxime/Magnetic Graphene Oxide Composite and Its Application for Efficient Extraction of Uranium(VI) from Aqueous Solutions in an Ultrasonic Field

“…Up to now, most research focuses on the application of adsorbents for uranium­(VI) removal due to its ease of operation, low cost, efficiency and wide adaptability. Many adsorbents such as magnetic materials, activated carbon, metal organic frameworks, ion-imprinted polymer, and other materials have been used to eliminate U­(VI) from aqueous solutions. − Nevertheless, it is still a challenge to develop efficient adsorbents for the removal of U­(VI) with high adsorption capacity, high adsorption speed, reusability, and high selectivity.…”