Sorption study of uranium from aqueous solution on ordered mesoporous carbon CMK-3

Adsorptive extraction of uranium (VI) from seawater using dihydroimidazole functionalized multiwalled carbon nanotubes

The adsorptive extraction of uranium (VI) was investigated using multiwalled carbon nanotubes functionalized with dihydroimidazole (DIM-MWCNTs). Dihydroimidazole was grafted onto the surface of MWCNTs via silane coupling agent, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole. The new adsorbent was characterized using Fourier transform infrared, scanning electron microscope and X-ray Photoelectron Spectroscopy. DIM-MWCNTs were compared with MWCNTs and amidoxime modified MWCNTs (AO-MWCNTs) for uranium adsorption under seawater conditions. The adsorption capacity of uranium onto DIM-MWCNTs was 54.9 mg g−1 at 298 K, which was about 4 times of MWCNTs and similar to that of AO-MWCNTs. Compared with AO-MWCNTs, DIM-MWCNTs were more suitable for seawater pH, and less affected by vanadium. Although DIM-MWCNTs were more affected by carbonate than AO-MWCNTs, DIM-MWCNTs maintained a higher adsorption capacity than AO-MWCNTs due to its alkali resistance. Pyridine-like nitrogen (CH=N–CH) contributed to the adsorption of uranium. The results suggested that DIM-MWCNTs were a potential effective adsorbent for the separation of uranium under seawater condition.

Simultaneous reduction and adsorption for immobilization of uranium from aqueous solution by nano-flake Fe-SC

Uranium containing radioactive wastewater is seriously hazardous to the natural environment if it is being discharged directly. Herein, nano-flake like Fe loaded sludge carbon (Fe-SC) is synthesized by carbothermal process from Fe-rich sludge waste and applied in the immobilization of uranium in aqueous. Batch isotherm and kinetic adsorption experiments are adopted to investigate the adsorption behavior of Fe-SC to uranium in aqueous. XPS analyses were conducted to evaluate the immobilized mechanism. It was found that the carbonized temperature played significant role in the characteristics and immobilization ability of the resulted Fe-SC. The Fe-SC-800 carbonized at 800°C takes more advantageous ability in immobilization of uranium from aqueous than the commercial available AC and powder zero valent iron. The adsorption behavior could be fitted well with the Langmuir isotherm adsorption model and pseudo-second order model. The equilibrium adsorption amount and rate for Fe-SC-800 is high to 148.99mgg^-1 and 0.015gmg^-1min^-1, respectively. Both reductive precipitation and physical adsorption are the main mechanisms of immobilization of uranium from aqueous by Fe-SC-800.

The synthesis and characterization of tributyl phosphate grafted carbon nanotubes by the floating catalytic chemical vapor deposition method and their sorption behavior towards uranium

An efficient method for grafting tributylphosphate onto carbon nanotubes (CNT-TBP) is described. CNT-TBP exhibited excellent adsorption towards U(vi) ions.

Facile functionalized of SBA-15 via a biomimetic coating and its application in efficient removal of uranium ions from aqueous solution

A novel dopamine-functionalized mesoporous silica (DMS), synthesized by grafting dopamine onto a mesoporous molecular sieve (SBA-15), was developed as a sorbent to extract U(VI) from aqueous solution. The method used to modify SBA-15 was simple, facile and cost-effective. The DMS was characterized by SEM, TEM, XRD and BET, showing that the material had an ordered mesoporous structure and a large surface area. The effect of contact time, pH, ionic strength, temperature, and solid-liquid ratio on the sorption process was investigated. It was demonstrated that the adsorption of U(VI) by DMS was fast and that it can be described by the pseudo-second order-equation where the equilibrium time was 20 min. Additionally, the adsorption isotherm data were fitted well by the Langmuir model with the maximum adsorption capacity of DMS of 196 mg/g at pH 6.0. Furthermore, the influence of the K(+) and Na(+) concentrations and solid-to-liquid ratio on the sorption was very weak, and the values of the thermodynamic parameters revealed that the sorption process was exothermic and spontaneous. All the results suggested that the DMS could be used as an excellent adsorbent to remove U(VI) from aqueous solution.

Studies on salophen anchored micro/meso porous activated carbon fibres for the removal and recovery of uranium

Stringent environmental regulations emphasize the removal of uranium from aqueous systems.