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Three types of magnetic mesoporous silicas (MMSs), namely, MMCM-41, MMCM-48 and MSBA-15 were prepared by a hydrothermal method using CTAB and P123 as templates. The structure and physicochemical properties of MMSs were characterized by small angle XRD, VSM, ζ potential analyzer, contact angle measurer, and XPS, etc. The potential applications of MMSs in U(VI) recovery were thoroughly investigated. The adsorptive kinetics, thermodynamics, and selectivity of MMCM-41, MMCM-48 and MSBA-15 were compared. The results show that MSBA-15 revealed a high capacity for U(VI) (341.94 mg·g−1) and a superior selectivity than MMCM-41 and MMCM-48. The adsorption mechanism was explored by using the relevant adsorption models and XPS. The results indicated that MSBA-15 could be considered a strong candidate for the adsorption and recovery of U(VI) from radioactive wastewater. [ABSTRACT FROM AUTHOR]

Amorphous titanium phosphates (ATP) doped with NH4+, K+, Na+, and Li+ ions (ATP-M, M = NH4, K, Na, and Li) were prepared by a co-precipitation method. The SEM&EDS, TGA, XRD characterizations displayed that ATP-M was successfully synthesized, and the doping of NH4+, K+, Na+, and Li+ ions did not change the crystal form of ATP. The results revealed that the optimum pH value for U(VI) extraction on ATP-M was determined to be 5.0. Moreover, the saturated adsorption capacity obtained by the Langmuir equation for ATP-NH4, ATP-K, ATP-Na, and ATP-Li was 505.1, 366.1, 273.3, and 144.1 mg g−1, respectively. Furthermore, the interaction between ATP-M and U(VI) was discussed. In short, ATP-NH4 may be an effective adsorbent to remove of U(VI) in wastewater due to its high adsorption ability. [ABSTRACT FROM AUTHOR]

The material of magnetic amorphous titanium phosphate (MATP-x-T, where x was the dosage of Fe3O4, T was synthesis temperature) was successfully synthesized and confirmed by various experimental characterization methods (FT-IR, XRD, SEM, and Zeta potential), and its adsorption property for U(VI) removal was evaluated. The adsorption of U(VI) on MATP-x-T were explored through batch experiments. The optimal value of x and T was 0.5 g and 70 °C, respectively. The saturated adsorption capacity of MATP-0.5-70 was 401.5 mg g−1 for U(VI) at 298.15 K. The U(VI) adsorption was well explained by the pseudo-second order kinetic model. The possible mechanism of the adsorption of U(VI) was explored based on XPS and FTIR analysis. MATP-0.5-70 could be employed as an auspicious candidate for U(VI) removal radioactive wastewater. [ABSTRACT FROM AUTHOR]

In this work, hexadecyltrimethylammonium-bromide (HTAB)-modified polythiophene (PTh)/TiO2 nanocomposite (HTAB/PTh/TiO2) was applied to remove uranyl ions (UO22+). FT-IR, XRD, ζ potential, TGA, SEM, and XPS were utilized to obtain the chemical and physical properties of HTAB/PTh/TiO2. The effects of HTAB content, preparation temperature, and adsorption conditions on UO22+ removal were investigated comprehensively. And the UO22+ adsorption process on HTAB/PTh/TiO2 was fitted to the Sips model with a saturated adsorption capacity of 234.74 mg/g, which was 6 times over TiO2. The results suggested that the surfactant of HTAB can significantly improve the adsorption ability of TiO2 for UO22+ ions. This work provides a strategy of surfactant modification for enhancing the separation and recovery ability of adsorbent toward UO22+ in the radioactive wastewater. [ABSTRACT FROM AUTHOR]

Mesoporous carbon (MC) functionalized with an amino group (MC–NH2) was prepared via a nitro-reduction strategy. TEM, FT-IR, porosity meter, and acid–base titration were utilized to obtain the physicochemical properties of MC–NH2. A batch adsorption experiment was conducted for U(VI) with MC–NH2. According to the results, the adsorption reached equilibrium at approximately 120 min under the optimal pH of 5.0, and the monolayer saturated adsorption capacity (qms) of MC–NH2 was up to 385.98 mg·g−1 for U(VI). Accordingly, adsorption of U(VI) on MC–NH2 exhibits the potential to diminish uranium pollution. [ABSTRACT FROM AUTHOR]

Fudan University (FDU)-type mesoporous polymer (FDU-15) was sulfonated by fuming sulfuric acid. The application of FDU-15 and sulfonated FDU-15 (FDU-15-SO3H/t, t = 9 h, 18 h, or 27 h) in removing of U(VI) was explored comprehensively. The adsorbents were characterized by various techniques. The effects of sulfonation time, initial pH values, shaking time, initial concentrations, and temperature on adsorption were optimized. Besides, the desorption and reusability, as well as adsorptive selectivity were investigated. The results indicated high adsorption (43.65 ± 2.11 mg g−1) was achieved under weak acid condition (pH 2.0) for FDU-15-SO3H/9 h. In short, FDU-15-SO3H/9 h may be a superior adsorbent to remove the U(VI) in wastewater. [ABSTRACT FROM AUTHOR]

An ultralight sulfonated graphene aerogel (GA-SO3H) was synthesized via simply gas phase sulfonation and was adopted to adsorb U(VI) from radioactive wastewater. The characterization confirmed plentiful sulfonate groups on GA-SO3H surfaces. GA-SO3H exhibited high U(VI) sorption capacity with maximum amount of 148.4 mg g−1 and reached maximum separation selectivity of 61.38% at 298 K and pH 5.0 due to the surface complexation between the O atoms of sulfonate groups and uranyl ions. Furthermore, GA-SO3H exhibited satisfied regeneration and excellent structural stability. This paper highlighted ultralight GA-SO3H as an efficient adsorbent for effective adsorption/recovery of uranyl ions from radioactive wastewater. [ABSTRACT FROM AUTHOR]

With the aim of gathering uranium from ground aquatic environment in which uranium mainly occurs in negative species, the montmorillonite (MT) intercalated with cetyltrimethylammonium bromide (CTAB) was fabricated. X-ray diffraction and Fourier transform infrared spectroscopy were utilized to prove the entrance of CTAB into MT. Adsorption of uranium onto CTAB-MT was studied with respect to effect of pH, carbonate, calcium, humic acid, contact time, initial uranium concentration, and temperature. The adsorption negatively depended on pH, carbonate and calcium ion and humic acid concentrations. CTAB-MT had a higher uranium adsorption ability. The maximum monolayer uranium adsorption amount of CTAB-MT calculated by well fitted Langmuir model was determined as 213.31 mg g−1, preceding 82.17 mg g−1 of MT. The adsorption kinetics was well fitted by pseudo-second-order model. The uptake mechanism involved ion exchange and electrostatic attraction. The adsorption was endothermic and spontaneous. The results demonstrated CTAB-MT was promising to separate uranium from ground water. [ABSTRACT FROM AUTHOR]

Hydrothermal carbon spheres (HCSs) functionalized with 4-aminoacetophenone oxime group (HCSs-oxime) were prepared by a grafting method and explored to adsorption of uranyl ions from aqueous solution. The results of FT-IR, elemental analysis and zeta potential indicate a successfully modification with oxime group. The adsorbent shows an excellent adsorption capacity (Langmuir, q = 588.2 mg g) and quick adsorption kinetic (equilibrium time of approximately 60 min) at optimal pH of 6.0. The adsorptive selectivity for uranyl ions has been also great improved in present with various co-existing ions. Overall, HCSs-oxime is a potentially promising material for selective removal of uranium in the contaminated solution. [ABSTRACT FROM AUTHOR]

Abstract: An interpenetration network (IPN) ion-imprinting hydrogel (IIH) was synthesized using uranyl ions as template for adsorption and removal of uranyl ions from aqueous solutions. The IIH was obtained via cross-linking of blended chitosan/polyvinyl alcohol (PVA) using ethylene glycol diglycidyl ether (EGDE). The ability of the IIH to adsorb and remove uranyl ions from aqueous solutions was assessed using a batch adsorption technique. The maximum adsorption capacity was observed in the pH range of 5.0–6.0. The adsorption process could be well described by both the Langmuir and Freundlich isotherms and the maximum adsorption capacity calculated from Langmuir equation was 156mg/g. Equilibrium was achieved within 2h. The kinetic data, obtained at optimum pH 5.0 could be fitted with to a pseudo-second order equation. The selectivity coefficient of uranyl ion and other metal cations on IIH indicated an overall preference for uranyl ions which was much higher compared with the non-imprinted hydrogel. This suggests that the IIH is a promising sorbent material for the selective removal of uranyl ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Hydroxyapatite samples doped with different metal ions (HAP-M, M ​= ​Cu, Sr, Al, Ce, and Ti) were successfully prepared by a simple co-precipitation method for effective U(VI) uptake. The applications of HAP-M in capturing U(VI) were investigated. Besides, numerous characterizations were taken to study the chemical and physical properties of HAP-M. The critical factors affecting U(VI) adsorption were examined, such as pH, contact time, initial concentration of U(VI) and solution temperature. The present study revealed that the adsorption effect of HAP for U(VI) can be affected by doping metal cations with different ionic radii, and HAP doping with Ti4+ ions increased its adsorption selectivity to U(VI). With the increase of the molar ratio of doped Ti4+ ions (5%–20%), the adsorption selection of U(VI) on HAP-Ti is also gradually increasing. HAP-Ti is a potentially efficient adsorbent in removing U(VI) from radioactive solutions. Hydroxyapatite samples doped with different metal ions (HAP-M, M ​= ​Cu, Sr, Al, Ce, and Ti) were successfully prepared by a simple co-precipitation method for effective U(VI) uptake. The applications of HAP-M in capturing U(VI) were investigated. Besides, numerous characterizations were taken to study the chemical and physical properties of HAP-M. [Display omitted] • In this paper, we systematically investigated the effect of direct doping of cations with different ionic radii into HAP on its structure and physicochemical properties, and explored their effects on U(VI) adsorption. • The as-synthesized novel metal cation-doped hydroxyapatite (HAP-Ti) exhibited better adsorption selectivity for U(VI) than other prepared hydroxyapatites. [ABSTRACT FROM AUTHOR]

Highlights: [•] In situ polymerization PANI–CMK-3 first applied to adsorption of uranium. [•] PANI–CMK-3 has a greater potential for removing of uranium compared to CMK-3. [•] PANI–CMK-3 has strong ability for selective adsorption of uranium and high desorption rate. [ABSTRACT FROM AUTHOR]

A simple hydrothermal method was adopted to synthesize different inorganic-organic hybrid materials (Zr -x), including zirconium ethylenediamine tetramethylene phosphine (Zr-EDTMP), 2-phosphobutane-1,2,4-zirconium tricarboxylate (Zr-PBTC), odium creatine phosphate zirconium phosphate (Zr-CP), and creatinol zirconium phosphate (Zr–COP). Various characterizations were utilized to explore the physical and chemical properties of materials. The applications of Zr -x in removing U(Ⅵ) were studied comprehensively. The effects of solution's pH value, contact time, initial concentration of U(Ⅵ), and temperature on adsorption were examined. Besides, the desorption, reusability, as well as adsorptive selectivity were investigated. The present study revealed that the U(Ⅵ) adsorption on Zr-EDTMP was in accordance with Sips isothermal model with the greatest adsorption capacity (317.4 ​mg/g) and the superior adsorptive selectivity for U(Ⅵ). Zr-EDTMP is a potentially high-efficient adsorbent for extracting U(Ⅵ) from radioactive wastewater. A simple hydrothermal method was adopted to synthesize different Zr(IV) organophosphate hybrids Zr- x (including zirconium ethylenediamine tetramethylene phosphine (Zr-EDTMP), 2-phosphobutane-1,2,4-zirconium tricarboxylate (Zr-PBTC), odium creatine phosphate zirconium phosphate (Zr-CP), and creatinol zirconium phosphate (Zr–COP)). And, the Zr- x hybrids were applied in removal of U(VI). [Display omitted] ∙Four Zr(Ⅳ) organophosphate hybrids have been prepared by a hydrothemal method. ∙The adsorptive kinetics and isothems of Zr(Ⅳ) organophosphate hybrids were investigated. ∙Zr-EDTMP displayed superior adsorption capacity (317.43 ​mg/g) and selectivity. [ABSTRACT FROM AUTHOR]

Using a co-impregnation technique, Sr-doped hydroxyapatite (HAP-Sr) loaded in magnetic mesoporous carbon (MMC) was successfully prepared. Extensive characterization was performed on MMC, HAP-Sr, and the composite (MMC/HAP-Sr) to determine their properties. In addition, their U(VI) adsorption capacities were thoroughly investigated. The key factors influencing U(VI) adsorption were investigated. In accordance with the results, the equilibrium of MMC/HAP-Sr on U(VI) was reached within 10 min. In addition, the substance's theoretical saturation capacity was 1229.9 mg·g−1. XRD and XPS tests showed the sorption of U(VI) by MMC/HAP-Sr is mainly via precipitation and complexation with hydroxyl (-OH) on the surface. Thus, MMC/HAP-Sr is an excellent adsorbent for the treatment of radioactive wastewater containing U(VI). [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel millimeter-sized carbon-based supramolecular recognition material (C4BisC6/MMCs-P) were innovatively designed to separate Cs(I). • The maximum adsorption capacity for Cs(I) was 24.18 mg·g−1 superior to most currently-reported adsorbents. • The optimal adsorption acidity was 3.0 mol∙L-1 HNO 3 , which was similar with the common HLLW. • C4BisC6/MMCs-P showed excellent structural stability, satisfactory regeneration and reusability. The efficient removal of Cs(I) from high-level liquid wastewaters (HLLW) is vital to the environmental remediation and development of nuclear energy. Herein, the novel millimeter-sized carbon-based supramolecular recognition material (C4BisC6/MMCs-P) were designed and constructed by coating polystyrene-divinylbenzene onto millimeter-sized hierarchically porous carbon spheres as matrix immobilization of calix[4]biscrown-6 (C4BisC6). The unique structure endows C4BisC6/MMCs-P with millimeter-sized, convenient recycling, and high selective adsorption capacity for Cs(I). The C4BisC6/MMCs-P-5 (where the weight percent of C4BisC6 was 28.4 %) achieved the greatest distribution coefficient of Cs(I) (225.79 mL·g−1), which is almost nine times higher than that of C4BisC6/MMCs. The optimal adsorption acidity was 3.0 mol∙L-1 HNO 3 that was similar acidity of common HLLW. The maximum adsorption capacity of Cs(I) by C4BisC6/MMCs-P-5 was 22.72 mg·g−1, surpassing to most currently-reported adsorbents. Meanwhile, C4BisC6/MMCs-P-5 showed high selectivity for Cs(I) competing with cations (Rb+, K+, Na+, Sr2+ and Ba2+). This work paves an efficient strategy for separation of Cs(I) from HLLW by ingeniously designing a supramolecular recognition material C4BisC6/MMCs-P-5 to address environmental contamination issue. [ABSTRACT FROM AUTHOR]

In this study, a 10%Fe-ZIF-8-300-PO 4 adsorbent was synthesized and its adsorption performance for U(VI) was investigated comprehensively. It was found that after a series of operations such as Fe doping, thermal activation and phosphorylation, the adsorption performance for U(VI) can be significantly improved on the basis of maintaining the skeleton characteristics of ZIF-8. The results showed that the optimal Fe-doping amount and thermal activation temperature was 10% and 300°C, respectively. The adsorption of U(VI) on 10%Fe-ZIF-8-300-PO 4 reached equilibrium within 60 ​min, and conformed to pseudo-second-order kinetic equation. Furthermore, a maximum saturated adsorption capacity of 691.83 ​mg/g was achieved. The above results demonstrated that 10%Fe-ZIF-8-300-PO 4 may be used to efficiently remove U(VI) from uranium-containing radioactive waste water. The 10%Fe-ZIF-8-300-PO 4 showed good adsorption performance for U(VI). After the thermal activation process, the Fe(II) active site was exposed, and the part of U(VI) was converted to U(IV) by redox reaction while the U(VI) was absorbed. Phosphate group can complexe with UO 2 2+, which increased the adsorption capacity and selectivity of the 10%Fe-ZIF-8-300-PO 4 by some extent. [Display omitted] • A new adsorbent was obtained by Fe doping, thermal activation and phosphorylation. • Their synergistic effects obviously improve the adsorption performance for U(VI). • 10%Fe-ZIF-8-PO 4 -300 has a higher adsorption capacity and faster adsorption rate. • Redox reaction and complexation constitute the main adsorption mechanism. [ABSTRACT FROM AUTHOR]

Synthesizing highly efficient adsorbent materials to remove U(VI) from contaminated water remains a major challenge. Here, using UiO66-NH 2 as a sacrificial template, porous carbons (ZrO 2 @PCs) were prepared by high-temperature calcination, and then a simple strategy was used for phosphorylation modification to prepare the target product ZrO 2 @PCs-PO 4. The microscopic surface morphology and structure of ZrO 2 @PCs-PO 4 characterized by SEM, FT-IR and XRD reveals that phosphate groups has been successful introduced on the surface of ZrO2@PCs-PO 4. Batch experimentation showed that the phosphorylation process improves the adsorption behaviors, and the maximum monolayer adsorption capacity for U(VI) is 496.5 ​mg/g. The adsorption isotherms and kinetics were simulated to explore its adsorption mechanism. The excellent selectivity and reusability ensure this material could apply in selective removal of U(VI) ions. MOF-derived phosphorylated porous carbons (ZrO 2 @PCs-PO 4) were obtained by a simple method. ZrO 2 @PCs-PO 4 shows a higher adsorption capacity (496.5 ​mg/g) and a faster adsorption rate (<30 ​min) for U(VI) in aqueous solution. The results show that ZrO 2 @PCs-PO 4 can be used as a potential adsorbent for the recovery of U(VI) ions in radioactive wastewater. Image 1 • MOF-derived porous carbons were obtained by calcination and phosphorylation. • ZrO 2 @PCs-PO 4 has higher adsorption capacity and faster adsorption rate for U(VI). • Phosphate groups played an important role in the high adsorption performance. • Main removal mechanism included electrostatic attraction and surface complexation. [ABSTRACT FROM AUTHOR]

• Oxidized millimeter-sized hierarchical porous carbon spheres (OMMCs) were fabricated. • OMMCs were applied to adsorb U(VI) originally. • OMMCs showed excellent absorbability, stability and satisfactory reusability. • Inner-sphere surface complexation and electrostatic interaction dominated adsorption. Efficient recovery U(VI) from wastewater by a simple adsorption strategy is a key point to eliminate environmental threats and recycle nuclear energy. Herein, we presented a series of millimeter-sized hierarchically porous carbon spheres (MMCs) with different sizes fabricated via evaporation-induced self-assembly and suspension polymerization. Importantly, the abundant oxygenated groups were introduced on the surface of MMCs (OMMCs) by the HNO 3 oxidation treatment. Thanks to the size effect, the OMMCs-S with size about 0.2 mm exhibits higher adsorption capacity and faster adsorption rate than that of OMMCs-L (size about 1.0 mm). The maximal U(VI) removal capacities on OMMCs-S reaches 232.45 mg∙g−1 at pH value of 4.5 and 298.15 K, which are nearly quadruple as high as that of untreated MMCs. Impressively, the OMMCs-S also exhibits sphere-shape structural stability, excellent regeneration and reusability. Furthermore, the U(VI) uptake reveals that the mainly interaction mechanism is formation of the inner-sphere surface complexation, which is also confirmed by the characterization analysis. Therefore, this research highlights a simple synthesis strategy for OMMCs-S, serving as an efficient adsorbent for the adsorption/recovery of U(VI) from radioactive wastewater. [ABSTRACT FROM AUTHOR]