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In this paper, a novel method was established for determination of fructose 1,6-diphosphate (F-1,6-BP) based on resonance light scattering (RLS), and a type of bipolar tetradentate schiff base H4L was synthesized. The study showed that under the optimization condition with the ligand concentration of 5 nmol mL−1, pH 6.5, the reaction temperature of 25 °C, the reaction time of 30 min, RLS intensity had good linearity with the concentration of F-1,6-BP within the range of 0.4–5.0 nmol mL−1, the limit of detection was 0.16 nmol mL−1 and the relative standard deviation (RSD) was 1.83%. In vitro feasibility study, four groups of medical injections and two groups of human urine were analyzed, the RSD of six parallel experiments was approximately 2%, and the recovery value changed from 98.0 to 102.5%. As shown herein, this method has high sensitivity, good precision and recovery. [ABSTRACT FROM AUTHOR]

In this paper, we report a method for the determination of uranium (VI) based on the using of a surface fluorescence sensor containing a europium (III) complex. The sensor was prepared by immobilizing the Eu(III)-salophen complex on a glass slide surface through Si–O covalent bonds. The sensor can generate strong surface fluorescence as a result of the Cation–Cation Interaction between U (VI) and Eu(III). We used this property to design a surface fluorescence sensing method to detect U (VI). Under suitable conditions, the linear range was 0.02–5 nmol mL−1 and the detection limit was 8 × 10−3 nmol mL−1. This method was successfully used in determine U (VI) in real samples with a recovery rate between 99.5 and 103.5%. [ABSTRACT FROM AUTHOR]

In this paper, cheap liquorice residue was used to prepare activated carbon (AC), thioacetamide (TAA) was used to modify the AC, and the adsorption experiments were conducted in the simulated acid radioactive wastewater with low uranium concentration to study the adsorption behavior and mechanism for uranium by TAA modified AC (TAA-AC). The removal efficiency by TAA-AC was 92.1-98.2% from the 1 mg L−1 uranium solution at pH 2-6. The adsorption equilibrium data were well fitted by Dubinin-Radushkevich model, and the maximum adsorption capacity was estimated to be 340 mg g−1. TAA-AC showed an enhanced selectivity for uranium in the presence of competitive ions. Furthermore, the adsorption experiments were conducted in the actual acid radioactive wastewater with low uranium concentration from an in situ leach uranium mine. The high adsorption rate (98.3%) and selectivity (Kd = 3.78×104 mL g−1) for uranium were observed in the actual acid radioactive wastewater, and the adsorption rate was found to maintain 96.2% over six cycles of adsorption-desorption. [ABSTRACT FROM AUTHOR]

In this work, the nanoparticles possessing a macro-initiator (MNPs@SCSOEt) were firstly obtained by surface-initiated RAFT polymerization. The structure of the nanocomposite was characterized by FT-IR, SEM, TEM, TGA, XPS and VSM. The effects of pH, contact time, initial uranium concentrations, coexisting ions and temperature on the U(VI) adsorption by MNPs@PAO were investigated in detail. The adsorption process was found to be in good agreement with pseudo-second order kinetic model and Langmuir adsorption isotherm model. The maximum adsorption capacity was estimated to be 216.45 mg/g by fitting Langmuir model with the equilibrium data. The adsorption process was endothermic and spontaneous. In addition, the adsorption capacity of MNPs@PAO for U(VI) decreased slightly after five successive adsorption/desorption cycles. [ABSTRACT FROM AUTHOR]

The adsorption of U(VI) from low concentration solution by HKUST-1@HPWO was studied as a function of various experimental parameters including pH, interfering ions, contact time, initial uranium concentration and temperature by batch experiments. Equilibrium data were found to fit with Langmuir isotherm model better than Freundlich isotherm model. The kinetic adsorption was fitted by the pseudo-second-order model well. Thermodynamic data from the adsorption experiments indicate that adsorption process is spontaneous and endothermic. HKUST-1@HPWO can selectively adsorb U(VI) from multi-metal ion solutions and the adsorption capacity of HKUST-1@HPWO don't decrease significantly after three cycles of desorption-reuse. The results show that HKUST-1@HPWO is suitable for removal of U(VI) from low concentration solutions. [ABSTRACT FROM AUTHOR]

The anaerobic microcosms amended with 30 mM bicarbonate and without bicarbonate were established, respectively, and the reduction of U(VI) in the microcosms by functionalized indigenous microbial communities was investigated. Results of the chemical extraction and XANES analysis showed that the proportions of U(IV) in the microcosms amended with bicarbonate were 10 % lower than without bicarbonate at day 46. The amount of Cellulomonadaceae, Desulfovibrionaceae, Peptococcaceae and Veillonellaceae amended with bicarbonate was lower than without bicarbonate, so the reduction of U(VI) was less. The experimental results show that the high concentration bicarbonate has a significantly inhibitory effect on the reduction of U(VI). [ABSTRACT FROM AUTHOR]

In order to study the synergistic effects between Azolla and Anabaena in the removal of uranium from wastewater by Azolla-anabaena symbiotic system (AASS), the Azolla without Anabaena (AWA) was separated from the AASS. The removal of uranium by the AWA and the AASS, the growth inhibition, the solution protein contents, the superoxide dismutase, catalase and peroxidase activities under the stress of different uranium solutions were measured and analyzed. The results show that there were synergistic effects between Azolla and Anabaena. [ABSTRACT FROM AUTHOR]

To verifying the feasibility of uranium recovery with fungal metabolic products in large-scale applications, column leaching and ion exchange of uranium was carried out. The uranium recovery reached 81.76 % in 14 days. The ion exchange curve for the leach solution obtained with the metabolic products of Aspergillus niger was in the shape of a wave. The elution curve was similar to that of leaching with HSO. The results indicate that leaching with the metabolic products of A. niger is a promising and environmentally friendly method for exploitation of low grade uranium ores in large-scale applications. [ABSTRACT FROM AUTHOR]

In order to verify whether the U(VI) in groundwater under anoxic conditions can be bioreduced, microcosms were prepared with the uranium contaminated groundwater and sediment, amended with ethanol, lactate and glucose, and incubated under anoxic conditions. After 121 days of incubation, uranium L-edge X-ray absorption fine structure spectra analysis indicated that more than 40 % of the U(VI) was reduced to U(IV) in the amended microcosms, and the initial U(VI) which was bound to C- and P-containing ligands was no longer bound to C-containing ligands after 121 days of incubation. The results show that the U(VI) in groundwater under anoxic conditions can be bioreduced. [ABSTRACT FROM AUTHOR]

The raw sodium feldspar (RSF) is activated with the concentrated sulfuric acid solution and the acid activated sodium feldspar (AASF) is obtained. The results obtained from the mercury intrusion method show that the acidification can increase the porosity and the specific surface area. The effects of the initial pH, contact time and ambient temperature on the adsorption of U(VI) ions are investigated in a batch process. The adsorption efficiency amounts to the highest at pH 6 and the adsorption equilibrium is reached in 600 min. The pseudo-second-order model is found to be more suitable for the adsorption process than the pseudo-first-order model and intra-particle model, indicating that the chemical adsorption is the predominant step for the adsorption process. Langmuir model is found to describe the adsorption process better than Freundlich model. This proves that the main form of U(VI) ions attached to RSF and AASF is the monolayer coverage. The thermodynamic parameters prove that the adsorption process is a spontaneous endothermic one. It was also found that acid activated treatment can help increase the adsorption rate and capacity. The results show that RSF and AASF can be used as a novel low cost adsorbent for removal of U(VI) ions from the low concentration aqueous solution. [ABSTRACT FROM AUTHOR]

The thermally activated sodium feldspar (TASF), a novel material, was prepared by calcinating the micron sodium feldspar (SF) at 450 °C for 45 min. The TASF and the SF were characterized using X-ray diffraction and mercury injection porosimetry, and the TASF was found to have larger specific surface area and larger porosity than SF. The effects of the initial pH, temperature, contact time and initial U(VI) ions concentration on the adsorption of U(VI) ions from the low concentration uranium solution by TASF were investigated. The maximum adsorption efficiency of TASF for 0.5 mg/L uranium solution amounted to 95.49 % when the initial pH was 5.0, the temperature, 318 K, and and the contact time, 600 min. The relationship between the adsorption capacity q and equilibrium concentration C can well be described by Freundlich equation. Adsorption isotherm and the analysis by FT-IR coupled with SEM revealed that U(VI) ions were adsorbed onto the surface of TASF in multimolecular or cluster states, and that the intraparticle diffusion occurred in spontaneous process. The basic thermodynamic parameters including free energy change, entropy change and enthalpy change were calculated to comprehend the intrinsic features and spontaneous nature of the adsorption process. The FT-IR spectroscopic characterization for the TASF indicated that many groups were involved in the adsorption process of U(VI) ions, and the -OH group played a more important role. The experimental results suggested that TASF had great adsorption efficiency and strong potentiality of enrichment and recovery for the low concentration U(VI). [ABSTRACT FROM AUTHOR]

Many kinetic models for heap leaching of low grade ores have been proposed and the model parameters have been treated as constants. However, some of these model parameters change with the depth of the heap. In the present work an apparatus consisted of six columns with different heights was designed and used to simulate the leaching behavior within a 3-m-high uranium ore heap at a uranium mine in South China. It was found that the model parameters α and ω for heap leaching of the uranium ore varied with the depth of the heap, and that the relationships between α and between ω and the depth of the heap were in the form of the logistic and the quadratic functions, respectively. Furthermore, a kinetic model for heap leaching of the uranium ore considering the variation of the model parameters with the depth of the ore was proposed. The kinetic model gave the fitting precision of more than 95 % and prediction precision of more than 93 %. The present work provided an approach for establishing the kinetic model for heap leaching of low grade uranium ores. [ABSTRACT FROM AUTHOR]

Both of culture temperature and pH value had impacts on the degree of uranium extraction through changing types and concentrations of mixed organic acids produced by Aspergillus niger, and significant interactions existed between them though pH value played a leading role. And with the change of pH value of mixed organic acids, the types and contents of mixed organic acids changed and impacted on the degree of uranium extraction, especially oxalic acid, citric acid and malic acid. The mean degree of uranium extraction rose to peak when the culture temperature was 25 °C (76.14 %) and pH value of mixed organic acids was 2.3 (82.40 %) respectively. And the highest one was 83.09 %. The optimal culture temperature (25 °C) of A. niger for uranium leaching was different from the most appropriate growing temperature (37 °C). [ABSTRACT FROM AUTHOR]

Experiments on the removal and recovery of U(VI) from aqueous solution by tea waste were conducted. The adsorbent was characterized by scanning electron microscope and energy dispersive spectrometer before and after the adsorption treatment. The removal of U(VI) amounts to 86.80 % at optimum pH 6. The adsorption process reaches its equilibrium in 12 h at 308 K, and the kinetic characteristic can be described by the pseudo-second-order kinetic equation. The amount of adsorption increases from 22.92 to 142.21 mg g with the decrease of tea waste dosage from 100 to 10 mg for solution with an initial uranium concentration of 50 mg L. Desorption for the four strippants is higher than 80 %. The equilibrium data are more agreeable with Freundlich isotherm than Langmuir isotherm. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the potential ecological danger and toxic effect of uranium mill tailings leaching solution (UMTLS) on aquatic animals. UMTLS was identified to contain two radioactive elements, nine heavy metal elements, and five non-metallic materials. The acute toxicity test indicated that the 1, 12, 24, 48, 72, 96 h LC values of UMTLS to the zebrafish were 12.1, 7.1, 4.4, 3.8, 3.4, and 2.9%, respectively. In sub-lethal toxicity tests, superoxide dismutase, catalase, Na-K-ATPase activities, and malondialdehyde content were respectively determined and analyzed in the zebrafish gill, gonad, muscle, and liver after exposed to four different concentration levels of UMTLS for 7 and 14 days, respectively. The result showed that the most sensitivity of the antioxidant system in zebrafish tissues in UMTLS was gill, and then decreased in gonad, muscle and liver respectively. Na-K-ATPase activity in the liver and gonad may be considered as a reference biomarker of UMTLS stress. The data in this study may be valuable that the toxicity of such as the leaching solution of potentially hazardous material was compared with that of each constituent. [ABSTRACT FROM AUTHOR]