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1.
The adsorption of uranium (VI) using tetraphenylimidodiphosphinate (Htpip) was studied. Factors of affecting sorption efficiency have been investigated and results showed the adsorption of uranium (VI) was equilibrium at pH 4.5, time 20 min, adsorbent dosage 0.005 g and initial concentration 50 mg L?1 reaching 99.86 mg g?1 of adsorption capacity and 99.86% of removal efficiency. Additionally, the interfering ions studies showed that the adsorbent possessed excellent adsorption selectivity of uranium (VI). The surface morphology of Htpip was investigated by SEM. The adsorption process of uranium (VI) onto Htpip fit the pseudo-second-order kinetic model and the Freundlich isotherm model very well.  相似文献   

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In this paper, the modified magnetic chitosan resin containing diethylenetriamine functional groups (DETA-MCS) was used for the adsorption of uranium ions from aqueous solutions. The influence of experimental conditions such as contact time, pH value and initial uranium(VI) concentration was studied. The Langmuir, Freundlich, Sips and Dubinin–Radushkevich equations were used to check the fitting of adsorption data to the equilibrium isotherm. The best fit for U(VI) was obtained with the Sips model. Adsorption kinetics data were tested using pseudo-first-order and pseudo-second-order models. Kinetic studies showed that the adsorption followed the pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. The present results suggest that DETA-MCS is an adsorbent for the efficient removal of uranium(VI) from aqueous solution.  相似文献   

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Journal of Radioanalytical and Nuclear Chemistry - Using steel slag as a raw material, a new type of adsorption material has been prepared by acid modification method. The preparation conditions of...  相似文献   

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The biomass pummelo peel was chosen as a biosorbent for removal of uranium(VI) from aqueous solution. The feasibility of adsorption of U(VI) by Pummelo peel was studied with batch adsorption experiments. The effects of contact time, biosorbent dosage and pH on adsorption capacity were investigated in detail. The pummelo peel exhibited the highest U(VI) sorption capacity 270.71?mg/g at an initial pH of 5.5, concentration of 50???g/mL, temperature 303?K and contacting time 7?h. The adsorption process of U(VI) was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it followed both the Langmuir adsorption isotherm and the Freundlich adsorption isotherm. The thermodynamic parameters values calculated clearly indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that the pummelo peel has potential application in the removal of the uranium(VI) from the radioactive waste water.  相似文献   

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Adsorption of U(VI) from aqueous solution by cross-linked rice straw(CRS) was studied with batch experiments. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR). The effect of contact time, initial pH, temperature, adsorbent amount and initial U(VI) concentration was investigated. Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption isotherms and two kinetic models of pseudo-first-order and pseudo-second-order were used to describe the adsorption process. The result showed that the adsorption process was highly pH dependent and the favorable initial pH was 5.0. The adsorption process was rapid within first 60 min and equilibrium reached at 100 min. The adsorption process could be well defined by the Langmuir isotherm and pseudo-second-order equation, which indicated that the chemical adsorption was the rate-limiting step. The thermodynamic parameters (?H°, ?S°, ?G°) of the adsorption system were also calculated. The negative value of ?H° and ?G° indicated that the reaction was endothermic and spontaneous in nature. All the above suggested that CRS has considerable potential for the removal of U(VI) from aqueous solution.  相似文献   

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Uranium is a toxic and radioactive heavy metal found in nuclear effluents and should be treated based on environmental considerations. The adsorption of uranyl cations (UO2 2+) by apricot shell activated carbon (ASAC) was investigated in a batch system. The effects of pH, contact time, temperature, adsorbent dosage on the adsorption kinetics and equilibrium adsorption isotherms of U(VI) were examined. The U(VI) uptake was fast within the first 60 min and reached an equilibrium state at 120 min. The adsorption process was highly pH dependent and the maximum adsorption was obtained at an initial solution pH of 6.0. Temperature over the range 25–45 °C had little effect on the U(VI) adsorption. The U(VI) removal efficiency increased concurrently with increasing ASAC dosage, whereas the U(VI) adsorption capacity decreased with increasing ASAC dosage. The adsorption process followed both Langmuir and Freundlich isotherms. On the basis of Langmuir model, the maximum adsorption capacity was found to be 59.17 mg U(VI)/g adsorbent. The adsorption kinetics can be very well defined by the pseudo-first-order rate model. The present results suggest that ASAC could be used as an adsorbent for an efficient removal of U(VI) from aqueous solution.  相似文献   

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Direct reduced iron (DRI), also called sponge iron, was used for the removal of U(VI) from aqueous solution. Batch experiments were conducted to evaluate the effect of various factors including contact time, solution pH, DRI dosage and initial uranium concentration on this removal process. The result suggested that U(VI) can be rapidly removed by DRI and this removal process followed an apparent first-order reaction kinetics. The optimum pH for uranium removal was between 2.0 and 4.0. Whether U(VI) can be fully removed was influenced by the molar ratio of DRI to U(VI) in solution. The aqueous U(VI) can be removed completely when this ratio was more than ca. 1,000. The U(VI) removal capacities of DRI decreased with increasing DRI dosages at a constant concentration of U(VI), but increased almost linearly with increasing initial U(VI) concentrations at a fixed dosage of DRI. The maximum U(VI) removal capacity was 5.71 mg/g DRI. Finally, the possible mechanism of U(VI) removal by DRI was also discussed. The XPS and XRD analysis showed that U(VI) was deposited as UO3 onto DRI surface, indicating that U(VI) can be removed without reduction.  相似文献   

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High surface area, ordered nanoporous carbon (CMK-3) and its chelating polymer composites were successfully prepared and utilized for the removal of U(VI) from aqueous solutions. Carboxymethylated polyethyleneimine (CMPEI) with a strong chelating property was introduced to the pore surface and inner pores of CMK-3 substrate. CMPEI-modified CMK-3 composite (CMPEI/CMK-3) was characterized by scanning electron microscopy and nitrogen sorption. U(VI) sorption capacity was significantly improved by the surface modification of CMK-3 by CMPEI. The CMPEI/CMK-3 showed enormously increased sorption capacities, compared with those of previous sorbents (e.g., surface-functionalized silicas). In particular, the CMPEI/CMK-3 showed a significantly high uranium retention property while allowing only about 1% U(VI) to leach out over a 4 month time period, when treated with polyacrylic acid.  相似文献   

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The sulfonated mesoporous carbon (CMK-3-SO3H) prepared by functionalizing mesoporous carbon (CMK-3) via vapor transfer method has been explored for the removal and recovery of uranium from aqueous solutions. The influences of different experimental parameters such as solution pH, initial concentration, contact time and temperature on adsorption were investigated. The results showed that CMK-3-SO3H has the highest uranium sorption capacity at initial pH of 5.0 and contact time of 120 min, and the adsorption process could be better described by the pseudo-second-order model and Langmuir isotherm. Selective adsorption studies showed that the CMK-3-SO3H could selectively remove of U(VI), and the selectivity coefficients of mesoporous carbon in the presence of co-existing ions, Mg(II), Zn(II), Mn(II), Cu(II), Ni(II), Sr(II) and Hg(II) improved after functionalization.  相似文献   

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This work aimed at investigating a novel chelating resin (PTDTR) containing acyl and thiourea groups for the removal of Ag(I) from aqueous solution by adsorption tests, FTIR, scanning electron microcopy (SEM), BET and XPS analyses. The maximum adsorption capacity of Ag(I) ions obtained from Langmuir model was 6.078?mmol/g at 30?°C. The uptake of Ag(I) on resin was found to follow liquid film diffusion and pseudo-second-order model. Thermodynamic parameters showed that the adsorption process of Ag(I) ions onto PTDTR resin was spontaneous and endothermic under nature conditions. The regeneration test indicated that PTDTR resin have good stability and the adsorption capacity decreased 2.7% after five cycles of adsorption-desorption. In addition, PTDTR resin showed good selectivity for Ag(I) ions in Ag(I)-Cu(II) binary system. The results of SEM suggested that Ag(I) adsorbed on the surface of PTDTR. The FTIR and XPS analyses further confirmed Ag(I) ions might chemisorb onto PTDTR surfaces through its acyl and thiourea groups.  相似文献   

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The removal of uranium from aqueous solution by hydromagnesite and its calcination products was investigated. Through the study, we found that the adsorption capacities of hydromagnesite, magnesium carbonate and magnesium oxide for uranium could reach 342.96, 493.79, 2154.14 mg g?1, respectively. The high temperature will reduce the activity of magnesium oxide, resulting in the adsorption capacity decrease. The results indicate that the optimum pH for the heat-treated samples was 3.0–4.5 and for hydromagnesite 6.0–7.0. Thermodynamic parameters such as ?G, ?H and ?S, indicated that the adsorption processes are spontaneous and endothermic.  相似文献   

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Sorption of51Cr(VI) by MnO2 has been studied as a function of pH and ionic concentration in the presence of certain added cations and anions. The findings are explained in the light of deprotonation/hydroxyl ion association reaction on oxide surface and its subsequent interaction with the tracer. Infrared spectroscopy has shown the chemical interaction of Cr(VI) on the surface of MnO2. The influence of certain interfering ions has been shown on the sorption of51Cr(VI) on MnO2 surface. An attempt has been made to concentrate traces of51Cr under optimum experimental conditions. The experimental observation shows that the activity sorbed under specified conditions can be recovered appreciably by leaching the pre-adsorbed carrier.  相似文献   

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