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1.
A macroporous silica-based supramolecular recognition absorbent (Calix[4]?+?Dodecanol)/SiO2?CP, was prepared by successive impregnation and fixing the 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-Calix[4]arene (Calix[4]arene-R14) and its molecule modifier 1-Dodecanol onto SiO2 silica-based polymer support. The characterization of (Calix[4]?+?Dodecanol)/SiO2?CP was examined by thermal gravimetry and differential thermal analysis and electron probe microanalysis. Relatively large separation factors of Cs and other metal ions (?? Cs/M n+ ) above 60 were obtained in the presence of 3?M HNO3. The adsorption data of Cs(I) fitted well with Langmuir isotherm and the maximum adsorption capacity was estimated to be 0.19?mmol?g?1. The Cs(I) in 3?M HNO3 were also effectively adsorption on (Calix[4]?+?Dodecanol)/SiO2?CP in the column operation, and the loaded Cs(I) was successfully eluted with an eluent of H2O. The column packed with (Calix[4]?+?Dodecanol)/SiO2?CP had excellent reusability after three cycles.  相似文献   

2.
Porous LiAl-layered double hydroxides (LiAl-LDHs) of [Li2Al4(OH)12](CO3)·4H2O were hydrothermally synthesized in one-pot by mixing LiCl, AlCl3, urea, and one surfactant each (sodium dodecyl sulfate (SDS), octadecyl amine (OA), and sodium lauryl sulfonate (SLS)) as soft templates. The LiAl-LDHs were granulated by crosslinked sodium alginate. The LiAl-LDHs were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and porosity. Special attention was focused on the rise of Li+ adsorption capacity based on the porous morphology in synthetic and real salt lake brine. The adsorption capacity of granulated LiAl-LDHs-SLS reaches 8.48 mg/g in a solution containing 300 mg/L of Li+ at pH = 7 and 11.8 mg/g from Da Qaidam brine with 1.0 g/L of Li+. Lithium adsorption followed the Langmuir isotherm and pseudo-second-order kinetics. Temperature, solution pH, and other electrolytes had a minor effect on the adsorption performance of porous LiAl-LDHs. The structure of surfactants had a significant influence on the porosity of synthesized LiAl-LDHs, and thus on the adsorption capacity.  相似文献   

3.
To separate Cs(I) from highly active liquid waste, a macroporous silica-based 25, 27-bis(iso-propyloxy)calix[4]arene-26,28-crown-6 (BiPCalix[4]C6) supramolecular recognition material, BiPCalix[4]C6/SiO2–P, was synthesized and characterized by SEM, FT-IR, and TG-DSC. The adsorption properties of BiPCalix[4]C6/SiO2–P and a macroporous polymer-based supramolecular recognition composite, BiPCalix[4]C6/XAD-7, were compared. It was found that BiPCalix[4]C6/SiO2–P exhibited better adsorption ability and faster adsorption dynamics than BiPCalix[4]C6/XAD-7. The adsorption isotherm of Cs(I) onto BiPCalix[4]C6/SiO2–P was studied at 298 K and it was well described by Langmuir isotherm model. The complex composition between BiPCalix[4]C6/SiO2–P and Cs(I) was determined as 1:1 type by investigating the effect of the concentrations of BiPCalix[4]C6, Cs(I), and H+ on the adsorption. Meanwhile, the selectivity of BiPCalix[4]C6/SiO2–P towards Na(I), K(I), Rb(I), Cs(I), Sr(II), Ba(II), Ru(III), Mo(VI), La(III), and Y(III) was investigated.  相似文献   

4.
UiO-66 and chitosan/UiO-66 composites were successfully synthesized by varying the mass addition of chitosan which were 0%, 2.5%, 5%, 10%, and 20% of the mass of UiO-66, denoted as UiO-66, Cs(2.5)/UiO-66, Cs(5)/UiO-66, Cs(10)/UiO-66, and Cs(20)/UiO-66, respectively. UiO-66 was modified with chitosan using the impregnation process. The X-ray diffraction patterns of the synthesized materials showed characteristic peaks at 2θ of 7.25° and 8.39°, which matched to that of the reported UiO-66. In addition, the Fourier transform infrared spectroscopy spectra of the materials showed absorption bands at the same wavenumber as UiO-66 and chitosan previously reported. The surface morphology of UiO-66 observed from scanning electron microscopy images was in the form of agglomerated small cube particles, where the smaller particles were observed for Cs(10)/UiO-66. From the N2 adsorption isotherms, it was found that the Brunauer-Emmett-Teller surface areas of UiO-66, Cs(5)/UiO-66, and Cs(10)/UiO-66 materials were 825.7 m2/g, 835.4 m2/g, and 882.2 m2/g, respectively. The results of the study on adsorption of methyl orange in aqueous solutions showed that Cs(5)/UiO-66 had the highest adsorption capacity of 370.37 mg/g and followed the pseudo–second-order adsorption kinetic with a Langmuir isotherm model.  相似文献   

5.
Sorption of Na(I), Cs(I) and Co(II) radionuclides from aqueous solutions by titanosilicate have been investigated. The time dependent studies for metal ions showed relatively rapid sorption kinetics between 5 and 30 min to reach equilibrium. A batch adsorption model based on assumption of the pseudo-second-order mechanism was applied to predict the sorption rate, while the equilibrium capacity was calculated at different temperatures. The adsorption of different radionuclides onto titanosilicate was found to be favored at high ions concentrations and low temperature for Na+ and Co2+ while at high temperature for Cs+. Activation energy of adsorption was computed to be 2.35, 24.11 and 5.74 kJ/mol for adsorption of Na(I), Cs(I) and Co(II), respectively. The results revealed that the adsorption of Cs+ is the highest relative to Na+ and Co2+ at different conditions which may be attributed to its low hydration energy. Further, the equilibrium isotherm for the interested ions was analyzed and it was found to obey Frundlich equation.  相似文献   

6.
《中国化学快报》2020,31(10):2835-2838
In this paper, a novel mesoporous silica gel evenly doped by Prussian blue nanoparticles (PBMSG) was successfully synthesized by using N,N-dimethylamide as template with a large Barrett-Emmett-Teller (BET) surface area of 505 m2/g and an average pore size of 2.9 nm. The static adsorption experiments showed that the equilibration time of PBMSG for Cs+ was about 30 min. The adsorption isotherm of PBMSG for Cs+ accorded with Langmuir model and the theoretical maximum adsorption capacity was 80.0 ± 2.9 mg/g. When the initial concentration of Cs+ was 1.00 mg/L, the adsorption partition coefficient Kd could reach 3.5 × 104 mL/g After adsorption, Cs+ could be eluted by dilute hydrochloric acid (pH 2) with an efficiency of 89.8%, while no K+, Fe3+, Fe2+ was eluted. PBMSG exhibited good selectivity toward Cs+ and Rb+. In the presence of high concentration of K+, the selective adsorption of PBMSG could change the mass ratio of K+, Rb+ and Cs+ from 96.63:0.83:1.00–1.12:0.73:1.00. The separation of Cs+ and Rb+ from K+ with similar concentration (100 mg/g) was realized by column experiment. This indicated that PBMSG was suitable for rapid recovery of low concentration of rubidium and cesium from complex matrixes, such as wastewater and salt lake brine, etc.  相似文献   

7.
Based on gradient anion exchange chromatography (AEC), a new strategy in As-speciation was evaluated. A narrow bore chromatographic system with lower flow rates (≤300 μL) well suitable for the low flow requirements of higher efficiency nebulizers was splitless coupled to a high resolution sector field ICP MS. The AEC system takes full advantage of the detector sensitivity allowing more diluted samples (50–100 times) to be injected, delivering substantially less sample matrix to the column and a lower eluent load to the plasma. The unique plasma compatibility of the NH4NO3-eluent salt used in this study enabled high linear salt ramps in gradient applications, highly reproducible retention times (±1%) and detection limits in the low ng/L range. The separation conditions were applied on two different polymeric anion-exchangers: a low capacity, weakly hydrophobic material (AS11, Dionex) and a more frequently used higher capacity, higher hydrophobic material (AS7, Dionex). On both columns, As-species (As(III/V), MMA, DMA, AsB) and Cl were separated in less than nine minutes and co-elution was circumvented by adapting the separation pH to the optimal column selectivity. The key-advantage of the NH4NO3-eluent is that it can adopt any separation pH without compromising the eluent strength which is not possible with all other eluents used so far. The influences of chloride and methanol were investigated and found not to affect the chromatographic performance. Column deposits caused strong reversible As(v) adsorption which reduced As(v) to As(III). A corresponding phosphate excess in the injected sample eliminated the adsorption and prevented artefacts in As(v)/As(III) ratios. The method applied to ground water samples provided robust separations and is compatible with any sample preservation procedure.  相似文献   

8.
采用失重法、电化学阻抗谱(EIS)、极化曲线、X射线光电子能谱仪(XPS)及扫描电子显微镜(SEM)研究了CO2饱和的3.5%NaCl腐蚀介质中,咪唑啉季铵盐(IAS)与十二烷基磺酸钠(SDSH)对Q235钢的缓蚀协同效应.结果表明,IAS与低浓度SDSH在腐蚀介质中具有较好的缓蚀协同效应,且当二者以1:1(50 mg·L-1:50 mg·L-1)的浓度比例复配时,协同效应最明显,缓蚀率为88.5%;而IAS与高浓度SDSH间会产生拮抗效应.本文通过建立合理的吸附模型,阐述了协同效应及拮抗效应的机理.SDSH与IAS在Q235钢表面的吸附过程均为放热的自发过程,前者符合Frumkin吸附模型,后者符合Temkin吸附模型.单独使用较高浓度的SDSH对Q235钢也有较好的缓蚀作用,缓蚀率接近90%.  相似文献   

9.
The composition of nickel hexacyanoferrate(II) complexes depends on the ratios of sodium hexacyanoferrate(II) and nickel nitrate solutions mixed. The adsorption behavior of nickel hexacyanoferrate(II) is described; acid treatment of Ni2Fe(CN)6 accelerates the adsorption rate of cesium, but does not increase the adsorption capacity. The Ni—Cs exchange ratios of Ni2Fe(CN)6 are discussed. In concentrated salt solutions, the distribution coefficients of 59Fe, 60Co, 65Zn. 137Cs, 95Zr and 144Ce are determined together with those of 85Sr and 106Ru. A simple determination of 137Cs in sea water containing 59Fe, 60Co, 65Zn, 95Zr, 144Ce, 85Sr and 106Ru is described.  相似文献   

10.
The ammonium molybdophosphate–silica (AMP–SiO2) nano-composites were prepared by sol–gel method. The material synthesized was nanocrystalline, with average crystallite size of primary particles in the range of 10–25 nm. Small angle X-ray scattering showed presence of mass fractal aggregates made of small particles with rough pore boundaries. To realize the scope of using AMP–SiO2 nano-composites sorbent for removal of 137Cs from nuclear waste solutions, its adsorption characteristics for cesium were evaluated. It was found that the AMP–SiO2 nanocomposites were amenable for column operation, have high affinity for Cs, and possess very high adsorption capacity for Cs. From the perspective of separation of 137Cs from acidic radioactive waste solution, AMP–SiO2 nanocomposite holds significant promise.  相似文献   

11.
The title subject has been studied by galvanostatic single-pulse, chronopotentiometric and equilibrium measurements on the Zn(Hg)/Zn(II) electrode in x M KI+(1?x) M KCl (x from 0 to 1), 1 M KBr and 1 M MeCl (Me=Li, Na, K and Cs) solutions of pH 3 at 25°C. Quantitative information about the effect of specifically adsorbed halides on the rates of the Zn(II)/Zn(I) and the Zn(I)/Zn(Hg) steps is obtained separately (for the latter step mainly at potentials near ?1.0 V(SCE)), and the latter step seems to be more influenced than the former by the adsorption. An attempt is made to correlate the adsorption effect on the rate of the Zn(II)/Zn(I) step to double-layer parameters according to recent models for such effects. The extra current observed at potentials where the halides are adsorbed, seems to vary with the surface activity of the specifically adsorbed ion. The lack of any observed kinetic effect of Cs+, which is specifically adsorbed at these potentials, is possibly due to the Cs+ specific adsorption enhancing the Cl? specific adsorption and vice versa, so that the decelerating and accelerating effects by these ions may cancel each other.  相似文献   

12.
An improved solvent extraction procedure for iodine separation from brine samples has been applied at Xi’an Accelerator Mass Spectrometry (AMS) center. Oil in the brine sample has to be removed to avoid appearance of the third phase during solvent extraction and to improve the chemical yield of iodine. The small amount of oil remained in the water phase was first removed by phase separation through settling down sufficiently based on their immiscibility, and then by filtration through a cellulose filter, on which oil was absorbed and removed. After oil removed, extraction recovery of iodine could achieve more than 90 %. The sodium bisulfite as an effective reductant should be added before acidification to avoid loss of iodine by formation of I2 in sample via reaction of iodate and iodide at pH 1–2, and then pH was adjusted to 1–2 to reduce the iodate to iodide followed by oxidation of iodide to I2 and solvent extraction to separate all inorganic iodine. As a pre-nuclear era sample, 129I/127I ratio in brine is normally more than two orders of magnitude lower than that in present surface environmental samples, so prevention of cross-contamination and memory effect in apparatus during processing procedure are very critical for obtaining reliable results, and monitoring the procedure blank is very important for analytical quality of 129I. The 129I/127I isotopic ratio in the brine samples and procedure blank of iodine reagents were measured to be (1.9–2.7) × 10?13 and 2.08 × 10?13, respectively, 3–4 orders of magnitudes lower than that in environmental samples in Xi’an, and the result of procedure blank is in the same level as the previous experiments in past 3 years, indicating contamination is not observed in our method.  相似文献   

13.
For source identification, measurement of 135Cs/137Cs atomic ratio not only provides information apart from the detection of 134Cs and 137Cs, but it can also overcome the application limit that measurement of the 134Cs/137Cs ratio has due to the short half-life of 134Cs (2.06 y). With the recent advancement of ICP-MS, it is necessary to improve the corresponding separation method for rapid and precise 135Cs/137Cs atomic ratio analysis. A novel separation and purification technique was developed for the new generation of triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-MS/MS). The simple chemical separation, incorporating ammonium molybdophosphate selective adsorption of Cs and subsequent single cation-exchange chromatography, removes the majority of isobaric and polyatomic interference elements. Subsequently, the ICP-MS/MS removes residual interference elements and eliminates the peak tailing effect of stable 133Cs, at m/z 134, 135, and 137. The developed analytical method was successfully applied to measure 135Cs/137Cs atomic ratios and 135Cs activities in environmental samples (soil and sediment) for radiocesium source identification.  相似文献   

14.
The possibility has been investigated of separating rare-earth fission fragment elements from106Ru and137Cs by high-temperature sublimation (950°C) of chlorides, with their subsequent gas adsorption separation in a quartz tube under a temperature gradient in a flow of the carrier-gas Ar+SOCl2. The temperature corresponding to the maxima of the element precipitation zones are: 630–660°C (144Ce), 770–780°C (0.7–6 μg140La+La), 920°C (1.5 mg Ce or La), 420–450°C (106Ru), 280–300°C (137Cs). The coefficients of element separation have been calculated. For the separation of indicator amounts of rare-earth elements and106Ru and137Cs, fractional sublimation of the chlorides of the latter at 650°C has been used. Rate constants and effective activation energies of the overall processes of chlorination-sublimation of the elements have been determined.  相似文献   

15.
Non-isothermal thermal studies of the dehydration of the double salt hydrates of the type M(I)2SO4·M(II)SO4·6H2O and their D2O analogues were carried out where M(I) = TI(I) and M(II) = Mg(II), Co(II), Ni(II), Cu(II) or Zn(II). Thermal parameters like activation energy, order of reaction, enthalpy change, etc. were evaluated from the analysis of TG, DTA and DTG curves. These thermal parameters were compared with those of other series, like NH4(I), K(I), Rb(I) and Cs(I) studied earlier. On deuteration the nature of dehydration altered in the case of Tl2Zn(SO4)2·6H2O only. The thermal stability of the salt hyd discussed in relation to the salt hydrates of other series. The role of divalent cation on the thermal properties of dehydration of salt hydrates is also discussed. The order of reaction was always found unity. The values of ΔH were within ≈12–≈16 kcal mol?1.  相似文献   

16.
Component solubility in HCl-LiCl-MgCl2-H2O system of high ionic strength at 20℃ was predicted by using the Pitzer's ion-interaction model. The results indicated that the model supplied a very good prediction of the component solubility of the system mentioned above. The values of parameters of β^0, β^1 and C^* of HCl, LiCl and MgCl2 were obtained from optimization of literature data, while those of θMN and ψMNX were calculated from a least-squares optimization procedure to couple activity coefficient with solubility data. According to the ion-interaction model, no additional parameters need to be determined for more complex systems. The study provided theoretical basis for the manufacture process, which was proposed by Gao and employed to extract LiCl and MgCl2·6H2O from salt lake brine.  相似文献   

17.
A novel Rh(III)-imprinted amino-functionalised silica gel sorbent was prepared by a surface imprinting technique for preconcentration and separation of Rh(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher adsorption capacity and selectivity for Rh(III). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Rh(III) was 29.86?mg?g?1 and 11.23?mg?g?1, respectively. The imprinted Rh(III) was removed with 2?mL of 3% thiourea?+?2?mol?L?1 HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Rh(III). The relatively selective factor (αr) values of Rh(III)/Ru(III), Rh(III)/Au(III), Rh(III)/Pt(IV), Rh(III)/Ir(IV), Rh(III)/Pd(II) were 26.7, 39.0 29.2, 28.1, 43.7, respectively, which were greater than 1. The detection limit (3σ) of the method was 0.26?µg?L?1. The relative standard deviation of the method was 1.79% for eight replicate determination of 10?µg of Rh3+ in 200?mL water sample. The method was validated by analysing standard reference material (GBW 07293), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace rhodium(III) in geological samples with satisfactory results.  相似文献   

18.
Clays and specially bentonite are widely used as natural adsorbents for wastewater treatment and as a barrier in landfills to prevent the contamination of subsoil and groundwater by leachates containing radioactive materials. The adsorption of four radionuclides, 134Cs(I), 90Sr(II), 133Ba(II) and 152Eu(III) by an Egyptian bentonite (Bent) and its modified Na+ form (Na-Bent) collected from a deposit within Alexandria governorate was investigated as a function of different parameters. The batch equilibrium technique was used and the kinetic results showed that the equilibrium was mostly reached within 10 min and the kinetic data fit well to the pseudo-second order model. The Langmuir model fits well the experimental data of all metals adsorption on Bent and Na-Bent except for adsorption of 133Ba on Bent, while 152Eu adsorption on Na-Bent fits better to the Freundlich model rather than to the Langmuir. Both Bent and Na-Bent fit well to the D-R model with adsorption energy of E > 8 kJ mol?1 that means that the adsorption reaction is expected to be controlled by both cation exchange and surface complexation reactions. At lower concentrations, the values of distribution coefficient (K d), follow the order of 152Eu > 90Sr > 134Cs > 133Ba for Bent and Na-Bent. The K d of 152Eu is higher than that of 134Cs in Bent up to 150 mg L?1. This order changes at higher concentration where the K d of 134Cs becomes higher than 152Eu after 150 mg L?1 for Bent and after 200 mg L?1 for Na-Bent. Na-Bent is preferred than Bent for the uptake of 90Sr and 134Cs especially at high concentration.  相似文献   

19.
A method was developed for the preconcentration and separation of trace manganese from natural water samples by complexation with dithiocarbamate followed by adsorption onto C18-solid phase extraction column prior to irradiation. The Mn recovery was better than 99.8% without inteference from iron(III) at 5 mg.l-1, copper(II), zinc(II), aluminum(III) and cobalt(II) at 0.5 mg.l-1 and sodium(I), potassium(I), magnesium(II) and calcium(II) at 1 mg.l-1. The separation factor was 100 and the detection limit was 0.01 μg.l-1 with good precision and accuracy with a relative error lower than 3%. The method was applied to the determination of Mn in tap, well, river and treated water samples. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

20.
With the gradual exhaustion of land mineral resources, oceans and lakes have attracted world attention because they are abundant in inorganic mineral resources including lithium, potassium, rubidium and cesium. Lithium is becoming the key material in manufacturing of primary and secondary batteries used in various portable devices and hybrid/electric vehicles. Rubidium has been widely applied inglobal positioning satellites, magneto‐optic modulators, solid‐state lasers, phosphors, and glass manufacturing. In this work, a novel dual‐functional magnetic ion imprinting polymer (Fe3O4@SiO2@IIPs) powder was prepared using 12‐crown‐4 (12C4) and 18‐crown‐6 (18C6) as functional monomer, and characterized by FT‐IR, elemental analysis, XRD, TGA, SEM and TEM. The adsorption performance of Fe3O4@SiO2@IIPs for simultaneous adsorption of lithium and rubidium from simulative salt lakes was evaluated by batches of experiments at various pH values, contact time, and initial concentrations. Kinetic experiments show that the adsorption process followed the pseudo second order kinetic model. Langmuir adsorption isotherm model and Freundlich adsorption equilibrium data were fitted; the results show that Langmuir isotherm model is more suitable for the adsorption process. Additionally, Fe3O4@SiO2@IIPs exhibit specificity towards Li(I) and Rb(I) and low competitive behavior with Na(I), K(I) and Mg (II). Additionally, the selectivity properties, reusability and adsorption thermodynamic were also investigated. The obtained results show that the prepared Fe3O4@SiO2@IIPs material remains high adsorption capacities after five cycles, exhibits excellent abilities to simultaneously and selectively recover Li+ and Rb+ and have a promising application in the simultaneous adsorption of lithium and rubidium ions.  相似文献   

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