Extraction Of Sr Research Articles

High extraction efficiency of N,N,N′,N′-tetracyclohexyldiglycolamide for Sr(II): An experimental and crystal structure study

To improve the ability of diglycolamide extractants for the extraction of Sr(II) from high-level waste liquid, N,N,N′,N′-tetracyclohexyl-diglycolamide (TCHDGA) was proposed and studied to extract Sr(II) from nitrate media. TCHDGA was prepared and characterized by 1H Nuclear Magnetic Resonance Spectroscopy (NMR), 13C NMR, and Fourier Transform Infrared Spectroscopy (FT-IR). Various factors affecting extraction were studied systematically. In just 20 s, the extraction rate can reach approximately 98.2 %. The extraction capacity of cyclohexyl-substituted extractant TCHDGA is tens of times higher than that with linear or branched chain alkyl. The chemical structure of the complex has been demonstrated to be [Sr 3TCHDGA]·(NO3)2, based on FT-IR, X-ray Photoelectron Spectroscopy (XPS), and crystal structure analysis. The crystal belongs to the monoclinic system, space group P21, and a strontium ion coordinates with nine oxygen atoms, all of which contribute from TCHDGA. The stripping rate can reach over 99 % when using distilled water or 0.50 mol·L−1 oxalic acid as stripping agents.

A comparison of various XAD-Amberlite resins impregnated with dicyclohexyl-18-crown-6 for strontium removal

In the present study, four different varieties of Amberlite resin impregnated with dicyclohexyl-18-crown-6 were employed as an adsorbent for the selective extraction of strontium ions (Sr2+) from nitric acid solutions and dicyclohexyl-18-crown-6 impregnated in XAD-4 resin shows highest adsorption of Sr2+ from nitric acid solution. The effect of important parameters such as concentration of nitric acidic in the medium, adsorbent dosage, contact time, initial Sr (II) concentration and temperature were investigated in a batch system. The results demonstrated that the adsorption rate is high in the first 30 min and equilibrium was achieved after 300 min at 3 mol/L nitric acid medium. The results of the kinetic evaluations fit excellently with the pseudo-second-order model with a correlation coefficient R2 = 0.998. The prepared adsorbent extracts Sr (II) by following the Langmuir isotherm with a maximum adsorption capacity of 9.17 mg/g. Thermodynamic investigations indicated that the Sr (II) adsorption is an exothermic and spontaneous process. Strontium ions desorbed from resin in an acceptable percentage (98.9%) with double distilled water. In addition, the adsorption capability of the adsorbent in real water samples and also the effect of the existence of coexisting ions on the extraction of Sr (II) were assessed.

Adsorption behavior of trace elements of 90Sr on MnO2–ZrO2 loaded with polyacrylonitrile polymer from aqueous solutions

A MnO2–ZrO2-polyacrylonitrile (MnO2–ZrO2-PAN) composite ion exchanger was produced and its properties were examined by Fourier-transformed infrared spectroscopy, scanning electron microscopy, The BET (Brunauer, Emmett and Teller) surface area, X-Ray diffraction analysis and thermogravimetric analysis. The adsorption of Strontium (Sr) from solutions by MnO2–ZrO2-PAN composite was studied thru batch experiments. The distribution Coefficient of Sr (II) on the composite sorbent was investigated against pH, interaction time, and primary concentration ion. To study the kinetics of adsorption, Pseudo-first-order and Pseudo second-order adsorption kinetics were studied and the results revealed that adsorption kinetics better fit to the pseudo-second-order model. Three iso-temperature models, Langmuir, Freundlich, and Temkin were applied to fit the experimental results. Among those models, Langmuir revealed the most suitable one with minimum deviation. The created composite exhibited strong compatibility to the elimination of Y (III), Ni (II), Pb (II), and Co (II) from radioactive waste streams. On the other, it is evident from the data that the quantifiable extraction of Sr (II) ions from Zr (IV), Mo (VI), and La (III) is feasible. MnO2–ZrO2 Loaded with (PAN) Polymer was figured out to have high ion exchange capacity and thermal stability and selectivity for strontium.

Green recovery of cerium and strontium from gold mine tailings using an adapted acidophilic bacterium in one-step bioleaching approach

BackgroundEnormous amounts of gold mine tailings (GMT) are produced as a result of mineral activities, but these mine tailings produced from previous ore processing still contain significant amounts of elements (e.g. strontium (Sr)) and rare earth elements (REEs) such as cerium (Ce). In this study, extraction of Ce and Sr from GMT using an adapted sulfur oxidizers acidophilic strain for developing a one-step bioleaching was performed for the first time. MethodsDetermination of the optimal conditions by response surface methodology (RSM), for maximizing Ce and Sr recovery, was carried out using influential factors of initial sulfur concentration, pH and pulp density. Significant findingsThe optimal values of pH, pulp density and initial sulfur concentration were 1.8, 2% (w v-1) and 0.55% (w v-1), respectively. The highest sulfate production was obtained in initial sulfur concentration of 0.5% (w v-1). In addition, among the various inhibition kinetic models, Tessier inhibition kinetic model was the most suitable based on the experimental data. In conclusion, the kinetic study of the process indicated that a high recovery of 75.8% of Ce and 86.4% of Sr was achieved from GMT under optimal conditions, where the chemical reaction was revealed to be the rate controlling step. Bioleaching of GMT by A. thiooxidans is a promising technology to reduce the environmental hazards of these wastes. The results showed that GMT can be a source of supply of Ce and Sr.

Sr(ii) extraction by crown ether in HFC: entropy driven mechanism through H2PFTOUD.

The solvent extraction of Sr(ii) was carried out using dicyclohexano-18-crown-6 (DCH18C6) and two HFC mixed solvents MS1 and MS2, where MS1 was composed of 30/60 (w/w)% trans-1,2-dichloroethylene/HFC-43 (HFC-43: 1,1,1,2,2,3,4,5,5,5-decafluoropentane) and MS2 was 5/95 (w/w)% heptane/HFC-43. Nitric acid and perfuruoro-3-6-9-trioxaundecane-1,11-dioic acid (H2PFTOUD) were used to study the effect of acid on the extraction. The maximum distribution ratio of Sr(ii) (DSr) observed for H2PFTOUD conditions was ∼180, and >10 times larger than aqueous nitric acid conditions. The DSr value was influenced by concentrations of the DCH18C6, Sr(ii), and acid, and by temperature. The composition of extracted complexes was estimated using slope analysis as an Sr(ii)–anion–DCH18C6 ratio of ∼1 : 2 : 1. From the extended X-ray absorption fine structure (EXAFS) measurements of Sr(ii) in the aqueous and organic phases, it is inferred that regardless of the acid used, DCH18C6 coordinates to the first coordination sphere of the Sr(ii) extracted complexes and Sr(ii) is hydrated (complexation with H2PFTOUD cannot be distinguished) in the aqueous phase. Thermodynamic data were significantly changed by choice of acid, i.e., both enthalpy and entropy values were negative for nitric acid conditions, on the other hand, entropy values were large and positive for H2PFTOUD conditions. These results have demonstrated that the combination of HFC solvent and crown ether is applicable for metal extraction.

Partitioning of heat generating fission product (137Cs & 90Sr) from acidic medium by 1,3-dioctyloxy-calix[4]arenecrown-6 (CC6) & Octabenzyloxyoctakis[[[(N,N-diethylamino)carbonyl)]methyl]oxy]calix[8]arene (BOC8A) in nitro octane diluent: Batch scale study & process parameter optimization

Partitioning of heat emitting fission product 137Cs & 90Sr in a single solvent extraction step with nearly zero actinide and lanthanide contamination have been studied using a mixture of calixarene based ionophore 1,3-dioctyloxy-calix[4]arenecrown-6 (CC6) & Octabenzyloxyoctakis[[[(N,N-diethylamino)carbonyl)]methyl]oxy]calix[8]arene (BOC8A) in a nitro alkane based diluent nitro octane (NO). A mixture of 0.03 M CC6 and 0.01 M BOC8A in NO showed high selectivity (separation factor greater than 100) towards Cs (Dcs = 4.0) & Sr (DSr = 4.6) with respect to almost all other element except Na (DNa = 0.9), Ba (DBa = 1.48) and Pu (IV) (DPu = 0.4) present in the simulated high level liquid waste (SHLLW). Role of different parameters effecting distribution of Cs & Sr such as equilibration time, feed acidity, extractant concentration, and temperature were evaluated to optimize the condition of extraction and stripping of Cs & Sr. Extraction of Cs & Sr was found to be exothermic in nature. The outcome of this work gives an insight into amenability of co-decontamination of heat generating fission products from high level waste (HLLW) using mixture of BOC8A & CC6 in NO diluent.

Sorbents Based on Bacterial Cellulose for Extraction of Sr, U, Pu, and Am from Solutions

Sorbents Based on Bacterial Cellulose for Extraction of Sr, U, Pu, and Am from Solutions

Mass transfer studies in a micromixer-settler: extraction of Cs and Sr with CCD-PEG-400 solvent from simulated acidic radwaste solutions

Mass transfer studies in a micromixer-settler: extraction of Cs and Sr with CCD-PEG-400 solvent from simulated acidic radwaste solutions

DETERMINATION OF METALS AND RADIONUCLIDES BY NEWEST FUNCTIONALIZED REAGENTS IN LIQUID MEDIA

The conditions for the formation of metal complexes (aluminium, radionuclides) in solutions are considered. The properties of solid extractants (TVEX) and their application for the selective extraction of metals and radionuclides are discussed. The extraction of 90Sr, 90Y, 137Cs and U(VI) radionuclides from aqueous TVEX solutions impregnated with calixarenes C45 and CIP67 has been studied. The use of surfactants in combination with OAR (PA) is a typical example of the fact that the analytical capabilities of even well-known reagents are far from exhausted, and the use of functionalized reagents can significantly improve the basic analytical characteristics of metal detection.

Extraction and kinetic analysis of Pb and Sr from the leaching residue of zinc oxide ore

NH4HCO3 conversion followed by HCl leaching was performed and proven to be effective in extracting Pb and Sr from zinc extracted residual. The mechanism and operating conditions of NH4HCO3 conversion, including molar ratio of NH4HCO3 to zinc extracted residual, NH4HCO3 concentration, conversion temperature, conversion time, and stirring velocity, were discussed, and operating conditions were optimized by the orthogonal test. Experimental results indicate that NH4HCO3 conversion at temperatures ranging from 25 to 85°C follows the shrinking unreacted core model and is controlled by inner diffusion through the product layer. The extraction ratios of Pb and Sr under optimized conditions reached 85.15% and 87.08%, respectively. Moreover, the apparent activation energies of Pb and Sr were 13.85 and 13.67 kJ·mol−1, respectively.

The Sr/Ba ratio response to salinity in clastic sediments of the Yangtze River Delta

The Sr/Ba ratio is a geochemical indicator that distinguishes between terrestrial and marine sedimentary environments in terrigenous clastic sediments. However, conclusions drawn from the Sr/Ba ratio is often inconsistent with those drawn from other sedimentary environment indicators during practical application; therefore, the usability of this indicator is not widely acknowledged. First, to verify this theory and accurately determine the differences between the sedimentary geochemical behaviours of Sr and Ba under different salinity conditions, 14 artificial deltaic sediments were prepared by mixing clean seawater and muddy river water in varying proportions to produce different constant salinities, ranging from 0.0 to 31.2 psu. The Sr and Ba concentrations in the different fractions were then examined via sequential extraction. The experimental results show that, on average, 87% of the total Ba and 65% of the total Sr in the 14 artificial deltaic sediments existed in the residual fraction that is independent of the geochemical conditions of the depositional environment. The experiment also revealed that the decrease in Ba in the sediments was caused by the desorption of adsorbed Ba, owing to the addition of seawater with increasing salinity. Furthermore, the Sr/Ba ratio in the exchangeable fraction yielded a strong linear correlation with salinity, and the Sr/Ba ratio in the carbonate-bound fraction tended to increase slightly with increasing salinity, the Sr/Ba ratios in the FeMn oxide-bound, organic and reductive, and residual fractions, and the total Sr/Ba ratio were not significantly correlated with salinity. Therefore, the Sr/Ba ratio (Sr/Ba-HAc) of exchangeable and carbonate-bound Sr and Ba extracted using dilute acetic acid (HAc) and the Sr/Ba ratio (Sr/Ba-NH4Ac) of exchangeable Sr and Ba extracted using ammonium acetate (NH4Ac) can be used to distinguish between marine and terrestrial sedimentary environments. If the Sr/Ba-HAc or Sr/Ba-NH4Ac ratio in the sediment is >1.0, it can be considered to have been deposited in a sedimentary environment affected by seawater with a salinity >5.0 psu. Second, to verify the aforementioned conclusions, the Sr and Ba in 24 field samples from the Yangtze River Delta were extracted using 10% HAc or 1.0 M NH4Ac. The results indicate that the increase in the amount of Sr in the estuarine terrigenous clastic sediments from the river to the marine environments is caused by the addition of Sr-rich, Ba-poor, marine carbonate shells. The extracted Sr/Ba-HAc ratios were < 1.0 in freshwater (fluvial), 1.0–3.0 in brackish water (delta front), 3.0–8.0 in saltwater (prodelta), and > 8.0 in normal seawater (neritic environments and relict sand); however, in the traditional bulk analysis, total Sr/Ba ratio did not change significantly with increasing salinity. Therefore, it is suggested that the selective extraction of sedimentogenic Sr and Ba is the only effective means of using the Sr/Ba ratio to discriminate between marine and terrestrial sedimentary environments in terrigenous clastic sediments, while the traditional method of using the total Sr/Ba ratio of whole samples is unsuitable.

Sodium(I)-doped graphitic carbon nitride with appropriate interlayer distance as a highly selective sorbent for strontium(II) prior to its determination by ICP-OES.

Multilayered and porous sodium-doped graphitic carbon nitride (GCN-Na) was prepared and employed to the solid-phase extraction of Sr(II). The sorbent exhibits high adsorption capacity and excellent selectivity for Sr(II). This is due to its small interplanar stacking distance caused by doping with Na(I) which matches the size of Sr(II) better than blank GCN. An original solid-phase extraction method based on GCN-Na coupled with ICP-OES was established for Sr(II), the calibration plots are linear ranging from 0.05-10mg·kg-1 with the correlation coefficients (R2) above 0.999, the limits of detection are in the range of 0.57-1.52μg·kg-1 and the preconcentration factor of 80 is achieved using 48mL sample. It was successfully applied in the extraction and detection of trace Sr(II) in tap water, rice and sea fish. Graphical abstractA multilayer porous sodium(I) doped graphitic carbon nitride nanosheet (GCN-Na) was synthesized and exhibited excellent adsorption capability and selectivity for Sr(II).

Sorbents Based on the Phosphates and Complex Oxides of Titanium(IV) for Decontamination of Liquid Radioactive Waste

The prospects of using of sorbents based on oxohydroxophosphate titanium(IV) to extract 134 Cs,137Cs and 90Sr from solutions close in composition to sea water have shown. The optimal conditions for the use of sorbents providing effective joint extraction of 134,137Cs and 90Sr in the presence of background macro components were determined. Modification of sorbents improves their sorption properties. It was established that the titanate ion exchangers are of interest for selective extraction of 90Sr. Optimum conditions of their application was defined. Heat treatment of waste sorbents provides reliable immobilization of radioactive sorbate. The titanium ortophosphate sorbents was tested for decontamination of liquid radioactive waste. The efficiency of their use is shown.

Extraction of plutonium(IV) from acidic feeds using several diamides with a tri-phenyl pyridine centre

Three tri-aryl-pyridine (TAP) diamides containing a pyridine spacer were evaluated for the extraction of Pu(IV) and U(VI) using a process compatible diluent mixture of 95% dodecane + 5% isodecanol. Preferential extraction of Pu(IV) was seen which showed a general increasing trend with increasing aqueous phase nitric acid concentration. The stripping was facile with several reducing/complexing agents and the results of 3 cycles of extraction and stripping were reproducible. The extraction of Am(III), Eu(III), Sr(II) and Cs(I) was < 0.1% suggesting effective decontamination from the fission and activation products which was proven by alpha and gamma ray spectrometric methods.

Extraction of Strontium and Yttrium from Alkaline Carbonate Media with Functionalized Calix[8]arenes

The extraction of 90Sr and 90Y from alkaline carbonate media with tetrachloroethylene solutions of p-tert-butyl and p-isononylcalix[8]arenes with various substituents in the lower rim was studied. The dependences of the 90Sr and 90Y distribution ratios on pH of the aqueous phase in the interval from 11 to 14 were studied. Among the calixarenes tested, p-alkylcalix[8]arenes with a bridging group in the lower rim show the highest performance in the extraction of 90Sr and 90Y.

Experimental Study of REEs, Ba, and Sr Interphase Partitioning in Fluid–Magmatic Silicate Systems at T = 1250°C and P = 2 kbar

The results of study of the alkaline silicate melt–hydrous saline (carbonate, sulfate, and fluoride) fluid system, as well as partitioning of ore metals (Ba, Sr, and REEs) between coexisting phases at T = 1250°C and P = 2 kbar are reported. It is shown that aqueous solutions with the compositions studied cannot be effective concentrators and transporters of ore elements such as REEs, Sr, and Ba. The sulfate melt accumulates Sr and Ba in the alkaline silicate melt–hydrous sulfate fluid system, which provides evidence for the efficiency of sulfate ore extraction of Sr and Ba from the melt. The results obtained support the important oregenerating role of dense saline phases formed upon the development of liquid heterogeneity in fluid–magmatic systems.

Extraction of heavy metal (Ba, Sr) and high silica glass powder synthesis from waste CRT panel glasses by phase separation

In this study, a novel process for the extraction of heavy metal Ba and Sr from waste CRT panel glass and synchronous preparation of high silica glass powder was developed by glass phase separation. CRT panel glass was first remelted with B2O3 under air atmosphere to produce alkali borosilicate glass. During the phase separation process, the glass separated into two interconnected phases which were B2O3-rich phase and SiO2-rich phase. Most of BaO, SrO and other metal oxides including Na2O, K2O, Al2O3 and CaO were mainly concentrated in the B2O3-rich phase. The interconnected B2O3-rich phase can be completely leached out by 5mol/L HNO3 at 90 ℃. The remaining SiO2-rich phase was porous glasses consisting almost entirely of silica. The maximum Ba and Sr removal rates were 98.84% and 99.38% and high silica glass powder (SiO2 purity > 90 wt%) was obtained by setting the temperature, B2O3 added amount and holding time at 1000–1100 ℃, 20–30% and 30 min, respectively. Thus this study developed an potential economical process for detoxification and reclamation of waste heavy metal glasses.

Extraction Behavior of Sr (II) from High-Level Liquid Waste using Ionic Liquid Extraction System with DtBuCH18C6

The extraction behavior of Sr(II) from high-level liquid waste (HLLW) has been investigated using 4’,4’(5")-di-(tert-butyl cyclohexano)-18-crown-6 (DtBuCH18C6) as an extractant in combination with three types of ionic liquids, [Cnmim][NTf2] (n = 2,4,6) as solvents, where [Cnmim]+ is 1-alkyl-3-methylimidazolium and [NTf2]- is bis(trifluoromethylsulfonyl)amide. DtBuCH18C6 in the [Cnmim][NTf2] system can be used as a good choice for matching, and a higher DSr can be achieved. Within the acidity range studied, the DSr follows the order of [C2mim][NTf2] > [C4mim][NTf2] > [C6mim][NTf2]. In their extraction systems, DSr decreases with increasing concentration of HNO3 in the aqueous phase. Thermodynamic parameters for the extraction of Sr(II) tested elements were calculated using the Van’t Hoff equation, showing that the reaction is spontaneous and exothermic. Existence of inorganic salts such as KNO3 usually reduces ESr for all systems, and the decreasing degree is much larger than that of NaNO3. The extraction systems exhibited high extraction efficiency and high selectivity for Sr(II) from simulated HLLW containing 25 typical elements and 2M HNO3. From the results, the DtBuCH18C6 in [Cnmim][NTf2] system may provide an alternative for extraction of Sr(II) under HLLW conditions.

Separation of americium (III) and strontium (II) using TEHDGA and 18-crown-6

Abstract This work describes extraction of Am(III) and Sr(II) together with tetra(2-ethylhexyl) diglycolamide (TEHDGA) and selective back-extraction of strontium with a strontium complexant, 18-crown-6, leading to their separation from each other. 0.3 M TEHDGA+5% isodecyl alcohol/n-dodecane was used to extract Am(III) and Sr(II) from 4 M nitric acid into organic phase with very high D (D Am=1000, D Sr=22) and 0.1 M 18-crown-6 dissolved in 4 M nitric acid is used for selective stripping of Sr(II) from loaded extract phase. Am(III) left in the extract phase was then stripped with 0.01 M nitric acid. Stripping of Sr(II) was found to increase with increase in 18-crown-6 concentration, at 0.1 M 18-crown-6 dissolved in 4 M nitric acid, 83% of the loaded strontium (D Sr=0.20) was back-extracted in a single contact while loss of Am(III) was 0.8% (D Am=122.45). Stoichiometry limit of 1:1 was observed between strontium and 18-crown-6. Strontium was precipitated and separated from the complexant by Na2SO4 or Na2CO3. This process was tested with simulated solution of high level waste and found suitable for quantitative recovery of strontium with high purity.

Influence of the characteristics of a water-in-CO2 microemulsion on the separation of metal species

ABSTRACTIn this study, AOT [sodium bis(2-ethylhexyl) sulfosuccinate] combined with fluorinated cosurfactant or alcohol was used to form a water-in-CO2 (W/C) microemulsion. The amount of water uptake in the microemulsion was closely related to the PFPE-PO4/AOT (P/A) ratio. The stability of the microemulsion decreased with the amount of water. Lower temperature and higher pressure stabilize W/C microemulsions. The extraction efficiencies of metals (Cd, Co, Cu, Pb, Zn), when this W/C microemulsion method was used, exceeded 90% (AOT + octanol). The efficiencies for the extraction of Eu, La, and Sr could exceed 94% (AOT + PFPE-PO4) in sc-CO2.