Di-tert-butylcyclohexano-18-crown-6 Research Articles

Study on Dynamic Column Behavior and Complexation Mechanism of DBS-Modified Crown Ether-Based Silica to 90Sr.

A crown ether-loaded hybrid adsorbent suitable for the separation and enrichment of strontium from high-level liquid waste was synthesized. 4',4'(5″)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its modifiers dodecyl benzenesulfonic acid (DBS) and 1-dodecanol were impregnated into silica-based polymer support. The hybrid adsorbent exhibited excellent Sr(II) selectivity ability, and effective chromatographic separation and recovery of Sr(II) from simulated high-level liquid waste could be achieved with a (DtBuCH18C6 + DBS + dodec)/SiO2-P packed column. The recovery rate of Sr(II) calculated based on the mass balance was approximately 99% and over 80% for the other coexisting metal ions. An appropriate increase in the concentration of Na-DTPA eluent was favorable to improve the efficiency of the elution process because of the increased complexation capacity of [DTPA]5- to Sr(II). The developed theoretical model can simulate the dynamic breakthrough curves of the material on the basis of short column data, thereby predicting the scale-up column of the practical operation. Density functional theory calculation was used to explore the action mechanism of DBS modifiers on the Sr(II) complexation process of crown ether groups. Two Sr(II) complexation isomeric models of DtBuCH18C6 were established, and the calculation results revealed a similar complexation ability. DtBuCH18C6 could form a stable Sr(II) complexation structure with DBS coordination, which further indicated that DBS could be a ligand to promote the Sr(II) adsorption ability of crown ether materials.

Development of chromatographic process for the dynamic separation of 90Sr from high level liquid waste through breakthrough curve simulation and thermal analysis

• Numerical simulation on adsorption dynamics and temperature field was performed for scale-up column. • The heat values per unit adsorbent volume was calculated to be 2292.877 W/m 3 . • A preliminary design was developed for Sr(II) adsorption processing. 4′,4′(5′’)-Di( tert -butylcyclohexano)-18-crown-6 (DtBuCH18C6) modified with dodecyl benzenesulfonic acid (DBS) and 1-dodecanol was impregnated into silica-based polymer support (SiO 2 -P). The stability of adsorbent was evaluated according to thermal decomposition and leakage property. The leakage of total organic carbon (TOC) and dodecyl benzenesulfonic acid from the adsorbent was approximately constant and was below 2.26 wt% at 298 K at 0.5–7 M HNO 3 . The O 1s and Sr 3p XPS spectra of the adsorbent after adsorption of Sr(II), suggesting that strong binding interaction of Sr(II) and oxygen in DtBuCH18C6. The adsorbent containing DBS promoted the adsorption of Sr(II) compared to the DBS-free one, demonstrating the DBS worked as a counter ion. By adsorption kinetic and isotherm analyses, linear driving force expression with external mass coefficient ( K fa ) and Freundlich model was found to be appropriate for the accurate description of adsorption dynamics. The separation column was designed by numerical thermal analysis and simulating breakthrough curve based on the short column data. Mathematical adsorption dynamics model was built, thereby obtaining the breakthrough curve of scale-up column. Thermal analysis was conducted due to the large heat value per unit adsorbent volume of 2292.877 W/m 3 . The effect of column length and diameter on breakthrough curve and temperature field was further computationally discussed. Thus, a preliminary design for Sr(II) processing column (Φ150 mm × H700 mm, breakthrough time: 9.55 h, processing volume: 76.92 dm 3 /cycle) from high-level liquid waste was proposed.

Extraction chromatographic materials based on polysulfone microcapsules for the sorption of strontium from aqueous solution

Crown ether-loaded polysulfone (PS) capsules suitable for the separation and preconcentration of strontium from acidic nitrate media have been prepared and characterized. Specifically, PS macro- and microcapsules have been impregnated with the macrocyclic polyether di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6), either undiluted or as a solution in 1-octanol, and their performance in the extraction of strontium from nitric acid solution evaluated. The DtBuCH18C6-loaded microcapsules were found to exhibit strontium uptake efficiency significantly greater than that observed for the analogous macrocapsules, confirming earlier observations of a marked size-dependence of the behavior of extractant-loaded PS capsules. Comparison of the microcapsules to a commercial extraction chromatographic (EXC) material (Sr-resin) comprising DtBuCH18C6-loaded beads of poly(methyl methacrylate) (PMMA) of comparable size (50–100 μm), showed that the two materials exhibit similar strontium retention, uptake kinetics, and selectivity. The microcapsules provide higher column efficiencies, however, and when fully loaded with extractant, higher strontium ion uptake capacity.

Determination of Extractant Solubility in Ionic Liquids by Thermogravimetric Analysis

ABSTRACTThe high thermal stability typical of many room temperature ionic liquids (RTILs) is exploited as the basis of a method employing thermogravimetric analysis (TGA) for the determination of the solubility of various metal ion extractants in these solvents. The approach is simple, applicable to extractants lacking functional groups that would permit their ready quantification by other methods, and requires only small (mg) quantities of sample. These features of the method, along with its limitations, are illustrated by the determination of the solubility of representative examples of several common extractant families, including bis(2-ethylhexyl)phosphoric acid (HDEHP) and di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6), in a series of 1,3-dialkylimidazolium (Cnmim+)-based ionic liquids.

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.

Adsorption Behavior of Sr(II) from High-level Liquid Waste using Crown Ether with Ionic Liquid Impregnated Silica Adsorbent

4’4’(5’)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) modified with 1-ethyl-3-methylimidazolium bis (trifluoro methylsulfonyl) imide ([C2mim][NTf2]) was loaded onto porous silica/polymer composite support (SiO2-P) particles with a mean diameter of 50 μm and used to extract Sr(II) from HNO3 solutions. The effect of HNO3 concentration on the equilibrium kinetics and thermodynamic properties of Sr(II) uptake were investigated by batch methods. The adsorbent exhibited excellent adsorption selectively for Sr(II) over a wide range of HNO3 concentrations. The adsorption of Sr(II) in the presence of 3 M HNO3 on (DtBuCH18C6+[C2mim][NTf2])/SiO2-P attained equilibrium within 1 h, and a relatively large distribution coefficient (Kd) of ca. 30 cm3·g−1 was obtained. Kinetic data were successfully modeled using pseudo-second-order kinetics. The adsorption of Sr(II) was a spontaneous and exothermic process. The uptake isotherm of Sr(II) for (DtBuCH18C6+[C2mim][NTf2])/SiO2-P followed a Langmuir-type adsorption equation.

Efficient co-extraction of strontium and cesium from nitric acid medium by mixtures of di-tert-butylcyclohexano-18-crown-6 and 1,3-di(2-propoxy)calix[4]arene-crown-6 in n-octanol

ABSTRACTThe co-extraction of strontium and cesium from nitric acid medium by di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6) and 1,3-di(2-propoxy)calix[4]arene-crown-6 (iPr-C[4]C-6) in n-octanol was studied. The effects of contact time, nitric acid concentration, extractant concentration and temperature on the co-extraction behavior were systematically investigated. Effective extraction of the two metals was achieved under a variety of conditions. The co-extraction from a simulated high-level liquid waste (HLLW) was also conducted, and strontium and cesium could be selectively extracted in the presence of a large number of other metals. Results in this work illustrate the feasibility of partitioning radioactive strontium and cesium simultaneously from HLLW by a mixture of DtBuCH18C6 and iPr-C[4]C-6 in n-octanol.

Sol-Gel Glass-Encapsulated Crown Ethers for the Separation and Preconcentration of Strontium from Acidic Media

Extraction chromatography employing an inert polymeric support impregnated with a crown ether (typically, 4,4’,(5’)-di-(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6)), either neat (i.e., undiluted) or as a solution in 1-octanol, has previously been shown to provide an effective means for the isolation of radiostrontium from a variety of sample types for subsequent determination. In this study, sol-gel chemistry has been employed to prepare sorbents in which DtBuCH18C6 is encapsulated in a silica matrix. The resultant materials have been evaluated for their ability to retain strontium ion and compared to a commercially available extraction chromatographic (EXC) resin. Certain of the new materials are shown to provide uptake efficiencies comparable to those obtained with the commercial resins, although unless a porogen is employed, the kinetics of strontium uptake are significantly slower. In contrast to conventional EXC materials, however, strontium uptake by DtBuCH18C6-loaded glasses does not increase in proportion to the amount of extractant present, indicating that not all of the crown ether present is available for interaction with the metal ion.

Studies on the separation of89Sr(II) from irradiated yttria target using 4, 4′(5′) di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6) by solvent extraction technique

Abstract The radioisotope 89Sr as 89SrCl2 is medically useful for bone pain palliation and is produced in fast reactors using the 89Y(n, p)89Sr reaction. A procedure for isolation of the radionuclide 89Sr by chemical processing of the irradiated Y2O3 target has been standardised and trial runs have been carried out at the Fast Breeder Test Reactor (FBTR), Kalpakkam. The chemical processing of the irradiated Y2O3 target involves i) the removal of target Y(III) by TBP extraction and ii) further purification of the separated 89Sr fraction by cationic exchange chromatography. However a selective isolation of 89Sr by the Sr-specific crown ether makes the above chemical processing faster and relatively simple. This work presents a study on the selective removal of Sr from the irradiated target dissolver solution using the Sr-specific crown ether 4,4′(5′) di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6) in octanol medium. The separation behaviour of the other impurities such as Ce(IV), Y(III), Tb(III), Eu(III), Zn(II), Mn(II) and Rb(I) present along with Sr(II) in the irradiated sample was also investigated. The method of separation by using the crown ether DtBuCH18C6 is proved to be a potential tool for the purification of 89Sr(II) source produced from yttria target in fast reactors.

Evaluation of solid-supported room-temperature ionic liquids containing crown ethers as media for metal ion separation and preconcentration

Extraction chromatographic (EXC) resins incorporating an appropriate crown ether in an oxygenated organic solvent such as 1-octanol are well established as sorbents for the analytical-scale separation and preconcentration of radiostrontium from a variety of sample types. Recent solvent extraction studies employing crown ethers in various 1-alkyl-3-methylimidazolium-based (CnC1im+) room-temperature ionic liquids (RTILs) indicate that under certain conditions, distribution ratios (DSr) for strontium far in excess of those observed with conventional organic solvents are observed. To determine if this increase in liquid–liquid extraction efficiency will lead to improved strontium sorbents, several EXC resins and sol-gel glasses incorporating di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6) in either 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C10C1imTf2N) or the related hydroxyalkyl-functionalized IL 1-(12-hydroxydodecyl)-3-butylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C12OHC4im Tf2N) were prepared and characterized. Unexpectedly the performance of these materials was not uniformly better than that of a conventional EXC resin, an apparent result of the greater viscosity of the ionic liquids and the lower solubility of the crown ether in ILs versus conventional organic solvents.

A novel method for the preparation of large-area 90Sr/90Y sources for the calibration of hand contamination monitors

This paper describes a method for the preparation of large-area 90Sr/90Y polymer film sources for the calibration of hand contamination monitors. The process consists of solvent extraction of predictable quantity of 90Sr into an organic solvent containing di-tert-butyl-cyclohexano-18-crown-6 (DCH18C6), formation of a polymeric solution of poly(methyl methacrylate) (PMMA), pouring the 90Sr-embedded polymer solution over a surface of a defined area followed by evaporation to create a thin film and peeling-off of the radioactive PMMA film. Quality control tests of the radioactive films were carried out to ensure nonleachability, uniform distribution of activity and stability. Sources having 5kBq±428Bq were prepared using this method and routinely used for calibration of contamination monitors.

Synthesis of crown ether modified cation exchange polymer particles for 90Sr urinalysis

Cation exchange polymer particles have been synthesized for urinalysis to monitor levels of strontium-90 (90Sr) exposure in humans. Two techniques were utilized in the incorporation of a Sr2+ selective chelating agent, di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6). The ion imprinting technique involved entrapment of DtBuCH18C6 during the formation of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) polymer particles. In the surface immobilization technique, adsorption of DtBuCH18C6 onto the surface of AMPS polymer particles was assisted by a molecular modifier. Ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB) were evaluated as cross-linking agents to provide better support for DtBuCH18C6. These polymer particles were characterized by scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. Radiometric binding assays demonstrated that surface immobilization, in comparison to matrix imprinting, achieved greater Sr2+ uptake. Application of the surface immobilized particles in urinalysis was successful, attaining 86±2% 90Sr uptake at pH 9.

Equilibrium and kinetic studies of selective adsorption and separation for strontium using DtBuCH18C6 loaded resin

A crown ether loaded resin was prepared by successive impregnation and fixing the 4′,4′(5″)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its molecule modifier, 1-dodecanol, onto the porous silica/polymer composite support (SiO2-P particles). The characterization of DtBuCH18C6 loaded resin was examined by thermal gravimetry and differential thermal analysis and electron probe microanalysis. The adsorption behavior of Sr(II), Cs(I), Ru(III), Pd(II), La(III), Nd(III), Sm(III), Gd(III), Zr(IV), and Mo(VI) was investigated by the batch method. Furthermore, the column test for Sr (II) was performed. The batch experiments were carried out by varying the shaking times, HNO3 concentration, and initial concentration of metal ions. A relatively large K d value above 182 cm3/g for Sr(II) was obtained in the presence of 3 M HNO3. In contrast, the K d values of Cs(I), Ru(III), Pd(II), La(III), Nd(III), Sm(III), Gd(III), Zr(IV), and Mo(VI) were considerably lower than 10 cm3/g. The adsorption of Sr(II) was found to be controlled by chemisorption mechanism, and followed a Langmuir-type adsorption equation. The breakthrough curve of Sr(II) had S-shaped profile, and the elution percentage was estimated to be 99.9% by using the eluent of H2O.

An ESR study of radiation-chemical transformation of 4,4′(5′)-di-(tert-butylcyclohexano)-18-crown-6 and its solution in 1-octanol at 77 K

Paramagnetic products stabilized in both 4,4′(5′)-di-(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its solution in 1-octanol upon low temperature (77 K) X-rays irradiation were studied by ESR spectroscopy. Macrocyclic –O–ĊH–CH2– radicals and acyclic O = C(H)–ĊH–O– radicals were found as main radiolysis products in neat DtBuCH18C6. Fraction of acyclic radicals resulting from the macrocycle cleavage was about 50%. No radical products resulted from t-Bu and cyclohexyl fragments were observed. It was concluded that the primary events were essentially concerned with ionization of the polyether moiety. Irradiation of frozen DtBuCH18C6 solutions in 1-octanol resulted in formation of radicals both from crown ether and alcohol.

Extraction of Radio-Strontium from Nitric Acid Medium Using Di-tert-Butyl Cyclohexano18-Crown-6 (DTBCH18C6) in Toluene–1-Octanol Diluent Mixture

An alternative extraction system to the SREX solvent using a diluent mixture comprising 4,4′(5′)di-tert-butylcyclohexano-18-crown-6 (DTBCH18C6) in 80% toluene–20% 1-octanol was developed and evaluated for Sr(II) extraction from pressurized heavy water reactor simulated high level waste (PHWR-SHLW). The acid uptake (5.7%) by the present solvent was significantly lower as compared to that by the SREX solvent (21%) which used 100% 1-octanol as the diluent. The extracted species conformed to the ion-pair [Sr(DTBCH18C6)(H2O)x]2+·2[(NO3)(H2O)y]−. Studies on Sr(II) extraction as a function of nitric acid concentration indicated more favorable extraction and stripping with the present solvent as compared to the SREX solvent. Loading studies with 0.025 M DTBCH18C6 in the diluent mixture, carried out using the Sr carrier, indicated a decrease in DSr from 3.1 with 10 ppm Sr carrier to 1.62 with 100 ppm Sr carrier. Other important physical parameters relevant for the extraction processes such as phase separation time (dispersion number), viscosity, and density were also measured. The radiation stability and reusability of the solvent was also investigated. In sharp contrast to the SREX solvent, with increasing absorbed dose the proposed solvent showed an increase in Sr extraction and an increased acid uptake.

SPEC: A New Process for Strontium and Cesium Partitioning Utilizing Two Macroporous Silica-Based Supramolecular Recognition Agents Impregnated Polymeric Composites

To effectively separate two heat generators Cs(I) and Sr(II) from a highly active liquid waste (HLW), two macroporous silica-based polymeric composites (Calix[4]arene-R14 + M)/SiO2-P and (DtBuCH18C6 + M)/SiO2-P were synthesized. It was done by impregnating and immobilizing the supramolecular recognition agent, 1,3-[(2,4-diethylheptyl ethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) or 4,4′,(5′)-di-(tert-butylcyclo hexano)-18-crown-6 (DtBuCH18C6), into the pores of the macroporous SiO2-P particles with a mean diameter of 50 µm. It was found that in the first column packed with (Calix[4]arene-R14 + M)/SiO2-P, all of the tested elements were effectively eluted and separated into two groups: (1) Na(I), K(I), Sr(II), Ba(II), Rh(III), Ru(III), Pd(II), Zr(IV), RE(III) (La-Lu and Y), and Mo(VI) (Sr-containing group), and (2) Cs(I)-Rb(I) (Cs-group) by eluting with 4.0 M HNO3 and water, respectively, at 298 K. The heat emitting element Cs(I) flowed into the second group along with Rb(I), while Sr(II) showed no sorption and flowed into the Sr-containing group. In the second column packed with (DtBuCH18C6 + M)/SiO2-P, the Sr-containing group was separated into (1) Na(I), K(I), Rh(III), Ru(III), RE(III) (La-Lu and Y), Pd(II), Zr(IV), and Mo(VI) (non-sorption group), and (2) Sr(II)-Ba(II) (Sr-group), by eluting with 2.0 M HNO3 and water, respectively. The heat emitting element Sr(II) adsorbed by (DtBuCH18C6 + M)/SiO2-P flowed into the second group along with Ba(II). Based on the results, a new process entitled SPEC (Strontium/Cesium Partitioning from HLW by Extraction Chromatography) for heat generator partitioning from a simulated highly active liquid waste utilizing two macroporous silica-based supramolecular recognition composites has been developed.

Preparation of macroporous silica-based crown ether materials for strontium separation

To develop a separation process of Sr(II), a macroporous silica-based 4,4′,(5′)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) polymeric material, (DtBuCH18C6+Oct)/SiO2-P, was synthesized by impregnating and immobilizing DtBuCH18C6 and 1-octanol into the pores of the macroporous SiO2-P particles support. DtBuCH18C6 was modified with 1-octanol through hydrogen bonding. The adsorption of simulant elements of some typical fission products Ru(III), Pd(II), Ba(II), Mo(VI), La(III), Y(III), Sr(II), Cs(I) and those of non-fission products Na(I) and K(I) onto (DtBuCH18C6+Oct)/SiO2-P were studied at 298 K. The effects of the HNO3 concentration in a range of 0.1–5.0 M and contact time on the adsorption were investigated. (DtBuCH18C6+Oct)/SiO2-P showed excellent adsorption ability and high selectivity for Sr(II) over all of the tested metals except Ba(II). Partitioning of Sr(II) from a 2.0 M HNO3 solution containing ~5.0 × 10−3 M of the tested metals was conducted utilizing (DtBuCH18C6+Oct)/SiO2-P packed column. Pd(II), Mo(VI), Y(III), La(III), Ru(III), K(I), Cs(I), and Na(I) showed no adsorption and flowed into effluent along with 2.0 M HNO3. Sr(II) was retained on (DtBuCH18C6+Oct)/SiO2-P and was eluted effectively by H2O, while Ba(II) showed similar elution behavior. The bleeding of total organic carbon leaked from (DtBuCH18C6+Oct)/SiO2-P was evaluated. It was demonstrated that the macroporous silica-based (DtBuCH18C6+Oct)/SiO2-P materials are promising in separation of Sr(II) from high level radioactive waste.

Adsorption Behavior of Sr(II) and some Typical Co‐existent Metals Contained in High Level Liquid Waste onto a Modified Macroporous Silica‐Based Polymeric DtBuCH18C6 Composite

To significantly reduce the bleeding of 4,4′,(5′)‐di(tert‐butylcyclohexano)‐18‐crown‐ 6 (DtBuCH18C6), an improved novel macroporous silica‐based polymeric composite (DtBuCH18C6+TBP)/SiO2‐P was synthesized. It was performed by impregnating and immobilizing DtBuCH18C6 into the pores of the SiO2‐P particles via the molecular modification of DtBuCH18C6 with a tri‐n‐butyl phosphate (TBP) through hydrogen bonding. The adsorption of a few typical simulated fission and non‐fission products Pd(II), La(III), Na(I), K(I), Sr(II), Ba(II), Ru(III), Cs(I), Mo(VI), and Y(III) onto (DtBuCH18C6+TBP)/SiO2‐P was investigated at 323 K. It was done by examining the effect of contact time and the HNO3 concentration in a range of 0.1–5.0 M. Sr(II), one of the main heat emitting nuclides, showed optimum adsorption onto (DtBuCH18C6+TBP)/SiO2‐P in 2.0 HNO3, while others showed very weak or almost no adsorption except a portion of Ba(II). The leaching of TBP and DtBuCH18C6 from (DtBuCH18C6+TBP)/SiO2‐P was evaluated. The average content of DtBuCH18C6, 298.7 ppm, leached from (DtBuCH18C6+TBP)/SiO2‐P in 2.0 M HNO3 at 323 K was obviously lower than that of 797.3 ppm leached from DtBuCH18C6/SiO2‐P at 298 K. The significant reduction of DtBuCH18C6 leaching from its macroporous silica‐based polymeric adsorbent was achieved. It is useful for the recycle operation of the silica‐based DtBuCH18C6 impregnated polymeric composite in chromatographic partitioning of Sr(II) from high level liquid waste (HLLW).

Modification of a novel macroporous silica-based crown ether impregnated polymeric composite with 1-dodecanol and its adsorption for some fission and non-fission products contained in high level liquid waste

A novel macroporous silica-based chelating polymeric composite, DtDo/SiO 2–P, was synthesized by molecular modification of 4,4′,(5′)-di-( tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) with a long carbon chain organic compound 1-dodecanol. It was performed through impregnation and immobilization of DtBuCH18C6 and 1-dodecanol molecules into the pores of the SiO 2–P particles. The adsorption of a few fission and non-fission product elements Sr(II), Ba(II), Cs(I), Ru(III), Mo(VI), Na(I), K(I), Pd(II), La(III), and Y(III) onto DtDo/SiO 2–P was investigated at 323 K. The effects of contact time and the HNO 3 concentration in a range of 0.1–4.0 M were investigated. It was found that at the optimum concentration of 2.0 M HNO 3, DtDo/SiO 2–P exhibited strong adsorption ability and excellent selectivity for Sr(II) over all of the tested elements, which showed very weak or almost no adsorption except Ba(II). The bleeding of total organic carbon (TOC) from DtDo/SiO 2–P was evaluated. The quantity of TOC in aqueous phase increased with an increase in HNO 3 concentration in terms of a linear equation [TOC] = 35.82[HNO 3] + 115.5 with a correlation coefficient of 0.9751. The TOC content leaked from DtDo/SiO 2–P modified by 1-dodecanol, 119.0–269.3 ppm, in the range of 1.0–4.0 M HNO 3 was significantly lower than that of 424.8–634.6 ppm in the case without modification. It resulted from the intermolecular interaction force of DtBuCH18C6 and 1-dodecanol through hydrogen bonding. The reduction of DtBuCH18C6 leakage by molecular modification was achieved. It is of great benefit to application of DtDo/SiO 2–P in partitioning of Sr(II), one of the main heat generators, from high level liquid waste (HLLW) in reprocessing process of nuclear spent fuel in MAREC (Minor Actinides Recovery from HLLW by Extraction Chromatography) process developed.

Impregnation synthesis of a novel macroporous silica-based crown ether polymeric material modified by 1-dodecanol and its adsorption for strontium and some coexistent metals

4,4′,(5′)-Di-( tert-butylcyclohexano)-18-crown-6(DtBuCH18C6) is a chelating agent having high selectivity mostly for Sr(II). To significantly reduce its leakage by molecular modification, a macroporous silica-based DtBuCH18C6 polymeric composite (DtDo/SiO 2–P) was synthesized. It was performed by impregnating and immobilizing DtBuCH18C6 and 1-dodecanol molecules into the pores of the SiO 2–P particles utilizing an advanced vacuum sucking technique. The adsorption of a few fission and non-fission products Sr(II), Ba(II), Cs(I), Ru(III), Mo(VI), Na(I), K(I), Pd(II), La(III), and Y(III) onto DtDo/SiO 2–P was investigated. It was done by examining the effects of contact time and the HNO 3 concentration in a range of 0.1–5.0 M at 298 K. At the optimum concentration of 2.0 M HNO 3, DtDo/SiO 2–P exhibited strong adsorption ability and high selectivity for Sr(II) great over all of the tested elements, which showed very weak or almost no adsorption except Ba(II). Meanwhile, It was found that the quantity of total organic carbon (TOC) leaked from DtDo/SiO 2–P in 2.0 M HNO 3, 187.5 ppm, was lower than 658.4 ppm that leaked from DtBuCH18C6/SiO 2–P, which was not modified. This was ascribed to the effective association of DtBuCH18C6 and 1-dodecanol through intermolecular interaction. The reduction of DtBuCH18C6 leakage by molecular modification with 1-dodecanol was achieved. It was of great benefit to application of DtDo/SiO 2–P in chromatographic partitioning of Sr(II), one of the main heat generators, from high level liquid waste (HLLW) in reprocessing of nuclear spent fuel in the MAREC (Minor Actinides Recovery from HLLW by Extraction Chromatography) process developed recently.