The effect of the synthesis method on the parameters of pore structure and selectivity of ferrocyanide sorbents based on natural minerals

Ferrocyanide sorbents were obtained via thin-layer and surface modification of natural clinoptilolite and marl. The effect of modification method on surface characteristics of these sorbents and their selectivity for cesium was studied. It was shown that the modification resulted in an increase of selectivity of modified ferrocyanide sorbents to cesium as compared with the natural clinoptilolite in presence of Na⁺, as well as in an increase of cesium distribution coefficients in presence of K⁺. The nickel–potassium ferrocyanide based on the clinoptilolite showed the highest selectivity for cesium at sodium concentrations of 10^?4—2 mol L^?1: cesium distribution coefficient was lg K _d = 4.5 ± 0.4 L kg^?1 and cesium/sodium separation factor was α(Cs/Na) = 250. In the presence of NH₄ ⁺, all modified sorbents showed approximately equal selectivity for ¹³⁷Cs. Probable applications of the sorbents were suggested.     

Comparison of Hydrophilic Polymeric Sorbents for On-Line Solid-Phase Extraction of Polar Compounds from Aqueous Samples

Two 4-vinylimidazole-divinylbenzene (4VIm-DVB) polymers were synthesized and applied as sorbents for on-line solid-phase extraction (SPE) followed by liquid chromatography for analyzing polar compounds in aqueous samples. The new sorbents (4VIm-DVB) were compared to another sorbent that had been previously synthesized by our group (N-vinylimidazole-divinylbenzene (NVIm-DVB)) and to the commercial OASIS^® HLB and Strata^TM X. All the sorbents enabled 100 mL of sample to be on-line concentrated with good recoveries for the studied polar compounds. Real water samples were analyzed using NVIm-DVB and OASIS^® HLB as SPE sorbent, for which the best results were obtained.     

聚乙烯亚胺修饰的氧化硅纳米管基吸附剂的制备及其CO_2吸附应用

以P123为模板,1,2-二(三甲氧基硅基)乙烷(BTME)为硅源合成了介孔氧化硅纳米管(E-SNTs).将ESNTs经过聚乙烯亚胺(PEI)修饰后制得吸附剂用于捕捉CO2.对吸附剂进行了透射电镜(TEM)、物理吸附、傅里叶变换红外(FTIR)光谱、热重分析(TGA)等表征.E-SNTs-PEI吸附剂的最佳CO2吸附温度为75°C.吸附剂的CO2吸附量随着PEI负载量的增加呈现先增大后减小的趋势,其中50%为最佳负载量,此时吸附剂的吸附量最大为3.32 mmol·g-1.相比较SBA-15基吸附剂,E-SNTs基吸附剂具有更优异的吸附性能.在有水汽的存在下,吸附剂E-SNTs-50的CO2吸附量达到3.75 mmol·g-1.经过四次循环吸脱附实验测试E-SNTs-PEI吸附剂的稳定性能,结果表明其CO2吸附量基本不变,该吸附剂表现出较好的稳定性和可再生能力.     

Stability of phenol-formaldehyde ion-exchange sorbents in aqueous solutions

It is shown that ion-exchange sorbents based on phenol-formaldehyde resins can be used for a long time for isolating and separating rare alkali metals without any significant changes in the ion-exchange selectivity and capacity. When the phenol sorbents were used in alkaline solutions at elevated temperatures, carboxyl groups gradually accumulated in them as a result of the oxidation of methylol groups with oxygen dissolved in the solution. This led to a considerable increase in the ion-exchange capacity of the sorbents and a simultaneous decrease in the selectivity with respect to Cs⁺-Rb⁺ and Rb⁺-K⁺ ions (it is desirable to avoid the drying of phenol ionites in air by storing them in a swelled state in closed vessels).     

Sol-gel synthesis and sorption properties of calcium monoaluminate

Method for synthesis of calcium aluminate and sorbents based on this compound was developed on its basis of the sol-gel technology. The method makes it possible to obtain the target product with specific surface areas in the range from 7 to 120 m² g^–1. The compounds obtained were characterized by scanning electron microscopy, X-ray phase analysis, and X-ray fluorescence microanalysis. It was found that the main phase of the sorbents is rhombohedral calcium monoaluminate CaAl₂O₄. The method of Hammett indicator adsorption was used to determine the content of active centers on the surface of the sorbents and the distribution of these centers over ionization constants. It was shown that the surface characteristics of the sorbents depend on their synthesis method. The retention parameters, polarities, and thermodynamic characteristics were determined for organic compounds of various classes. The possibility of using calcium aluminate modified with sodium chloride for gas-chromatographic separation of aliphatic and aromatic hydrocarbons and carbonyl compounds was demonstrated.     

Americium(III) sorption from multicomponent solutions by macrocyclic polyester-based sorbents

Americium sorption by crown-ether-impregnated polymeric sorbents from nitric acid solutions and multicomponent nitrate solutions that model process solutions was studied. Sorption of ballast elements by the unimpregnated Porolas-T support was studied. The sorption coefficients K _d of these elements on Porolas-T do not exceed 0.01. Sorption of the same elements by crown-ether-impregnated sorbents was also studied. Dicyclohexano-18-crown-6 (DCH18C6) and its alkyl derivatives were used. Sorption coefficients were determined for all ballast elements. At the final stage of the study, ²⁴¹Am sorption coefficients of from multi-component solutions were determined. The data obtained signify the utility of crown-ether-impregnated sorbents for recovering ²⁴¹Am from multicomponent technological solutions.     

Selective removal of heavy metal ions using sol-gel immobilized and SPE-coated thiacrown ethers

Sorbent materials based on three thiacrown ethers, 1,4,7,10-tetrathiacyclododecane (12S4), 1,4,7,10,13-pentathiacyclopentadecane (15S5) and 1,4,7,10.13,16-hexathiacyclooctadecane (18S6) were prepared either by immobilizing the ligands into sol-gel (SG) matrix or coating on commercial solid phase extraction (SPE) column. SG sorbents were characterized by FT-IR, energy dispersive X-ray microanalysis (EDX) and thermogravimetric analysis/derivative thermogravimetric analysis (TGA/DTG). A marked thermal stability of the ligands when immobilized in sol-gel matrix was noted. The competitive sorption characteristics of a mixture of eleven metal ions (Mg²⁺, Zn²⁺, Cd²⁺, Co²⁺, Mn²⁺, Ca²⁺, Cu²⁺, Ni²⁺, Ag⁺, V⁴⁺, Hg²⁺) using: (i) batch method with ligands trapped in SG matrices, and (ii) off-line SPE column containing coated ligands were studied using ICP-MS. The extraction of metals were optimized for key parameters such as pH, contact time/flow rate, particle size (for SG sorbents) and ligand concentration. Under the optimized conditions, all the immobilized thiacrown ethers exhibited highest selectivity toward Ag⁺, with lesser responses to Hg²⁺ while the extraction of other metal ions were negligible. Among the SG sorbents, 18S6-SG offer the highest capacity and the best selectivity over Hg²⁺. However, for practical applications such as for selective isolation and preconcentration of Ag⁺, the SPE type especially based on 18S6 is preferred as analysis time and recoveries are favorable. The sorbents can be repeatedly used three times as there was no significant deterioration in the metal uptake (%E > 90%) or interference from other metal ions. The optimized procedures were successfully applied for the separation and preconcentration of traces Ag⁺ in different water samples.     

Study on the fluoride adsorption of various apatite materials in aqueous solution

The aim of this study was to evaluate the defluoridation efficiencies of various sorbents in aqueous solution. These sorbents include synthetic nano-hydroxyapatite (n-HAp), biogenic apatite (bone meal), treated biogenic apatite (bone meal prepared by H₂O₂ oxidation) and geogenic apatite (rock phosphate), which were characterized by XRD, FTIR, TEM and SEM. It has been observed that the defluoridation capacities follow the order: n-HAp > BH₂O₂ > B > rock phosphate. The controlling factors, sorbent dose, initial fluoride concentration, pH, contact time and temperature were investigated. The defluoridation capacities increased with the increase in the initial fluoride concentration and contact time, decreased with the increase in the sorbent dose. The optimum pH range for removal of fluoride on various apatite sorbents was considered to be 5.0-6.0. The fluoride adsorption can be explained by Langmuir, Freundlich isotherms, and the adsorption kinetic data follow the pseudo-second-order model. Thermodynamic parameters such as ΔH⁰, ΔS⁰ and ΔG⁰ indicated that the adsorption on various apatite sorbents was spontaneous and endothermic. These results showed that bone meal is a promising material for fluoride adsorption.     

Separation of cobalt from thiocyanate solutions by crown ether-based impregnated sorbents

A number of impregnated sorbents based on di-(tert-butyldibenzo)-18-crown-6 (DTBDB18C6) and di-(tert-butylcyclohexano)-18-crown-6 (DTBDCH18C6) was obtained using different diluents for the crown ether and the styrene–divinylbenzene support. Sorption characteristics of the sorbents in relation to cobalt ions and ⁶⁰Co radionuclide in thiocyanate solutions were determined within the range of pH of 1–7. It was found the DTBDB18C6-based sorbents were the most efficient for the sorption of cobalt macro quantities whereas the DTBDCH18C6-based ones for the sorption of ⁶⁰Co radionuclide, using nitrobenzene as a diluent. A possibility was shown of the complete cobalt desorption by hydrochloric and nitric acid solutions with the concentration of 0.1–1.0 mol L^–1.     

Sorbents based on calix[4]arenes for extraction of technetium(vii) from acidic and alkaline media

Sorption of Tc^VII from solutions of various compositions with new sorbents prepared by the noncovalent immobilization of (thia)calix[4]arenes on the Amberlite XAD-7™ support was studied. The sorbents studied efficiently extract technetium(vii) from both acidic and alkaline media. The sorption capacity of the sorbent with thiacalix[4]arene groups is superior to that of the sorbents with calix[4]arene groups and several times higher than that of the sorbents previously proposed for the sorption of Tc^VII. Technetium(vii) is sorbed by this sorbent as 1: 1 and 1: 2 thiacalix[4]arene—NH₄TcO₄ and 1: 1 and 1: 2 thiacalix[4]arene—NaTcO₄ complexes.     

New hybrid chelating sorbents with grafted 3-aminopropionate groups based on mixed silicon,aluminum, titanium,or zirconium oxides

A series of new hybrid organo-inorganic sorbents with the 3-aminopropionate chelating group was synthesized. The synthesis includes the copolycondensation (sol—gel method) of tetraethoxysilane, 3-aminopropyltriethoxysilane, and several modifiers (MeSi(OEt)₃, EtSi(OEt)₃, Ti(OEt)₄, AlONO₃, ZrOCl₂) followed by carboxyethylation with acrylic acid. The obtained chelating sorbents were characterized by elemental analysis, FT-IR and ¹H NMR spectroscopy, and thermogravimetry. The N-carboxylated sorbents have a higher sorption capacity with respect to metal ions (0.5–0.9 mmol g⁻¹, pH 6.3, NH₄OAc, 20 °C) than the starting sorbents with the primary amino group (0.05–0.2 mmol g⁻¹) and manifest high selectivity for copper(II) ion extraction. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1783–1788, August, 2005.     

Synthesis and physicochemical properties of chelating sorbents containing functional groups of N-aryl-3-aminopropionic acids

Two types of chelating sorbents with different types of addition of iminodipropionate groups to a polymeric matrix were synthesized: carboxyethylated aminopolystyrene (sorbent 1) based on linear polystyrene and carboxyethylaminomethylpolystyrene (sorbent 2) based on the copolymer of styrene and divinylbenzene. The ionization constants and concentrations of functional groups of the sorbents (exchange capacity for hydrogen ions) were determined. The sorbents exhibit high selectivity for copper(II) ions with the maximum of sorption from ammonia—acetate buffer solutions lying in a range of pH 5.0–7.5. The time needed for a solution of copper(II)—sorbent system with continuous stirring to reach exchange equilibrium is 3.5 and 2 h for sorbents 1 and 2, respectively. The exchange capacity for copper(II) ions is 2.54 and 0.10 mmol g⁻¹, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 800–806, May, 2006.     

The preparation of the 239Np tracer from 243Am and the purification of the stock solution

The present work describes preparation of ²³⁹Np tracer from ²⁴³Am stock solution and the purification of this solution from ferric cation. The method of the preparation of tracer involves stabilization of Np(IV) by ascorbic acid and ferric nitrate, separation of ²³⁹Np from ²⁴³Am by extraction chromatography and determination of recoveries of ²³⁹Np by means of gamma spectroscopy. We used the commercially available sorbents TEVA^®Resin for the ²³⁹Np preparation and DGA Resin for ²⁴³Am purification. All sorbents were purchased from Eichrom Industries, Inc. The first eluate from the column can be stored for a future preparation of the tracer and fraction with ²³⁹Np will be used to monitor radiochemical yield of ²³⁷Np.     

Amphiphilic poly(ethylene glycol) gels and their swelling features

This article describes the preparation of poly(ethylene glycol) (PEG) ‐based gels for removal of both organic solvents and water through a clean synthesis process without using any initiator, catalyst, activator, or liquid medium. The synthesis of the gels is based on the condensation of different molecular weights of PEG macromolecules with the nine‐functional crosslinker tris[3‐(trimethoxysilyl) propyl] isocyanurate (ICS). Solid‐state ¹³C and ²⁹Si cross‐polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and elemental analysis were used to characterize the prepared sorbents. Thermal properties of the synthesized sorbents were examined using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The swelling capacities of the sorbents were determined by swelling tests in dichloromethane (DCM), tetrahydrofuran (THF), benzene, acetone, and toluene. The water absorbency of the PEG‐based sorbents is also investigated. The effect of the reaction time and reaction temperature on swelling features of the sorbents was studied systematically. The prepared PEG gels have high swelling ratios both in polar and nonpolar solvents. Copyright © 2015 John Wiley & Sons, Ltd.     

Immobilized Metal Affinity Chromatography of Phosphorylated Proteins Using High Performance Sorbents

The interactions of two model phosphoproteins (porcine pepsin and ovalbumin) with two different immobilized metal affinity chromatography (IMAC) sorbents containing immobilized Fe³⁺, Ga³⁺, and UO₂ ²⁺ ions have been investigated under various conditions. Both proteins were adsorbed on immobilized uranyl ions under acidic conditions similar to those on immobilized Fe³⁺ and Ga³⁺ ions. The retained proteins could be released either by the presence of phosphate ions in the elution buffer (immobilized Ga³⁺ and Fe³⁺ ions) or by an increased pH (all tested immobilized ions). The IMAC sorbents employed could be used under the conditions of high-performance chromatography and are suitable for the separation and analysis of intact phosphoproteins.     

Synthesis and application of sorbents for affinity chromatography of serine proteases

Summary A synthetic peptide derivative,—alanyl-alanyl-leucylmorpholide, (Ala-Ala-Leu-N(CH₂CH₂)₂O), is suggested as a specific ligand for affinity chromatography of subtilisin-like serine proteases that prefer hydrophobic amino acid residue in P1 position of their substrates. Z-Ala-Ala-Leu-N(CH₂CH₂), a weak and reversible inhibitor of serine proteases, was synthesized by the carbodiimide method. Affinity sorbents were prepared by coupling the synthesized pepitide derivates to CH or AH Sepharose. Serine proteases from different sources were purified up to 17 fold on these sorbents with yields varying from 25% to 100%. Three enzymes (serine protease X, kallikrein and leucine aminopeptidase) were isolated from urine of children with glomerulonephritis with yields of 57, 22 and 55%. Proteolytic enzymes from the dandelion root, Kamchatka crab and culture filtrates of different microorganisms were also purified on the affinity sorbents. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996.     

Effect of microscopic additions of fullerenes on the absorption capacity of inorganic sorbents for <Emphasis Type="Italic">d</Emphasis> elements

It was shown that raising the sorption activity of an industrial silica gel of KSK-G brand and zeolite of NaX brand via their surface modification with microscopic amounts of fullerenes (1.0 × 10^–3, 2.0 × 10^–3, and 5.0 × 10^–3 wt%) is possible and promising. The low content of fullerenes in the modified samples predetermines the economic basis of their practical applications. The sorption activity of the modified sorbents (up to 30%) exceeds the similar characteristic of the starting industrial sorbents.     

Uptake of plutonium from nuclear waste water by natural and chemically modified sorbents

The uptake of plutonium from model solution of boric acid labelled with²³⁹Pu by natural sorbents was studied. The range of pH of solution was from 5.1 to 8. For the uptake of Pu were used different natural and chemically modified natural sorbents of different mineralogical composition and from different deposits. The distribution coefficients for plutonium uptake were calculated and the best conditions for uptake were evaluated.     

Composite cellulose-inorganic sorbents for 137Cs recovery

In this study, cellulose-inorganic sorbents based on bleached cotton fibres and ferrocyanides of different d-metals have been prepared and used for separation of ¹³⁷Cs from simulated aqueous solutions. Comparative analysis has been carried out of the sorption properties of obtained sorption materials towards to micro- and macroquantities of caesium at different liquid to solid phases ratios. Various characterization methods including X-ray analysis, IR spectroscopy, and differential thermal analysis were used to determine the structural properties of the obtained composite sorbents. It has been confirmed that the sorbents obtained at approximately the same content of the inorganic component are characterized by different values of the recovery rate and ¹³⁷Cs distribution coefficient.     

Comparative study on Th(IV) sorption on alumina and silica from aqueous solutions

The effects of pH, ionic strength and concentration on the sorption of Th(IV) on alumina and silica were investigated and the sorption isotherms of Th(IV) on alumina and silica at different pH values were determined. It was found for both sorbents that the absorbability of silica is less than that of alumina. The relative sorption rate of silica is similar to that of alumina. The sorption edges are similar to each other, that the insensitivity of sorption to ionic strength is about the same. These similarities between the sorbents suggest that the speciation of Th(IV) in aqueous solutions plays a significant, but subtle role, in controlling the sorption process, because the charges of both sorbents are distinctly different. The mechanism of Th(IV) sorption on alumina is distinctly different from that of the sorptions of Cs⁺, Eu³⁺ and Yb³⁺ on alumina, and similar to that of the sorption of Co(II) on alumina.