Showing papers in "Separation Science and Technology in 1995"
TL;DR: In this article, the authors evaluated diamides and picolinamides, extractants which have the common characteristic of being totally combustible, and selected DMDBTDMA as the reference extractant.
Abstract: In the framework of the SPIN(ACTINEX) program for the partitioning and transmutation of actinides contained in effluents generated during the nuclear fuel reprocessing cycle, diamides and picolinamides, extractants which have the common characteristic of being totally combustible, were evaluated. Among the diamides, N,N-dimethyl N,N-dibutyl tetradecyl malonarmide (DMDBTDMA) was chosen as the reference extractant. It has been shown that actinides(III) may be extracted from concentrated nitric acid effluent; the actinides(III) may be readily stripped from the loaded solvent. There is restricted third-phase formation. Long alkyl groups (R″) and different R and R' on the amide nitrogen limit the extent of third-phase formation. The second class of extractants studied, the picolinamides, seem to have potential for the separation of An(III)/Ln(III).
123 citations
TL;DR: Chitosan is a novel glucosamine biopolymer derived from the shells of marine organisms as discussed by the authors, which is very attractive for heavy metal ion separations from wastewater because it is selective for toxic transition metal ions over less toxic alkali or alkane earth metal ions.
Abstract: Chitosan is a novel glucosamine biopolymer derived from the shells of marine organisms. This biopolymer is very attractive for heavy metal ion separations from wastewater because it is selective for toxic transition metal ions over less toxic alkali or alkane earth metal ions. Highly porous, 3-mm chitosan beads were prepared by an aqueous phase-inversion technique for casting gel beads followed by freeze drying. In the attempt to simultaneously improve material properties and adsorption capacity, chitosan was chemically modified by 1) homogeneous acylation of amine groups with nonanoyl chloride before bead casting, and 2) heterogeneous crosslinking of linear chitosan chains with the bifunctional reagent glutaric dialdehyde (GA) after bead casting but before freeze drying. The random addition of C8 hydrocarbon side chains to about 7% of the amine groups on uncrosslinked chitosan beads via N-acylation improved the saturation adsorption capacity from 169 to 216 mg Cd2+/g-bead at saturation (pH 6.5, ...
109 citations
TL;DR: In this article, the adsorption of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method.
Abstract: In this study, adsorptions of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method. The hydrogels were prepared by irradiating with γ-radiation. In the experiment of uranyl ions adsorption, Type II adsorption was found. One gram of acrylamide-itaconic acid hydrogels sorbed 178–219 mg uranyl ions from the solutions of uranyl acetate, 42–76 mg uranyl ions from the aqueous solutions of uranyl nitrate, while acrylamide hydrogel did not sorb any uranyl ion. For the hydrogel containing 40 mg of itaconic acid and irradiated to 3.73 kGy, swelling of the hydrogels was observed in water (1660%), in the aqueous solution of uranyl acetate (730%), and in the aqueous solution of uranyl nitrate (580%). Diffusions of water onto hydrogels were a non-Fickian type of diffusion, whereas diffusions of uranyl ions were a Fickian type of diffusion.
97 citations
TL;DR: In this paper, the effects of pH and three inorganic salts (KCl, KI, and NaCl) on the adsorption isotherms of phenol (from a dilute aqueous solution) on activated charcoal was conducted.
Abstract: An experimental investigation of the effects of pH and three inorganic salts (KCl, KI, and NaCl) on the adsorption isotherms of phenol (from a dilute aqueous solution) on activated charcoal was conducted. Each salt was studied at three different concentrations, i.e., 0.1, 0.001, and 0.005 M. The effect of pH (in the pH range 3 to 11) in the presence of KI, KCl, and NaCl was also investigated. The concentration of phenol in the aqueous systems studied ranged from 10 to 200 ppm. The temperature effect was also studied, and the resulting experimental equilibrium isotherms at 30, 40, and 55°C are well represented by Freundlich, Langmuir, and Redlich—Paterson isotherms. The relevant parameters for these isotherms are presented.
92 citations
TL;DR: In this paper, a cloud-point extraction of organic compounds from aqueous solutions by using the nonionic surfactant PONPE10 has been investigated for phenol and three pyridines to clarify the effect of operating factors on its extractability.
Abstract: Cloud-point extraction of organic compounds from aqueous solutions by using the nonionic surfactant PONPE10 has been investigated for phenol and three pyridines to clarify the effect of operating factors on its extractability. Phase separation of the surfactant solutions is attained at temperatures above the cloud point, and it is improved by adding NaCl or phenol. Phenol is extracted successfully in a wide pH range from acidic to neutral solutions with and without NaCl, where the extraction efficiency increases with an increase in the surfactant concentration. Backextraction of phenol from the surfactant-rich phase was found to be possible with alkaline solutions. Three pyridine derivatives can also be extracted from the solution under neutral and alkaline conditions, although the efficiencies are somewhat low compared with phenol. Moreover, selective separation of the pyridines from each other could be accomplished because of the difference in their hydrophobicities.
86 citations
TL;DR: In this paper, an acrylamide-maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by γ-radiation for adsorption of some heavy metal ions such as uranium, iron, and copper.
Abstract: In this study, acrylamide—maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by γ-radiation. They have been used for adsorption of some heavy metal ions such as uranium, iron, and copper. For the hydrogel containing 40 mg of maleic acid and irradiated at 3.73 kGy, maximum and minimum swellings in the aqueous solutions of the heavy metal ions have been observed with water (1480%) and the aqueous solution of iron(III) nitrate (410%), respectively. Diffusions of water and heavy metal ions onto hydrogels have been found to be of the non-Fickian type of diffusion. In experiments of uranyl ions adsorption, Type II adsorption has been found. One gram of AAm/MA hydrogels sorbed 14–86 mg uranyl ions from solutions of uranyl acetate, 14–90 mg uranyl ions from solutions of uranyl nitrate, 16–39 mg iron ions from solutions of iron(IV) nitrate, and 28–81 mg copper ions from solutions of copper acetate, while acrylamide hydrogel did not sorb any heavy metals ions.
85 citations
TL;DR: In this article, a low-waste process for biodiesel is introduced, and a survey of production methods is presented, along with a discussion of reasons that support the arguments for the biodiesel.
Abstract: The acceptance of methylesters (biodiesel) as an alternative fuel has rapidly increased in recent years. This development has been followed by increasing research activities in the field of methylester processes. After listing reasons that supporte arguments for biodiesel and a survey of production methods, a low-waste process for biodiesel is introduced.
80 citations
TL;DR: The magnetically assisted chemical separation process (MACS) as discussed by the authors combines the selective and efficient separation afforded by chemical sorption with the magnetic recovery of ferromagnetic particles for treating the underground storage tanks at Hanford.
Abstract: The magnetically assisted chemical separation process (MACS) combines the selective and efficient separation afforded by chemical sorption with the magnetic recovery of ferromagnetic particles. This process is being developed for treating the underground storage tanks at Hanford. These waste streams contain cesium, strontium, and transuranics (TRU) that must be removed before this waste can be disposed of as grout. The separation process uses magnetic particles coated with either 1) a selective ion exchange material or an organic extractant-containing solvent (for cesium and strontium removal) or 2) solvents for selective separation of TRU elements (e.g., TRUEX process). These coatings, by their chemical nature, selectively separate the contaminants onto the particles, which can then be recovered from the tank using a magnet. Once the particles are removed, the contaminants can either be left on the loaded particles and added to the glass feed slurry or stripped into a small volume of solution so...
76 citations
TL;DR: The use of polyelectrolyte-enhanced ultrafiltration (PEUF) for water softening has been studied at several temperatures in the presence and absence of added salt as discussed by the authors.
Abstract: The use of polyelectrolyte-enhanced ultrafiltration (PEUF) for water softening has been studied at several temperatures in the presence and absence of added salt. It is shown that in the absence of added salt. PEUF is highly effective in the rejection of up to 99.7% of hardness ions from an aqueous stream. At a low concentration of added salt. PEUF is effective in the removal of hardness. As salt concentration increases, however, hardness rejection decreases dramatically. The experimental results have been effectively modeled using an ion-binding model based on Oosawa's two-phase approximation theory.
70 citations
TL;DR: In this paper, the influence of the blend composition and feed composition on the pervaporation performance of a polymer blend of poly(acrylic acid) and poly(vinyl alcohol) was investigated.
Abstract: Membranes made of a polymer blend of poly(acrylic acid) and poly(vinyl alcohol) were evaluated for the separation of methanol from methyl tert-butyl ether (MTBE) by pervaporation. The influence of the blend composition and the feed composition on the pervaporation performance were investigated. Methanol permeates preferentially through all tested blend membranes, and the selectivity increases with increasing poly(vinyl alcohol) content in the blends. However, a flux decrease is observed with increasing poly(vinyl alcohol) content. With increasing feed temperature the flux increases, and the selectivity remains constant. In addition, the influence of crosslinking on the permselectivity was investigated. The pervaporation flux decreases with increasing crosslinking density, but the selectivity is enhanced. This is due to a more rapid decrease in the component flux of MTBE compared to that of methanol.
64 citations
TL;DR: In this article, a model that yields liquid phase diffusion coefficients as a function of molecular weight was utilized to determine molecular weights from degree of separation, and the separations obtained were used to develop a relationship between flow FFF separation and species molecular w...
Abstract: The ability to characterize molecules whose physical and chemical properties are intimately linked to their diffusion coefficients and molecular weight is important to further understanding of chemical transport in the environment. Flow field-flow fractionation (flow FFF) was used to obtain separations of water-soluble macromolecules of varying molecular weight, including polystyrene sulfonates and humic substances. The separation occurs due to differing diffusion rates for chemical species of differing molecular weight in aqueous solution. Flow FFF uses fluid flow as the mechanism of separation. A model that yields liquid phase diffusion coefficients as a function of molecular weight was utilized to determine molecular weights from degree of separation. Separations of polystyrene sulfonates, a humic acid, and two fulvic acids of known molecular weight were accomplished using flow FFF. The separations obtained were used to develop a relationship between flow FFF separation and species molecular w...
TL;DR: In this article, a polymer-assisted ultrafiltration method was proposed to remove boron contamination of natural waters using the pH-dependent complexation between boric acid and a macromolecule containing vicinal diol groups.
Abstract: Boron contamination of natural waters is a widespread environmental problem which lacks a cost-effective solution. Polymer-assisted ultrafiltration is a method of boron removal that is compatible with other water-treatment processes. This boron removal technique exploits the pH-dependent complexation between boric acid and a macromolecule containing vicinal diol groups to prevent boric acid from passing through an ultrafiltration membrane. The concentration of boron in treated water was reduced from 10.5 ppm to less than 2 ppm through ultrafiltration of an aqueous solution containing boric acid and a polymer synthesized by grafting N-methyl-D-glucamine (NMG) onto poly(epichlorohydrin). The NMG groups, when tethered to the polymer, exhibited stronger affinity for boron than expected from equilibria between NMG and boric acid.
TL;DR: In this paper, a packed bed absorber-stripper system was used to remove selected indoor pollutants during the dehumidification of air by triethylene glycol solutions, and both random and structured packings were employed to provide the contact surface between the liquid and gas phases.
Abstract: A packed bed absorber-stripper system was used to remove selected indoor pollutants during the dehumidification of air by triethylene glycol solutions. Triethylene glycol concentrations of 90% and 95% by weight in water were used. Both random and structured packings were employed to provide the contact surface between the liquid and gas phases. A six-inch I. D. absorption column was operated between 50% and 80% of flooding conditions. The heights of a transfer unit for mass transfer for randomly packed 5/8-inch polypropylene Flexi rings and 1/2-inch ceramic Intalox saddles varied from 0.12 m to 0.17 m when dehumidifying air only. However, the height of a transfer unit was in the range of 0.31 m to 0.40 m for the cross corrugated cellulose and PVC structured packings. Heat and mass transfer coefficients were also calculated from the experimental data and were correlated with various process variables. The values predicted by these correlations were within ±10% of the experimental data. Pollutants ...
TL;DR: Experimental data obtained in this study clearly demonstrate that the electrostatic interactions between dissimilar molecules may control the solute rejection and the filtration rate in upward ultrafiltration of binary protein mixtures.
Abstract: Upward dead-end ultrafiltration of aqueous solutions of mixtures of bovine serum albumin (BSA) and egg white lysozyme was conducted using membranes which are almost completely retentive for BSA but permeable for lysozyme. The dependence of lysozyme rejection and the filtration flux rate on pH and the addition of salts has been investigated. The experimental data obtained in this study clearly demonstrate that the electrostatic interactions between dissimilar molecules may control the solute rejection and the filtration rate in upward ultrafiltration of binary protein mixtures. For instance, the BSA and lysozyme molecules have opposite electric charges at pH 7. Consequently, lysozyme rejection is large because both molecules within the filter cake pack more tightly due to heterocoagulation. On the other hand, the BSA and lysozyme molecules have the same electric charge at pH 4. Thus, lysozyme is rejected by the filter cake of the retained BSA molecules due to repulsive electrostatic interactions b...
TL;DR: Carbon prepared from peanut hulls (PHC) has been used for the adsorption of Pb(II) over a range of initial metal ion concentrations (10−20 mg/L), agitation times (5−140 minutes), adsorbent dosages (5 −100 mg/100 mL), and pH values (1.5−10.0) as mentioned in this paper.
Abstract: Carbon prepared from peanut hulls (PHC) has been used for the adsorption of Pb(II) over a range of initial metal ion concentrations (10–20 mg/L), agitation times (5–140 minutes), adsorbent dosages (5–100 mg/100 mL), and pH values (1.5–10.0). Adsorption of Pb(II) obeyed the Langmuir isotherm. The applicability of the Lagergren kinetic model has also been investigated. Quantitative removal of 20 mg/L Pb(II) by 0.3 g carbon per liter aqueous solution was observed in the pH range of 3.0 to 10.0. A comparative study with a coal-based commercial granular activated carbon (CAC) showed that the adsorption capacity of PHC was 18 times larger than that of CAC.
TL;DR: Palladium acetate vapor was sublimed at reduced pressure and was evacuated through the porous wall of an α-alumina support tube of 18 mm id and 24 mm od Due to chemical vapor deposition (CVD), a thin palladium membrane was formed in macropores of the support as mentioned in this paper.
Abstract: Palladium acetate vapor was sublimed at a reduced pressure and was evacuated through the porous wall of an α-alumina support tube of 18 mm id and 24 mm od Due to chemical vapor deposition (CVD), a thin palladium membrane was formed in macropores of the support The membrane part was about 50 mm in length and was used without any pretreatment The palladium membrane, prepared at a maximum CVD temperature of 400°C, showed hydrogen permeance and selectivity to nitrogen higher than 10−6 mol·m−2·s−1·Pa−1 and 1000 at 300–500°C, respectively Even after the permeation temperature was repeatedly varied between 100 and 300°C in a hydrogen atmosphere, the membrane exhibited no hydrogen embrittlement The amount of palladium deposited in pores of the support tube was 22 g/m2 of the outer surface of the tube The thickness of the palladium membrane calculated from this value was 44 μm
TL;DR: In this article, the authors present a review of the mechanisms of the degradation of the solvent system in TBP and diluent radiation-chemical transformations occurring on decomposition of a solvent system.
Abstract: Reprocessing spent nuclear fuel is indispensable for the economical use of uranium in nuclear energy production, and has been used industrially for more than 40 years. These processes involve the use of an extractant/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate (TBP) diluted with normal-paraffin hydrocarbon. However, on repeated use, the solvent becomes degraded due to thermal, radiolytic, and chemical attacks, resulting in chemical as well as physical damage. In view of the considerable expansion in the knowledge and understanding regarding the chemical and radiolytical decomposition of both TBP and the hydrocarbon diluent, an up-to-date review seemed appropriate. This review is concerned mainly with the mechanisms of the degradation of the solvent system. Schemes of TBP and diluent radiation-chemical transformations occurring on decomposition of the solvent system are presented.
TL;DR: In this article, a dimensionless dispersion number (NDi) is proposed to characterize the ability of a solvent to separate from a two-phase dispersion and to estimate process throughput for equipment of a given size.
Abstract: When developing new solvent extraction processes, one often has to evaluate new solvents, new aqueous phases, or both for their ability to work in plant-scale equipment. To facilitate solvent characterization, a simple test is proposed based on the dimensionless dispersion number (NDi). It allows one to characterize the ability of the solvent to separate from a two-phase dispersion and to estimate process throughput for equipment of a given size. Several ways to carry out the NDi test are given, including a standard test procedure. The NDi test was applied to the performance of solvent extraction equipment with discrete process stages, the leaching of plasticizers from plastic tubing, and the development of a new solvent for the combined extraction of strontium and transuranic elements.
TL;DR: In this article, a systematic study of the extraction behavior of selected components of camomile flowers in extraction with supercritical carbon dioxide was carried out, where α-Bisabolol and its A and B oxides were selected.
Abstract: A systematic study of the extraction behavior of selected components of camomile flowers in extraction with supercritical carbon dioxide was carried out. (–)-α-Bisabolol and its A and B oxides, which have a wide importance in pharmacology and standardization of camomile flower products, were selected. The dependence of the yield of selected components on the pressure and/or temperature of supercritical extraction was investigated. The results obtained were correlated.
TL;DR: In this article, the effect of EDTA, a strong agent, on the removal of copper ion from solutions using activated carbon adsorption was investigated. And the results indicated that the desorption of chelated copper ions from activated carbon by NaOH and HClO4 solutions was influenced by the initial adaption conditions.
Abstract: This paper addresses the effect of EDTA, a strong agent, on the removal of copper ion from solutions using activated carbon adsorption. Experimental studies indicate the presence of EDTA significantly altered the adsorption behavior of copper on the activated carbon due to the formation of copper chelate species in the solution. The adsorption isotherms and kinetics were found to be strong functions of solution pH and the ratio of copper ion and EDTA concentrations. Adsorption of EDTA-Cu chelates was found to be more favorable than those of free copper ion and unbound EDTA species in the solution. Experimental results indicated that the desorption of chelated copper ion from activated carbon by NaOH and HClO4 solutions was influenced by the initial adsorption conditions. A significantly higher quantity of copper ion was recovered with HClO4 than with NaOH. Combining the adsorption and desorption data of copper and EDTA, and an understanding of the species distribution of copper in the presence of...
TL;DR: In this article, a few complexane types of chemically modified chitosan, i.e., monocarboxymethylated (MCM)-chitosans, and IDA-and DTPA-types of CHITOSAN (IDA- and DTPA-) were synthesized to examine the adsorption of palladium(II), platinum(IV), and iridium(III) from hydrochloric acid solution as well as the elution of Palladium and platinum.
Abstract: A few kinds of complexane types of chemically modified chitosan, i.e., monocarboxymethylated chitosan (MCM-chitosan) and IDA- and DTPA-types of chitosan (IDA- and DTPA-chitosan) were synthesized to examine the adsorption of palladium(II), platinum(IV), and iridium(III) from hydrochloric acid solution as well as the elution of palladium and platinum and compared with those by crosslinked copper(II)-complexed chitosan (crosslinked chitosan). The adsorption of palladium(II) monotonously decreased with increasing hydrochloric acid concentration with all kinds of adsorbents. The adsorption of platinum(IV) also decreased with increasing hydrochloric acid concentration with all kinds of adsorbents except for DTPA-chitosan, with which it decreased in the low concentration region and increased in the high concentration region. The adsorption of iridium(III) also decreased with increasing concentration of hydrochloric acid with all kinds of adsorbents except for IDA-chitosan, but that on DTPA-chitosan was ...
TL;DR: In this article, the removal of metal ions from aqueous solution by colloid precipitate flotation using sodium sulfide as the coagulent and oleic acid (HOL) as the surfactant was investigated.
Abstract: The removal of Cd(II), Pb(II), Hg(II), Sn(II), Sn(IV), Sb(III), Sb(V), As(III), and As(V) from aqueous solutions by colloid precipitate flotation using sodium sulfide as the coagulent and oleic acid (HOL) as the surfactant has been investigated. The complete flotation (about 100%) of these elements was attained at pH values of 5.5–6.5, 3–6.5, ≤1, 1–4, 0.5–3, and ≤2, respectively. The effects of some other factors, such as surfactant and coagulent concentrations, sequence of adding reagents, some selected foreign ions, ionic strength, and temperature, on the floatability of these elements have been studied. It was found that both temperature and ionic strength have no appreciable effect on the flotation efficiency of the metal ions investigated. The method was successfully applied to remove completely these metal ions added to 1 L samples of drinking and seawaters at the optimum conditions for each element. Moreover, the mechanism of flotation is proposed.
Abstract: A kinetic study concerning chemical complexation-based solvent extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved as an extractant in n-heptane was carried out using a microporous hydrophobic hollow fiber membrane extractor. The effects of concentration of chemical species in aqueous and organic feed solutions on the apparent permeabilities of metal species for extraction and stripping, respectively, were investigated to clarify the permeation mechanism. From the experimental results it was predicted that the permeation rate is controlled by diffusion of the chemical species in aqueous and organic phases and by interfacial chemical reaction. The experimental data were analyzed by the diffusion model accompanied with an interfacial reaction, taking into account the velocity distributions of the aqueous and organic phases through the inner and outer sides of the hollow fiber.
TL;DR: The multimembrane hybrid system (MHS) as mentioned in this paper was developed and used for the transportation and separation of divalent metal ions from multicomponent solutions, which consists of three membranes in series ion-exchange membrane | liquid membrane | ion exchange membrane.
Abstract: The multimembrane hybrid system (MHS) has been developed and used for the transportation and separation of divalent metal ions from multicomponent solutions. The system consists of three membranes in series ion-exchange membrane | liquid membrane | ion-exchange membrane The experiments were performed with liquid membranes composed of di(2-ethylhexyl)phosphoric acid in kerosene and Nafion-120 perfluorosulfonic acid polymer membranes. The fluxes and separation characteristics have been determined for MHS separating a solution of Zn(II), Mn(II), Cu(II), and Ni(II) sulfates as the feed phase, and the strip phase containing sulfuric acid. The results of competitive permeation experiments have shown the selectivity order Zn(II) > Mn(II) > Cu(II) ≫ Co(II), Ni(II). High separation coefficients were found for Zn(II), Cu(II), and Mn(II) compared to Ni(II) and Co(II).
TL;DR: In this article, the authors investigated the destruction of organic model substances by indirect electrooxidation and showed that the residual carbon in the process solution was determined by TOC measurement to be about 20 ppm and the remaining amount of adsorbahle organic halogens was less than 3 ppm.
Abstract: The destruction of organic model substances by indirect electrooxidation was investigated. The oxidation agent Co(II1) was used because of the high redox potential of the Co(III)/Co(II) redox couple (E0 = 1.808 V). Experiments were performed in a batch and in a continuous electrolytic cell by using various model substances (especially phenol and different chlorophenols). Intermediate and final products of the oxidation were identified and quantified. Organic carbon is ultimately transformed to CO2 and to small amounts of CO. The residual carbon in the process solution was determined by TOC measurement to be about 20 ppm. Organic chlorine is oxidized via chlorate to perchlorate. The remaining amount of adsorbahle organic halogens (AOX) was less than 3 ppm. Based on these results, a pilot plant was constructed and is presently in operation.
TL;DR: In this paper, the separation of cupric ions from aqueous solution by adsorption onto modified corncobs (hemicellulose-free) was studied.
Abstract: The separation of cupric ions from aqueous solution by adsorption onto modified corncobs (hemicellulose-free) was studied. The adsorption process was found to take ∼ 15 minutes to attain equilibrium in experiments with continuous agitation at 35°C. The process was found to be pH-dependent, with increasing adsorption as pH increases up to 6.00. There is evidence that the adsorption mechanism is an ion-exchange one involving carboxylate groups, and that two binding sites may be present at the adsorbent. The adsorption was found to fit a Langmuir isotherm, and the parameters n s (adsorbent capacity) and b (adsorption intensity) were calculated. The results obtained show that corncobs are an interesting adsorbent because they are available in large quantities at several places in the world at little or no cost, and they retain cupric ions rapidly. The corncobs studied also contain aliphatic and phenolic hydroxyl groups that allow for the incorporation of other functional groups and thus increase the ...
TL;DR: In this paper, the partitioning behavior of Sr2+ and Cs+ in aqueous biphasic systems formed by the addition of polyethylene glycol (PEG)-2000 to either NaOH, (NH4)2SO4, or K2CO3 was investigated.
Abstract: The partitioning behavior of Sr2+ and Cs+ in aqueous biphasic systems formed by the addition of polyethylene glycol (PEG)-2000 to either NaOH, (NH4)2SO4, or K2CO3 was investigated. Phase diagram data reveal that on a weight percent basis the salting out effects of the three salts increase in the order (NH4)2SO4 < K2CO3 < NaOH. In the presence of traditional extractants 12-crown-4, 15-crown-5, or 18-crown-6, only the partitioning of Sr2+ from (NH4)2SO4 media using 18-crown-6 resulted in the expected 1:1 extractant dependency. All other measured distribution ratios in the presence or absence of extractants and regardless of salt system appear to be governed by cation enthalpy of hydration and system composition. The distribution ratio for cesium, DCs is greater than DSr due to cesium's lower enthalpy of hydration. DM vs. percent salt and percent PEG both reveal an increase in DM with decreasing salt or PEG.
TL;DR: In this paper, the properties of polyamphoteric activated carbon fiber (ACF) were investigated theoretically and experimentally and compared with those from granular activated carbon (GAC) and ion-exchange resin (IER) materials.
Abstract: The properties of a new type of polyamphoteric activated carbon fiber (ACF) were investigated theoretically and experimentally. Results are compared with those from granular activated carbon (GAC) and ion-exchange resin (IER) materials. The adsorption rate of ACF was found to be two orders of magnitude higher than that of the GAC and one order of magnitude higher than that of the IER.
TL;DR: Potassium-Dicyclohexyl-18-Crown-6 Complex was used as a highly efficient carrier for the Uphill Transport of Copper As Cu(SCN)2−4 Complex Ion through a Chloro-form Bulk Liquid Membrane as mentioned in this paper.
Abstract: Potassium-Dicyclohexyl-18-Crown-6 Complex Was Used As A Highly Efficient Carrier For The Uphill Transport Of Copper As Cu(SCN)2− 4 Complex Ion Through A Chloroform Bulk Liquid Membrane. By Using Histidine As A Metal Ion Acceptor In The Receiving Phase At The Optimum Ph Of 7.4, The Amount Of Copper Transported Across The Liquid Membrane After 2 Hours Was 90.2 ± 1.0%. The Selectivity And Efficiency Of Copper Transport From Aqueous Solutions Containing Equimolar Mixtures Of Ag+, Cd2+, Zn2+, Ni2+, Fe2+, Co2+, Pb2+, Mn2+, Fe3+, Bi3+, And Cr3+ Ions Were Investigated. In The Presence Of Pyrophosphate As A Suitable Masking Agent In The Source Phase, The Interfering Effects Of Co2+, Zn2+, Pb2+, And Cd2+ Ions Were Completely Eliminated.
TL;DR: In this article, the authors compared the results of simple dialysis of single and multiionic solutions with the results obtained by the technique of Donnan dialysis in preconcentrating ions for further separation in a multimembrane hybrid system employing a specific carrier.
Abstract: Transport of sulfates of divalent metals [M = Mn(II), Cu(II), Co(II), Ni(II)] in a system made up of multicomponent solution of MSO4 ∣ Nafion membrane∣sulfuric acid solution was studied. It was found that Donnan dialysis results in a recovery factor amounting to 80–90% with the concentration ratio CM. strip/CM, feed not less than 30. The results of M(II)/H countertransport were compared with the results of simple dialysis of single and multiionic solutions. The technique of Donnan dialysis is efficient in preconcentrating ions for further separation in a multimembrane hybrid system employing a specific carrier of ions.