Extraction of Cesium by a Calix[4]arene‐Crown‐6 Ether Bearing a Pendant Amine Group

Abstract

The goal of this work was to evaluate the role of the amino group of 5‐aminomethylcalix[4]arene‐[bis‐4‐(2‐ethylhexyl)benzo‐crown‐6] (AMBEHB) in the extraction of cesium from acidic and basic mixtures of sodium nitrate and other concentrated salts. The extraction of cesium from nitrate media was measured as a function of extractant concentration, nitrate concentration, cesium concentration, and pH over the range 1–13. The initial studies showed a moderate decrease in the extraction of cesium in acidic media, which indicated the binding of cesium by the calixarene‐crown was weakened by the protonation of the amine group. The results also indicated that a 1∶1∶1 Cs‐ligand‐nitrate complex is formed in the organic phase. To further evaluate AMBEHB, the empirical data were mathematically modeled to determine the formation constants of the complexes formed in the organic phase. The resulting formation constants showed that the attachment of the amine group to the calixarene‐crown molecule reduced the binding stability for the cesium ion upon contact with an acidic solution. This supports the hypothesis of charge repulsion as the basis for more efficient stripping of cesium via pH‐switching.     

Phosphorus Recovery by Liquid–Liquid Extraction

Abstract

It is acknowledged that phosphorus removal is more crucial in comparison with nitrogen removal for preventing algae glooming and eutrophication. Chemical and biological methods are common methods for the P removal. Excessive sludge production and difficulties of recovering phosphorus are concerns in terms of sustainable waste management. A liquid-liquid extraction (LLE) process is thus considered for the study aiming at recovering phosphorus from wastewater in a sustainable way. The results revealed that the best extractant is a mixture of kerosene and benzyl-di-methyl-amine (BDMA) at a volume ratio of 2:1. Under the study conditions, one part of extractant can react with four parts of wastewater to transfer >97% of P to the organic phase. In addition, in the stripping step, a 1:1 ratio of extract to recycled acid can result in 96% recovered P, implying an overall 93% phosphorus recovery efficiency can be achieved by the LLE process. Most importantly, the extractant can be recycled and reused at least 5 times if the residual P concentration should be less than 4 mg/L vs. the original P concentration of 21 mg/L. A complexion between amine groups in BDMA and phosphates and the positive charge of the micelles surface when the extractant (composed of kerosene and BDMA) mixed with P containing wastewater would contribute to the P recovery and this is a novel approach to recover P from wastewater.     

Removal of Dichromate Anions with Nanofiltration‐Complexation by using Amino Calix[4]arene Derivative

Abstract

Herein the removal and recovery of chromium anions from aqueous solutions by using nanofiltration pilot‐scale equipment (Osmonics Sepa CF Membrane Cell) with a water‐soluble amino calix[4]arene derivative was studied. To understand the selectivity, the authors also examined the retention of chromium anions in the presence of Cl^?, NO₃ ^?, SO₄ ^2?, HSO₄ ^?, CO₃ ^2?, PO₄ ^3?, H₂PO₄ ^? anions in nanofiltration‐complexation. From the results water‐soluble amino calix[4]arene was effective and selective ligand for dichromate anions over nitrate anions, in a nanofiltration‐complexation system at pH 2.5. Moreover, the recovery and reusability studies of dichromate and nitrate anions and also ligand were performed.     

Recovery of Furfural from Aqueous Solution by Ionic Liquid Based Liquid–Liquid Extraction

Abstract

Liquid–liquid extraction with imidazolium based ionic liquids ([C₄mim][PF₆], [C₆mim][PF₆], and [C₈mim][PF₆]) is proposed for the separation of furfural or 5-methylfurfural from aqueous solution. Factors affecting the extraction of furfural or 5-methylfurfural have been studied. It was shown that the extraction equilibria can be achieved within 30 min and the process was less affected by the factors such as volume ratio and feed concentration. The partition coefficients of furfural and 5-methylfurfural decreased with increasing temperature. [C₆mim][PF₆] was found to have the best extraction ability among the three ionic liquids studied. Presence of small amount of NaCl or Na₂SO₄ in the aqueous phase results in the considerable increase in the partition coefficients of furfural because of the competitive hydration of the salts with furfural. A thermodynamic study revealed that the extraction process was driven mainly by hydrophobic interactions. Further experimental results indicated that furfural can be separated selectively from aqueous furfural/acetic acid mixtures.     

Studies on the Extraction—Simultaneous Back-Extraction of Alkali Metal Picrates Using 1,3 Bis-Benzo-Crown-6-Calix[4] Arene in Hollow-Fiber Contactors

Abstract

An extraction and simultaneous back-extraction process with two hollow-fiber membrane contactors is evaluated for the continuous recovery of alkali metals and 1,3 bis-benzo-crown-6-calix[4]arene. The results show that this configuration operates as a “liquid membrane” (permeable only with alkali picrate) and order of the recovery yields is in agreement with the Donnan equilibrium. It is higher for the rubidium (75.8%) than for the cesium (68.1%) while it is only 11% for the potassium. This is a case where the high affinity of cesium picrate for the 1,3 bis-benzo-crown-6-calix[4]arene cannot be neglected and, as a consequence, its release in the back-extraction aqueous phase is more difficult. The effect of the alkali metal and the initial concentration on the system behavior shows that the concentration gradient controls the mass transfer. The kinetics are similar for the cesium and the rubidium whereas the mass-transfer resistance increases for the potassium. A high mass transfer in the first module can slow down the global-transport kinetics.     

Salt Effects on the Recovery of Phenol by Liquid‐Liquid Extraction with Cyanex 923

Abstract

In this work, the effect of salt addition on the recovery of phenol from a 46 g/L aqueous solution simulating a phenolic resin plant effluent by liquid‐liquid extraction at 298 K has been studied by using an organic phase containing 0.6 M Cyanex 923 extractant in ShellSol T. Addition of sodium sulfate, potassium nitrate, and sodium chloride to the aqueous phase was tested and sodium chloride was selected. Based on the obtained results, a study of phenol recovery process was undergone by taking advantage of the salting‐out effect. Equilibrium curves are presented for liquid‐liquid extraction with and without salt addition to the aqueous phase. An integrated process involving salting‐out and liquid‐liquid extraction was proposed. The stripping concentrates can be reused for phenolic resin production.     

Calix[4]arene–carbazole-containing polymers: Synthesis and properties

New highly fluorescent calix[4]arene-containing phenylene-alt-ethynylene-3,6- and 2,7-carbazolylene polymers (CALIX-PPE-CBZs) have been synthesized for the first time and their photophysical properties evaluated. Both polymers were obtained in good isolated yields (70–84%), having M_w ranging from 7660–26,700 g mol⁻¹. It was found that the diethynyl substitution (3,6- or 2,7-) pattern on the carbazole monomers markedly influences the degree of polymerization. The amorphous yellow polymers are freely soluble in several nonprotic organic solvents and have excellent film forming abilities. TG/DSC analysis evidences similar thermal behaviors for both polymers despite their quite different molecular weight distributions and main-chain connectivities (T_g in the range 83–95 °C and decomposition onsets around 270 °C).The different conjugation lengths attained by the two polymers dictates much of their photophysical properties. Thus, whereas the fully conjugated CALIX-PPE-2,7-CBZ has its emission maximum at 430 nm (E_g = 2.84 eV; Φ_F = 0.62, CHCl₃), the 3,6-linked counterpart (CALIX-PPE-3,6-CBZ) fluoresces at 403 nm with a significant lower quantum yield (E_g = 3.06 eV; Φ_F = 0.31, CHCl₃). The optical properties of both polymers are predominantly governed by the intrachain electronic properties of the conjugated backbones owing to the presence of calix[4]arenes along the polymer chain which disfavor significant interchain interactions, either in fluid- or solid-state.     

Extraction of Copper by Selective Ion Exchangers with Pendent Ethyleneimine Groups—Investigation of Active States

Abstract

Selective ion exchangers with pendent ethyleneimine groups of the type -(NHC₂H₄)n · NH₂, where n = 1 to 5, have been prepared, and their ability to extract cationic and anionic-chelated copper(II) ions has been evaluated. Copper has been extracted from aqueous solution, and the equilibrium capacities of extraction vary according to the active sites in the selective ion exchangers. The poor exchange properties of selective ion exchangers with short pendent groups have been related to the nature of the active coordination sites. The active sites on these selective ion exchangers change from two nitrogen atoms and two oxygen atoms (N₂O₂) with short chains (n = 1) to four nitrogens when n = 2 to 5. Those which have N₄ active sites appear to extract cationic copper(II) efficiently, but those with N₂O₂ sites have low capacities and copper is easily leached from the resin even when the loading of the resin is low. When copper is complexed to EDTA to form an anionic complex, a side chain like pentaethylene hexamine is required to extract the copper from aqueous solution. A macroporous polystyrene resin had a lower capacity for anionic chelated copper than a polystyrene gel resin with the same functional groups due to the poorer accessibility of the active (N₄) sites to the large anion.     

Extraction of 4‐Hydroxycinnamic Acid from Aqueous Solution by Emulsion Liquid Membranes

Abstract

This work reports a study of 4‐hydroxycinnamic acid extraction by emulsion liquid membranes. The effect of the presence of additives in the membrane phase on solute permeation was tested. The membrane with 2 wt.% of isodecanol, 2 wt.% of ECA4360J, and Shellsol T as diluent was selected to examine the permeation of 4‐hydroxycinnamic acid. The modeling of solute extraction was done by taking into account the mass transfer in the external phase and globule, and the reaction between the diffusing component and the stripping reagent. The agreement between the calculated results and the experimental data was found satisfactory.     

Liquid–Liquid Extraction of Silver From Chloride Media by N,N′-Tetrasubstituted Dithiomalonamide Derivatives

N,N′-dimethyl-N,N′-diphenyldithiomalonamide (DMDPHDTMA) and N,N′-dimethyl-N,N′-dicyclohexyldithiomalonamide (DMDCHDTMA) were synthesized and tested as extractants for silver in chloride solutions. Even when relatively low concentrations are used, both compounds effectively extract Ag(I) from 2–5 M chloride concentrated aqueous phases. Ag(I) is successfully stripped by a stabilized sodium thiosulfate solution. Results obtained from sequential cycles of extraction-stripping suggest that both extractants exhibit a high Ag(I) loading capacity. The effects of the equilibration time, concentrations of extractant, chloride and hydrogen ions on Ag(I) extraction have been investigated. The chemical reactions involved on Ag(I) extraction are proposed. There is no selectivity of DMDPHDTMA or DMDCHDTMA for Ag(I) when Cu(II) and Fe(III) co-exist in the chloride aqueous solution.     

Liquid–Liquid Extraction of GSH Using DEHAP/Octanol Reverse Micelles

Abstract

In this study, di-(2-ethylhexyl) ammonium phosphate (DEHAP)/octanol reverse micellar extraction was investigated and demonstrated to be an effective method to separate GSH from yeast fermentation broth. The effect of several important factors i.e., pH, DEHAP concentration, and type & concentration of cations on both extraction and strip-extraction was investigated. The optimum operating conditions for both extraction and strip-extraction were obtained by two groups of orthogonal experiments. At the optimum operating conditions, the yield of GSH can reach 68%. In the lyophilized product, the purity of GSH was higher than 75%, all the proteins can be separated, and only a small portion of amino acids were left.     

Liquid—Liquid Extraction of Goid(III) with Diluted Tributyl Phosphate

Abstract

A new method is developed for the. solvent extraction of gold with diluted tributyl phosphate. In this method, 50% tributyl phosphate in toluene extracts gold quantitatively from 3 M hydrochloric acid containing 2 M lithium chloride as the salting-out agent. Gold from the organic phase is stripped with 1 M ammonium hydroxide and determined photometrically as its complex with stannous chloride. It is possible to extract gold in the presence of a large number of ions.     

Liquid–Liquid Extraction of Butanol from Dilute Aqueous Solutions Using Soybean-Derived Biodiesel

Liquid–liquid extraction (LLE) of mixtures of butanol, 1,3-propanediol (PDO), and ethanol was performed using soybean-derived biodiesel as the extractant. The composition of the mixtures simulated the product of the anaerobic fermentation of biodiesel-derived crude glycerol, which has recently been reported for the first time by the authors. Using a biodiesel: with an aqueous phase volume ratio of 1:1, butanol recovery ranged from 45 to 51% at initial butanol concentrations of 150 and 225 mM, respectively. Less than 10% of the ethanol was extracted, and essentially no PDO was extracted. The partition coefficient for butanol in biodiesel was determined to be 0.91 ± 0.097. This partition coefficient is less than that of oleyl alcohol, which is considered the standard for LLE. However, butanol is suitable for blending with biodiesel, which would eliminate the need for separating the butanol after extraction. Additionally, biodiesel is much less costly than oleyl alcohol. If biodiesel-derived glycerol is used as the feedstock for butanol production, and biodiesel is used as the extractant to recover butanol from the fermentation broth, production of a biodiesel/butanol fuel blend could be a fully integrated process within a biodiesel facility. This process could ultimately help reduce the cost of butanol separation and ultimately help improve the overall economics of butanol fermentation using renewable feedstocks.     

The Effect of Nanoparticles on the Mass Transfer in Liquid–Liquid Extraction

This article investigates the effect of nanoparticles on mass transfer in the liquid–liquid extraction for the chemical system of n-butanol–succinic acid–water. For this purpose, nanofluids containing various concentrations of ZnO, carbon nanotubes (CNT), and TiO₂ nanoparticles in water, as base fluid, were prepared. To examine the flow mode effect on mass transfer rate, different fluid modes including dropping and jetting were employed in the process. Results show that mass transfer rate enhancement depends on the kinds and the concentration of nanoparticles and the modes of flow. It was observed that after adding nanoparticles, the mass transfer rate significantly increases up to two-fold for ZnO nanoparticles. Furthermore, the results indicate that under the circumstances in which the mass flow rate is high enough, the effect of nanoparticles on the mass transfer phenomenon is too slight.     

Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System

Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature.     

Liquid–Liquid Extraction of Lithium Ions Using a Slug Flow Microreactor: Effect of Extraction Reagent and Microtube Material

Lithium ions were extracted from aqueous solutions into cyclohexane containing di-(2-ethylhexyl)phosphoric acid (D2EHPA) through slug flow in millimeter-diameter glass and polytetrafluoroethylene (PTFE) tubes. The PTFE tube produced a higher initial mass transfer coefficient than the glass tube by increasing internal circulation in the organic phase, and maintained its specific surface area. Slug flow occurred in the PTFE tube when the interfacial tension between the aqueous and organic phases exceeded 50–55 mN/m, which increased the rate of extraction owing to increased circulation in both phases. The addition of tributyl phosphate (TBP) enhanced the extraction efficiency, but did not affect the extraction rate.     

Liquid—Liquid Extraction of Mercury with High-Molecular-Weight Amines from Iodide and Bromide Solutions

Abstract

New systems are described for the highly efficient solvent extraction of mercury with high-molecular-weight amines from aqueous iodide or bromide solutions. Mercury extracts essentially quantitatively at both the sub-nanogram and macro levels. The quaternary amines are especially attractive because of their ability to extract mercury from alkaline as well as acidic solutions. Regeneration of the amine solvent is readily achieved by stripping the mercury with alkaline solutions of cysteine.     

New Alkylation Route of Benzene with Ethylene Catalyzed by [bmim]Cl/FeCl_3 Ionic Liquid

Up to now the mechanism of Friedel-Crafts reactions catalyzed by ionic liquid have not been fully understood, while carbocation mechanism was assumed. It was found that the source of H and the route of reaction initiated the alkylation of benzene with ethylene catalyzed by [bmim]Cl/FeCl3 ionic liquid. The fact that dewatered ionic liquids have catalytic activity for the alkylation of benzene with ethylene suggests that there exists a new catalytic route. The distinctly Bronsted acid properties of 2-H in [bmim]Cl were found through FT-IR and HNMR     

Cloud Point-Dispersive Liquid–Liquid Microextraction for Extraction of Organic Acids from Biological Samples

A new method combining cloud point extraction (CPE) with dispersive liquid–liquid microextraction (DLLME) named “cloud point‐dispersive liquid–liquid microextraction (CP‐DLLME)” was presented in this work for the first time for the determination of organic acids as model compounds in biological samples using high performance liquid chromatography and UV detection (HPLC–UV). Water (disperser solvent) containing tert‐octylphenol ethoxylate (7.5EO) as extraction solvent, was rapidly injected into a warmed sample solution and cloudy state formed immediately. After that, phase separation was performed by centrifugation. The surfactant‐rich phase was diluted with acetonitrile and injected into a HPLC–UV apparatus. The influence of several important parameters on the extraction efficiencies was evaluated. Under optimized experimental conditions, the calibration graphs were linear in the range of 0.06–1,500 µg L^?1 for target analytes. Coefficient of determination (r²) ranged from 0.9985 to 0.9994. The limits of detection were in the range of 0.05–17.1 µg L^?1. The new method was successfully applied with satisfactory results for analysis of target analytes in spiked samples. The relative mean recoveries of the spiked samples ranged from 91.8 to 107.1 % with relative standard deviations in the range of 2.1 to 4.3 %.     

Extraction Kinetics of Lanthanum in Chloride Medium by Bifunctional Ionic Liquid [A336][CA-12] Using a Constant Interfacial Cell with Laminar Flow☆

The extraction kinetics of La(III) from aqueous chloride solutions into n-heptane solutions of bifunctional ionic liquid extractant [A336][CA-12] (tricaprylmethylammonium sec-octylphenoxy acetic acid) ...