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Use of methyltrioctyl/decylammonium bis 2,4,4-(trimethylpentyl)phosphinate ionic liquid (ALiCY IL) on the boron extraction in chloride media
Abstract
Recent restriction of boron concentration in drinking water has produced some problems in the seawater desalinization plants because the rejection of boron in most of the plants is inadequate. Three ionic liquids derived from Cyanex 272 as an anion with different cations (from Aliquat 336, Cyphos IL 101 and Cyphos IL 167) were prepared to be used as boron extractants. Liquid–liquid extraction experiments were carried out to evaluate the viability of boron separation from high chloride media. The effect of ILs and boron concentration and pH were determined. Successive extractions, maintaining the organic phase, provided satisfactory results in order to implement these ILs on supported liquid membrane technologies.
The use of the ionic liquid as a carrier can overcome the inconvenience associated with the membrane stability. In this sense, the ionic liquids ALiCY and the mixture of Cyphos IL 101 and Cyphos IL 167 with Cyanex 272 have been tested as liquid carrier for boron separation by using a flat sheet supported liquid membrane. The results obtained allow us to think about the application of this kind of ILs on the process intensification to remove boron from chloride solutions.
... Plus, a recent focus has been towards producing Fe marketable products from waste liquors by applying SX [40,41]. Interestingly, when the self-prepared ionic liquid trioctylmethylammonium/2,4,4-trimethylpentyl phosphinate synthesized from the two extractants Aliquat 336 and Cyanex 272 (called AliCy when first tested for boron extraction by Fortuny et al. [42]) was investigated by Devi [43] for Cu extraction from a synthetic multimetallic sulfuric acid solution revealed an extraction rate of metal ions in the order of Fe > Zn > Cu > Cd > Co > Ni. Yet, to our knowledge, the so-called ionic liquid AliCy was never explored for the separation of Fe prior to the recovery of other metals. ...
... The tested AliCy was prepared as described by Fortuny et al. [42] with minimal modifications: equimolar concentrations (varying depending on the test) of Aliquat 336 and Cyanex 272 diluted in kerosene were mixed with an equal volume of 0.5 M sodium bicarbonate (NaHCO 3 ) aqueous solution for 10 min with vigorous magnetic stirring, in an open flask to allow the release of the CO 2 formed. Then, the aqueous phase was discarded using a decantation funnel and the organic phase mixed again with 0.5 M aqueous sodium bicarbonate solution as described before. ...
... Carson et al. [78] recently reported results suggesting that SO 4 2− is co-extracted in a 1:2 molar ratio with Fe by Cyanex 272 and proposed that the extracted species is likely to be a polynuclear ferric iron sulfate complex. When AliCy was first tested by Fortuny et al. [42] for boron extraction, the authors calculated a slope of 1.37 for the plot of log(D) vs. log[AliCy], and based on that they proposed that one molecule of extractant is involved in the extracted complex of boron with the extraction equilibrium represented as follows: ...
Zn recovery attempts from a copper-free extreme Acid Mine Drainage with ~ 53 g/L Fe and ~ 2 g/L Zn revealed Fe co-extraction in solvent extraction with 0.9 M D2EHPA or a mixture of 0.72 M D2EHPA and 0.18 M Cyanex 272, and simultaneous precipitation of Fe during zinc sulfide recovery through biogenic sulfide addition. Therefore, alkalinization, solvent extraction with the self-prepared ionic liquid AliCy diluted in kerosene, and combinations of both these methods were studied for the separation of ferric iron (Fe3+) from such water, prior to Zn recovery. The most efficient strategy tested was a solvent extraction cycle with AliCy followed by alkalinization of its aqueous raffinate to pH 3.25 or 3.5. As a result of this approach, ~ 92% of Fe3+ is separated by SX and the remaining is removed by precipitation, with just ~ 12% or ~ 17% Zn losses, respectively. Afterwards, the highest Zn recovery from water resulting from such combination of processes was achieved by precipitation through addition of biogenic sulfide at pH = 3.5. The obtained precipitates are nanoparticles of Wurzite and Sphalerite (ZnS) of sizes between 2 to 22 nm agglomerated into larger structures. This work shows for the first time the potential of AliCy to separate Fe3+ from acidic multimetallic solutions, a known contaminant of several metal recovery processes.
... Liquid membranes fundamentally create a double liquid-liquid separation processes in which the amount of organic solvent is reduced. Although liquid membranes have numerous disadvantages, such as instability under long-term operation, they are increasingly being explored for wastewater treatment due to their operational characteristics (Comesaña et al. 2011;Fortuny et al. 2012a). They are commonly classified as bulk liquid membranes, emulsion liquid membranes, and supported liquid membranes (SLM), where capillary forces in a fine, stable, microporous layer immobilize the organic carrier solution, forming a barrier between two aqueous solutions (the source and receiving phases) (Bachelier et al. 1996). ...
... Consequently, the process must employ multiple unit operations and becomes technologically unappealing (Kocherginsky et al. 2007). SLMs (Fig. 8) are an effective way to remove or recover metals at low concentrations (Fortuny et al. 2012a). ...
... SLM combines the stripping and extraction processes in one step that takes place at the interfaces of the aqueous solution and the organic liquid. A chemical pumping carries the species through the liquid membrane (Güell et al. 2011;Fortuny et al. 2012a). SLMs have high separation factors, low energy requirements, low initial and operational costs, scale-up potential, and can be used with inexpensive carriers, which make them an attractive alternative to conventional methods of treatment and removal (Kocherginsky et al. 2007). ...
Boron is an important element for plants, humans, and animals in limited amounts. However, excess amounts can cause adverse effects in both humans and plants, necessitating its removal from certain systems. Boron compounds are used in many industrial applications, including in developing sectors like alternative energy technology; as a result, the need for this element is increasing and industries are looking towards boron recovery for the sustained use of this element in their products. While the literature on boron removal strategies is abundant, there is a relative lack of studies on boron recovery, with no review papers having yet addressed this topic. In this review, both boron removal and recovery techniques involving conventional approaches and membrane processes are examined to juxtapose the states of the science in these two related—and increasingly important—processes.
Graphical abstract
... [13][14][15] Therefore, ionic liquids (ILs) can be easily synthesized by replacing the chloride ion of Aliquat 336 with hydrophobic anion of organophosphorus acids or weakly hydrophilic anions like thiocyanate. 13,16,17 These ILs can extract metal ions through either ion exchange or ion pair mechanism because of their dual function as well as their extraction power of hydrogen ions. 13,17,18 Furthermore, synthetic IL derived from Aliquat 336 with a thiocyanate functional group has been employed to separate transition metal ions from various media because of its efficient extraction and separation capacity. ...
... Decanol (Daejung Co., >98%) was added to the organic solution (10% v/v) as a modifier to avoid the formation of a third phase in the synthesis of ionic liquids. Ionic liquid, ALi-CY (R 4 N·A), was prepared according to the method reported in the literature: 16 an equimolar concentration of Aliquat 336 and Cyanex 272 in kerosene was mixed in a beaker, and then 0.5 mol L −1 NaHCO 3 solution was added. The mixture was stirred to expel CO 2 gas and promote the formation of ALi-CY. ...
... The rise in equilibrium pH verifies the role of ALi-CY as an extractant for hydrogen ions during the extraction. 16,18,35 After the extraction of Mn(II), only Li(I) is left in the raffinate. Therefore, the equilibrium pH should be selected on the basis of the recovery process of Li(I). ...
BACKGROUND
Cobalt, nickel and lithium are crucial in the manufacture of batteries. Therefore, the recovery of these metals from spent lithium ion batteries (LIBs) has attracted much attention because of their benefits in terms of economics and the environment.
RESULTS
In the present work, the recovery of metals such as cobalt, nickel, manganese and lithium from synthetic sulfuric acid leaching solutions of spent LIBs was performed by solvent extraction using synthetic ionic liquids (ILs) and a mixture of Cyanex 301 and Alamine 336. First, cobalt was selectively extracted over other metal ions by extraction with IL(ALi‐SCN). The role of SCN⁻ during the extraction was also investigated, and the extraction reactions of cobalt by both ALi‐SCN and Aliquat 336 were verified. The cobalt in the loaded ALi‐SCN was stripped by ammonia solution. After adjusting the raffinate pH, extraction with the mixture of Cyanex 301 and Alamine 336 selectively extracted nickel over manganese and lithium. The extracted nickel was completely stripped by 75% aqua regia. Manganese was selectively extracted by IL(ALi‐CY) after adjusting the pH of the raffinate. The manganese in the loaded ALi‐CY was stripped by HCl solutions. Therefore, three‐step solvent extraction resulted in a raffinate containing only lithium.
CONCLUSIONS
A process was proposed to separate Co(II), Ni(II) and Mn(II) from the sulfuric acid solutions of spent LIBs. The mass balance of continuous experiments indicated that the purity of the stripping solution of Co(II) and Mn(II) was higher than 99.9%. © 2020 Society of Chemical Industry
... [182] Deep eutectic solvents, alcohols, and ionic liquids have also been used for B adsorption/removal. [183][184][185] C.-H. Lee then compared the extraction efficiencies of B from desalination brine through 2,2,4-trimethyl-1,3-pentanediol (TMPD) and trioctyl/decylmethylammonium-bis(2,4,4-trimethilpentyl) phosphinate (ALiCy). [186] The TMPD system was dissolved in 2ethylhexanol and kerosene because TMPD was only slightly soluble in kerosene, and ALiCy was directly dissolved in kerosene. ...
... The reason is that TMPD extracts H 3 BO 3 , whereas ALiCy extracts B(OH) 4 − under normal conditions (Equations (11) and (12)). [184][185] Furthermore, H 3 BO 3 exhibits weak Lewis acid behavior following hydrolysis, specifically when the pH surpasses 9.23 (Equation (13)). This phenomenon indicates that H 3 BO 3 predominantly exists at pH levels lower than 9.23, while B(OH) 4 − becomes more prevalent at higher pH values. ...
Desalination brine is a concentrated stream that is generated during the desalination process. Brine commonly has high salinity and TDS (total dissolved ions), which contains ions such as Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , Cl ⁻ , SO 4 ²⁻ , HCO 3 ⁻ , PO 4 ³⁻ , and some critical elements. Currently, the brine treatment mainly applies direct disposal, like surface water discharge, sewer discharge, deep‐well injection, and evaporation ponds. However, these methods can cause harm to marine ecosystems, soil, and groundwater. Therefore, brine can be regarded as a resource to be reutilized. This work then aims to highlight the novel developments of brine application. For example, Na, Ca, and Mg in brine can be employed for carbon capture and utilization with ammonia, amines, and alkaline substances. With slight adjustment, brine can also be directly used as irrigation water, aquaculture water, and the activation of biochar. Furthermore, brine holds a higher concentration of critical elements, which makes many countries and scholars start to conduct element extraction, reducing the amount of ore exploitation. At last, the major obstacles related to these advancements in sustainability, expenses, and technological aspects are outlined, and promising research trends of brine reutilization are also suggested.
... A binary mixture, Ala336-Cy272 was prepared by mixing Cyanex 272 and Alamine 336 at an equimolar concentration ratio in kerosene. An ionic liquid, ALi-Cy272 (N-methyl-N,N-dioctyloctan-1-aminium bis(2,4,4-trimethylpentyl)phosphinate) was synthesized by reacting Aliquat 336 and Cyanex 272 according to the method reported in the literature (Fortuny et al., 2012). The synthesis of the ionic liquid, ALi-Cy272 was verified by identifying its chemical structure with FT-IR spectroscopy in our previous work (Tran and Lee, 2020). ...
... According to the reported literatures, ALi-Cy272, a bi-funtional ionic liquid can extract both cationic and anionic species from aqueous solutions (Martak and Schlosser, 2007;Fortuny et al., 2012). Hence, to consider the extraction behavior of organic acids from aqueous solution by ALi-Cy272, a mixture of organic acid and dilute HCl solutions in the absence of Tb(III) was used in this work. ...
Addition of organic acids to dilute hydrochloric acid solution can improve the extraction of rare earth elements by single cationic extractants. However, the correlation between the chemical structure of organic acids and the extraction of REEs as well as the variation in equilibrium pH has not been elucidated. In this study, we investigated the extraction of Tb(III) from dilute HCl solutions containing an organic acid like formic, lactic, fumaric, or maleic acid. As extractants, single Cyanex 272, a mixture of Cyanex 272 and Alamine 336 (Ala336-Cy272), and an ionic liquid (ALi-Cy272) synthesized by Cyanex 272 and Aliquat 336 were used. The speciation of Tb(III) in dilute HCl solutions containing organic acids was analyzed. In extraction of Tb(III), organic acids showed two roles as complexing and buffering agent, which depended on the chemical structure of the acids. There was some difference in the extraction of Tb(III) between single Cyanex 272 and ionic liquid, ALi-Cy272. During extraction with ALi-Cy272, formic and lactic acid negatively affected the extraction of Tb(III). The fact that the chemical structure of organic acids affected the extraction of Tb(III) from dilute HCl solution by the studied extractants can provide important information on the selection of suitable extraction systems.
... Binary mixtures of Aliquat 336, D2EHPA, PC88A and Cyanex 272 were prepared by directly mixing them in the desired composition. The Bif-ILs were synthesized by mixing these mixtures and treated by NaHCO 3 solution according to the method reported in the literature [26,27]. The synthesized ILs are represented as R 4 ND2, R 4 NPC, and R 4 NCy, respectively. ...
... Binary mixtures of Aliquat 336, D2EHPA, PC88A and Cyanex 272 were prepared by directly mixing them in the desired composition. The Bif-ILs were synthesized by mixing these mixtures and treated by NaHCO3 solution according to the method reported in the literature [26,27]. The synthesized ILs are represented as R4ND2, R4NPC, and R4NCy, respectively. ...
In this work, separation and recovery of gallium from aqueous solutions was examined using acid-base bifunctional ionic liquids (Bif-ILs) in both solvent extraction and supported liquid membrane (SLM) processes. The influence of a variety of parameters, such as feed acidity, extractant concentration and metal concentration on the solvent extraction behavior were evaluated. The slope method combined with FTIR spectroscopy was utilized to determine possible extraction mechanisms. The SLM containing Bif-ILs demonstrated highly selective facilitated transport of 96.2% Ga(III) from feed to stripping solution after optimization. During the evaluation of the separation performance of SLM for the transport of Ga(III), in the presence of Al(III), Mg(II), Cu(II) and Fe(II), 88.5% Ga(III) could be transported with only 6% Fe(II) and a nil quantity of other metals co-transported. SLM exhibited excellent long-time stability in five repeated transport cycles. Highly selective transport and separation performance was achieved using the SLM containing Bif-ILs, indicating considerable potential for application in Ga(III) recovery.
... Ionic liquid methyltrioctyl/decylammonium bis 2,4,4-(trimethylpentyl)phosphinate denoted as R 4 NCy was synthesized according to procedures published in the literature [35,36], mixing equimolar ratio of Cyanex 272 (HCy) and Aliquat 336 (R 4 NCl), and dissolved the mixture in kerosene to obtain the desired IL concentration. The mixture of Cyanex 272 and Aliquat 336 was washed twice with sodium bicarbonate 0.5 M to remove the chloride anion and the proton from the organic phase. ...
... Ionic liquid methyltrioctyl/decylammonium bis 2,4,4-(trimethylpentyl)phosphinate denoted as R4NCy was synthesized according to procedures published in the literature [35,36], mixing equimolar ratio of Cyanex 272 (HCy) and Aliquat 336 (R4NCl), and dissolved the mixture in kerosene to obtain the desired IL concentration. The mixture of Cyanex 272 and Aliquat 336 was washed twice with sodium bicarbonate 0.5 M to remove the chloride anion and the proton from the organic phase. ...
The leaching of copper ores produces a rich solution with metal interferences. In this context, Fe(III), Zn(II), and Mn(II) are three metals contained in industrial copper-rich solutions in high quantities and eventually can be co-extracted with the copper. The purpose of the current study was to determine the feasibly of solvent extraction with the use of ionic liquid methyltrioctyl/decylammonium bis (2,4,4-trimethylpentyl)phosphinate (R4NCy) as an extractant of Cu(II) in the presence of Fe(III), Zn(II), and Mn(II). In general terms, the results showed a high single extraction efficiency of all the metals under study. In the case of Fe(III) and Zn(II), the extraction was close to 100%. On the contrary, the stripping efficiency was poor to Fe(III) and discrete to Zn(II), but very high to Cu(II) and Mn(II). Finally, the findings of this study suggest that the ionic liquid R4NCy is feasible for the pre-treatment of the copper solvent extraction process to remove metal impurities such as Fe(III) and Zn(II).
... Instead of mixing some extractants, synthesis of some kinds of task specific ionic liquids (ILs) is regarded as a means to achieve synergistic extraction [11,12]. In particular, the synthesized ILs derivated from commercial extractants such as Aliquat 336 (N-Methyl-N,N,N-trioctylammonium chloride) or Cyphos IL (phosphonium ionic liquid) have been employed for the extraction and separation of metals [11][12][13][14][15][16][17][18]. Some advantages of the above-mentioned ILs are good extractability, efficient separation, high recovery, and environmental friendliness [14,18]. ...
... Organic phases were prepared by diluting the extractants with kerosene (Daejung Co., Shiheung, Korea, >90%). Ionic liquid, IL ALi-D2, was synthesized by mixing an equimolar concentration of Aliquat 336 (R 4 NCl, BASF Co., Ludwigshafen, Germany, 93%) and D2EHPA (HA) (Daihachi Chemicals, Osaka, Japan, 95%) as reported in the literature [16,18]. A sufficient amount of NaHCO 3 (Daejung Co., Shiheung, Korea, 99%) was added to the mixture to promote the formation of IL ALi-D2. ...
The development of extraction systems to improve the extraction efficiency of metals using commercial extractants and ionic liquids is of importance. The extraction behavior of Co(II) between mixture of Alamine 336/Aliquat 336 and D2EHPA and synthesized ionic liquid ALi-D2 was compared in this work. Some factors, such as equilibrium pH, properties of the extractants, and concentration of components in the mixture had a remarkable effect on the extraction of Co(II). The interactions occurring in the mixtures as well as the change in solution pH were analyzed. Co(II) was completely extracted by ionic liquid when equilibrium pH was higher than 6.5, while it was difficult to extract Co(II) by employing the mixture of D2EHPA and Alamine 336/Aliquat 336. The formation of ionic liquid in the mixture of D2EHPA and Aliquat 336 was verified through FT-IR spectra. In addition, the competition extraction of hydrogen ion and Co(II) by ionic liquid ALi-D2 was explained. Among the three kinds of extractants, the ionic liquid showed the best extraction efficiency for Co(II) and pH control from weak acidic solutions. The present study provides valuable information on the extraction behavior of metal ion by the mixtures of commercial extractants, and thus can give some light on the development of metal extraction systems.
... During exploitation of salt lake brine, high-efficiency separation of boron can lead to high-quality boric acid products, while minimizing influence of boron on the quality of valuable elements such as lithium and magnesium [3] . For the recovery of boric acid, several methods which have been studied are boron precipitation [4,5] , adsorption [6][7][8] , membrane filtration [9,10] , electrodialysis [11,12] , reverse osmosis [13,14] , solvent extraction [15][16][17] . However, most of these processes are unsuitable for SL industrial application due to the low boron recovery rate and the high concentration of brine components. ...
... The pH of the aqueous solution has been considered as the crucial parameters affecting the H 3 BO 3 extraction process [17,28] . To determine the effect of pH on H 3 BO 3 extraction, experiments were performed at pH from 1 to 10 with a constant O/A of 1/1. ...
... The bi-functional ionic liquid is prepared according to the straightforward method described by Sastre et al. ( [30], [31]). In brief, an equimolar mixture of Aliquat-336 and the extracting molecule are mixed in n-dodecane and vigorously shaken, allowing to form the ionic liquid. ...
... This organic mixture is then mixed several times with an aqueous solution of NaHCO3 (0.5 mol.L -1 ), allowing to wash the hydrochloric acid formed during the reaction. These two steps can be presented by the following equations [31]: ...
The recovery of lithium from brines is a major field of study with an increase in lithium-ion batteries consumption and the subsequent growth of lithium consumption. The recovery of lithium from shale gas produced water is promising since these sources could contain non-negligible concentrations of lithium. In this study, lithium extraction was investigated using solvent extraction with a bifunctional ionic liquid (IL) as an extracting agent diluted in n-dodecane. The components of these IL are cheap and commercially available products, namely Aliquat-336 (methyltrioctylammonium chloride) and DEHPA (di-(2-ethylhexyl)phosphoric acid), and its synthesis is straightforward. Lithium extraction was optimized by studying several experimental parameters (mixing time, aqueous phase acidity, IL concentration in the solvent phase, aqueous lithium concentration). The mechanism of extraction was detailed, and the stripping was shown to be complete with 0.5 mol.L−1 of HCl. A two stages strategy was defined to recover lithium from synthetic brine. In the first stage, divalent metals are removed using five successive cycles of extraction with DEHPA (1 mol.L−1) dissolved in n-dodecane. In the second stage, the IL extracting agent [Aliquat-336][DEHPA] (1 mol.L−1) allowed to remove 83% of lithium in one cycle of extraction, which is higher than reported solvent extraction results with conventional extracting molecules.
... In another approach, neutral extractants such as TBP (tributyl phosphate), MDP (methyl diphenyl phosphate), and Cyanex 923 (a mixture of four trialkylphosphine oxides) can also extract hydrogen ions efficiently via the solvating mechanism [9,10] and Cyanex 272 or their mixtures with other extractants has a significant effect on the extraction of hydrogen ions in inorganic acids [11,12]. It has also been reported that some mixtures fail to enhance the extraction of hydrogen ions [6,13]. ...
... NaCl (Tedia Company, Inc., 99%) was employed to fix the Additionally, the concentration of hydrogen ions in the aqueous phase was also measured before and after extraction by volumetric titration method [22]. When the solution pH was higher than 4, it was difficult to determine the 1) and (2-3), respectively [11,24]. ...
During the extraction of metal ions from a weak acidic chloride solution by ionic liquids consisting of an organophosphorus extractant and Aliquat 336, the equilibrium pH is sometimes observed to be higher than the initial pH. To compare the hydrogen ion extraction behavior of tertiary and quaternary amines, Alamine 336, Aliquat 336 and their mixture with Cyanex 272, and an ionic liquid (prepared by mixing Cyanex 272 and Aliquat 336, R 4 NA) were employed in solvent extraction experiments at a pH range from 0.05 to 5. R 4 NA showed the highest extraction percentage of hydrogen ions. The initial pH of the chloride solution had a great effect on the extraction of hydrogen ions and the equilibrium pH value produced by these extractants. The order of hydrogen ion extraction was R 4 NA>Alamine 336>mixture of Alamine 336 and Cyanex 272. The addition of sodium chloride improved phase separation. The solvent extraction reaction of hydrogen ions with R 4 NA in the chloride solution was verified by applying a slope analysis method to the extraction data. UV-Vis and FT-IR spectra indicated a strong interaction between the hydrogen ions and R 4 NA during the extraction. The obtained results provide some information on the change in solution pH during the extraction of metal ions from weak acidic solution by an ionic liquid (R 4 NA).
... To summarize the effective techniques applied to boron removal in the past, there is adsorption [71,73,74], reverse osmosis (RO) [75][76][77][78], and ion exchange [79][80][81][82][83][84][85], electrocoagulation [58,[86][87][88][89][90], Donnan dialysis [91][92][93], chemical coagulation [3,94], hybrid process [95,96], polymer enhanced ultrafiltration (PEUF) [97][98][99][100][101], adsorption membrane filtration (AMF) [72,96,[102][103][104][105][106][107][108][109][110][111], and extraction by ionic liquids [112] etc. Adsorption is a particularly efficient way of removing boron from extremely low-concentration aqueous solutions in these approaches. ...
Boron is one of the essential elements for plants, animals, and humans, but its excess poses a great risk to life. Therefore, it is necessary to effectively remove boron from various boron-containing aqueous solutions to reduce damage to living things. There have been many studies on the adsorbent for removing boron from the boron-containing aqueous solution, but many of them are expensive or cannot be industrialized or commercialized, so they remain in the laboratory stage. Reducing the cost of adsorbent and realizing commercialization can be said to be the key links to successfully solving the problem of boron removal from an aqueous solution. The purpose of this review is to conduct a comprehensive analysis of inexpensive adsorbents used for boron removal from industrial wastewater and drinking water and to discuss future research directions. This article summarizes the development and utilization of inexpensive adsorbents, including inorganic materials, natural materials, and wastes. The limitations of performance, applicable conditions, sources, et al., of inexpensive adsorbents currently developed and utilized were analyzed, and future research directions were discussed. Most inexpensive adsorbents have a limited range of use, and compared to organic materials, inorganic materials have very low adsorption performance. The development of adsorbents using natural materials or waste is not active. Therefore, further research is needed to improve the performance of inorganic adsorbents, develop environmentally sustainable and efficient adsorbents, and recycle adsorbents.
... Generally, when solid borate ore, such as borax, colemanite, ulexite or kernite, is used as a raw material, boric acid is produced by reacting the solid ore with strong sulfuric acid, which will cause serious corrosion of the equipment and high requirements for the quality of the borate minerals (B 2 O 3 content is generally greater than 18%) [3,4]. During the exploitation of brine borate ore, several technologies for boron recovery from water have been applied including precipitation [5,6], adsorption [7,8], membrane filtration [9,10], electrodialysis [11,12] and solvent extraction [13][14][15][16][17][18], among which solvent extraction is considered to be the most promising process of large-scale application for extracting boron from the brine. ...
The extraction kinetics of forward extraction of boron by 2,2,4-trimethyl-1,3-pentanediol (TMPD) were investigated, using a Lewis cell. Factors affecting the extraction rate, including stirring speed, concentrations (TMPD and B(OH)3), interfacial area, and temperature were examined. Results indicated that the extraction rate is controlled by chemical reaction at interface. The activation energy Ea was measured depending on experimental conditions. The extraction rates of B(OH)3 and TMPD are first-order dependent with respect to B(OH)3 and TMPD concentrations, and rate equation is proposed. The rate-determining step is to form the complex at the interface, and the derived extraction mechanism is in good agreement with the experimental results. Based on the above-mentioned regime, an extraction mechanism for boron was also presented.
... Kerosene was used as a diluent to reduce viscosity of the extractants. The phosphonium ionic liquids were prepared following a bicarbonate neutralization process described elsewhere [35] and used without further purification of separation. ...
Acid mine drainage is a legacy environmental issue and one of the largest pollutants in many mining districts throughout the world. In prior work, the authors have developed a process for the recovery of critical materials, including the rare earth elements, from acid mine drainage using a preconcentration step followed by solvent extraction as a concentration and purification technology. As part of the downstream technology development efforts, we have synthesized a suite of ionic liquid extractants that facilitate greater separation factors leading to lower capital costs and reduced environmental impacts. This article provides a comparison of the conventional extractants D2EHPA, EHEHPA and C572 with their respective ionic liquids [c101][D2EHP,c101][EHEHP] and [c101][C572] for the recovery of rare earth elements from acid mine drainage. In the study, laboratory-scale, multi-contact solvent extraction tests were conducted at high and low extractant/dosages. The results show that the ionic liquids varied in performance, with [c101][D2EHP] and [c101][EHEHP] performing poorer than their conventional counterparts and [c101][c572] performing better. Recommendations for further study on [c101][c572] include stripping tests, continuous pilot testing, and techno-economic analysis.
... Ionic liquids (ILs) were prepared according to the literature as follows. ALi-D2, ALi-PC, ALi-CY272 (ALi represents Aliquat 336) were synthesized by the reported method (Fortuny et al., 2012). ALi-SCN was prepared by contacting Aliquat 336 (R4N·Cl) and an aqueous solution of 1.6 M KSCN in several times for the complete conversion of chloride to thiocyanate (Preston, 1982;Nayl, 2010). ...
... Ionic liquids such as ALi-D2, ALi-PC, ALi-CY and ALi-CY301 (R3CH3N·A) were prepared according to the method reported in the literature [28]: an equimolar concentration of Aliquat 336 and acidic extractants in kerosene were mixed in a beaker, and then 0.5 M NaHCO3 solution was added. The mixtures were stirred to expel CO2 gas and to promote the formation of bi-functional ILs. ...
Palladium (Pd) electroplating is widely practiced in the manufacture of advanced electronic devices. The Pd(II) present in spent electroplating solutions is treated by cementation with zinc (Zn) metal powder. In order to recover pure Pd from the cemented Pd, a process that consisted of leaching followed by solvent extraction was investigated. For this purpose, solvent extraction experiments using synthesized ionic liquids (ILs) with organic and inorganic anions were performed to find separation conditions at which selective extraction of Pd(II) over Zn(II) from synthetic H2SO4 leaching solutions is possible. The concentration of sulfuric acid was varied from 0.5 to 9 M. The complete separation of Pd(II) over Zn(II) by ILs such as ALi–CY301 (N-methyl-N,N,N-trioctylammonium bis(2,4,4-trimethylpentyl) dithiophosphinic), ALi–SCN (N-methyl-N,N,N-trioctylammonium thiocyanate), ALi–I (N-methyl-N,N,N-trioctylammonium iodide) and ALi–Br (N-methyl-N,N,N-trioctylammonium bromide) depends on H2SO4 concentration, while ALi–LIX63 (N-methyl-N,N,N-trioctylammonium 5,8-diethyl-7-hydroxydodecane-6-oxime) and ALi–LIX84 (N-methyl-N,N,N-trioctylammonium 2-hydroxy-5-nonylacetophenone oxime) can completely separate Pd(II) irrespective of H2SO4 concentration. Additionally, the mixture of HCl and thiourea, aqua regia solution, NH3 solution and the mixture of NH4Cl and NH3 are powerful stripping agents for Pd(II) from the loaded ALi–LIX63/ALi–LIX84, ALi–CY301, ALi–Br/ALi–I and ALi–SCN, respectively. However, application of the separation conditions to the real 5 M sulfuric acid leaching solutions of cemented Pd indicated that it was difficult to separate the two ions by extraction with ALi–LIX63 and ALi–LIX84. Use of NaClO as an oxidizing agent during the sulfuric acid leaching of real cemented Pd resulted in an enhancement of Zn(II) extraction by ALi–LIX63 and ALi–LIX84. Therefore, removal of chloride ions from the sulfuric acid leaching solutions is necessary to apply the separation conditions obtained from synthetic sulfuric acid leaching solutions.
... On the basis of these mechanisms, many researchers have developed different types of extractants for boron extraction, such as long-chain alcohols, 7,15-17 phenols, 18 amine compounds, 19,20 and ionic liquids. 21,22 The monohydric alcohol is suitable for extracting boric acid under the conditions of high salting-out and acidity. Diol has higher extraction efficiency than monohydric alcohol, but it is difficult to realize large-scale industrial production due to high viscosity and solution loss. ...
The recovery of boron from salt lake brines has become an effective way to meet the increasing demand, particularly in China. In this study, nine commercially available monohydric alcohols with different structures were selected for boron extraction from a salt lake brine with high magnesium content. Passing through the optimization, isodecanol was finally selected for the detailed study on boron recovery from brine due to its moderate viscosity, lower solubility water entrainment and high extraction efficiency. Parameter effects on boron extraction were systematically studied, including equilibrium pH, organic concentration, phase ratio, temperature, and salting-out effect. A McCabe-Thiele diagram was established to determine the boron extraction and stripping stages. An organic solution containing 2.5 mol L-1 isodecanol was used for a simulated three-stage counter-current extraction test under optimized extraction conditions, and the boron extraction reached 99.07%. A simulated four-stage counter-current stripping test was carried out with water with the stripping efficiency of 98.71%. In total the boron recovery reached 97.79%. Additionally, the mechanism of boron extraction by isodecanol was investigated using both slope analysis method and Fourier transform infrared spectroscopy (FTIR). The stoichiometric ratio of isodecanol to boron required to form boric acid ester was found to be 1.268. These results indicate that the extraction system has great potential for commercial application in boron recovery from salt lake brines with high magnesium content.
... The acidity of the solution was adjusted by adding doubly distilled water to concentrated HCl (Daejung Co., 35%). ALiCY (N-Methyl-N, N, N-trioctylammonium bis(2,4,4trimethylpentyl)phosphinate, R 4 NA) was prepared by mixing an equimolar concentration of Aliquat336 (R 4 NCl) andCyanex272 (HA) in kerosene according to the method reported in the paper[29]. ...
Ionic liquids have emerged in hydrometallurgy as potential extractants for metals. In this work, the interactions of ALiCY (R<sub>4</sub>N<sup>+</sup>A<sup>-</sup>) synthesized by Aliquat336 and Cyanex272, and a mixture of ALiCY and TBP, were analyzed using extraction data and FT-IR spectroscopy. Co(II) and Ni(II) were extracted from two HCl concentrations (1.0×10<sup>-4</sup> and 6.8 mol·L<sup>-1</sup>) using ALiCY and its mixture with TBP. The extraction results indicated that ALiCY has a dual function, as a cationic extractant at low HCl concentration and an anionic extractant at high HCl concentration depending on the types of metal complexes. The addition of TBP to ALiCY had a negative effect on the extraction of Co(II) from the 6.8 mol·L<sup>-1</sup> HCl, while the effect was negligible from the 1.010<sup>-4</sup> mol·L<sup>-1</sup> HCl. The solvation of R<sub>4</sub>N<sup>+</sup> by TBP significantly affected the extraction behavior of ALiCY for metal ions. The formation of hydrogen bonding between TBP and Cyanex272 was verified. These findings shed light on the behavior and interaction occurring between bif-ILs and solvating extractants for the extraction of metals in acidic media.
... Commercial grade kerosene (Daejung Co., > 90%) was used as a diluent. ALi-D2 solutions were prepare by diluting 1.0 M ALi-D2 in kerosene to the desirable concentrations, which were prepared by mixing 1.0 M Aliquat336 and 1.0 M D2EHPA in kerosene according to the method reported in the paper [21]. The formation of ALi-D2 was confirmed in the previous work [20]. ...
... To find an appropriate extractant for selective extraction of V(V), PC88A, ionic liquids derived from Aliquat 336 with D2EHPA/PC88A, and Aliquat 336 were employed by varying their concentration from 0.2 to 1 M. In this work, ionic liquids were prepared by mixing an equimolar concentration of the above commercial extractants according to the method reported in the literature.33 The concentrations of the synthetic solution were 2317 mg L −1 of V(V), 760 mg L −1 of Ni(II), and 175 mg L −1 of Al(III) in HCl concentration of 3.16 M.Figure 6 ...
BACKGROUND
A large number of spent catalysts are regularly discharged by petrochemical industries. The spent catalysts contain some valuable metals, such as molybdenum, nickel, and vanadium. Therefore, it is necessary to recover these high purity metals from the spent petroleum catalysts with environmentally friendly processes.
RESULTS
In order to recover valuable metals such as molybdenum, vanadium, nickel, and aluminum from spent petroleum catalysts, a hydrometallurgical process consisting of leaching followed by solvent extraction was developed in the present work. First, molybdenum was separated from the leaching solution by extraction with D2EHPA and the loaded organic phase was stripped by a mixture of NH4OH and (NH4)2CO3. Second, the molybdenum free raffinate was contacted with Aliquat 336‐decanol to separate the vanadium, and then a hydrochloric acid solution was employed to strip vanadium from the corresponding loaded extractant. Since the acidity of the leach solution was high, TEHA (tris‐2‐ethylhexylamine) was chosen for the extraction of hydrochloric acid in order to increase the pH of solution. The loaded TEHA phase was then stripped by distilled water, which enabled the recovery of HCl. The nickel and aluminum in the molybdenum and vanadium free raffinate were separated by the extraction of nickel with saponified Cyanex 301 at a solution pH of 2.5. It was possible to strip nickel from the loaded organic phase by a strong hydrochloric acid solution.
CONCLUSIONS
A flow sheet of the proposed process for the separation of Al(III), Mo(VI), Ni(II), and V(V) was presented. The current process can be applied to aqueous solutions containing these four metals from diverse material resources. © 2020 Society of Chemical Industry
... Some amount of the prepared succinimide ILs were weighted and diluted in kerosene. The Bif-ILs solutions were prepared by diluting 1 M Bif-ILs, which were prepared by mixing 1 M Aliquat336 and 1 M organophosphorus acids in kerosene according to the method reported in the paper [20]. The structures of succinimide ILs and Bif-ILs are presented in Table 1. ...
... As extractant, AliOle IL was prepared by reacting Aliquat 336 with an equimolar amount of Oleic Acid. It was synthetized by following the procedure established in previous research (Coll et al., 2014;Fortuny et al., 2012). Reactions (R1) and (R2) summarize the synthesis of the extractant. ...
A study of the solvent extraction process of Nd(III) from chloride solutions has been carried out using an ionic liquid (AliOle) prepared from Aliquat 336 (Methyl-tri(octyl/decyl)ammonium chloride) and Oleic Acid. The IL was chosen among other homemade ionic liquids and commercial extractants due to its high Nd(III) extraction ability and good phase separation. Increasing AliOle concentration improves the extraction of Nd(III) as expected. The pH of the aqueous phase strongly influences the extraction process. The appropriate equilibrium pH region has been established in the range 5–6.5. The effect of chloride concentration in the aqueous phase has been investigated. High concentrations of Cl⁻ anion contribute to increasing the extraction yield by promoting neodymium(III) speciation in the aqueous phase. Two extraction models are proposed from experimental data. Chloride concentration in the aqueous phase determines the Nd(III) extraction mechanism. The models consider extraction of Nd3 + species when chloride concentration in the solution is low and NdCl2 + species when chloride concentration is high. Competitive extraction between HCl and the metal ions is also included in the models. They are able to reproduce feasibly the experimental Nd(III) extraction extension.
... As an organic phase, the synthetized IL AliOle, prepared by reacting equimolar amounts of Methyl-tri(octyl/decyl)ammonium Chloride (Aliquat 336) and Oleic Acid following the procedure established in previous studies was used (Coll et al., 2014;Fortuny et al., 2012). Kerosene was used as a diluent. ...
... Therefore, it is indispensable to develop efficient and cheap technologies for boron removal. Currently, the reported boron removal methods include boron extraction [8], adsorption [9], ion exchange [10], reverse osmosis (RO) [11], electrodialysis (ED) [12] etc. However, boron removal still remains a big challenge for most commercial desalination technologies due to its small molecular size, high diffusion rate and nonionic nature at normal pH range [11]. ...
The immobilisation of ionic liquids (ILs) in porous solid matrices enables the design of ionogels, which are now regarded as a promising material in extraction science. Here, by the co-gelation of TMOS and MTMS in a commercially available ionic liquid, Aliquat 336 (A336Cl), a series of ionogels were synthesised with various levels of IL content and matrix hydrophobicity. Both of these factors were shown to have a small effect on Fe(III) extraction efficiency (57–70%), while they strongly influenced the re-extraction efficiency (15–45%) of the materials. The ionogels with the highest IL content (80%) and a highly hydrophilic silica matrix showed the best extraction and re-extraction performance. A thorough characterisation of the ionogels confirmed the confinement of the IL in silica and revealed Fe(III) extraction mechanisms. It was shown that iron was extracted from the aqueous solutions by A336Cl@SiO2 ionogels in the form of FeCl4– ions typical of the extraction by pure A336Cl. Unexpectedly, the iron extraction by the ionogels resulted in the formation of Fe2Cl7– species that had not been observed earlier in the A336Cl-based extraction systems. Moreover, iron(III) directly bound to hydrophilic silica through Si–O–Fe bridges, and it was also found that, in the ionogels, the admixtures of alcohols could even reduce ferric ions to ferrous species. For the ionogels, both iron extraction and re-extraction followed pseudo-second order kinetics. Iron re-extraction from the ionogels with aqueous sulfuric acid solution resulted in the loss of recyclability, most probably due to the formation of FeSO4*H2O in the ionogels. The cycling performance of the ionogels can be improved by their conditioning in chloride-rich media after re-extraction stages.
Desalination technologies have been widely implemented since the 1970s to solve the problem of freshwater scarcity. However, brine, the by-product of the desalination process, which has a higher salinity and total dissolved solids (TDS) than seawater, can cause severe environmental problems. For instance, brine could change the composition and temperature of seawater, decrease dissolved oxygen, and influence the organism’s habitat. Under this circumstance, circulating critical resources from brine is acceptable for minimizing brine disposal. This study employed two extraction systems (TMPD, 2,2,4-trimethyl-1,3-pentanediol and ALiCy, trioctyl/decylmethylammonium-bis(2,4,4-trimethilpentyl) phosphinate), which are solvent extraction and ionic liquid extraction, to recover boron from brine. The parameters, including pH value, concentrations of TMPD and ALiCy, O/A (organic/aqueous) and I/A (ionic liquid/aqueous) ratios, contacting time, and reaction temperature of boron extraction through the TMPD and ALiCy systems, would be optimized. The results reveal that extraction efficiencies of TMPD and ALiCy systems were 93.8% and 72.3%, respectively. Moreover, different agents can be evaluated to strip boron from TMPD and ALiCy. The boron product and the extractants could then be generated and reused. Briefly, the environmental hazards caused by the desalination brine and boron resources can be reduced and circulated through this research with two different extraction systems.
Since the discovery of microemulsions, they have attracted great attention due to its unique properties, such as ultra-low interfacial tension and nanoscale droplets. During the past several decades, microemulsions have shown unparalleled advantages in critical metal separation and recovery, e.g., high separation rate, high recovery efficiency, and good selectivity. Therefore, fundamental understandings of such metal recovery behavior are of great significance for the continuous development of microemulsion-based separation technology in this field. Herein, we first systematically reviewed the application of regular microemulsion in the separation and recovery process of critical metals focusing on their separation mechanisms. Then, we summarized the recent progress of CO2-responsive microemulsions and highlighted their potential application in critical metal separation and recovery, aiming to provide some insights into alleviating the difficulties in demulsification during the stripping stage using regular microemulsions. In this section, the latest development of CO2-responsive microemulsions is introduced, and the relationship between their composition, microstructure and macroscopic properties is discussed. Discussion and future perspectives are provided highlighting the design of new microemulsions and potential application of CO2-responsive microemulsions for metal separation and recovery in the future.
With increasing consumption of lithium-ion batteries (LIBs), recycling of spent LIBs has attracted much attention owing to their potential environmental impacts and metal values. In this work, a hydrometallurgical process for the recovery of metals from metallic alloys containing Co, Ni, Cu, Fe, and Mn generated from the reduction smelting of spent LIBs was developed. From the experimental data, optimum conditions for the complete leaching of the metals from the alloys were obtained as 2.0 mol/L H2SO4 and 10% (v/v) H2O2 solutions at 60°C for 240 min. The separation of metal ions from the sulfate leachate was achieved by using synthesized ionic liquids such as ALi-Cy301 and ALi-SCN and an oxidizing agent like NaClO. First, most of the Cu(II) was selectively extracted over others by 0.2 mol/L ALi-Cy30. Sequentially, Co(II) and Fe(III) from the Cu(II) free raffinate were co-extracted by 0.5 mol/L ALi-SCN and then Co(II) was selectively stripped over Fe(III) by 10% (v/v) NH3 solution. Finally, Mn(II) in the raffinate at pH 3 was precipitated to MnO2 by adding 10% (v/v) NaClO solution, while Ni(II) remained in the filtrate. Mass balance of the whole process indicated that the recovery and purity percentage of metals were higher than 99%. A process is proposed for the effective recovery of valuable metals from the spent LIBs.
In this work, the extraction of boron from salt lake (SL) brine using 2,2,4-trimethyl-1,3-pentanediol (TMPD) was investigated. Factors affecting boron recovery during the solvent extraction process, including feed pH, concentrations of extractant and H3BO3, phase ratio of organic to brine (O/A), and temperature, were investigated. Increasing feed pH initially resulted in a high boron extraction rate, but there was a limitation, as further increasing feed pH resulted in rapid formation of B[OH]4⁻ having a low capacity to complex with TMPD, and therefore lower boron extraction. Boron recovery increased as the TMPD concentration and O/A increased. Salting-out effect experiment indicated that the addition of magnesium chloride showed two opposite effects on boron extraction. The combination of pH <7, O/A = 1 & TMPD/H3BO3 molar ratio = 2:1 was ideal for boron recovery, resulting in single-stage boron extraction efficiency of >85% and three-stage of 99.79%. To investigate the extraction mechanism, the slope ratio method was combined with Raman spectroscopy and infrared spectroscopy to characterize the structure of TMPD and boron complex in organic extraction solvent. Furthermore, under the optimal conditions, a three-stage extraction and two-stage stripping process was performed, resulting the extraction and stripping efficiency of boron were 97.12% and 88.98%, respectively. The results of the study reveal a promising strategy of boron recovery from SL brine without acidification.
Boron removal from lithium-rich brine was systematically investigated by solvent extraction using 2,2,4-trimethyl-1,3-pentanediol (TMPD) dissolved in 2-ethylhexanol and sulfonated kerosene. The extraction parameters were determined, including the concentration of mixed alcohols, lithium and solvents loss. During the extraction, a single TMPD molecule reacted with a single boric acid molecule to form a complex with two C–O–B ester bonds. The mechanism was also verified using density functional theory (DFT). The overall extraction efficiency reached 99.95% by a two-stage countercurrent extraction. NaOH (0.2 mol/L) with an O/A phase ratio of 1:2 was used to strip the loaded organic phase with 99.99% stripping efficiency. The feasible industrial application of this boron extraction method was validated.
The manufacture of semiconductor materials containing gallium and indium requires the separation of these metals owing to their coexistence in the resources of these materials. In this work, solvent extraction of In(III) and Ga(III) from a hydrochloric acid solution by ionic liquids (ILs) was investigated to separate them. The ILs were synthesized by reacting organophosphorus acids (Cyanex 272, PC88A and D2EHPA) and Aliquat 336 (ALi-CY, ALi-PC, and ALi-D2). In(III) was selectively extracted over Ga(III) by the ILs in the range of initial pH from 0.1 to 2.0. The equilibrium pH was always higher than the initial pH because of the coextraction of hydrogen ions. The highest separation factor between In(III) and Ga(III) was 87, which was obtained by ALi-PC at an initial pH of 1.0. Stripping of the loaded ALi-PC with hydrochloric and sulfuric acid led to selective stripping of In(III) over Ga(III). Scrubbing of the loaded ALi-PC with pure In(III) solution was not effective in removing the small amount of Ga(III) present in the loaded ALi-PC. Batch simulation experiments for the three counter-current extraction stages indicated that the complete separation of both metal ions was possible by extracting In(III) using ALi-PC, with remaining Ga(III) in the raffinate.
Nonaqueous solutions were employed to investigate the selective recovery of vanadium and molybdenum from the spent petroleum catalysts. In this work, commercial extractants such as D2EHPA, Alamine336 and Aliquat336, and an ionic liquid synthesized from Aliquat336 and D2EHPA, ALi-D2, were employed as a lixiviant and extractant for the target metal ions in the presence of oxidizing agent, H2O2. Among the 4 nonaqueous systems, ALi-D2 showed the best performance for the selective and effective leaching of vanadium and molybdenum over alumina, nickel and iron. The effect of several parameters on the leaching efficiency was also studied. Under the optimum conditions, the leaching percentage of vanadium and molybdenum was 74.6 and 89.6% in the first stage and 26.0 and 66.9% in the second stage by ALi-D2 system. Vanadium and molybdenum from the ALi-D2 loaded phase can be sequentially precipitated by NH4Cl and BaCl2 solutions in alkaline media. Precipitation percentage of vanadium were 94.2% and its purity was 99.5%, whereas that of molybdenum was 99.4% with 84.1% purity. A process was proposed for recovery of vanadium and molybdenum from the spent petroleum catalysts. Pure vanadium and molybdenum compounds can be recovered by this process with less burden to the environment.
The dielectric constants and viscosities of binary mixtures of organophosphorus acids (D2EHPA, Cyanex 301, PC88A, and Cyanex 272) and quaternary amine (Aliquat 336) were measured by varying their chemical compositions. The strength of the interaction between the components in the binary mixture was analyzed through the deviation of dielectric constant, viscosity, and Grunberg-Nissan interaction parameters. The interaction of binary mixture was also verified through Fourier-transform infrared spectroscopy (FT-IR). The results indicated that the mixtures of D2EHPA/ Cyanex 301 + Aliquat 336 showed the stronger interaction among four acidic extractants in this work. FTIR data and analysis of the interaction on the basis of chemical structure indicate that ionic liquid can form in the mixture of D2EHPA and Aliquat 336 at specific composition. Adduct can be formed between Aliquat 336 and organophosphorus acids through hydrogen bond of methyl group. Our results can give some information on the selection of the composition of binary mixtures between organophosphorus acids and Aliquat 336 for the synergistic extraction of metal ions in hydrometallurgy.
Two new succinimide compounds such as 3-butyl-1-methyl-1H-imidazol-3-ium 4-(dioctylamino)-4-oxobutanoate ([N88SA]⁻[C4min]⁺) and 1-butylpyridin-1-ium 4-(dioctylamino)-4-oxobutanoate ([N88SA]⁻[C4Py]⁺) were synthesized as task-specific ionic liquids (TSILs) for the extraction of metal ions. The extraction behavior of Co(II) and Ni(II) from chloride solution was compared between these TSILs and Bif-ILs synthesized from Aliquat336 and organophosphorus acids such as Cyanex 272, PC 88A and D2EHPA. The extraction percentage of Co(II) and Ni(II) by TSILs was eight times higher than that by Bif-ILs at the initial pH of 4.0. Moreover, the extraction percentage of Ni(II) by the TSILs was slightly higher than that of Co(II). However, Bif-ILs extracted more hydrogen ions than TSILs. The extraction of Co(II) and Ni(II) by [N88SA]⁻[C4min]⁺ was higher than that by [N88SA]⁻[C4Py]⁺. The addition of TBP to TSILs reduced the extraction of metals but the loss of TSILs into the aqueous was significantly decreased. Succinimide ionic liquids can be employed for the extraction of metals from weak acidic solutions.
The application of hydrophobic magnetic nanoparticles functionalized with long carbon chain molecules, such as oleic acid, in the solvent extraction process results in a faster phase disengagement and does not affect the extraction and stripping percentages of cobalt with Cyanex 272, as has been reported in previous studies. However, the chemical stability of this organic phase is limited by its applicability only in contact with aqueous solutions of pH ≥ 2.0. Aiming to overcome such an operational constraint, this study proposed the use of nanoparticles coated with silica and functionalized with a long carbon-chain silane (OTS) in the solvent extraction process. Due to the silica-layer coating of the magnetic core of magnetite and maghemite, such nanoparticles became stable when in contact with aqueous solutions of high acidity of up to 2 mol/L. The proposed nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and magnetic analysis. Their effect on the solvent extraction of cobalt with Cyanex 272 was investigated using magnetic fluids with different concentrations (0, 10, 20, and 30 g/L of magnetic nanoparticles). It was also observed that, under the conditions studied in this work, the presence of these magnetic nanoparticles did not interfere in the efficiency of metal extraction and stripping. Moreover, the time for the phase disengagement can be reduced by a factor of 25 when compared to the process without magnetic nanoparticles.
Cyanex 272 shows the highest separation factor for the rare earth elements from hydrochloric acid solution among the organophosporus acidic extractants, D2EHPA and PC 88A. Solvent extraction of Tb(III) from weak hydrochloric acid solution with an initial pH 3 to 6 was compared with Cyanex 272, its mixture with Alamine 336, and ionic liquid with Aliquat 336. The solvent extraction reaction of Tb(III) using Cyanex 272 was the same as that of light rare earth elements. Synergism was observed for the extraction of Tb(III) by the mixture with Alamine 336 when the initial concentration ratio of Cyanex 272 to Alamine 336 was higher than 5. Use of the ionic liquid led to a great increase in the extraction percentage of Tb(III) from the same initial extraction conditions. While the equilibrium pH of the mixture was always lower than the initial pH, under some conditions extraction with the ionic liquid resulted in a higher equilibrium pH than the initial pH. The loading capacity of the mixture and the ionic liquid was the same and 2.6 times larger than that using Cyanex 272 alone. Ionic liquid was recommended as a suitable extractant for the extraction of Tb(III) from hydrochloric acid solution based on the ease of handling and higher extraction percentage.
Solvent extraction of yttrium(III) from chloride and nitrate solutions were carried out using two bifunctional ionic liquids Cyphos IL 104 and [A336/Cy272]. Comparative study with their constituent extractants showed higher extraction abilities of the ionic liquids for Y(III). The extraction behavior of yttrium using the above ionic liquids was studied as function of different parameters. Ion association neutral complexes were formed in the organic phase. 0.5 M HNO3 could strip 82% and 75.6 % yttrium from the loaded organic phases of 0.01M [A336/Cy272] and Cyphos IL 104, respectively. Separation studies involving binary systems were also investigated.
KEYWORDS: Yttrium, [A336/Cy272], Cyphos IL 104, extraction, separation
Imidazolium bis(2-ethylhexyl)phosphate ionic liquid was anchored on a polystyrene-divinylbenzene (PS-DVB) copolymer and the product (R-Im-DEHP) was studied for the extraction of Am(III) and Eu(III) from dilute nitric acid medium to examine the feasibility using the anchored adsorbent for their mutual separation. The effect of various parameters such as the duration of equilibration, concentration of nitric acid, europium ion, and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase on the distribution coefficient (
Phosphonium-based ionic liquids have been successfully impregnated on several Amberlite XAD resins for recovering Au(III) chloro-anions. Sorption performance was evaluated through sorption isotherms (very favorable profiles) and uptake kinetics (controlled by the resistance to intraparticle diffusion). The binding mechanism consists of an ion-exchange between AuCl4⁻ and the counter ion bound to the phosphonium cation. Increasing the IL loading proportionally increases the sorption capacity but decreases the sorption speed (by increasing the resistance to intraparticle diffusion). Changing the counter ion on the phosphonium cation (i.e., complex anion vs. chloride ion) does not improve sorption performance. Highly porous resin (high pore volume and large pore size), such as Amberlite XAD-1180, shows the best diffusion performance and highest sorption velocity (lower equilibrium time).
The separation of neodymium and praseodymium was carried out from a chloride solution containing the similar composition of NdFeB magnet leach liquor. A comparative study between extractants demonstrated that the extraction efficiency of bi-functional ionic liquids (Bif-ILs) tri octylmethylammonium bis(2,4,4-trimethylpentyl)phosphate (R4NCy) and trioctylmethylammonium di(2-ethylhexyl)phosphate (R4ND) was higher than the conventional extractants such as tri-octyl methyl ammonium chloride (Aliquat 336), bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) and di-2-ethylhexyl phosphoric acid (D2EHPA) under same experimental condition. The extraction efficiency of different extractants for Nd and Pr was in the order: R4NCy > R4ND > Cyanex 272 > D2EHPA > Aliquat-336. As the extraction of Nd and Pr was maximum with R4NCy Bif-ILs, the McCabe-Thiele diagram was constructed with R4NCy which showed 2 stages at 1:1 phase ratio. A 2-stage counter current simulation study showed 98.97% Nd and 99.02% Pr extraction. The loaded organic phase was stripped with H2SO4 acid and the stripping efficiencies for Nd and Pr were 98.11% and 98.75%, respectively. The extracted species was found to beMCl3 ⋅ 3R4NCy. The thermodynamic parameters were also determined for extraction of Nd and Pr with ionic liquid.
In this study, the mechanism of Fe³⁺ ion extraction was investigated in the tri-n-butyl phosphate (TBP)/triethyl-pentyl-phosphonium (P2225) bis(trifluoromethyl-sulfonyl)amide (TFSA) system. According to the performed analysis, the Fe³⁺ extraction is based on cation exchange with ionic liquids:
Moreover, the removal of Fe and B by continuous extraction was investigated. It was determined that nine extraction cycles led to the removal of all B and most of the Fe and increased the concentration of rare earth ions in the organic phase by a factor of 2.2.
The electrochemical behavior of the extracted [Fe(III)(TBP)3(TFSA)3] complex was investigated at 373 K, and two reduction steps were detected:
Based on these results, potentiostatic electrodeposition from an electrolytic bath was carried out at −1.75 V at 373 K after the ninth cycle of continuous extraction. Electrodeposits with 0.8–0.9 μm diameter were recovered on the Cu substrate, and metallic Fe in these deposits was identified by their energy dispersive X-ray spectrometry (EDX) spectra. Finally, the effectiveness of solvent extraction and direct electrodeposition in the recovery process was demonstrated in this study.
In this study, a magnetic organic liquid called ferrofluid was used to improve the speed and efficiency of the phase disengagement of solvent extraction processes applied to hydrometallurgical systems. The ferrofluid consisted of magnetic nanoparticles (mean diameter of 10.2 nm), comprised of magnetite (Fe3O4) and maghemite (γ-Fe2O3), which were coated by oleic acid and dispersed in an organic diluent. The nanoparticles were characterized by applying various methods: transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric and magnetic analysis. The effect of the nanoparticles on the solvent extraction of cobalt sulfate with Cyanex 272 was investigated using ferrofluids at different concentrations (0, 10, 20, and 30 g/l of magnetic nanoparticles in commercial aliphatic kerosene Exxsol D80). It was observed that, under the conditions studied, the presence of nanoparticles does not interfere in the efficiency of metal extraction and stripping, and that the time necessary for phase disengagement can be up to five times faster. However, the ferrofluid containing nanoparticles coated solely by oleic acid is not stable when in contact with aqueous solutions at pH ⩽ 2.0. Limited stability restricts the application of the magnetic fluid used in the present study in solvent extraction processes that operate at a pH level beyond 2.
For bio-butanol to be competitive with other commercially available fuels like gasoline, the development of energy-efficient technologies for its separation from dilute fermentation broth is necessary. Due to their special properties as extractants, the suitability of selected ammonium and phosphonium cation-based room temperature ionic liquids (RTILs) for butanol separation is investigated in this work. Determination of the RTIL extractants’ partition coefficients (KP) for butanol and other broth components is accomplished. To tune butanol extractability, RTIL–RTIL and RTIL–organic solvent blends are also tested. In addition, the toxicity of the extractants to Clostridium acetobutylicum and Clostridium beijerinckii is studied. Results indicated that KP for butanol is more controlled by RTIL anion moieties with the trend: dihexylsulfosuccinate ([DHSS])>dicyanamide ([DCN])>bis(trifluoromethylsulfonyl)imide; while the alkylammonium cation showed stronger effect on KP than the alkylphosphonium cation counterpart. All extractants showed the same KP trend for typical fermentation products: butanol>acetone>ethanol. [DHSS] and [DCN] anion-based RTILs exhibited pH dependence for acetic and butyric acids partitioning. Butanol affinities in extractant blends exhibit strong dependence on blend composition. The extractants’ cytotoxic effect varied according to their concentration, the type of exposed bacterial strain and fermentation conditions.
Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of the values of those properties for ionic liquids are identified. A roadmap for the literature values of density, viscosity, melting and glass transition temperatures, thermal stability, empirical solvent parameters, absorption, toxicity, surface tension, heat capacity, and thermal conductivity is provided.
Previously, we reported on using room temperature ionic liquids (RTILs) in place of traditional solvents in liquid membranes and showed that stabilized RTIL-membranes outperformed standard polymers for the separations of CO2/CH4 and CO2/N2 (considering ideal gas permeabilities). Here, we report on mixed-gas permeances and selectivities for the gas pairs CO2/CH4 and CO2/N2 using continuous flows of the mixed gases at various carbon dioxide concentrations (up to 2 bars of CO2 partial pressure). Under mixed-gas test conditions, three of the tested membranes still operated with commercially attractive mixed-gas selectivity combined with CO2-permeability for CO2/CH4 separations. In addition, one of the tested membranes is, potentially, economically viable for CO2 capture from flue gas. We answer three objections to reduction-to-practice of RTIL-membranes for gas separations; namely, mixed-gas operations did not reduced the gas selectivities, membranes give advantageous performance even under dry gas feed conditions, and we achieved long-term stability in continuous operation, up to 106 days, without performance degradation. Furthermore, the RTIL-membranes operated under CO2-partial pressures of at least 207 kPa without decrease in separation ability. The RTIL-membranes tested include [emim][BF4], [emim][dca], [emim][CF3SO3], [emim][Tf2N], and [bmim][BETI].
The extraction behavior of (152+154)Eu(III) and 241Am(III) in a solution of bis(2-ethylhexyl)phosphoric acid (D2EHPA) or bis(2-ethylhexyl)diglycolamic acid (HDEHDGA) in the ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide (omimNTf2), was studied at 298K. The extractant HDEHDGA was synthesized and characterized by IR, 1H NMR and mass spectroscopy. The effect of various parameters such as the concentrations of nitric acid, D2EHPA, HDEHDGA and diethylenetriaminepentaacetic acid (DTPA) on the extraction behavior of 241Am(III) and (152+154)Eu(III) was studied and the results are reported in this paper. Superior extraction of the target metals and excellent separation factors achieved with the use of the ionic liquid diluent indicates the feasibility of separating lanthanides from actinides present in high-level liquid waste (HLLW).
Supported liquid membranes (SLM) are studied in various fields like analytical, inorganic and organic chemistry, chemical engineering, biotechnology and biomedical engineering. This technique offers the advantages of active transport, possible usage of expensive carriers, high selectivity, easy scale-up, low energy requirements, low capital and operating costs, etc. This paper gives a brief overview of mechanism and kinetic studies of SLM based separations. The problems with stability and possible applications of SLM are also reviewed.
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Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of the values of those properties for ionic liquids are identified. A roadmap for the literature values of density, viscosity, melting and glass transition temperatures, thermal stability, empirical solvent parameters, absorption, toxicity, surface tension, heat capacity, and thermal conductivity is provided.
Partitioning of sodium ions between aqueous nitrate media and 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imides (Cnmim+Tf2N−) in the presence of dicyclohexano-18-crown-6 is shown to take place via as many as three pathways: conventional nitrato complex extraction and/or either or both of two ion-exchange processes, the relative importance of which is determined by aqueous acidity and the hydrophobicity of the ionic liquid cation. Contrary to expectations, increasing the alkyl chain length of the IL cation (from C5mim+ to C10mim+) is insufficient to eliminate the possibility of ion exchange as a mode of metal ion partitioning between the two phases, an observation with negative implications for the utility of ILs as environmentally benign extraction solvents.
The preliminary results described here show that unprecedentedly large distribution coefficient (D) values can be achieved using ionic liquids as extraction solvents for the separation of metal ions by crown ethers. This work highlights the vast opportunities in separation applications for ionic liquids with crown ethers.
Tetraalkylphosphonium ionic liquid (IL) with a bis 2,4,4-trimethylpentylphosphinic anion (Cyphos IL-104) is an effective extractant of lactic acid (LA) achieving at low LA concentrations the distribution coefficients for aqueous systems above 40. L/L equilibrium data for pure Cyphos IL-104 and its solutions in n-dodecane have been measured. With increasing acid concentration the value of the distribution coefficient of LA decreases. Cyphos IL-104 extracts only undissociated molecules of lactic acid (LAH) via H-bonding. Increase in the concentration of IL-104 in n-dodecane results in increasing distribution coefficient of LA and the water solubility. The high water content in the solvents with Cyphos IL-104 is connected with the formation of reverse micelles. An interesting phenomenon of the liberation of water from the solvent in extraction of LA has been observed. It is suggested that splitting of the reverse micelles due to the formation of LAH/IL complexes occurs. With increasing temperature the values of the distribution coefficients of LA practically does not change or only slightly increases. In contrary to this, the increase in temperature decreased the water solubility in solvents containing IL-104. This is interpreted by the lower stability of reverse micelles at higher temperatures. Based on experimental equilibrium data the formation of stoichiometrically defined complexes with the structure (LAH)p(IL)(H2O)2 and (p, 1, 2) stoichiometry, where p is in the interval from 1 to 3, is suggested. The proposed model fits the equilibrium data well and indicates the domination of the (2, 1, 2) complex at medium aqueous acid concentrations in the interval from 0.2 to 2kmolm−3. There are two mechanisms of water extraction into the solvents with Cyphos IL-104: the formation of reverse micelles, and the formation of hydrated complexes of LAH with IL. A sharp decrease in the viscosity of solvents with IL-104 with increasing concentration of water or LA was observed.
The effect of water content in 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) on CO2/N2 separation performance of polyethersulfone supported ionic liquid membrane has been investigated theoretically and experimentally. A small addition of water in [bmim][BF4] obviously improves the performance of the membrane. CO2 permeance increases from 11.5 to 13.8GPU and CO2/N2 selectivity increases from 50 to 60, where the water molar fraction increases from 0 to 0.10 at the cross-membrane pressure difference of 0.24MPa. The improvement of the CO2 permeance at low water content can be attributed to the increase of CO2 diffusivity due to the decrease of viscosity with increasing the water content. While, the CO2 permeance decreases at high water content because of the decreasing CO2 solubility, which is mainly caused by the hydrogen bond interaction between water and [bmim][BF4]. A corrected solubility coefficient model of CO2 in ionic liquid is proposed to evaluate the influence of water–[bmim][BF4] interaction on CO2 solubility. The comparison of CO2 permeance between theoretical values and experimental ones demonstrates that the number of water molecule bound to a [BF4]− is between 1 and 2 in the range of the water content in our research.
Iron(III) was efficiently extracted from a 6 M hydrochloride solution with the ionic liquid trihexyl(tetradecyl)phosphonium chloride, Cyphos (R), dissolved in chloroform. Spectroscopical data revealed that iron exists as tetrachloroferrate species in the organic phase. In contrast, nickel(II) was not extracted under experimental conditions. Satisfying back extraction of Fe(III) was achieved with a 0.5 M HCl solution.
Consequent time-dependent transport studies with Cyphos IL101 as ionic liquid carrier in chloroform (0.01 M), showed a successful quantitative transport of 0.1 M Fe(III) from a 6 M hydrochloride source phase to a 0.5 M hydrochloride receiving phase and a favorable separation from Ni(II). The transport of Fe(III) through the bulk liquid membrane (BLM) was assumed to follow a nonsteady kinetic regime with two consecutive and irreversible first-order reactions. With an initial Fe(III)/Cyphos IL101 concentration ratio of 10, an apparent rate constant k(s) of 31.4 x 10(-3) min(-1) was obtained for the Fe(III) transport from the membrane- to the receiving phase, whereas the rate constant k(f) for the Fe(III) transport from the source- to the membrane phase was 11.8 x 10(-3) min(-1). (C) 2010 Elsevier B.V. All rights reserved.
A process to remove and recover cadmium from wastewater has been developed which includes solvent extraction and supported liquid membrane transport for Cd(II) using Cyanex 923 as an extractant/carrier. The influence of acid and chloride ion concentration on the extraction of Cd(II) was studied. In acidic medium, the appearance of a third phase was observed and the limiting organic concentration for Cd(II) in 5 and 10% Cyanex 923/Exxsol D100 at different concentrations of H+ ions were determined. The effect of aliphatic and
aromatic diluents on the extraction and permeation of Cd(II) in neutral and acidic medium was studied and
permeation coefficients were evaluated, together with the influence of third phase and pore size on transport
of Cd(II) through microporous membrane. It was found that the appearance of a third phase in acidic medium
could be avoided by using an aromatic diluent. In order to improve the stability of supported liquid membrane and to scale up for continuous operation, the performance of hollow fiber strip dispersion (HFSD) technique for the extraction/recovery of Cd(II) from acidic as well as neutral chloride media was examined.
This study emphasizes the potential of a HFSD system to be a part of sustainable wastewater treatment
technologies, enabling the separation/recovery of cadmium.
Ionic liquid (IL)-based extraction is a promising high-efficiency and environmentally benign separation technology. Imidazolium ILs lose their cations or anions to aqueous phase during extraction, the release lead to water pollution. To develop sustainable IL-based extraction system, we firstly investigate quaternary ammonium nitrate IL-based extraction strategy. Alkylated phosphine oxides (Cyanex925) in tricaprylmethylammonium nitrate ([A336][NO3]) are studied for separating Sc from Y and lanthanides. Distribution ratio and separation factor of the Cyanex925–[A336][NO3] system for Sc3+ are by far larger than those achieved using Cyanex925–[C8mim][PF6] system. The stability and solvating mechanism of Cyanex925–[A336][NO3] extraction system can avoid release of [A336][NO3] to aqueous phase. The novel quaternary ammonium nitrate IL-based extraction system is an efficient and sustainable separation strategy.Graphical abstractHighlights► The solubility of [A336][NO3] is low in acidic aqueous phase. ► Extractability and selectivity of Cyanex925 in [A336][NO3] for Sc3+ are large. ► Solvating mechanism of [A336][NO3] system avoid the loss of IL. ► Cyanex925–[A336][NO3] system maintains high extractability after five cycles.
The crown ethers 18-crown-6 (18C6), dicyclohexano-18-crown-6 (DCH18C6), and 4,4‘-(5‘)-di-(tert-butylcyclohexano)-18-crown-6 (Dtb18C6) were dissolved in 1-alkyl-3-methylimidazolium hexafluorophosphate ([Cnmim][PF6], n = 4, 6, 8) room-temperature ionic liquids (RTILs) and studied for the extraction of Na+, Cs+, and Sr2+ from aqueous solutions. In the absence of extractant, the distribution ratios for the metal ions indicate a strong preference for the aqueous phase. With the crown ethers as extractants in RTIL-based liquid/liquid separations, the resulting metal ion partitioning depends on the hydrophobicity of the crown ether and also on the composition of the aqueous phase (e.g., concentration of HNO3 vs Al(NO3)3). Aqueous solutions of HCl, Na3 citrate, NaNO3, and HNO3 (the latter at low concentrations) decrease the metal ion distribution ratios and also decrease the water content of the RTIL phase. High concentrations of HNO3 decompose PF6- and increase both the water content and the water solubility of the RTIL phase. Highly hydrated salts such as Al(NO3)3 and LiNO3 salt out both the RTIL ions and the crown ethers; thus, when the aqueous phase contains Al(NO3)3, the trend more closely resembles traditional solvent extraction behavior where DSr > DCs and the most hydrophobic extracting phase produces the highest partitioning. When [C8mim][PF6] is used as the extracting phase, the metal ions can be loaded from Al(NO3)3 and stripped using water. Dtb18C6 forms 1:1 complexes with Cs+ and Sr2+ and also yields the highest distribution ratios out of the three crowns examined. In comparison to traditional solvent extraction behavior, the metal ion partitioning in these systems exhibits exceptional behavior and, in certain instances, suggests a complicated partitioning mechanism, which necessitates a more thorough understanding of RTILs as solvents before interpretation of the results.
Transport of salicylic acid (SA) through flat-sheet supported liquid membrane (SLM) was investigated using as liquid membrane the ionic liquids 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim][PF6]) or ethylammonium nitrate (EAN). Using [C6mim][PF6], it has been observed that the transport efficiency decreases with increasing pH, indicating that the un-dissociated form of SA is mainly extracted. On the other hand, the ionic dissociated form of salicylic acid is mostly extracted via the anion exchange mechanism between nitrate and salicylate anions when EAN is used as liquid membrane. Parameters such as nature and concentration of the strippant in the receiving phase and concentration of the SA in the feed phase were studied. By comparing the SLM transport efficiency of SA (initial flux) of the two used ionic liquids, EAN appears to be slight efficient than [C6mim][PF6].Despite the use of different stripping solutions (NaCl, NaOH and Na2CO3) and even with pH maintenance around initial values, uphill transport driven by pH difference was not observed using both ionic liquids. The absence of uphill transport has been attributed to the formation, along the course of the experiment, of water microenvironments (aggregates) inside the ionic liquid. SA transport through these water microenvironments inside the liquid membrane becomes the main mechanism. The main feature of SLMs based on ionic liquids is their higher stability compared to classical SLMs. In fact, our SLM system retained its stability and initial performance during the 9 days long experiment.
Liquid membranes have traditionally been employed for liquid/liquid mass transfer and have found applications in industrial, biomedical and analytical fields as well as in hydrometallurgical processes, wastewater treatment and remediation of polluted groundwater. However, in spite of the known advantages of liquid membranes, there are few examples of industrial application. The development of reliable mathematical models and design parameters (mass transport coefficients and equilibrium or kinetic parameters associated with the interfacial reactions) is a necessary step for design, cost estimation, process optimisation and scale-up. This work reports an overview of the different approaches that have been proposed in the literature to the mathematical modelling of liquid membrane separation processes in hollow fibre contactors providing, at the same time, a useful guideline to characterise the mass transport phenomena and a tool for the optimal design and intensification of separation processes. Copyright © 2009 Society of Chemical Industry
This report describes for the first time that the ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide can be used as effective solvents in extractive distillation for the separation of an azeotropic mixture containing tetrafluoroethylene and carbon dioxide. The solubility of tetrafluoroethylene was measured at isothermal conditions (about 283–348 K) over a range in pressure from 0 to 1.4 MPa using a volumetric view cell. The solubility of carbon dioxide was measured at four isothermal conditions (about 283–348) K from 0 to 2.0 MPa using a gravimetric microbalance. The binary data were correlated and the feasibility of the extractive distillation process was modeled using ASPEN Plus® simulator. The tetrafluoroethylene and carbon dioxide were efficiently separated using a single absorption column and flash tank. The purity of the tetrafluoroethylene distillate from the top of the absorption column and the purity of the carbon dioxide from the flash tank exceed 99 mol%.Graphical abstractHighlights► Separation of an azeotropic mixture containing TFE and CO2. ► Solubility of TFE in ionic liquids. ► Solubility of CO2 in ionic liquids. ► Extractive distillation process modeled using ASPEN Plus® simulator.
Room-temperature ionic liquids (ILs) are a class of novel green chemicals being designed to replace traditional volatile organic solvents in industrial processes. The potential effects of ILs on aquatic ecosystems have been poorly studied, despite the possibility of unintentional discharge into rivers and lakes, and their intentional disposal in wastewater treatment plants. We studied the effects of three imidazolium ionic liquids, 1-butyl-, 1-hexyl-and 1-octyl-3-methylimidazolium bromide, on the growth rates of two freshwater algae, Scenedesmus quadricauda and Chlamydomonas reinhardtii, in 96 h standard toxicity bioassays. Increases in alkyl chain length increased the toxicity of these ionic liquids to both S. quadricauda (EC 50 values of 0.005–13.23 mg L 21) and C. reinhardtii (EC 50 values of 4.07–2138 mg L 21). Bioassays were performed in both nutrient-amended media and low-nutrient groundwater to evaluate if test conditions altered IL toxicity. EC 50 values for S. quadricauda were similar between nutrient media and groundwater for all ILs tested, while the presence of nutrient media appeared to partially mitigate the toxicity of ILs to C. reinhardtii (groundwater EC 50 , media EC 50). Overall, S. quadricauda was much more sensitive than C. reinhardtii to all ILs tested, perhaps reflecting differences in cell wall structure. EC 50 values suggest that ILs are more, or just as, toxic to algae than many of the solvents they are intended to replace. Results of this study show that ionic liquids can elicit a range of algal responses, suggesting that a diversity of target organisms be tested in order to predict the effects of ILs in natural environments.
Pseudomonas cepacia lipase supported in the 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid is an alternative “green” method for the production of biodiesel from the alcoholysis of soybean oil. The transesterification reaction catalyzed by this ionic liquid-supported enzyme can be performed at room temperature, in the presence of water and without the use of organic solvents. It is also compatible with various alcohols (including isoamyl alcohol). The biodiesel is separated by simple decantation and the recovered ionic liquid/enzyme catalytic system can be re-used at least four times without loss of catalytic activity and selectivity.
Phosphonium ionic liquid: trihexyl(tetradecyl)phosphonium chloride (Cyphos®IL 101) has been used as a novel reagent in the presence of toluene to extract palladium(II) from hydrochloric acid solutions of various concentrations. Extraction data indicate that Cyphos®IL 101 is a very efficient and fast extractant. The increase in HCl concentration has negative influence on the extraction and about 97 and 54% of palladium(II) can be effectively extracted with Cyphos®IL 101 from 0.1 and 3 M HCl, respectively. The equilibrium of palladium(II) extraction from aqueous 0.1 and 3 M HCl with this phosphonium ionic liquid is achieved after 5 min. Successful stripping of palladium(II) from the loaded organic phase is achieved with 0.5 M ammonia solution. Cyphos®IL 101 can be reused at least in 5 cycles of extraction-stripping process.
A kind of solvent (ionic liquid) impreganated resin (IL-SIR) was developed herein for ameliorating imidazolium-type IL-based liquid–liquid extraction of metal ions. In this study, [C8mim][PF6] containing Cyanex923 was immobilized on XAD-7 resin for solid–liquid extraction of rare earth (RE). The solid–liquid extraction contributed to ameliorating mass transfer efficiency, i.e. shortening equilibrium time from 40 min to 20 min, increasing extraction efficiency from 29% to 80%. In additional, the novel IL-SIR could separate Y(III) from Sc(III), Ho(III), Er(III), Yb(III) effectively by adding water-soluble complexing agent. Thus, the solid–liquid extraction by IL-SIR coupled with complexing method could be regarded as an effective strategy for improving mass transfer efficiency and increasing selectivity of IL-based liquid–liquid extraction.
Ionic liquids (ILs) are composed of organic cations and either organic or inorganic anions that remain liquid over a wide temperature range, including room temperature. IL characteristics can be dramatically adjusted (e.g., hydrophobic vs. hydrophilic) by changing the anion type, or subtly altered by changing the length or number of alkyl groups appended to the cation. Changing alkyl chain lengths in the 1-alkyl-3-methylimidazolium cation, in combination with PF6− or N(SO2CF3)2− anions, produces hydrophobic ILs with rheological properties suitable for their use in liquid/liquid separations. Actinides exhibit significant partitioning to these ILs from aqueous solutions with the addition of an extractant (e.g., octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide) to the IL. Ionic liquids can, thus, be considered for actinide chemistry as a new class of materials with adjustable solvent characteristics, unique properties, and the potential for enhancing the principles of “green” chemistry in various chemical processes. Here we highlight the unique physical properties of some ILs and their use in liquid/liquid separations.
The predominant mode of strontium ion transfer from aqueous nitrate media into a series of 1-fluoroalkyl-3-methylimidazolium bis[(trifluoromethylsulfonyl)]imides containing dicyclohexano-18-crown-6 (DCH18C6) is shown to shift from cation exchange to strontium nitrato-crown ether complex partitioning as the length of the fluoroalkyl substituent is increased. Fluoroalkyl substituents are shown to be only slightly more effective than their non-fluorous analogs at inducing this shift. At the same time, the fluorinated ionic liquids (ILs) yield strontium distribution ratios as much as an order of magnitude lower than the corresponding 1-alkyl-3-methylimidazolium (C(n)mim(+)) salts. Fluorous ILs thus appear to offer no compelling advantages over C(n)mim(+) ionic liquids as extraction solvents.
Multiple linear regression (MLR), radial basis network (RB), and multilayer perceptron (MLP) neural network (NN) models have been explored for the estimation of toxicity of ammonium, imidazolium, morpholinium, phosphonium, piperidinium, pyridinium, pyrrolidinium and quinolinium ionic liquid salts in the Leukemia Rat Cell Line (IPC-81) and Acetylcholinesterase (AChE) using only their empirical formulas (elemental composition) and molecular weights. The toxicity values were estimated by means of decadic logarithms of the half maximal effective concentration (EC(50)) in microM (log(10)EC(50)). The model's performances were analyzed by statistical parameters, analysis of residuals and central tendency and statistical dispersion tests. The MLP model estimates the log(10)EC(50) in IPC-81 and AchE with a mean prediction error less than 2.2 and 3.8%, respectively.
An improved method for the preparation of 1-alkyl-3-methylimidazolium hexafluorophosphates provides a series of room-temperature ionic liquids (RTILs) in which the 1-alkyl group is varied systematically from butyl to nonyl. For competitive solvent extraction of aqueous solutions of alkali metal chlorides with solutions of dicyclohexano-18-crown-6 (DC18C6) in these RTILs, the extraction efficiency generally diminished as the length of the 1-alkyl group was increased. Under the same conditions, extraction of alkali metal chlorides into solutions of DC18C6 in chloroform, nitrobenzene, and 1-octanol was undetectable. The extraction selectivity order for DC18C6 in the RTILs was K+ > Rb+ > Cs+ > Na+ > Li+. As the alkyl group in the RTIL was elongated, the K+/ Rb+ and K+/Cs+ selectivities exhibited general increases with the larger enhancement for the latter. For DC18C6 in 1-octyl-3-methylimidazolium hexafluorophosphate, the alkali metal cation extraction selectivity and efficiency were unaffected by variation of the aqueous-phase anion from chloride to nitrate to sulfate.
The Sr(II)-crown ether complexes formed in a room-temperature ionic liquid (RTIL), 1-methyl-3-pentylimidazolium bis[(trifluoromethyl)sulfonyl]amide, have been studied by X-ray absorption fine structure measurements at the Sr K-edge. When a Sr(NO(3))(2)-crown ether complex is directly dissolved in a water-saturated RTIL, both nitrate ligands and the crown ether coordinate the Sr, as observed in a conventional two-phase water-octanol system. When the cationic Sr-crown ether complex is created in a two-phase water-RTIL system, however, only cationic Sr-crown ether complexes are observed in the RTIL phase. This difference in the coordination complexes arises from differences in the mechanism of cation extraction between the RTIL and conventional molecular organic solvents, a finding with important implications for synthesis, catalysis, and ion separations using two-phase water-RTIL systems.
The structure and stoichiometry of the lanthanide(III) (Ln) complexes with the ligand 2-thenoyltrifluoroacetone (Htta) formed in a biphasic aqueous room-temperature ionic liquid system have been studied by complementary physicochemical methods. Equilibrium thermodynamics, optical absorption and luminescence spectroscopies, high-energy X-ray scattering, EXAFS, and molecular dynamics simulations all support the formation of anionic Nd(tta)4(-) or Eu(tta)4(-) complexes with no water coordinated to the metal center in 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C4mim+Tf2N(-)), rather than the hydrated, neutral complexes, M(tta)(3)(H2O)n)(n = 2 or 3), that form in nonpolar molecular solvents, such as xylene or chloroform. The presence of anionic lanthanide complexes in C4mim+Tf2N(-) is made possible by the exchange of the ionic liquid anions into the aqueous phase for the lanthanide complex. The resulting complexes in the ionic liquid phase should be thought of as weak C4mim+Ln(tta)4(-) ion pairs which exert little influence on the structure of the ionic liquid phase.
Solvent extraction of cesium ions from aqueous solution to hydrophobic ionic liquids without the introduction of an organophilic anion in the aqueous phase was demonstrated using calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) as an extractant. The selectivity of this extraction process toward cesium ions and the use of a sacrificial cation exchanger (NaBPh(4)) to control loss of imidazolium cation to the aqueous solutions by ion exchange have been investigated.
Supported ionic liquid catalysis is a concept which combines the advantages of ionic liquids with those of heterogeneous support materials. The viability of this concept has been confirmed by several studies which have successfully confined various ionic phases to the surface of support materials and explored their potential catalytic applications. Although the majority of the evaluated supports were silica based, several studies focused on polymeric materials including membranes. The preparation of these materials was achieved by using two different immobilization approaches. The first approach involves the covalent attachment of ionic liquids to the support surface whereas the second simply deposits the ionic liquid phases containing catalytically active species on the surface of the support. Herein recent advances made in this area are described.
Selective extraction-separation of yttrium(Ill) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF6]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim] [PF6]/[Tf2N]-based extraction system without increasing the loss of [C(n)mim](+). (c) 2007 Elsevier B.V. All rights reserved.