Article

A supported liquid membrane (SLM) with resorcinarene for facilitated transport of methyl glycopyranosides: Parameters and mechanism relating to the transport

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Abstract

A supported liquid membrane (SLM) containing a resorcinarene carrier, previously used for the transport of aldoses and alditols, has been used for the selective transport of methyl-α-d-glucopyranoside, methyl-β-d-glucopyranoside, methyl-β-d-galactopyranoside, methyl-α-d-mannopyranoside, and methyl-β-d-xylopyranoside from concentrated (0.20–0.025M) aqueous solutions. The membrane is made of a microporous polytetrafluoroethylene film (PTFE), impregnated with a 0.01M solution of the carrier in CCl4. The permeabilities of the SLM for all studied methyl aldopyranosides were calculated. On the basis of the flux dependence on the initial concentrations of carrier and methyl aldopyranoside, the rate-determining step in the transport mechanism is shown to be the migration of the (1/1) carrier–carbohydrate complex in the immobilized organic phase. The flux of sugar is related to the initial concentration of methyl aldopyranoside in the feed phase by a saturation law, which allowed the determination of the apparent diffusion coefficients and the stability constants of the resorcinarene complexes of methyl aldopyranosides formed in the liquid membrane. The stability constants of the complexes fall into two classes: aldopyranosides with trans HO groups form complexes of low stabilities (K≈0.36±0.01) whereas aldopyranosides with cis HO groups form complexes of high stabilities (K≈0.84±0.01).

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... Kinetic and mechanistic models have been developed and tested to the facilitated extraction phenomenon of VO 2 + ions from acid solutions. The macroscopic parameters, permeabilities , and initial fluxes 0 were determined and related to the microscopic parameters, the apparent diffusion coefficient * and the association constant ass characteristics of the formation of entity "Extractive agent-Substrate" (TS) and its diffusion across organic phase [4][5][6][7]. For a better understanding of this phenomenon, the explanation of the results and the identification of the mechanism for this process, we studied the temperature factor influence on the evolution of the parameters , 0 , * , and ass , as well as the performance of adopted SLMs. ...
... Acidic solutions (0.10 to 0.0125 M) of VO 2 + ions are prepared in pure distilled water from stock solutions. Before being used, each of the prepared MLSs was treated in a conditioning step by pure water for 20 hours [6,19], to remove a long induction period preceding the facilitated extraction process of a substrate by a SLM. Each used SLM was placed for a period of about 20 hours between the two compartments of the used cell for this facilitated For experiments relating to the facilitated extraction of VO 2 + ions, the feed phase is a fixed acidity solution of nitric acid containing a known concentration of VO 2 + ions, and the receiving phase is a hydrochloric acid solution to same acidity. ...
... The analysis of the results shows that the facilitated extraction process VO 2 + ions is a phenomenon governed by a structural term related to the nature and the structure of the interaction site of each extractive agents; then the influence of energetic term is negligible. On the other hand, recent studies [5,6,30,31] and this analysis confirm previous results which indicate that the substrate movement across each of the developed membranes cannot be a pure diffusion movement (way A), but it takes place by successive jumps of one site to an another of used extractive agent, via interaction reactions of VO 2 + ions with the extractive agent according to the way B indicated by the diagram in Figure 15. ...
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To conduct experiments related to the facilitated extraction phenomenon of vanadium ions (VO 2 +), three supported liquid membranes (SLMs) were prepared, each containing 0.01 M of methyl cholate (MC), resorcinarene (RESO), or trioctylamine (TOA) as extractive agents. Kinetic and thermodynamic models were developed, based on the interaction of the substrate (VO 2 +) with the extractive agent T and the diffusion of the formed entity (TS) through the membrane. The experimental results verify the models, and to determine, macroscopic parameters, permeabilities (P) and initial fluxes (í µí°½ 0), and microscopic parameters, association constants (í µí°¾ ass) and apparent diffusion coefficients (í µí°· *) related to formed entities (TS) and their diffusion through the membrane organic phase. The experimental results indicate that the mechanism on the migration of the VO 2 + ions through the membrane organic phase is based on the successive jumps of substrate, from one site to another of the extractive agent. To explain these results and understand the mechanism, we studied influence of temperature factor, and we determined activation parameters (í µí°¸íµí°¸í µí±Ž , Δí µí°» ̸ = , and Δí µí±† ̸ =). The results show that this extraction phenomenon is governed by a structural term. Therefore, the membrane performance changes according to nature and structure of the association site presented by each of extractive agents.
... Kinetic and mechanistic models have been developed and tested to the facilitated extraction phenomenon of VO 2 + ions from acid solutions. The macroscopic parameters, permeabilities , and initial fluxes 0 were determined and related to the microscopic parameters, the apparent diffusion coefficient * and the association constant ass characteristics of the formation of entity "Extractive agent-Substrate" (TS) and its diffusion across organic phase [4][5][6][7]. For a better understanding of this phenomenon, the explanation of the results and the identification of the mechanism for this process, we studied the temperature factor influence on the evolution of the parameters , 0 , * , and ass , as well as the performance of adopted SLMs. ...
... Acidic solutions (0.10 to 0.0125 M) of VO 2 + ions are prepared in pure distilled water from stock solutions. Before being used, each of the prepared MLSs was treated in a conditioning step by pure water for 20 hours [6,19], to remove a long induction period preceding the facilitated extraction process of a substrate by a SLM. Each used SLM was placed for a period of about 20 hours between the two compartments of the used cell for this facilitated For experiments relating to the facilitated extraction of VO 2 + ions, the feed phase is a fixed acidity solution of nitric acid containing a known concentration of VO 2 + ions, and the receiving phase is a hydrochloric acid solution to same acidity. ...
... The analysis of the results shows that the facilitated extraction process VO 2 + ions is a phenomenon governed by a structural term related to the nature and the structure of the interaction site of each extractive agents; then the influence of energetic term is negligible. On the other hand, recent studies [5,6,30,31] and this analysis confirm previous results which indicate that the substrate movement across each of the developed membranes cannot be a pure diffusion movement (way A), but it takes place by successive jumps of one site to an another of used extractive agent, via interaction reactions of VO 2 + ions with the extractive agent according to the way B indicated by the diagram in Figure 15. ...
Article
Full-text available
To conduct experiments related to the facilitated extraction phenomenon of vanadium ions (VO2+).Three supported liquid membranes (SLMs) were prepared, each containing 0.01 M of Methyl cholate (MC), Resorcinarene (RESO) or Trioctylamine (TOA) as extractive agents. Kinetic and thermodynamic models were developed, based on the interaction of the substrate (VO2+) with theextractive agent T, and the diffusion of the formed entity (TS) through the membrane. The experimental results verify the models and to determine, macroscopic parameters, permeabilities (P) and initial fluxes (J0), and microscopic parameters, association constants (Kass), and apparent diffusion coefficients (D*), relating to formed entities (TS) and their diffusion through the membrane organic phase. The experimental results indicate that the mechanism on the migration of the VO2+ ions throughthe membrane organic phase is based on the successive jumps of substrate, from one site to another of the extractive agent. To explain these results and understand the mechanism, we studied influence of temperature factor, and we determined activation parameters (Ea, ΔH≠, ΔS≠). The results show that thisextraction phenomenon is governed by a structural term. Therefore, the membrane performance change according to nature and structure of the association site presented by each of extractive agents.
... This development should be increased because of its good performance (low energy and use simple techniques), offered by membrane processes and due to the emerging needs of environmental protection (effluent treatment, clean processes, and so on). Meanwhile, these different applications, a research increasingly pushed to better understand the functioning of these membrane processes, create and develop more efficient or more specific and new methods to access new applications [1][2][3][4][5][6]. ...
... Our work will be limited to the supported liquid membranes (SLMs), made of a polymer film, inert, micro porous polyvinylidene difluoride (PVDF), a thickness of 100 mm and 69% porosity with pores of 0.45 mm in diameter, containing one of the following amphiphilic carriers (Fig. S1): methyl cholate or resorcinarene, soluble in toluene phase [5,6]. A kinetic model as well as a transport mechanism have been developed and tested for the facilitated transport of Cr 2 O 7 2À ions from different solutions. ...
... C 0 is the substrate initial concentration. In experimental conditions with an excess of substrate S relative to the carrier T, recent studies show the equation relating permeability P to C r concentration of substrate S, is given by the relationship [6,24,25]: ...
... In the present cases, one may easily imagine that the cyclic glycopyranosyl group reacts (by a diol system) with a second carrier site. This hypothesis is strongly supported by recent studies, published by Hlaïbi et al. [32] on the facilitated transport of methyl glycopyranosides across a similar SLM, that show that carbohydrates in cyclic forms can indeed react with the resorcinarene carrier to form complexes in the organic phase. Methyl ␣ and ␤-glucopyranosides form weak complexes (K ≈ 0.36, like glucose), and methyl ␤-galactopyranoside forms a complex (K ≈ 0.85), stronger than the ␣-gluco compound, in agreement with the lactitol complex being stronger than the maltitol complex. ...
... Methyl ␣ and ␤-glucopyranosides form weak complexes (K ≈ 0.36, like glucose), and methyl ␤-galactopyranoside forms a complex (K ≈ 0.85), stronger than the ␣-gluco compound, in agreement with the lactitol complex being stronger than the maltitol complex. So, from the large values of stability constants (K malt = 1.80 and K lact = 2.84) for the complexes involved in the transport of these two disaccharides through the SLM, and from recent studies on the transport of glycopyranosides [32], we conclude that maltitol reacts by two diol sites, respectively the (HO-2,3) threo site of the linear chain and the (HO-3,4) trans site of the pyranoside ring. In the same way, lactitol also reacts with the resorcinarene carrier to form a stable complex by two different diol sites, respectively the same (HO-2,3) threo site of the linear chain and the (HO-3,4) cis site, belonging to the pyranoside ring (Fig. 2). ...
... The analysis of the evolution of microscopic parameters, the stability constant K of the substrate-carrier complex and the apparent diffusion coefficient D* for facilitated transport of carbohydrates through SLMs, is very important to understand the movement nature of transported substrates in the organic phase of this membrane type. Indeed, various studies [12,13,23,[32][33][34] show that the values of parameters K and D* depend on several factors, especially, the nature of the transported substrate, the carrier, and the composition of the SLM. These values are comparable only for transported compounds with similar natures. ...
Article
A supported liquid membrane (SLM) containing a resorcinarene carrier has been used for the selective transports of arabinitol and perseitol from concentrated aqueous solutions (0.2–0.025M). Maltitol and lactitol, two alditols derived from disaccharides, were also studied. The membrane is made of a microporous poly(tetrafluoroethylene) film impregnated with a 0.01M solution of the carrier in CCl4. The permeabilities of the SLM for all alditols were calculated. For each alditol, the initial flux is related to initial concentration in the feed phase by a saturation law, indicating that the rate-determining step in the transport mechanism is the migration of a (1/1) carrier–carbohydrate complex in the immobilized organic phase. Using a model previously published, the apparent diffusion coefficients D* and the stability constants K of the carrier–alditol complexes were determined. The magnitudes of the stability constants are related to the structures of the alditols, particularly to the number and orientation of hydroxyl groups that interact with the carrier. In small alditols that contain an arabino triol system, the site of binding to the carrier is the erythro diol group. In the large molecules of disaccharides and perseitol in which more OH groups are available, more stable carrier–alditol complexes are formed: it is believed that two remote sites of binding interact with two independent recognition sites of the carrier.
... After 25 hours of SILM operation, the totality of the initial cobalt placed in the feed solution was found in the receiving solution. It seems that cobalt is transported across the membrane in a solution diffusion-mechanism, characterized by stable complexes [62]. The IL-cobalt complexes ([/ ;;;<8 = ][ $ 7 8 9 ]) migrates from the feed to the receiving phase, while the IL ([/ ;;;<8 = ] [ 7 ]) migrates through the membrane in the opposite direction. ...
... The proposed mechanism of extraction is displayed in the following figure: The CoCl4 2complexes are extracted by the IL at the feed/liquid membrane interface and then back-extracted at the liquid/membrane/interface in a continuous process. It seems that that the facilitated transport of cobalt across the membrane is a solution diffusionmechanism, characterized by stable complexes [62]. The IL-cobalt complexes ([/ ;;;<8 = ][ $ 7 8 9 ]) migrates from the feed to the receiving phase, while the IL ([/ ;;;<8 = ] [ 7 ]) migrates through the membrane in the opposite direction. ...
Article
The selective separation of cobalt from nickel is of major importance for the recovery of cobalt from primary or secondary sources, as well as for analytical purposes. In this paper, the extraction of cobalt from the mixtures was examined using a supported liquid membrane employing the undiluted hydrophobic ionic liquid, namely tri(hexyl)tetradecyl phosphonium chloride ([P66614][Cl]), as a carrier and polyvinylidene difluoride (PVDF) as a membrane material. In the preliminary study, the efficiency of this supported ionic liquid membrane (SILM) for the cobalt extraction was evaluated by conventional static mode sorption experiments. Up to 86% of cobalt can be recovered under optimal conditions (by contacting SILM with 9.8 cm² in 5 mL of aqueous phase for 1 hour at 100 rpm, with 9 mol.L⁻¹ HCl in the aqueous phase). Next, metal ion transport through a flat sheet SILM was investigated with pure water as a receiving phase. Permeation coefficients values of 2.2x10⁻⁶ m.s⁻¹ and 8.0x10⁻⁶ m.s⁻¹ were obtained with a hydrophobic and a hydrophilic membrane, respectively. The SILM showed selectivity for cobalt over nickel with separation factors as high as 218. Membrane stability was proven to be excellent, since the same SILM was used three times without losses of performances.
... Others have merged Fick's second law of diffusion with the kinetics of reversible reactions [26][27][28], and some researchers have also described the process kinetics as first order mechanisms [29][30][31][32][33][34]. These schemes have sometimes merged the diffusion process in flux terms [35][36][37][38][39][40]. These schemes are still deficient because they address certain aspects of the state and neglect others. ...
... In contrast, the mean concentration of dissolved atropine in benzene in both arms of the tube does not give a simple expression that can be used to calculate the constants in an experimental way to compare the proposed kinetic model with experimental results, but it can simplify equations (28) and (31) through the study of these equations during the initial time periods (primary sections of the curves), where in the initial time periods, the exponential terms can be replaced by (− ) ≈ 1 − according to the Taylor series [52]. Therefore, equation (28) becomes the following: Equations (32), (35) and (36) in addition to the equilibrium constant relationship which is: (37) All of the kinetic constants for this system can be determined, thus allowing the supposed kinetic model to be compared with the experimental results for the purpose of determining the efficiency of this model to describe the overall process. ...
Article
Full-text available
In this study, a mathematical model for the kinetics of solute transport in liquid membrane systems (LMSs) has been formulated. This model merged the mechanisms of consecutive and reversible processes with a “semi-derived” diffusion expression, resulting in equations that describe solute concentrations in the three sections (donor, acceptor and membrane). These equations have been refined into linear forms, which are satisfying in the special conditions for simplification obtaining the important kinetic constants of the process experimentally.
... Others have merged Fick's second law of diffusion with the kinetics of reversible reactions [26][27][28], and some researchers have also described the process kinetics as first order mechanisms [29][30][31][32][33][34]. These schemes have sometimes merged the diffusion process in flux terms [35][36][37][38][39][40]. These schemes are still deficient because they address certain aspects of the state and neglect others. ...
... In contrast, the mean concentration of dissolved atropine in benzene in both arms of the tube does not give a simple expression that can be used to calculate the constants in an experimental way to compare the proposed kinetic model with experimental results, but it can simplify equations (28) and (31) through the study of these equations during the initial time periods (primary sections of the curves), where in the initial time periods, the exponential terms can be replaced by (− ) ≈ 1 − according to the Taylor series [52]. Therefore, equation (28) becomes the following: Equations (32), (35) and (36) in addition to the equilibrium constant relationship which is: (37) All of the kinetic constants for this system can be determined, thus allowing the supposed kinetic model to be compared with the experimental results for the purpose of determining the efficiency of this model to describe the overall process. ...
Article
Full-text available
In this study, a mathematical model for the kinetics of solute transport in liquid membrane systems (LMSs) has been formulated. This model merged the mechanisms of consecutive and reversible processes with a “semi-derived” diffusion expression, resulting in equations that describe solute concentrations in the three sections (donor, acceptor and membrane). These equations have been refined into linear forms, which are satisfying in the special conditions for simplification obtaining the important kinetic constants of the process experimentally. Key words: kinetic model, diffusion, liquid membranes, mathematical model, solute diffusion in a LMS.
... In fact this technique has been used to study transport and apply it to the selective extraction and enrichment of very different organic compounds, such as amino acids [18,19], the aromatic aminophosphate [20] sugars [21][22][23], herbicides [24,25] or organic acids [26,27]. ...
... −1 ) [30,31]. The same remark was made for the transport of some alditols and sugars [24,25]. ...
Article
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The technique of supported liquid membranes (SLM) was used to achieve the facilitated transport of Cr2O72-, using an amphiphilic organic molecules as carriers, methyl cholate, widely used for facilitated transport of metal ions and carbohydrates (sugars and alditols). For our prepared SLM, toluene as organic phase and film of polyvinylidene difluoride (PVDF), as microporous and hydrophobic polymer support with 100μm in thickness and 0.45μm as the diameter of the pores. The macroscopic parameters, permeability P and initial flux Ji, on the facilitated transport of the Cr2O72- anions were determined for several acidities of the medium of the three mineral acids: hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4). For the different studied environments, the prepared SLM is highly permeable for the transported substrate (Cr2O72-), and a clear evolution of these parameters was observed for the used carrier. The initial flux on the facilitated transport of the Cr2O72- anions is related to the initial concentration of this substrate in the feed phase by a saturation law, which allowed the determination of the microscopic parameters, apparent diffusion coefficient D* and the association constant Kass of the (carrier-substrate) complexes, formed in the organic phase for the used SLM. The experimental results clearly indicate that the (carrier-substrate) complexes formed in the organic phase are unstable, which results in higher apparent diffusion coefficients D* and thus a high permeability of this membrane type, to facilitated transport on this type of oxygen anions (Cr2O72-).
... This development should be increased because of the good performance offered by membrane processes and due to the emerging needs of environmental protection (effluent treatment, clean processes…). Meanwhile, these different applications, research increasingly pushed to better understand the functioning of these membrane processes, create more efficient or more specific, and develop new methods to access new applications [1][2][3][4][5][6]. ...
... Various studies show that the characteristics nature and structure of the carrier are two important and decisive factors for the facilitated transport of metal ions and organic molecules through the (SLM)s [6,23,24,33,34)]. To complement our results, and examine the influence of the carrier nature, we conducted the same experiments under the same conditions with a new SLM containing Resorcinarene as carrier. ...
Article
Full-text available
The technique of supported liquid membranes was used to achieve the facilitated transport of Cr(III) ions, using tow amphiphilic carriers, the methyl cholate and resorcinarene. For prepared SLMs, toluene as organic phase and film of polyvinylidene difluoride, as hydrophobic polymer support with 100 μm in thickness and 0.45 μm as the diameter of the pores. The macroscopic parameters (P and J 0) on the transport of these ions were determined for different medium temperatures. For these different environments, the prepared SLMs were highly permeable and a clear evolution of these parameters was observed. The parameter J 0 depended on the temperature according to the Arrhenius equation. The activation parameters, Ea, ΔH ≠ and ΔS ≠ , for the transition state on the reaction of complex formation , were determined. To explain these results for this phenomenon, and achieve a better extraction of the substrate, a model based on the substrate complexation by the carrier and the diffusion of the formed complex   ST   ST was developed. The experimental results verify this model and determine the microscopic parameters (K ass and D *). These studies show that these parameters K ass and D * are specific to facilitated transport of Cr(III) ions by each of the carriers and they are changing significantly with temperature.
... This development should be increased because of the good performance offered by membrane processes and due to the emerging needs of environmental protection (effluent treatment, clean processes…). Meanwhile, these different applications, research increasingly pushed to better understand the functioning of these membrane processes, create more efficient or more specific, and develop new methods to access new applications [1][2][3][4][5][6]. ...
... Various studies show that the characteristics nature and structure of the carrier are two important and decisive factors for the facilitated transport of metal ions and organic molecules through the (SLM)s [6,23,24,33,34)]. To complement our results, and examine the influence of the carrier nature, we conducted the same experiments under the same conditions with a new SLM containing Resorcinarene as carrier. ...
Article
Full-text available
The technique of supported liquid membranes was used to achieve the facilitated transport of Cr(III) ions, using tow amphiphilic carriers, the methyl cholate and resorcinarene. For prepared SLMs, toluene as organic phase and film of polyvinylidene difluoride, as hydrophobic polymer support with 100 μm in thickness and 0.45 μm as the diameter of the pores. The macroscopic parameters (P and J 0) on the transport of these ions were determined for different medium temperatures. For these different environments, the prepared SLMs were highly permeable and a clear evolution of these parameters was observed. The parameter J 0 depended on the temperature according to the Arrhenius equation. The activation parameters, Ea, ΔH ≠ and ΔS ≠ , for the transition state on the reaction of complex formation , were determined. To explain these results for this phenomenon, and achieve a better extraction of the substrate, a model based on the substrate complexation by the carrier and the diffusion of the formed complex   ST   ST was developed. The experimental results verify this model and determine the microscopic parameters (K ass and D *). These studies show that these parameters K ass and D * are specific to facilitated transport of Cr(III) ions by each of the carriers and they are changing significantly with temperature.
... However, other types of membranes are sometimes used, such as bulk liquid membranes or emulsion liquid membranes. A very small volume of organic solvent is indispensable, and since this solvent is trapped in a porous medium, the quantity of harmful volatile chemicals released to the atmosphere is reduced; this aspect can be the fundamental advantage of SLM over classical extraction (Touaj et al., 2009;Valenzuela et al., 2009). SLM can be a perfect choice for recovering organic compounds, because it mixes the two processes of stripping and extraction into one. ...
... Because of this drawback, most SLM-based systems cannot be scaled up to industrial level. The reason SLM systems become unstable is the liquid membrane phase (extractant and=or solvent) being removed from the pores of the support material (Touaj et al., 2009;Venkateswaran and Palanivelu, 2006). This loss of extractant and=or membrane solvent can be due to several parameters, such as osmotic pressure difference over the membrane, solubility of extractant and membrane solvent in adjacent feed, chemical degradation of strip solution, and wetting of support pores by aqueous phase. ...
Article
Transport of phenol through a flat sheet supported liquid membrane (SLM) containing cooking oil as liquid membrane (LM) was investigated. Factors affecting permeation of phenol such as membrane phase, support material, feed phase pH, stripping phase concentration, stirring speed, and initial concentration of phenol were studied. It was found that these parameters strongly influence phenol removal efficiency; PTFE membrane as support material, grape seed oil as liquid membrane, feed pH of 2.0, initial phenol concentration of 100 mg/L, stirring speed of 350 rpm, and 0.2 M sodium hydroxide as effective stripping agent were found as the best conditions for greater phenol transport. Under these conditions, permeability was found to be 7.46 × 10−6 m/s. After 10.5 h, phenol was completely removed from the feed phase to strip phase. According to stability experiments, it was observed that the SLM is stable after 22 h. Thus, the use of cheap, nontoxic, and naturally oil as a novel and green membrane for recovery of phenol from wastewater was demonstrated.
... We also referred to a number of scientific studies to gain insight into the rheology of PVA solutions and deduce the amount of water and organic solvent needed to give our membrane solution a certain viscosity, which in turn provides our membrane with adequate elasticity and mechanical strength [31,32] Then these membranes are adapted to conduct studies relating to the extraction and recovery processes of the substrate VO 2 + ions, from acidic wastewater. Different parameters are determined and analyzed for the quantification of studied processes according to two theoretical models designed in the laboratory [33][34][35][36][37][38]. The influence of several factors (initial concentration C 0 , co-ion nature, temperature) was examined to identify optimal conditions, explain the performances, and elucidate the mechanisms of studied processes as well as the energetic and kinetic aspects that control these mechanisms. ...
Article
Full-text available
The present work describes the quantification of the extraction processes of VO2⁺ ions through polymeric inclusion membranes. β-cyclodextrin (β-CD) and resorcinarene (RESO) were used as extractive agents, and polyvinyl alcohol (PVA) was used as polymer support. After the characterization of developed membranes, they were adopted to carry out the studied processes. Different parameters were determined, such as permeability (P) and initial flux (J0), specific to membrane performance, association constant (Kass), and apparent diffusion coefficient (D*) relating to the movement of VO2⁺ ions through the membrane phase. A significant effect was observed for temperature influence, and activation parameters were identified. The results indicate a high performance of the PVA/RESO membrane and the mechanisms by successive jumps of VO2⁺ ions on semi-mobile sites. Energy and kinetic control aspects are elucidated for studied processes through the employed membranes. This study allows a new approach to developing high-performance green membranes for the recovery of Vanadium from wastewater and reducing their negative impact on the aquatic environment.
... In this case, the reaction rate is higher than the diffusion rate [54]. This helps to explain the high permeability of supported ionic liquid membranes (SILMs) for facilitated transport [55]. A new "task-specific" IL type can be used as carriers in facilitated transport membranes. ...
Article
The major gaseous pollutants emitted during the combustion of fossil fuels, during energy-intensive production of materials, and during waste processing are CO2, SO2, and NOx. The combined efforts of industry and the research community aim to intensify their capture and decrease their emissions, with the final objective of meeting stricter emission limits, which is becoming more challenging with conventional technologies. Membrane separation technology is a particularly significant environmental protection application because it can be effectively combined with other separation technologies and generally uses much less energy. As membrane processes represent an energy-efficient alternative to traditional separation processes, in view of today's emissions policy, they have become economically competitive to purify flue gases emitted from small point sources, such as waste incineration units and steel or cement production facilities. Different membrane types with various specific functions, such as high solubility for certain gases, thermal and mechanical stability, and ease of manufacturing, are presented as perspective technologies for flue gas purification. Unique systems are also discussed, including facilitated or retarded transport of permeants in membranes and mixed-matrix membranes. We first describe the basic operating mechanism based on their structure and material properties to compare the advantages and disadvantages of suitable membranes. This review presents state-of-the-art membrane technologies in CO2, SO2, and NOx separation from flue gases and discusses the potential applications of the most promising membranes.
... The system is immersed in a thermostat bath containing water in order to keep the temperature constant throughout the experiments. A multi-position stirrer is used to ensure the homogeneity of the two phases [33][34][35]. Micro volumes samples were taken from the feed phase at regular time intervals and analyzed by a Mettler Toledo UV-visible spectrophotometry device. ...
Article
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In the present work, we prepared three polymer inclusion membranes (PIM), based on polyvinyl alcohol (PVA) as polymeric support and containing three extractive agents: Nitrilotriacetic acid (NTA), Ethylene diamine tetra acetic acid (EDTA) and tris (2-aminoethyl) amine (TREN). The morphology structures of these membranes were determined using different spectroscopical techniques by Fourier-transform infrared spectrometry and scanning electron microscopy techniques. The membranes were used to conduct experiments of oriented extraction processes for the facilitated recovery of Nickel (II) ions from lithium-ion (Li-ion) battery waste. The obtained results allowed to determine the values of different macroscopic and microscopic parameters of paramount importance such as respective permeability (P), initial flux (J0) and apparent diffusion coefficient (D*), constant association (Kass) related to the movement of the substrate through the membrane. The influence of several factors, as the initial substrate concentration and temperature (C0, T) was studied. The results indicate that the different parameters (P, J0, D* and Kass) vary strongly with the temperature of the medium and that of the performances of the used membranes increase with the temperature factor. The activation and thermodynamic parameters (Ea, ΔH#ass and ΔS#, ∆Hth and ∆Hdiss#) were also determined and their values indicate a kinetic control for the mechanism of the studied processes, which explains the high performances of the developed membranes and indicates a mechanism by successive jumps of Nickel (II) ions on fixed sites of the extractive carriers immobilized in the membrane phase.
... The kinetic model developed by Verchère in the PBS laboratory in Rouen was used in this study. The reliability of this model was reassured by using it in several other studies in our laboratory [25,26]. ...
Article
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In this study, two types of affinity polymer membranes containing new organometallic complexes (Gd-glucaric acid) as extractants were prepared and characterized. They were used to extract Cr (VI) ions from concentrated solutions (0.0068M–0.0009 M). These affinity polymer membranes were tested designing an easier extraction process from the substrate at different concentrations and different temperatures. Additionally, macroscopic parameters such as permeability (P) and initial flux (J0) were evaluated to explain the extraction process of the substrate using these membranes. The results showed that the value of the initial flux (J0) of the extracted substrate was related to its initial concentration C0 by the saturation law, which allowed determining the microscopic parameters, the apparent diffusion coefficient (D*), and the substance formed (substrate-extraction agent) along with its constant correlation (Kass). The substrate factors and the temperature significantly affected the evolution of these parameters and the performance of the membrane during extraction. The activation parameters (Ea, ΔH≠, and ΔS≠) were determined, and the results indicated that the high performance of these types of membranes is related to the use of advanced techniques. The efficiency was related to the movement properties of the substrate through the organic phase and the structure of the membrane.
... If the kinetic model is verified, after an induction time (t I ), the function (− Ln (C 0 − 2C R ) versus time) evolves linearly. The slope (a) of the obtained straight line allows the determination of the permeability parameter P according to the following equation [59,60]. ...
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Background Paracetamol compound remains the most used pharmaceutical as an analgesic and antipyretic for pain and fever, often identified in aquatic environments. The elimination of this compound from wastewater is one of the critical operations carried out by advanced industries. Our work objective was to assess studies based on membrane processes by using two membranes, polymer inclusion membrane and grafted polymer membrane containing gluconic acid as an extractive agent for extracting and recovering paracetamol compound from aqueous solutions. Result The elaborated membrane characterizations were assessed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Kinetic and thermodynamic models have been applied to determine the values of macroscopic ( P and J 0 ), microscopic ( D* and K ass ), activation and thermodynamic parameters ( E a , ΔH # , ΔS # , ΔH # diss , and ΔH # th ). All results showed that the PVA–GA was more performant than its counterpart GPM–GA, with apparent diffusion coefficient values (10 ⁷ D* ) of 41.807 and 31.211 cm ² s ⁻¹ respectively, at T = 308 K. In addition, the extraction process for these membranes was more efficient at pH = 1. The relatively low values of activation energy ( Ea ), activation association enthalpy ( ΔH ≠ ass ), and activation dissociation enthalpy ( ΔH ≠ di ss ) have indicated a kinetic control for the oriented processes studied across the adopted membranes much more than the energetic counterpart. Conclusion The results presented for the quantification of oriented membrane process ensured clean, sustainable, and environmentally friendly methods for the extraction and recovery of paracetamol molecule as a high-value substance.
... Since the first commercialization under the trademark SLiM by Commodore Separation Technologies Inc (Touaj et al., 2009), Supported Liquid Membranes (SLMs) have been widely used for the extraction of valuable metal ions from aqueous resources due to the significant advantages related to combination of extraction and stripping into a single stage, high selectivity, mass-transfer not limited by equilibrium conditions (Chmielewski et al., 1997;Parhi, 2013). In general, a SLM is formed by a thin layer of organic phase (containing a carrier for the ion target) immobilized onto a microporous support (usually polymeric and hydrophobic) interposed in between an aqueous feed solution (or "source phase") and a stripping solution (or "receiving phase") (Fig. 9c). ...
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Mining is an economically-beneficial activity recognized as crucial in modern society since almost every aspect of our lives relies on minerals. However, intensive mining activities impose a severe strain on the water-energy nexus. In fact, mining ventures: i) need massive amount of water in various ore processing steps; ii) generate a huge amount of waste (tailings), generally transferred to tailing ponds or dams, that are a potential source of contamination and adverse ecological effects; iii) are energy-intensive practices in the extraction and transformation phases. These aspects confirm the urgent need of a paradigm shift towards a sustainable mining industry. Herein, we provide a comprehensive and critical survey on the opportunities offered by the integration of conventional and emerging membrane technologies for a sustainable development of copper mining industry, coherently with the Circular Economy paradigm. This work critically discusses the potential and challenges of conventional and innovative membrane processes for water management of the mining industry value chain, with specific focus on the remediation of waste aqueous streams and reuse of clean water. Beside the alleviation of the pressure on water bodies, attention is paid to the valorization by the recovery of valuable minerals and blue energy generation via advanced technologies such as highly selective membrane separation, membrane distillation/crystallization and reverse electrodialysis. Economic implications elucidated about the benefits from the recovered water and raw materials from mining waste. Due to its prominence and strategic relevance in global copper market, Chilean copper mining industry is here considered as case study.
... It could be concluded that the values of the apparent diffusion coefficient D were about 1 × 10 −6 for Ag(I) ion transport with different calixpyrrole ligands and were comparable to the literature values [41,42]. The same mechanism was proposed during the transport of sugars [43,44]. The explanation of this phenomenon was that the diffusion process took place by a slight convection movement, which was typical for liquid membranes. ...
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Cellulose-triacetate-based polymer inclusion membranes (PIMs) with different concentrations of a calixpyrrole ester derivative as the membrane carrier were studied to determine their ability to transport Ag(I) from aqueous nitrate solutions. The effects of the concentrations of ion carriers and metal ions, the pH of the source aqueous phase, and stripping agents on the effective transport of Ag(I) were assessed. All studied parameters were found to be important factors for the transport of Ag(I) metal ions. The initial fluxes were determined at different temperatures. The prepared membranes were found to be highly permeable. The selectivity of silver transport from an aqueous solution containing Ag(I), Cu(II), Pb(II), Cd(II), Ni(II), Zn(II), and Co(II) ions was also investigated.
... Several studies are being conducted to improve the processes of removing chromium Cr(VI) as a preferential pollutant from wastewater from the industry by methods such as liquid -liquid extraction which requires large amounts of volatile organic solvents often considered as pollutants for the environment [6], microbial treatment [7], coagulation [8], membrane separation [9], desalination by freezing [10], photo catalytic reduction [11,12], ion exchange [13] ,constructed wetland [14]. Today, membrane processes are among the most efficient extraction technologies in different fields to see the benefits (low energy consumption and use of simple efficiency techniques) [15][16][17][18]. In the present work, we have developed a graft polymer membrane (GPM) based on polysulfone as polymeric support and the extractive agent sodium gluconate ( Fig. 1) (PSU-Glu)) for the facilitated extraction of Cr(VI) and Cr(III) ions from dilute solutions. ...
... As shown in Fig. 11 (Meng et al., 2015). This decline is due to a loss of the liquid membrane phase from the support (Jaber et al., 2005;Kumar et al., 2016;Touaj et al., 2009). Zidi et al. studied the extraction of phenol by SLM. ...
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This work is a comprehensive study on removal of phenols from coal gasification wastewater (CGW) through a polypropylene hollow fiber supported liquid membrane (HF-SLM). Factors affecting removal of phenols such as composition of liquid membrane phase, design of mass transfer process, proportion of organic phase in feed phase and stripping phase, feed phase pressure, system temperature, were investigated. The operating conditions obtained for the removal of phenols are as follows: mixture of 20% tributyl phosphate and 80% kerosene as liquid membrane phase, system temperature 20 °C, feed phase went through tube side, stripping phase went through shell side, organic phase proportion in feed phase 2%, countercurrent flow for feed phase and stripping phase, feed phase pressure 0.015 MPa. Under the optimum conditions, a removal rate of phenols was obtained exceeding 90% after 120 min. These results suggest that HF-SLM could be promising in removal of phenols from CGW.
Thesis
Le développement de nouvelles technologies basées sur les batteries lithium-ion induit une augmentation de la consommation des métaux, et en particulier du lithium, qui sont à la base de cette technologie. Le développement d’une filière de recyclage de ces métaux est nécéssaire et implique de développer des procédés efficaces et respectueux de l’environnement. Dans ce travail, nous présentons plusieurs procédés d’extractions liquide-liquide applicables pour l’extraction et la séparation du manganèse, du nickel, du cobalt et du lithium. Ces procédés sont basés sur des liquides ioniques et des solvants eutectiques profonds et ont montré une sélectivité accrue par rapport aux procédés existants. Nous avons aussi développé des procédés de membranes liquides applicables à l’extraction du lithium et du cobalt. Cette technique permet d’extraire l’ion métallique avec une très faible quantité de solvant. Nous avons mis en évidence l’importance de la viscosité du liquide ionique sur la stabilité à long terme du procédé. Nous avons démontré la possibilité d’extraire très sélectivement le cobalt avec un procédé qui peut fonctionner en continu sur plusieurs cycles sans baisse de performances, avec moins d’un millilitre de liquide ionique pour traiter 250 millilitres de phase aqueuse.
Chapter
Natural ion channels are of outstanding importance in all living cells. Based on them more and more artificial ion channels are prepared for many biomedical and bioengineering applications, separation devices, environmental monitoring, food safety and so on. Moreover, the comprehensive study of their mechanism of action can lead to deep understanding of life at the cellular level. Unfortunately, ion transport across lipid bilayer membranes is an elusive phenomena difficult to evidence. This review focuses on the main techniques suitable to evidence it starting from liposomes as biomimetic model for the cellular membrane and going to the use of fluorescence spectroscopy to study membrane active molecules.
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The processes for the extraction and removal of Cr (VI) ions using the polymer inclusion membranes (PIMs) that contained Nitrilotriacetic acid (NTA) or Tris (2-aminoethyl)amine (TAM) as the extractive agent were reported in this study. Each PIM was prepared and characterized using SEM and FTIR technique to understand the correlation between its structure (morphology and composition) and its performance. The effects of several factors were studied. The parameters permeability P, initial flux J0 association constant Kass, apparent diffusion coefficient D*, and activation parameters (energy Ea, enthalpy ΔH# and entropy ΔS#) were determined and quantified using the kinetic and thermodynamic models. Therefore, we can affirm that the mechanisms of these oriented processes are governed kinetically rather than energetically. The extractive agent TAM (P = 35.26 × 10−7 cm2.s–1, D* = 11.5326 × 10–5 cm2.s–1, Ea = 6.03 Kj.mol-1, and ΔH# = 3.53 kJ.mol-1) was determined to be better for the selective extraction process of Cr (VI) ions, in comparison to its counterpart NTA (P = 22.49 × 10–7 cm2.s–1, D* = 9.58 × 10–5 cm2.s–1, Ea = 7.12 kJ.mol-1, and ΔH# = 7.12 kJ.mol-1). Therefore, the membranes developed using the TAM agent were adopted further to conduct experiments related to the processes of selective extraction and removal of Cr(VI) ions from the mixtures containing industrial P3R dye. The results of these experiments were conclusive and indicated a total and selective separation of the Cr(VI) ions and the P3R dyes, with the observance of a clear improvement in the P, J0, and D* parameters and better membrane performance.
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The rare earth elements (REEs) such as lanthanum, cerium, praseodymium, and neodymium were successfully recovered from the leaching solutions of phosphate ores through a Supported Liquid Membrane (SLM). The extractant, N,N,N′,N′-tetraoctyl diglycol amide (TODGA), was employed as novel carrier for REEs transport. Permeation rate was observed to be significantly fast and more than 95.0% of REE³⁺ was collected using 0.10 M TODGA as carrier. The mechanism of transport was investigated by studying various parameters, such as feed HNO3 and NaNO3 concentration, TODGA concentration in the membrane and the stirring rate etc. In view of practical application to the collection of REEs from the phosphate ore leaching liquor, the stability of the membrane was also studied. The result shows that the membrane was highly selective for lanthanides. This research would provide a new environmentally friendly and new sustainable green approach for the recovery of REE with SLM technique.
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Our objective is to develop a grafted polymer membrane (GPM), with polysulfone (PSU) as polymer support and gluconic acid (GA) as extractive agent. The obtained membrane was characterized by the IR spectroscopic technique which shows the integration of GA agent into the polymer matrix. While the SEM technique allowed to characterize the morphology as well as the porosity of the elaborated membrane. This membrane has been adopted to carry out experiments on the oriented process of extraction and removal of Cr(VI) and Cr (III) ions. The system was quantified and the macroscopic parameters, Permeability (P) and initial Flux (J0) were determined, as well as the specific microscopic parameters, apparent diffusion coefficient (D*) and association constant (Kass) relating to the association of substrate S with extractive agent T (GA) to form unstable entities (ST) during the migration of Cr(VI) and Cr (III) ions through the membrane phase. Studies on the influence of C0 initial concentration of the Cr(VI) and Cr(III) ions, acidity (pH) and temperature factors of the medium on the evolution of these parameters (J0, P, Kass and D*) were carried out. The results show that these factors greatly influence the variation of the values of these parameters, as well as the performance of this membrane type adopted for the studied process.
Article
Membrane processes represent one of the most promising technologies for separation and extraction in modern industries, because they have several advantages. Today these processes are an important research topic, including affinity polymer membranes that are highly efficient for oriented processes. Three affinity polymer membrane types containing lipophilic compounds, methyl cholate (MC) and cholic acid (CA) as extractive agents were prepared and characterized. They have been used to extract active ingredient paracetamol (acetaminophen), from concentrated solutions (0.08–0.01 M). Substrate acetaminophen is an important active ingredient and its recovery as a pure compound, is very useful for the pharmaceutical industry. These affinity polymer membranes were adopted to perform experiments on a facilitated extraction process of this substrate at different medium acidities and temperatures. Macroscopic parameters, permeabilities (P) and initial fluxes (J0) for a facilitated extraction of this substrate through each membrane were determined. The results indicate that values of initial fluxes (J0) of the extracted substrate are related to its initial concentration C0 by a saturation law, which allowed to determine microscopic parameters, apparent diffusion coefficients (D*) and association constants (Kass) of formed entity (substrate - extractive agent) (ST). The results show a clear influence of temperature and acidity factors on the evolution of these parameters and membrane performances in this studied process. Activation parameters (Ea, ΔH≠, and ΔS≠) were determined and the values indicate that high performances of these membrane types are certainly related to the movement nature of the substrate across the organic phase, and the structures of the substrate and the extractive agent.
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The technology of supported liquid membranes (SLM's) was used to achieve the facilitated extraction of Chromium ions (Cr(VI) and Cr(III)), using Methyl Cholate (MC) and Resorcinarene (RESO) as carriers, widely used for a facilitated extraction of carbohydrates. For our (SLM's), we use Toluene as an organic phase and PVDF microporous film as support. A kinetic model as well as an extraction mechanism have been developed and tested, in the first time, for the facilitated extraction of Cr ions from different acidic solutions. The macroscopic parameters, permeabilities P and initial fluxes J0 were determined and related to microscopic parameters, the association constant Kass, and apparent diffusion coefficient D*, relating to the stability of the complex (Carrier-Substrate TS), formed at the membrane interface, and its diffusion through the SLM organic phase. The obtained results are important and used to determine the complexation nature of Cr ions in the organic phase of the studied SLM and to explain the high permeability of such membranes for facilitated extraction of these species. These studies show that these parameters Kass and D* are changing significantly with different used carriers so the better extraction of these substrates is possible.
Article
In the present work, 5,11,17,23 tetrakis[(propylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (1) was utilized as Hg(II) selective carrier in supported liquid membrane (SLM) transport. For impregnation of carrier 1, Celgard 2500 and 2400 membranes were utilized as solid support. Influence of solvent type (chloroform, xylene, diphenyl ether, and toluene), as well as anion type (Cl−/NO−3) was also explored on the transport of Hg(II). Danesi mass transfer model and Fick's first law of diffusion were followed for determining permeability (P) and flux (J) values. From the results of the solvents, it was revealed that permeability values increase in the order of diphenyl ether>chloroform>xylene>toluene. Moreover, Cl− was proved to be more effective co-anion for Hg(II) than NO−3 due to lipophilicity in membrane phase. Efficient transport across SLM relies upon carrier specificity towards metal ion, appropriate solvent and co-anion. Hence, this study shows that Hg(II) transport is efficient and reproducible through SLM by using carrier 1.
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A Carbon dioxide-facilitated transport highway (CO2-FTH) on the microporous surface of a membrane matrix was designed using the amino carrier 3-aminopropyltriethoxysilane (APTES). Owing to the reversible reaction between CO2 molecules and fixed-site carriers, this supported ionic liquid membrane was able to selectively transfer CO2 more quickly. This concept may inspire means of fabricating a highly permeable and selective membrane to break through Robeson's upper bound.
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The applications of resorcinarene derivatives in modern separation techniques including high performance liquid chromatography (HPLC), gas chromatography (GC), capillary electrophoresis (CE), ion chromatrography (IC), and liquid membranes are reviewed in this paper. Resorcinarenes are macrocyclic compounds which can be modified with various substituents on upper and lower rims to provide specific functionality and selectivity. The derivatives can be adsorbed or covalently bound to the stationary phase of HPLC, GC, and IC, or used as pseudo-stationary phase in CE to separate organic or inorganic species. They have been tested as carriers to selectively transfer species from source phase to receiving phase in bulk liquid membranes, supported liquid membranes, and polymer inclusion membranes. These broad applications of resorcinarene-based macrocyclic ligands indicate that they are a promising class of compounds that are worthwhile to be explored in both synthesis and separation applications.
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The review demonstrates the progress in the chemistry of calix[4]resorcinarenes over the last decade. Special attention is paid to their synthesis, conformational behaviour, functionalization and ability to serve as cavitands and capsules, to form monolayers and host-guest complexes. Practical applications of calix[4]resorcinarenes and their derivatives in various fields are surveyed.
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Three fluorous resorcin[4]arenes (1a-c) were synthesized and characterized for their potential application in separation science. A crystal structure of 1b confirmed its ring size and conformation. The fluorous resorcin[4]arenes are soluble in hybrid fluorous solvents. Preliminary studies demonstrated that 1a immobilized in a fluorous bulk membrane is capable of transporting tetramethylammonium cation from an aqueous source phase into an aqueous receiving phase. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
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Without any transformation into ionized derivatives, carbohydrates themselves were transported across ion-exchange membranes against their concentration gradients. Amounts of moved sugars were affected by their pKa values.
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The acid-catalyzed condensation of resorcinol with heptanal or dodecanal followed by acetylation produces three stereoisomeric tetrameric macrocycles. The product distribution is controlled by the relative solubilities of the stereoisomeric octols in the reaction medium. These isomers comprise the previously described boat conformation (C2v, symmetry) and chair conformation (C2h symmetry) plus a new one with a diamond-like conformation (Cs symmetry). The corresponding relative configurations of the alkyl substituents, determined from NOE enhancements and NMR spectra, are all-cis, cis-trans-trans, and cis-trans-cis. In all three isomers, the alkyl substituents are in the less hindered axial position. The thermodynamically more stable boat octols can be obtained selectively in high yields (50-80%) by heating the crude initial condensation mixtures at reflux for 4 h.
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The involvement of carbohydrates in biological processes has greatly fuelled the current interest in this diverse range of molecules. This book has been produced in order to answer the need for a handbook of up-to-date laboratory protocols in this field. It gives details of the approach needed to analyze a wide variety of carbohydrates and carbohydrate-containing molecules, such as polysaccharides, glycoproteins, and glycolipids, and shows how particular analytical problems should be tackled. This second edition of a very successful title in the Practical Approach series covers the new methods that are now being used, particularly those involving HPLC, mass spectrometry, supercritical fluid chromatography, capillary electrophoresis, and NMR.
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Using a CCI4 solution saturated with water, alditols and sugars are extracted by forming host-guest complexes with resorcinarene 1. The selectivity is lower than in anhydrous conditions. However, carbohydrates that possess xylo or ribo configurations are extracted in higher yield than those with arabino or manno configurations.
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1H NMR spectroscopy on the water complex of resorcinol-dodecanal cyclotetramer indicates that a bound water molecule and a pair of OH groups on adjacent benzene rings of the macrocycle are strongly NOE correlated, but the proton exchange in the resulting hydrogen-bond network is very slow.
Article
The transport of rare-earth metal ions through a supported liquid membrane mediated by 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(diphenylphosphinoylmethoxy)calix[4]arene (1) (cone conformation) in o-nitrophenyl hexyl ether (NPHE) has been investigated. The effect of the initial metal concentration, salting-out agent concentration in the feed phase and temperature as well as the carrier concentration on the flux was studied. The separation ability of ligand 1 was tested for the separation of a mixture of 11 rare-earth metal ions (La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Y). The flux depends on the salting-out agent and varies according to the order Al(NO3)3>NaNO3>HNO3. In each case the maximum flux was found for Pr and Nd. Calixarene 1 exhibits an improved intragroup separation efficiency with respect to the non-macrocyclic ligand tri-n-octylphosphine oxide (TOPO).
Article
A carrier admixture of phenylboronic acid and ionophore (cryptand or crown ether) simultaneously co-transports p-nitrophenyl β-glucopyranoside, M+ and OH−, through a liquid organic membrane. The transport mechanism involves the apparent self-assembly of a lipophilic ion-pair, comprising of anionic, phenylboronate-glucopyranoside adduct and metal cation-ionophore complex. Active glucopyranoside transport (i.e. uphill transport against a concentration gradient) was achieved in the direction of a metal cation concentration gradient.
Article
Uphill transport of monosaccharides, mediated by phenylboronic acid, was observed when a pH difference was imposed across and organic liquid membrane.
Article
1H NMR and circular dichroism spectroscopic investigation of the complexation of octyl glycoside derivatives of various monosaccharides as guests with cyclic resorcinol tetramer as host in chloroform indicates that the complexation-responsible intracomplex sugar–sugar interaction is markedly dependent on the stereochemistry of the sugar glycosides.
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This review summarizes the recent research on a new application with boronic acids, namely their ability to act as transport carriers in bulk, liquid organic membranes. To date, boronic acids have been shown to facilitate the transport of reducing monosaccharides, ribonucleosides, aryl glycosides, catecholamines, á-amino acids, and riboflavin. The transport can either be passive (down a solute concentration gradient) or active (against a solute concentration gradient). The various chemical mechanisms for boronic acid mediated transport are described, as well as the chemical and physical factors that control transport rates.
Article
The conformational behaviour of the three macrocyclic octaols (4)–(6), obtained by acid-catalysed condensation of resorcinol with heptanal, is elucidated for the first time. Two of them, namely the diamond (5a) and the chair (6a) stereoisomers, undergo a ring-inversion conformational process in acetone to give the corresponding crown conformers (5b) and (6b). In DMSO or on addition of acetic acid to an acetone solution of diamond octaol (5), conformer (5a) is favoured. The presence of such equilibria and solvent effects are interpreted as an interplay between the tendency of the phenolic OH groups to form intramolecular hydrogen bonds and the alky chains to assume the endo position, avoiding steric repulsions and allowing self-aggregation.
Article
Fructose is separated from a fructose–glucose mixture using a polymer-supported liquid membrane containing a boronic acid carrier; addition of immobilized glucose isomerase to a solution of glucose in the source compartment of a liquid membrane transport cell produces a receiving phase mixture that is more than 80% fructose.
Article
Mechanistic insight is gained for saccharide transport through plasticized cellulose triacetate (CTA) membranes containing lipophilic ion-pair transport carriers. The molecular structures of the different membrane components are systematically varied and diagnostic transport characteristics such as saccharide–carrier diffusion constant and saccharide extraction constant are determined. The observed percolation thresholds support a jumping mechanism, however, the diffusion constants are found to decrease as the size of the saccharide, carrier cation, and carrier anion increase, indicating that the rate-limiting step in the transport process involves diffusion of a complex comprised of all three components. The data is reconciled in terms of mobile-site jumping mechanism where the saccharide is relayed along a sequence of ion-pair carriers that are locally mobile. In an attempt to improve saccharide selectivity, calix-[4]-arene dicarboxylates were evaluated as potential ditopic transport carriers. This produced no major change in saccharide extraction constants.
Article
The reaction of glucose with the borate ion has been studied in an anion exchange membrane. Two complexes, BL− and BL2−, form in the membrane, and their corresponding stability coefficients β1∗ and β2∗ have been determined. The results have revealed that the BL− complex is much more stable in the membrane than BL2−, and the stability coefficient β1∗ varies as a function of the relative proportions of the borate ion and the BL− complex. The facilitated transport of glucose was performed through an anion exchange membrane by using the borate ion as carrier; the content of the latter was fixed by the concentration of boric acid in solution. The permeance of the membrane was measured in two cases. In the first case, the boric acid concentration was fixed and the concentration of glucose varied. In the second case, the glucose concentration was fixed and the influence of boric acid concentration was examined.
Article
The extraction and competitive transport of fructose, glucose and sucrose through dichloroethane facilitated by combinations of aryl boron acids and tetraalkyl ammonium salts is described. Although extraction abilities of the boron acids are comparable, there are distinct differences in their sugar transport properties. The aqueous solubility of the aryl boron acid is apparently a critical controlling factor of sugar flux. A combination of PBA and aliquat® 336 in the membrane effectively separates fructose from an equimolar mixture of fructose, glucose and sucrose, despite extraction experiments displaying comparable extraction of glucose and fructose.
Article
A supported liquid membrane (SLM) containing methyl cholate, a bile acid ester, as carrier for the facilitated transport of sugars has been prepared with cyclohexane as a solvent instead of the previously used aromatic solvents, opening the way to industrial applications. The SLM consists of a microporous poly(vinylidene difluoride) support impregnated with a solution of carrier (C). The transport of several commercial sugars and deoxy-sugars has been studied. The initial flux Ji of sugar (S) shows a linear dependence on [C]0, the concentration of carrier, but behaves according to the saturation law with respect to c0, the initial concentration of sugar in the feed phase. Thus, the rate-determining step of the transport is the migration within the SLM of a carrier–sugar complex (CS) formed rapidly at the interface between the SLM and the feed solution. The apparent diffusion coefficient D⁎ and the equilibrium constant K of the complex have been determined for each sugar, revealing noticeable differences that confirm molecular recognition by the HO-3,7,12 triol system of methyl cholate. The complexes of D-xylose, L-rhamnose and L-fucose, three sugars that do not possess an HO-6 group, are weaker than those of the corresponding hexoses, i.e. glucose, mannose and galactose. The importance of the presence of the exocyclic HOCH2 group for efficient binding of the sugar may be related to the long distance between HO-3,12 of the carrier.
Article
D-Fructore, a ketohexose, is readily solubilized in CCl4 via complex formation with resorcinol-dodecanal cyclotetramer (1) , in marked contrast to D-glucose, a closely related aldohexose, which shows almost no affinity to 1. The affinity of fructose can be further enhanced by oligomeric modification of 1.
Article
This is an exhaustive review of calixarenes containing transition metals. General preparative routes to calixarene ligands suitable for transition metal complexation are briefly reviewed. The aspects concerning their coordinative properties are organized according to the site and type of donor atom(s) involved in complexation. Emphasis has been placed on synthetic aspects so as to allow the reader to acquire a useful knowledge of the construction of transition metal complexes derived from calixarenes. Structural aspects have been systematically discussed for those complexes which have been characterized by X-ray analysis. Many interesting features of calixarene-derived ligands have been emphasized, e.g. the ability to act as bulky ligands or to behave as a polyoxo surface and the possibility to form novel supramolecular assemblies and to associate a catalytic centre with a potential receptor cavity. It is shown that transition metals are ideal partners for shaping or assembling calixarenes, thus allowing the construction of a number of large molecular systems, leading to various applications, notably liquid crystals, sensors for analytical purposes or molecular filters.
Article
A carrier mixture of lipophilic boronic acid and bis(quaternary ammonium cation) greatly facilitates the transport of ribonucleoside monophosphates through liquid organic membranes, at neutral pH. Transport selectivity was determined for the isomers of GMP. The observed order of non-competitive transport rates was 5′-GMP > 2′-GMP > 3′-GMP.
Article
The scope of limitations of the syntheses of octols 1 by the fourfold condensations of various aldehydes with resorcinol and 2-substituted resorcinols are reported. At most, two stereoisomers of 1 were detected, one with C4v and the other with C2v symmetry (1H NMR). With aliphatic aldehydes, only 1 (C4v) product was isolated in yields ranging from 45 to 92%. With 4-substituted benzaldehydes (R = (4-XC6H4)), the yields and isomer ratios varied with the character of the X substituent. With X = CH3 and CH3CH2, the C4v/C2v ratios were >32 and the yields were 73-96%. With X = H or Br, C4v/C2v values ranged from 1.0 to >30 as a function of reaction time. With X = OCH3 or X = C6H5, the C4v/C2v ratio was 1.5 and the yields were 93 and 99%, respectively. When X = NC, (CH3)3C, HO2C, and AcNH, the C4v/C2v ratios (yields) were <0.03 (52%), 0.03 (28%), 0.4 (79%), and 0.5 (52%), respectively. With X = O2N, OHC, or CH3(CH2)3C≡C, no cyclic tetramer was detected. Condensation of 2-methylresorcinol with CH3CHO gave 79% of the C4v isomer, but with C6H5CHO, C4v/C2v = <0.03 (78%). No cyclic tetramer was obtained with either aldehyde and 2-nitroresorcinol or 2-bromoresorcinol. An indeterminate mixture of isomers was produced with CH3CHO and 2-carboxyresorcinol. Crystal structures of two octols 1 (C4v) were determined (A = H, R = CH3 and A = H, R = CH3(CH2)3) as solvates, and these octols exhibited bowl-shaped conformations. These compounds serve as important starting materials for the syntheses of cavitands and carcerands.
Article
The ability of phenylboronic acid and 3-(1-adamantylcarboxamido)phenylboronic acid to mediate the transport of p-nitrophenyl beta-D-glucopyranoside (glucoside), p-nitrophenyl beta-D-galactopyranoside (galactoside), p-nitrophenyl beta-D-mannopyranoside (mannoside), and p-nitrophenyl beta-D-xylopyranoside (xyloside) through a liquid dichloroethane membrane in the presence and absence of trioctylmethylammonium chloride was determined. In the absence of the lipophilic ammonium cation, the boronic acids transported significant amounts of galactoside, suggesting that transport was mediated by reversible formation of a trigonal boronate ester. Extraction and transport experiments as a function of pH provided confirming evidence for this transport mechanism. The apparent order of diol selectivity for the trigonal boronate transport pathway was observed to be cis-alpha,gamma-diol>cis-alpha,beta-diol approximate to trans-alpha,gamma-diol much greater than trans-alpha,beta-diol. Uphill transport of galactoside was achieved by including boric acid in the receiving phase and lipophilic boronic acid in the organic layer, representing a functionally biomimetic example of active transport driven by group translocation.
Article
A series of crown boronic acids, 1−4, were synthesized and studied as carriers for catecholamine transport through bulk liquid membranes (BLMs) and supported liquid membranes (SLMs). Carrier 1 greatly facilitated the transport of primary catecholamines through BLMs; whereas, the more lipophilic analogues 3 and 4 were less effective. A combination of kinetic, mass spectral, and NMR evidence suggests that the transported species in BLMs is the cyclic, zwitterionic, 1:1 complex 7. The SLM transport studies used a liquid membrane of 2-nitrophenyl octyl ether supported by a thin, flat sheet of porous polypropylene. In the absence of carrier there was neglible dopamine transport (<5 × 10-9 mol/m2·s) at pH 7.2. When the membrane contained carrier 3 (33 mM or about 2% wt), facilitated catecholamine transport was observed in the order of dopamine (5 × 10-7 mol/m2·s) > epinephrine (1.5 × 10-7 mol/m2·s) > norepinephrine (0.8 × 10-7 mol/m2·s). SLMs containing carrier 3 were stable, implying that carrier 3 is a very good candidate for transport mechanism studies. Crown boronic acid 4 was an even better transport carrier of primary catecholamines with a transport order of norepinephrine (4.7 × 10-6 mol/m2·s) > dopamine (3.5 × 10-6 mol/m2·s) epinephrine (3 × 10-8 mol/m2·s). It is 10 times more effective than an equimolar mixture of boronic acid 5 and crown 6, which is one of best examples of ditopic cooperativity yet observed in SLM transport. SLMs containing 4, however, did not exibit long-term stability. Overall, it is possible that a device based on SLMs containing crown boronic acid carriers can be developed to selectively extract catecholamines from clinical samples.
Article
Twenty-one boronic acids were studied for their ability to transport saccharides in and out of liposomes. The rates of liposome efflux were determined using an enzymatic assay, whereas the influx studies used a radiotracer method. All boronic acids examined, except those that were highly hydrophilic, facilitated monosaccharide transport. The order of transport selectivity was sorbitol > fructose > glucose. The disaccharides maltose and sucrose were not transported to any significant degree. Facilitated transport was demonstrated with a variety of liposome types, including multilamellar and unilamellar vesicles with anionic or cationic polar lipid additives. Transport mechanism studies included the accumulation of structure−activity data, as well as systematic investigations of various environmental changes such as pH, added salt, membrane potential, and temperature. Overall, the evidence is strongly in favor of a membrane carrier mechanism. The boronic acid combines reversibly with a diol group on the monosaccharide to produce a tetrahedral, anionic boronate, which is the major complexed structure in bulk, aqueous solution. At the bilayer surface, the tetrahedral boronate is in equilibrium with its neutral, trigonal form, which is the actual transported species. At low carrier concentrations, a first-order dependence on carrier was observed indicating that the transported species was a 1:1 sugar−boronate. At higher carrier concentrations the kinetic order approached 2, suggesting the increased participation of a 1:2 sugar−bisboronate transport pathway. The effect of boronic acids on liposomal bilayer fluidity was probed by fluorescence spectroscopy using appropriate reporter molecules. Adding cholesterol to the liposome membranes reduced translational fluidity by “packing and ordering” the bilayer. Addition of lipophilic arylboronic acids (either free or complexed with monosaccharides) induced a similar but smaller effect.
Article
The resorcinol-aldehyde cyclotetramer 1a as a lipophilic polar host solubilizes glycerol and water (neat liquids) and ribose (in an aqueous solution) as polar guests in CCl4 upon formation of monomeric complexes 1a-4(glycerol), 1a-4H2O, and 1a-(ribose)·2H2O, where ribose is bound highly selectively in the α-pyranose form. The extraction of 1,4-cyclohexanediol is also stereoselective, the cis isomer being extracted readily. A pair of hydrogen-bonded OH groups on adjacent benzene rings in 1a provide the essential binding site for a guest OH group. While glycerol and H2O are singly bound with such a binding site via hydrogen bonding, α-ribopyranose and CM-1,4-cyclohexanediol are doubly bonded with two binding sites separated by a metaphenylene bridge. Examination of CPK molecular models indicates that such a two-point 1a-guest interaction is possible when the six-membered ring of a guest has cis OH groups on 1-C and 4-C, as in the case of α-ribopyranose and cis-1,4-cyclohexanediol. The extractabilities, or affinities to 1a, of various aldopentoses, aldohexoses, and their deoxy derivatives decrease in the following order: fucose (6-deoxygalactose) > 2-deoxyribose > ribose > arabinose ≅ rhamnose (6-deoxymannose) ≫ galactose ≅ xylose as lyxose ≅ mannose ≅ glucose. The affinities of sugars are governed by three factors: (1) the stereochemistry of the OH groups on 3-C and 4-C (cis ≫ trans), (2) the lipophilicity of the substituent on 5-C (CH3 ≫ H ≫ CH2OH), and (3) the nature of the substituent on 2-C (H > cis-OH > trans-OH, where cis and trans are with respect to the OH group on 3-C). Structural requirements for the formation of stable 1a-sugar complexes are discussed in terms of maximization of favorable hydrogen-bonding interaction and minimization of unfavorable exposure of the sugar OH groups to bulk solvent.
Article
The ability of phenylboronic acid, [3-(1-adamantylcarboxamido)phenyl]boronic acid, and diphenylborinic acid to extract and transport p-nitrophenyl [beta]-D-glucopyranoside (glucoside), p-nitrophenyl [beta]-D-galactopyranoside (galactoside), and p-nitrophenyl [beta]-D-mannopyranoside (mannoside) through a liquid organic membrane, in the presence of trioctylmethylammonium or tetrabutylammonium chloride, was determined. Under the conditions examined, glycoside transport was facilitated by the reversible formation of covalent tetrahedral, anionic glycoside-boronate complexes, which partitioned into the organic membrane as lipophilic ion pairs. The results of various experiments indicated the rate-limiting step in the transport process was diffusion of the solutes through the narrow unstirred boundary layers adjacent the organic/aqueous interfaces. A plot of glycoside transport rate versus glycoside extraction constant, K[sub ex], formed an approximate bell-shaped relationship. Maximal transport occurred when the carrier admixture had an extraction constant of log K[sub ex(max)] approximately 2.2. 20 refs., 4 figs., 2 tabs.
Article
Relatively hydrophobic monosaccharide derivatives (some aldopentoses and deoxy and methylated sugars) including nucleoside cytidine and its 5'-phosphate, as well as simple aliphatic alcohols (ethanol through hexanol), are bound to the tetrasulfonate derivatives 1a-c of resorcinol cyclic tetramer via a well-defined host-guest complexation in water. On the other hand, unmodified aldohexoses, disaccharides, and the nucleoside uridine show much lower affinities. The H-1 NMR complexation-induced shift data indicate that the hydrophobic moiety, e.g., methyl, of the guest is incorporated in the polyhydroxy aromatic cavity of the host. In respect to the change in substituent X on 2-C of the benzene rings of the host, both 1b (X = CH3) and 1c (X = OH) exhibit higher binding affinities than the parent host 1a (X = H). These results suggest that guest-host CH-pi interaction involving electron-rich benzene rings of the host as pi-bases is at least partially responsible for the present host-guest complexation in water. The implications of the present findings are discussed in light of biological sugar-binding processes.
Article
The resorcinol cyclic tetramer (1) binds methyl and n-octyl glucopyranosides via hydrogen-bonding in apolar organic media. The complexation behaviors of these two alkyl glucosides are markedly different from each other. Methyl glucoside (2), which is otherwise insoluble in CHCl3 or CCl4, is solubilized in that solvent upon formation of a 2:1 (host to guest) sugar-encapsulation complex with a remarkable beta/alpha anomer selectivity. Octyl glucoside (3), on the other hand, is soluble in CHCl3 and is bound to host 1 to give a 1:4 (host to guest) complex with only a low anomer selectivity. The four guest molecules are bound at the four unit hydrogen-bonding sites of the host with an exceptionally high cooperativity that arises from intracomplex guest-guest hydrogen-bonding involving the 5-CH2OH and 2-OH groups of the adjacent glucoside molecules. The way to achieve a maximal hydrogen-bond network is discussed in terms of solvophobicity/solvophilicity control by an alkyl group of the geometry, stoichiometry, stereoselectivity, and cooperativity.
Article
Resorcinol-dodecanal cyclotetramer 1 as an achiral host in chloroform forms hydrogen-bonded complexes with a variety of chiral di(poly)ols (2-24) including steroids and sugars. The complexation processes can be followed very conveniently by the induced circular dichroism (CD) spectroscopy. The binding constants as determined by CD titration increase in the order 15 (steroidal monool, K = 8.7 M-1) < 3, 6, and 8 (acyclic glycols, (4.9-7.1 x 10) < 9-alpha, 10-alpha, 12, and 13 (cyclic glycols and steroidal diols, (0.94-2.7) x 10(2)) < 11 (steroidal triol, 6.9 x 10(2)). This order reflects the extents of multiple host-guest hydrogen-bonding interactions. All of the resulting complexes exhibit CD with split Cotton effects as a result of exciton chirality induction in otherwise symmetric 1 upon binding of a chiral guest. The signs of split Cotton effects for complexes derived from glycols are correlated with the chiralities or absolute configurations of the guests, while those for sugar complexes are governed by the ring conformations (C1 or 1C) of sugar pyranoses. These results suggest that host 1 can be used as a novel, supramolecular probe for the assignments of stereochemistry of chiral guests.
Article
The condensation reaction between p-tert-butylphenol and formaldehyde leads in a single step to good yields of cyclic oligomers in which, depending on the reaction conditions, either four, six, or eight phenol units are joined by methylene bridges. The beakerlike shape of the most stable conformation of the tetramer has led to their being given the name “calixarenes” (calix = chalice). Resorcinol can undergo condensation in a similar manner with a variety of aldehydes to afford cyclic tetramers with the same basic structure (the resorcarenes). In both cases the reaction does not require the use of dilution techniques, so that large quantities of product can be readily obtained. In addition, the parent compounds can be modified in various ways, in particular at the phenolic hydroxy groups or the phenyl residues; these approaches can be used separately or in combination. Calixarenes are thus ideal starting materials for the synthesis of various types of host molecules and can also act as building blocks for the construction of larger molecular systems with defined structures and functions. Their potential applications range from use as highly specific ligands for analytical chemistry, sensor techniques and medical diagnostics to their use in the decontamination of waste water and the construction of artificial enzymes and the synthesis of new materials for non-linear optics or for ultrathin layers and sieve membranes with molecular pores.
Article
Supported liquid membranes (SLMs) have been prepared that contain methyl cholate as a novel type of supramolecular carrier designed for the transport of sugars. This commercial amphiphilic sterol ester probably binds sugars at its HO-3,7,12 triol system, allowing their extraction in apolar solvents. The support was a poly(vinylidene difluoride) flat-sheet microporous film. Experiments with glucose revealed very large differences in sugar permeability due to the solvent, hence special attention was paid to the choice of the organic solvent. No transport occurred with aliphatic hydrocarbons. With aromatics, SLMs prepared with benzene had the largest permeabilities. The rate laws of the transport were compared for the three aldoses: glucose, galactose and mannose. In all cases, the transport kinetics showed a linear dependence of the flux with the carrier concentration, but a saturation law with the aldose concentration, in agreement with a mechanism in which the rate-determining step is the migration of a sugar–carrier complex in the SLM. Molecular recognition of the aldoses by methyl cholate was demonstrated by determining noticeable differences between the stability constants of the corresponding complexes.
Article
A supported liquid membrane (SLM) containing methyl cholate as carrier 1b has been used for the facilitated transport of monosaccharides from concentrated (0.4–0.025 M) aqueous solutions. The SLM is made of a microporous poly(vinylidene difluoride) film impregnated with a 0.1 M solution of the carrier in cyclohexane. The SLM prepared with cyclohexane is remarkably stable for at least 23 days. The permeabilities of the SLM for various sugars were determinated. On the basis of the flux dependence on the initial concentrations of sugar, the rate-determining step in the transport mechanism is shown to be migration of a carrier–sugar complex within the SLM. The flux of sugar is related to the initial concentration of sugar in the feed phase by a saturation law, which allowed the determination of the apparent diffusion coefficient D* and the stability constant K of the methyl cholate complexes of sugars formed in the liquid membrane. The variation of K with structure of sugars confirm molecular recognition by the carrier and show that the complexation sites are HO-2,3,6 for glucose and HO-1,2,6 for galactose.
Article
The transport of sugar was facilitated via complexation with borate ion fixed on an anion-exchange membrane. The sugar was highly distributed on the membrane and was transported by the carrier-relay mechanism. The flux across the borate ion type membrane increased with increasing concentration but became constant at a lower flux than across a chloride ion type membrane. Sugars were selectively transported and the permeability of the sugar depends on its distribution in the membrane.
Article
Supported liquid membranes (SLM) containing the resorcinarene carrier 1 have been used for the selective transport of monosaccharides (pentoses and hexoses) from concentrated aqueous solutions. The membranes, made of PTFE films of different porosities impregnated with a CCl4 solution of 1, are stable for at least 10 days. The permeabilities of the SLMs for various sugars were calculated. The results are compared with those of selective extraction of sugars performed with a CCl4 solution of 1. On the basis of the flux dependence on the initial concentrations of carrier and sugar, the rate-determining step in the transport mechanism is shown to be the migration of the 1 : 1 carrier–sugar complex in the immobilized organic phase.
Article
Boric acid is selectively transported by 1,3-diols from a source aqueous phase into a receiving alkaline aqueous phase through a phase of organic solvent (o-dichlorobenzene). Measurements of the transport rates were made using a U-tube apparatus. The process was adapted to liquid membranes supported on polypropylene films. The factors which influence the stability of the supported liquid membrane are discussed. Assuming that the transport of the neutral 1:1 diol-boric acid complex within the organic phase is diffusion-limited, a model is proposed that realistically represents the fluxes of boric acid as a function of the initial concentrations of boric acid and diol. The experimental diffusion coefficients were determined and agreed satisfactorily with the calculated values.
Article
The instability behavior of several supported liquid membranes (SLMs) has been studied for a system in which nitrate ions are removed from an aqueous feed phase and concentrated in a stripping phase. The composition of the aqueous phases and of the membrane liquid has been determined after the aqueous phases had flowed parallel to the membranes for a period of six days. From the experimental data it can be concluded that SLM-failure results from the removal of LM-phase from the support. Contrary to literature data this is not caused by an osmotic pressure difference. It is shown that the membrane stability depends largely on the type of solvent and the molecular structure of the carrier. Furthermore the membrane stability increases with an increasing salt content in the stripping phase (at constant composition of the feed solution).
Article
A supported liquid membrane (SLM) containing a resorcinarene carrier has been used for the selective transport of erythritol, threitol, ribitol and xylitol from concentrated (1.0-0.01 M) aqueous solutions. The membrane is made of a microporous polytetrafluoroethylene film impregnated with a 0.01 M solution of the carrier in CCl4. The permeabilities of the SLM for all alditols were calculated. On the basis of the flux dependence on the initial concentrations of carrier and alditol, the rate-determining step in the transport mechanism is shown to be the migration of the 1:1 carrier-carbohydrate complex in the immobilized organic phase. The flux of sugar is related to the initial concentration of alditol in the feed phase by a saturation law, which allowed the determination of the apparent diffusion coefficients and the stability constants of the resorcinarene complexes of alditols formed in the liquid membrane.
Selective sugars and alditols transport through supported liquid membranes
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T. Rhlalou, Selective sugars and alditols transport through supported liquid membranes, Ph.D. Thesis, University Mohamed V, Rabat Agdal, Morocco, 1999.
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Corporate Communication from Commodore Separation Technologies
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SliM, Corporate Communication from Commodore Separation Technologies (1999), Inc., Separation Technology and Recovery System Known as SLiM (Supported Liquid Membrane).
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Membrane process for separating carbohydrates
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Macrocycles with (almost) unlimited possibilities
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