Modification of the transport properties of a membrane by selective solvation: Hyperfiltration of acetonitrile/water mixtures

Pfenning, D.; Woermann, D.

doi:10.1016/s0376-7388(00)81578-1

Cited by 14 publications

(5 citation statements)

References 16 publications

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“…Binary solvent mixtures of water and organic components like AN, tetrahydrofuran (THF), etc., are often used in modern bio- and nanotechnological applications and various processes of mezo-structuring. , Solutions of AN and THF in H 2 O or D 2 O are homogeneous for any molar ratio of the components at room temperature. However, even a very small amount of dissolved ions can significantly change their phase diagrams. − This phenomenon has been intensively studied and interpreted to occur due to the competition between entropic and energetic effects. , Multicritical behavior and crossover of critical regimes have also been scrutinized. , …”

Section: Resultsmentioning

confidence: 99%

Hydrogen Bonding in Pyridine N-Oxide/Acid Systems: Proton Transfer and Fine Details Revealed by FTIR, NMR, and X-ray Diffraction

et al. 2012

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The H-bonded complexes of pyridine N-oxide (PyO) with H(2)O, acetic, cyanoacetic, propiolic, tribromoacetic, trichloroacetic, trifluoroacetic, hydrochloric, and methanesulfonic acids have been studied by FTIR and NMR spectroscopy, X-ray diffraction, and quantum chemical DFT calculations. Correlations between vibrational frequencies of the NO stretching and PyO ring modes and geometric parameters of the H-bond have been established. FTIR experiments show and DFT calculations confirm that definite discontinuity is present in the vicinity of the midpoint in the proton transfer pathway. The established correlations significantly aid in the understanding of fine effects such as the isotope (deuteration) effect, crystal-to-solution transition, or criticality of aqueous solutions induced by ionic pairs. Geometric isotope effect in the ionic H-bond aggregate of PyO·H(D)Cl was found to be extraordinary large. Measured FTIR, CP/MAS, and high-resolution (13)C NMR spectra indicate that H-bond in the PyO·HCl complex in polar solvent can potentially be more ionic than in the crystal. Vibrational modes of ionic pairs originating via proton transfer in H-bond complexes can provide new information concerning the interionic interaction and its role in the phase separation and mezo-structuring processes. The results are compared to the relevant data for PyO·HCl complex in argon matrix.

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Section: Resultsmentioning

confidence: 99%

Hydrogen Bonding in Pyridine N-Oxide/Acid Systems: Proton Transfer and Fine Details Revealed by FTIR, NMR, and X-ray Diffraction

et al. 2012

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“…Some features of NMR spectra were processed using the Microcal Origin program package. [13], [14]. It is also known, that an ionic solute in systems exhibiting this phenomenon acts as increasing pressure [15], [16] which shifts the phase separation point towards higher temperatures.…”

Section: Methodsmentioning

confidence: 94%

NMR study of heterogeneity in pyridine-N-oxide...HCl crystal

2004

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An origin of narrow 1 H NMR signals in pyridine-N-oxide (PyO). . . HCl crystal has been investigated by means of MAS, SPEDAS, NOESY and COSY techniques. Spectra of crystalline samples are compared with those of solid phase obtained from liquid PyO. . . HCl solutions (in acetonitile/H 2 O) after the heterogeneous phase separation. It has been concluded that partially resolved peaks in 1 H NMR spectra of solids are related with heterogeneity of spin system and presence of di¬erent H-bond clusters of water molecules. NOESY spectra show no cross-peaks even at very long mixing time (500 ms). This indicates there is no exchange process between spins causing di¬erent peaks, and thus the corresponding molecular aggregates are captured in \islands of mobility8 without any channels su¯cient for exchange. Appearance of MAS side bands as \pseudo8 cross-peaks in 2D NMR spectra using MAS/COSY technique is reported. In the case of accidental coincidence of spinning frequency (! M AS ) with spectral distances between some diagonal signals, intensive non-diagonal peaks are observed at the corresponding cross-positions. A misleading conclusion concerning spin coupling is easy to avoid using various ! M AS .

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“…As well as azeotropic distillation, other approaches have been reported for the separation of MeCN from water. For example, Pfenning and Woermann describe hyperfiltration experiments using phenolsulfonic acid (PSA) membranes for the separation of MeCN from water. More recent work on the use of commercial membrane based techniques for solvent dehydration has been reviewed by Hoof et al Whilst some promising results have been achieved, the major technological challenge in this area is producing membranes of sufficient robustness and chemical stability for commercial use.…”

Section: Relevant Previous Research On Mecn Replacement or Recoverymentioning

confidence: 99%

“…of MeCN from water. For example, Pfenning and Woermann34 describe hyperfiltration experiments using phenolsulfonic acid (PSA) membranes for the separation of MeCN from water. More recent work on the use of commercial membrane based techniques for solvent dehydration has been reviewed by Hoof et al35 Whilst some promising results have been achieved, the major technological challenge in this area is producing membranes of sufficient robustness and chemical stability for commercial use.Khayet 36 used the pervaporation process to successfully separate binary solutions of acetone-water, MeCN-water and ethanol-water as well as multicomponent systems using Sulzer Pervap® 4060 membranes.…”

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confidence: 99%

The Importance of Acetonitrile in the Pharmaceutical Industry and Opportunities for its Recovery from Waste

McConvey¹,

Woods²,

Lewis³

et al. 2012

Org. Process Res. Dev.

109

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Acetonitrile is regarded as a key solvent in the pharmaceutical industry. However, the volatility in acetonitrile supply in recent years, coupled with its relatively poor environmental profile, has presented significant challenges to its use in manufacturing processes and laboratories. This study investigates the importance of acetonitrile in the pharmaceutical industry and critically examines several options for reducing the exposure of the industry to future supply problems whilst also improving its life cycle management. The physicochemical properties of acetonitrile were compared with other typical process solvents and the Conductor-like Screening Model (COSMO) surfaces and sigma profiles were used to help explain the favourable solvation behaviour of acetonitrile. Several options for the replacement or recovery and recycle of acetonitrile were critically examined in the contexts of environmental, technical and economic feasibility. Azeotropic distillation was found to be the most likely approach to recovering acetonitrile from aqueous waste streams. Several potential breaking agents were assessed against a range of selection rules based on residue curve maps, determined using the Universal Functional Activity Coefficient (UNIFAC) method, and potential processing issues. A range of ionic liquids were screened via the predictive Conductor-like Screening Model for Realistic Solvation (COSMO-RS) approach and several promising candidates were identified. Experimental vapour-liquid equilibria studies were carried out, confirming the feasibility of ionic liquid-enhanced azeotropic distillation as a novel approach to acetonitrile recovery.

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Modification of the transport properties of a membrane by selective solvation: Hyperfiltration of acetonitrile/water mixtures

Cited by 14 publications

References 16 publications

Hydrogen Bonding in Pyridine N-Oxide/Acid Systems: Proton Transfer and Fine Details Revealed by FTIR, NMR, and X-ray Diffraction

Hydrogen Bonding in Pyridine N-Oxide/Acid Systems: Proton Transfer and Fine Details Revealed by FTIR, NMR, and X-ray Diffraction

NMR study of heterogeneity in pyridine-N-oxide...HCl crystal

The Importance of Acetonitrile in the Pharmaceutical Industry and Opportunities for its Recovery from Waste

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