Anne Jonquières

Industrial state-of-the-art of pervaporation and vapour permeation in the western countries

This work reviews the current trends of industrial pervaporation (PV) and vapour permeation (VP) in Europe and the USA after the great changes that have been occurring since 1995. More than simply being an up-to-date state-of-the-art, the paper provides key data and information about patented applications and current suppliers for PV and VP membranes and membrane separation systems. It also discusses several examples for PV and VP industrial applications and points out many inherent advantages of these separation processes as compared to other more conventional approaches, in particular in terms of very significant savings in energy and raw materials. On the basis of information provided by the leading industrial companies in the field, the past trends and future prospects of PV and VP are eventually analysed to help draw new guidelines for the promotion of these technologies in the near future.

Permeability of block copolymers to vapors and liquids

Abstract Permeability of block copolymers is an important feature for a broad range of applications including packaging, bio-materials (e.g. for controlled release or encapsulating membranes), barrier materials, high performance impermeable breathable clothing and membrane separation processes. This paper reviews the literature on permeability of block copolymers to pure or mixed vapors and liquids for the past 40 years. Different types of block copolymers are considered, starting with the most investigated polyurethanes and polyurethaneureas followed by polyimides, polyamides and miscellaneous types of block copolymers (e.g. block copolymers containing siloxane segments, hydrocarbon block copolymers and related materials). Block copolymers offer a great structure versatility which is highly interesting for a fundamental analysis of permeation through polymeric materials. A special attention has been paid to the key permeability properties and their correlation to the chemical structure of block copolymers. Systematic structure/property relationships have been emphasized to promote the future design of block copolymers with improved permeability properties. Far from being limited to fundamental investigations, this literature review points out the originality of block copolymers, which combine a great structure versatility with several high potential industrial prospects. Many patents on block copolymers indeed reflect a strong industrial interest in applications based on their (selective) permeability. A sharp increase in the related patents for the past 10 years certainly shows the strong potential of block copolymers to take up several current challenges in the medical, chemical and petrochemical fields.

Filled and unfilled composite GFT PDMS membranes for the recovery of butanols from dilute aqueous solutions: influence of alcohol polarity

Abstract The pervaporation performance of the silicalite-filled GFT PDMS membrane has been investigated for the separation of binary mixtures of BuOH/water and termary mixture of BuOH/acetone/water at 40°C. These components are relevant to the acetone-butanol-ethanol (ABE) fermentation process. In the range of concentrations of industrial interest ( C

Modified BET models for modeling water vapor sorption in hydrophilic glassy polymers and systems deviating strongly from ideality

The use of two modified BET models for modeling water vapor sorption in various nonideal systems involving strong interactions (textiles, polyamides, polyimide, vinyl polymers, proteins, and related compounds) has been investigated. Contrary to the original BET model derived for multimolecular adsorption and restricted to low water activities only, the three-parameter BET model, which considers sorption on a limited number of sorption layers, allowed the modeling for activities up to 0.9. This model has been shown to be an important extension of the original model but remains limited, due to the divergence of the model for a → 1. Releasing an other important assumption of the BET model, the GAB model was then investigated and its striking efficiency, in terms of high correlation coefficients and low residual sums of squares, was demonstrated for activities up to 0.95, thus covering all the usual experimental range.

Modelling of vapour sorption in polar materials: Comparison of Flory–Huggins and related models with the ENSIC mechanistic approach

Abstract This work focuses on the analysis of organic vapour sorption in polymer systems strongly deviating from ideality. The sorption of three different types of organics (i.e. alcohol, ether, ester) in polyurethaneimide block copolymers has been investigated using a microgravimetric technique over the entire activity range. For all the polyurethaneimides, sorption increases in the following order: ETBE χ towards penetrant concentration, which cannot be accounted for by the FH theory. A theoretical modification of the FH theory, previously reported by Koningsveld and Kleintjens to account for the variation by a three-parameter law, was shown to be really efficient for sorption modeling over the entire activity range. Despite a systematic divergence for the very low sorption levels, an empirical modification of the FH theory using a power law χ = aφ b could also be an interesting alternative which requires only two parameters for a fairly good modeling for activities higher than 0.1–0.2. Considering the sorption phenomenon as a mechanical anisotropic process, the recent ENSIC approach, reported by Favre et al., proved its striking efficiency allowing the sorption modelling of all the sorption isotherms with a mean correlation coefficient R =0.9983.

Comparison of UNIQUAC with related models for modelling vapour sorption in polar materials

Abstract By a systematic investigation of solvent polymer systems of even greater complexity, this work analyses the relative performances of UNIQUAC and related models to account for sorption phenomena in polar elastomers (polyurethaneimides) with vapours of moderate to strong polarity (ether, ester, alcohol). Four different UNIQUAC-type models have been chosen for this study: UNIQUAC, UNIQUAC-HB, UNIQUAC-FV and UNIQUAC-FV+HB. They mainly differ in corrective and/or additional terms accounting for particular effects such as free volume (FV) effects or hydrogen bonding (HB) or a combination of both (FV+HB). Their main respective advantages are discussed with regard to the solvent and polymer chemical structures and the type of interactions involved in the sorption phenomenon. UNIQUAC-FV is shown to provide the best results for the sorption of aprotic species (ether, ester) in polyurethaneimides, as could be expected for elastomers for which free volume effects are usually believed to be significant. However, the sorption of a protic species (alcohol) is best described by UNIQUAC-HB, i.e. the UNIQUAC model specifically modified for systems involving strong interactions by hydrogen bonding. Hydrogen bonding could therefore prevail on free volume effects for these particular systems.

Solubility and polarity parameters for assessing pervaporation and sorption properties. A critical comparison for ternary systems alcohol/ether/polyurethaneimide

This paper considers the comparative use of two semi-empirical parameters δ and ET(30) for the correlation of PV and sorption properties in complex ternary systems. First, the PV properties of various polyurethaneimides PUI were investigated for the separation of the azeotropic mixture ethanol/ethyltertiarybutylether (ETBE). A new parameter called the interaction selectivity Y was derived from the solubility parameters of the different species involved and allowed the PV selectivity to be correlated quantitatively. The separation selectivity was also successfully related to the PUI soft segment polarity parameter ET(30). The results of an analysis of the properties of various systems involving a given PUI and different alcohols and ethers in mixtures EtOH/ether or alcohol/ETBE were then reported. The liquid chemical structure was shown to strongly affect the mass transfer properties in such systems. Inaccuracy of the values of ether solubility parameters led to a relative failure of the first correlative approach for EtOH/ether mixtures. The same approach was however successful for correlating the properties obtained with different alcohol/ETBE mixtures. The use of semi-empirical polarity parameters revealed interesting structure-property relationships to describe the sorption properties of the different liquids in binary or ternary systems. The PV selectivity could be correlated in the same way providing that the permeant molecular size did not influence very significantly the diffusion process.

Polymer design for pervaporation membranes: influence of the soft segment size of block copolymers (polyurethaneimides or polyureaimides) on their pervaporation features

Abstract Three sets of new block copolymers PUI with increasing soft segment lengths were obtained by a method which allows the control of the material structure by a step-by-step polycondensation: polyetherurethaneimides (PEG-MDI-AP), polyetherureaimides (JFA ED-MDI-AP) and polyesterurethaneimides (PCL-MDI-AP) with soft block molecular weights in the range of 300–2000. At 30°C, all the PUI exhibited selectivity towards ethanol during the pervaporation of EtOH/ethyl tert -butylether mixtures close to the azeotropic composition and the PV fluxes were related to the polymer structure in a quantitative way. They were shown to vary exponentially with the soft segment weight fraction in the case of PUI polyethers whereas linear relationships described the partial and total fluxes obtained with PUI polyesters. The second part of the investigations dealt with the influence of the soft segment length on the PV features of PUI at higher temperatures. Despite one particular polymer leading to a significant deviation from the usual behaviour, the PV mass transfer of both permeants in all the PUI investigated obeys an Arrhenius type law in the temperature range of 30–60°C. The activation energies could be related to the material structure qualitatively, showing an important decrease of these parameters for the polymers with the longest soft segment.

From binary to ternary systems: general behaviour and modelling of membrane sorption in purely organic systems strongly deviating from ideality by UNIQUAC and related models

Abstract This work reports the results of a study of the thermodynamic swelling behaviour of polar polymeric membranes in contact with purely organic liquid mixtures of strong polarity. The sorption of two aprotic/protic liquid mixtures ETBE/EtOH and AcOEt/EtOH in polyurethaneimide block copolymers was investigated over the entire activity range at 30°C. The polymers used were built from the same pyromellitimide hard blocks and oligomeric segments of different chemical natures (polyether: PTMG, PPG; polyester: PCL) and led to strongly non-ideal ternary systems. The sorption behaviour in these systems revealed particular features that cannot be easily anticipated from the vapour sorption isotherms obtained for the related binary systems. The occurring of strong sorption synergy effects, characterised by sorption coupling factors, led to very significant modifications of the polymer swelling to the detriment of the sorption selectivity. The strongest synergy effects were observed for the swelling of the PUI membranes in ETBE/EtOH mixtures. A comparative study of the semi-predictive modelling of the ternary system behaviours was described on the basis of the properties of the related binary systems and UNIQUAC or derived models. Accurate descriptions of the partial isotherms were obtained for most of the ternary systems investigated but the only system where sorption synergy effects were of particularly great importance.

Synthesis and characterization of new highly permeable polyamideimides from dianhydride monomers containing amide functions: An application to the purification of a fuel octane enhancer (ETBE) by pervaporation

Six polyamideimides (PAI) were synthesized from six dianhydride monomers containing amide functions. The dianhydride monomers were obtained from the reaction of trimellitic anhydride chloride with six aromatic diamines—1,4-phenylenediamine, 2,2-bis(4-aminophenyl) propane, 4,4′-oxydianiline, 4,4′-methylenedianiline, 1,1-bis(4-aminophenyl)cyclohexane, and bis(4-aminophenyl)sulfone—by a low-temperature condensation with yields ranging from 35 to 98% depending on the monomer solubility in organic media. The monomers were characterized by Fourier transform infrared (FTIR) and 1H NMR. In accordance with a synthesis scheme implying the reaction of a macrodiisocyanate with dianhydride monomers containing amide functions, six PAIs with a highly flexible soft block (polytetramethylene glycol PTMG 650) were synthesized with inherent viscosities ranging from 0.38 to 1.3 dL/g. Their characterization by FTIR and 1H NMR fully confirmed their chemical structure. The strong physical crosslinking provided by polar hard blocks containing up to eight aromatic rings enabled the casting of PAI films that were very tough in the dry state and could withstand exposure to rather strong solvating media (e.g., ethers, alcohols, and chlorinated solvents). First experiments showed these materials could be good candidates for membrane-separation applications. They revealed interesting features for the separation of organic aprotic–protic mixtures as shown by the first results obtained for the purification of a fuel octane enhancer (ethyl-tert-butyl ether) used in the European Community.