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Poly-(4,4′-oxydiphenylene) pyromellitimide or Kapton is the most widely available polyimide with high chemical and thermal stability. It has great prospects for use as a membrane material for filtering organic media due to its complete insolubility. However, the formation of membranes based on it, at the moment, is an unsolved problem. The study corresponds to the rediscovery of poly(4,4′-oxydiphenylene–pyromellitimide)-based soluble copoly(urethane-imides) as membrane polymers of a new generation. It is shown that the physical structure of PUI films prepared by the solution method becomes porous after the removal of urethane blocks from the polymer, and the pore size varies depending on the conditions of thermolysis and subsequent hydrolysis of the membrane polymer. The film annealed at 170 °C with a low destruction degree of polycaprolactam blocks exhibits the properties of a nanofiltration membrane. It is stable in the aprotic solvent DMF and has a Remasol Brilliant Blue R retention coefficient of 95%. After the hydrolysis of thermally treated films in acidic media, ultrafiltration size 66–82 nm pores appear, which leads to an increase in the permeate flow by more than two orders of magnitude. This circumstance provides opportunities for controlling the membrane polymer structure for further optimization of the performance characteristics of filtration membranes based on it. Thus, we proposed a new preparation method of ultra- and nanofiltration membranes based on poly(4,4′-oxydiphenylene–pyromellitimide) that are stable in aprotic solvents.

Organic solvent nanofiltration (OSN) is an emerging membrane separation technology, which urgently requires robust, easily processed, OSN membranes possessing high permeance and small solutes-selectivity to facilitate enhanced industrial uptake. Herein, we describe the use of two 2,2′-biphenol (BIPOL) derivatives to fabricate hyper-crosslinked, microporous polymer nanofilms through IP. Ultra-thin, defect-free polyesteramide/polyester nanofilms (≈5 nm) could be obtained readily due to the relatively large molecular size and ionized nature of the BIPOL monomers retarding the rate of the IP. The enhanced microporosity arises from the hyper-crosslinked network structure and monomer rigidity. Specifically, the amino-BIPOL/PAN membrane exhibits extraordinary permselectivity performances with molecular weight cut-off as low as 233 Da and MeOH permeance of ≈13 LMH/bar. Precise separation of small dye mixtures with similar M.W. based on both their charge and molecular size are achieved.

Die Methodik EDUAR&D, kurz für Energiedaten und -analyse R&D, wird zur Bewertung von Energieeffizienztechniken genutzt. Es handelt sich um einen strukturierten Such- und Analyseprozess, der verschiedene methodische Ansätze zur Darstellung, Analyse und Bewertung der Techniken miteinander verbindet. Ziel ist es, Handlungsempfehlungen, z. B. bzgl. thematischer Schwerpunktsetzung, für die zukünftige Energieforschung im Rahmen der Forschungsförderung und für die Energiepolitik abzuleiten. Die Methodik wird hier am Beispiel der organophilen Nanofiltration und der Latentwärmespeicher vorgestellt.

Membranes synthesized by stacking two-dimensional graphene oxide (GO) hold great promise for applications in organic solvent nanofiltration. However, the performance of a layer-stacked GO membrane in organic solvent nanofiltration can be significantly affected by its swelling and interlayer spacing, which have not been systematically characterized. In this study, the interlayer spacing of the layer-stacked GO membrane in different organic solvents was experimentally characterized by liquid-phase ellipsometry. To understand the swelling mechanism, the solubility parameters of GO were experimentally determined and used to mathematically predict the Hansen solubility distance between GO and solvents, which is found to be a good predictor for GO swelling and interlayer spacing. Solvents with a small solubility distance (e.g., dimethylformamide, N-methyl-2-pyrrolidone) tend to cause significant GO swelling, resulting in an interlayer spacing of up to 2.7 nm. Solvents with a solubility distance larger than 9.5 (e.g., ethanol, acetone, hexane, and toluene) only cause minor swelling and are thus able to maintain an interlayer spacing of around 1 nm. Correspondingly, GO membranes in solvents with a large solubility distance exhibit good separation performance, for example, rejection of more than 90% of the small organic dye molecules (e.g., rhodamine B and methylene blue) in ethanol and acetone. Additionally, solvents with a large solubility distance result in a high slip velocity in GO channels and thus high solvent flux through the GO membrane. In summary, the GO membrane performs better in solvents that are unlike GO, i.e., solvents with large solubility distance.

Bottom-up approaches to producing aqueous crystal suspensions of active pharmaceutical ingredients (APIs), such as anti-solvent crystallisation, are gaining interest as they offer better control over surface properties compared to top-down approaches. However, one of the major challenges that needs to be addressed is the removal of organic solvents after the crystallisation step due to strict limitations regarding human exposure. Within this work, we investigated a process concept for the removal of solvent (i.e., ethanol) from the API crystal suspension using membrane-based diafiltration. A four-stage diafiltration process successfully reduced the ethanol concentration in the API (here, naproxen) crystal suspension below 0.5 wt% (the residual solvent limit as per ICH guidelines) with a water consumption of 1.5 g of added water per g of feed. The solvent exchange process had no negative influence on the stability of the crystals in suspension, as their size and polymorphic form remained unchanged. This work is a step towards the bottom-up production of API crystal suspension by applying solvent/anti-solvent crystallisation. It provides the proof of concept for establishing a process of organic solvent removal and offers an experimental framework to serve as the foundation for the design of experiments implementing a solvent exchange in API production processes.

The widely used dyes in the pharmaceutical, chemical, and medical industries have brought about an intensive concern for the sustainable development of the environment. Membrane separation offers a versatile method for classified recycling and the reuse of residual components. In this work, polyimide membranes were synthesized via the polymerization of 4,4′-(hexafluor-isopropylidene) diphthalic anhydride and 1,4-bis (4-aminophenoxy) benzene diamine. The organic solvent nanofiltration membrane was prepared by casting onto a glass plate and precipitating in the non-solvent phase. The properties of the membranes were recorded by FTIR, 1HNMR, TGA, and GPC. The molecular simulations were carried out to analyze the affinity between the membrane and different solvents. The membrane was used in the removal of Rose Bengal, methyl blue, Victoria blue B, and crystal violet from methanol. The effects of the feed liquid concentration, operating pressure, swelling degree, organic solvent resistance, and long-term running on the membrane performance were studied. Results showed that membranes prepared in this work demonstrated high solvent permeation and dye rejection due to the sieving effect and solvent affinity. For methyl blue, the solvent performance achieved a permeability of 2.18 L∙m−2∙h−1∙bar−1 corresponding to a rejection ratio of 94.2%. Furthermore, the membrane exhibited good stability over 60 h of continued testing. These results recommend a potential strategy in the development of a suitable monomer to prepare a polyimide membrane for dye separation.

Polymeric membranes have been extensively studied for organic solvent nanofiltration (OSN) but many fail to show sufficient chemical resistance in strong solvents like dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This study focuses on harnessing the outstanding chemical resistance of polytetrafluoroethylene (PTFE), to develop polyamide-PTFE thin film composite (TFC) membranes that are resistant to such aprotic solvents. A defect-free polyamide thin film layer was successfully synthesized on the microfiltration PTFE hollow fibre substrates, overcoming challenges such as large and uneven pore size, and hydrophobicity of the PTFE substrates. A simple polydopamine (PDA) coating was carried out to improve the substrate's hydrophilicity prior to the polyamide synthesis via interfacial polymerization (IP). Polyethyleneimine (PEI) and trimesoyl chloride (TMC) were used as the monomers and a two-time IP method was employed to obtain a defect-free polyamide coating. The synthesized membranes showed high acetonitrile (ACN) and DMF permeabilities of 7.94 and 3.70 lm−2h−1bar−1, respectively, with acid fuchsin (585 Da) rejections of > 90 %. The molecular weight cut-off (MWCO) of the membranes could be further reduced to ∼300 Da by the addition of piperazine (PIP) monomers. The membranes also showed excellent stability and performance in a 72-hour OSN test performed in DMF indicating their great potential in effective molecular separation in harsh solvents. This study demonstrates how a simple modification and coating technique can transform commercially available microfiltration PTFE hollow fibres into durable and high value OSN membranes. Economic Development Board (EDB) Submitted/Accepted version The authors would like to acknowledge the funding support from the Singapore Economic Development Board to the Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute (NEWRI) at Nanyang Technological University (NTU), Singapore.

Sideritis scardica and Sideritis syriaca are considered highly valuable plant materials and their total polyphenols (TP) and total flavonoids (TF) extracts can be employed in nutraceutics and cosmetics. A two-step process was proposed consisting in the ultrasound-assisted extraction (UAE) and concentration of the biologically active compounds via nanofiltration (NF). An extensive comparison between UAE and conventional high-temperature stirring was performed, taking into account the effect of process parameters such as solvent, temperature and ultrasonication. In terms of radical scavenging activity and time optimization, UAE was found more effective, providing – after only 1 h – extraction yields comparable to 20 h of the conventional thermo-mechanical method. The extract was then concentrated by nanofiltration in tangential mode at 20 bar using 300 and 500 Da cut-off Duramem membranes. Permeate and rejection flux was monitored during the filtration process. The lower molecular weight membrane showed higher permeability towards TP and TF and contributed to a more stable flux and lower fouling processes. To predict operational drawbacks, computational fluid dynamic simulations were performed to model the complex rotational flow occurring during membrane filtration.

We have developed stable organic solvent nanofiltration (OSN) membranes that are electrically conductive. These membranes overcome key issues with current tuneable membranes: molecular weight cut off (MWCO) limited to the UF-range and lack of filtration stability. Polyaniline (PANI) was in-situ doped by poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) using chemical oxidative polymerization that leads to formation of interpolymer complex. The PANI-PAMPSA membranes were prepared by phase inversion method and the pore sizes were shrunk by annealing the membranes at temperatures lower than the crosslinking temperature. The membranes were systematically evaluated using visual and chemical analysis and in-filtration experiments. The developed membranes were solvent stable, reusable, had a denser structure and lower MWCO and there was no thermal crosslinking as seen by IR. The solvent permeance obtained were: 0.46, 0.60 and 0.74 Lm −2 h −1 bar −1 for acetone, 2-propanol and methanol respectively, with MWCO below 300 Da and 266 Da for methanol. For the tuneability investigation, when applying an electrical potential (20 V) in a custom-made cross-flow membrane cell, an increase in MWCO and permeance (10.4% and 55.6%, respectively) was observed. These results show that this simple in-situ doping method with heat treatment can produce promising and stable PANI membranes, for OSN processes in different solvents, with the distinctive feature of in-situ performance control by applying external electrical potential.

Compared to the traditional chemical-crosslinking-based polymer, the porous polytetrafluoroethylene (PTFE) substrate is considered to be an excellent support for the fabrication of thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes. However, the low surface energy and chemical inertness of PTFE membranes presented major challenges for fabricating a polyamide active layer on its surface via interfacial polymerization (IP). In this study, a triple-layered TFC OSN membrane was fabricated via IP, which consisted of a PA top layer on a carbon nanotube (CNT) interlayer covering the macroporous PTFE substrate. The defect-free formation and cross-linking degree of the PA layer can be improved by controlling the CNT deposition amount to achieve a good OSN performance. This new TFC OSN membrane exhibited a high dye rejection (the rejection of Bright blue B > 97%) and a moderate and stable methanol permeated flux of approximately 8.0 L m−2 h−1 bar−1. Moreover, this TFC OSN membrane also exhibited an excellent solvent resistance to various organic solvents and long-term stability during a continuous OSN process.

Organic solvent nanofiltration (OSN) is still a niche technology in the chemical industry due to time and money consuming process development, as organic solvents cause complex interactions between membrane, solvent, and solute. These interactions are not fully identified, and a fundamental understanding of mass transfer through OSN membranes is not established so far. Accordingly, mathematical models in OSN lack a general predictive capability. To overcome this problem, we aim to extend the current knowledge by a comprehensive experimental investigation of two polyimide membranes in combination with 17 solutes with molecular weights of 114–339 g/mol covering the range from nonpolar to polar, and five solvents with various properties. The results indicate solvent-dependent rejection phenomena that may be explained by a difference in the impact of solute properties on the rejection in dependency of the solvent. Based on these findings, three solvent-dependent solute sensitivity regions are derived similarly to previous results for PDMS membranes. The investigation of membrane–solvent interactions revealed an impact of the spatial distance in the 3D space of the total Hansen solubility parameter between solvent and membrane with a specific impact on membrane–solute sensitivity. These new findings contribute to a better understanding of transport phenomena and can serve as a new basis for predicting the separation performance in OSN.

Membranes with excellent separation performance and stability are needed for organic solvent nanofiltration in industrial separation and purification processes. Here we reported a newly PPSU-MoS2/PA-MIL-101(Cr) composite membrane with high permeance, good selectivity and stability. The MIL-101(Cr) was introduced in the polyamide (PA) layer via the PIP/TMC interfacial polymerization process on a microporous PPSU-MoS2 substrate. At a small doping amount of 0.005 wt% MIL-101(Cr), the PPSU-MoS2/PA-MIL-101(Cr) composite membrane exhibited a high methanol permeance of 12.03 L m−2 h−1 bar−1, twice higher than that of the pristine membrane without sacrificing selectivity. Furthermore, embedding MIL-101(Cr) notably enhanced the stability of the composite membrane, with permeance only decreasing by 8% after a long time operation of 80 h (pristine membrane decreased by 25%). This work demonstrated a composite membrane modified by MIL-101(Cr) with superior separation performance, which provides potential application of MOF materials for high-performance membranes in organic solvent nanofiltration and a theoretical foundation for future research in studying MOF’s influence on membrane properties.

During the last decades, the interest in organic solvent nanofiltration (OSN), both in academia and industry, increased substantially. OSN provides great potential for an energy-efficient separation of complex chemical mixtures with dissolved solutes in the range of 200–1000 Dalton. In contrast to conventional thermal separation processes, the pressure-driven membrane separation operates at mild temperatures without energy intensive phase transition. However, the complex interaction of different phenomena in the mass transfer through the membrane complicate the prediction of membrane performance severely, such that OSN is virtually not considered as an option in conceptual process design. Several attempts have been made to determine predictive models, which allow the determination of at least pure solvent flux through a given membrane. While these models correlate different important physical properties of the solvents and are derived from physical understanding, they provide a limited accuracy and not all of their parameters are identifiable based on available data. In contrast to previous approaches, this work presents a machine learning based approach for the identification of membrane-specific models for the prediction of solvent permeance. The data-driven approach, which is based on genetic programming, generates predictive models that show superior results in terms of accuracy and parameter precision when compared to previously proposed models. Applied to two respective sets of permeation data, the developed models were able to describe the permeance of various solvents with a mean percentage error below 9% and to predict different solvents with a mean percentage error of 15%. Further, the method was applied to solvent mixtures successfully.

In this study we describe a novel and simple method to couple covalently poly (maleic anhydride-alt-1-alkenes) to γ-alumina nanofiltration membranes for the first time. The 1-alkenes varied from 1-hexene, 1-decene, 1-hexadecane to 1-octadecene. The grafting reaction was between the reactive anhydride moieties of the polymer and surface hydroxyl groups, resulting in highly stable bonds. The modified membranes were investigated for their permeation and rejection performance of Sudan Black (SB, Mw 457 Da) in either toluene or ethyl acetate (EA) solution, and very high rejections (> 90%) and high permeation flux were observed compared to unmodified membranes. Initially, the SB in toluene solution was found to bind strongly to the surface hydroxyl groups of the unmodified membranes, an effect not observed in EA solution.

International audience; This paper aims at proposing a graphical representation composed of several performance maps to help to answer to some current questions that can puzzle membrane end-users facing the arrangement of membranes in cascade in order to better master separation of complex media. Indeed, different compromises can be highlighted according to realistic goals for the separation such as quality and recovery yield of each fraction/component, energy consumption and required membrane area. This representation needed first the systematic simulations of cascades of pre-selected configurations. These last ones were chosen thanks to the target application field, namely the organic solvent nanofiltration of a final synthesis media of hydroformylation that is a homogeneous catalysed reaction. We voluntary assumed the a priori limitation of the number of stages to 5, anticipating that more complex cascades will probably be too expensive (both operating and capital costs). The graphical representation by itself is based on sets of six 2D-maps. Each map highlights relationships selected in an appropriate way between two of the six selected criteria extraction/recovery, retentate/permeate quality/purity, membrane filtering area and overall energy consumption. For sake of illustration, the separation of 2 components C and A was considered. C/A has been chosen in a 1/1000 molar ratio, where C corresponds to the less retained component of the catalytic system that must be recovered in the retentate and A corresponds to the less transmitted product to extract in the permeate. In realistic nanofiltration conditions achieved in toluene, the rejections were experimentally determined on the initial media to filter. C has a high rejection (88%) whereas A has a low one (30%). The simulations of cascades were established using these constant values for rejection and the experimental permeate flux. For sake of an illustration of the use of the graphical representation, a case study was finally discussed regarding a given target of recovery for the two desired components, namely at least 99% of C recovery and better than 70% of A extraction. A complementary multi-criteria analysis was added aiming at facilitating the decision-making.

International audience; Due to the lack of efficient membranes to achieve subtle separations in a single step, membrane cascades appear as an alternative to improve the separation of solutes, especially in the case of close rejections. However, there is still a need for their rational design. In this work, a systematic study of all configurations up to seven stages is proposed through a unique and flexible simulation architecture. Different recycling modes in between stages are detailed and developed. The same VRR is imposed at each stage, ranging from 2 to 10. The case study is the olefin hydroformylation catalytic reaction, for which the simulations aim at the separation of two components, one modelling all organic products to extract in the permeate and the other one modelling the catalytic system to recover in the retentate for its further re-use in the synthesis reactor. Input data for the simulations (rejections and fluxes) are obtained from preliminary experimental studies. The separation performances are evaluated through seven criteria, amongst which the outflows extraction/recovery and the membrane area. The analysis of the simulation results allows to determine the optimal configuration that fulfills the targeted criteria or to fine tune these separation criteria according to the potentialities or the limitations of the membrane cascades. Even though focusing a priori on specific criteria, a careful attention should be paid to all parameters to ensure realistic proposals of cascades or to revise the objectives for more realistic ones.

Electrospun polymeric membranes are promising substrates for thin-film composite (TFC) membranes due to their unique interconnected pores and high porosity. However, it is still challenging to fabricate desirable electrospun substrates for organic solvent nanofiltration (OSN) owing to the relatively complex processing procedures and the organic operating environment. In this work, solvent-resistant electrospun polyimide (PI) nanofiber substrates were successfully fabricated through electrospinning followed by chemical cross-linking and heat-pressing. The cross-linking step improved the solvent tolerance of the membranes, while the heat-pressing step reduced the substrate pore size and surface roughness. However, it was found that heat-pressing at high temperatures (>140 °C) could degrade the cross-linking of PI, undermining their solvent-resistant property. A polyamide thin film layer was then synthesized on the solvent-resistant electrospun nanofibrous substrates via interfacial polymerization using reactant monomers m-phenylenediamine (MPD) and trimesoyl chloride (TMC). The TFC membranes exhibited excellent acetonitrile and acetone permeabilities of 31.28 ± 1.93 and 26.58 ± 1.13 L m−2 h−1 bar−1, respectively, with acid fuchsin (585 Da) and methyl orange (327 Da) rejections of 98.55 ± 1.24% and 92.42 ± 1.66%, respectively, in acetone. This study successfully demonstrated the potential use of electrospun PI nanofibers substrates for TFC membranes in OSN. Economic Development Board (EDB) Submitted/Accepted version The authors acknowledge Economic Development Board (EDB) of Singapore for funding the Singapore Membrane Technology Centre (SMTC) at Nanyang Environment and Water Research Institute, and Interdisciplinary Graduate Programme of Nanyang Technological University

Pickering emulsions (PEs) have received increasing interest for their application in catalytic multiphase reactions. Organic solvent nanofiltration of PEs was shown to be a promising procedure for efficient and effective catalyst recycling. In this work, a systematic parameter study to identify the main influencing parameters on PE filtration was conducted for a large variety of PE compositions for the first time. In addition to temperature, only the type of organic solvent significantly influenced the filtration performance, which could be mathematically modeled via a combination of the solution–diffusion and the resistance in the series model. Particle type and concentration, dispersed phase fraction and the presence of reaction (by-)products did not show any significant impact on the permeability. The stirrer speed only became important when emulsions stabilized by particles without the tendency to form 3D network structures were filtered in long-term filtration experiments. These results pave the way towards the application of PE membrane filtration for catalyst recovery in continuous liquid/liquid multiphase reactions and enable broad operation windows. As the mechanical separation of PEs was shown to be a very robust process, the emulsion composition can now be tuned to meet the needs of the reaction without any (significant) loss in filtration performance.

The prevalence of homogeneous catalysts, to produce high value commodities in the surfactant and detergent range by upgrading inter alia syngas and short chain olefins, through metathesis, hydroformylation and hydrogeneration, is hampered by the expensive, waste generating and destructive thermal separation methods required for the recovery of these catalysts. By using the membrane technology of organic solvent nanofiltration (OSN), the successful recovery of two commercially available homogeneous catalysts, the rhodium-based complex, HRh(CO)(PPh3)3, and the cobalt-based complex, Co(C5H7O2)3, from the solvents representative of the hydroformylation and hydrogenation reactions, with the STARMEM 240 membrane, was performed. The energy-efficiency of OSN for homogeneous catalyst recovery, commonly alluded to in literature, was investigated by performing a technological evaluation between OSN and a conventional downstream recovery process such as distillation. It was found that, using the ST-240 membrane, catalyst concentrations in the permeate stream can be successfully reduced to near negligible amounts (

This work deals with the use of octadecylamine (ODA)-functionalized reduced graphene oxide (rGO) for thin film nanocomposite (TFN) membranes. The functionalization of rGO with ODA leads to graphene-based nanofillers, more hydrophobic than GO, and thus to the easier dispersion in the organic phase of the interfacial polymerization (IP) reaction carried out to produce polyamide (PA) TFN membranes. The performance of the new TFN membranes is evaluated by organic solvent nanofiltration (OSN) of alcoholic solutions containing dyes Acridine Orange (AO, MW 265 g·mol−1), Sunset Yellow (SY, MW 452 g·mol−1) and Rose Bengal (RB, MW 974 g·mol−1). The functionalized nature of the nanoparticles introduced into the hydrophilic PA layer allows an increase of the ethanol permeance from 2.8, 3.4 and 3.7 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, corresponding to the bare thin film composite membrane (without rGO-ODA particles), to 4.3, 4.6 and 6.0 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, for the rGO-ODA based TFN membrane. In fact, we hypothesize that the increase of the ethanol flux achieved with the use of rGO-ODA as a filler in TFN membranes is owing to a combination of the simultaneous presence of polar and non-polar groups from rGO-ODA nanosheets and the creation of still selective narrow gaps between these particles and the polyamide (PA)., Financial support from the Research Project MAT2016-77290-R (MINECO/AEI/FEDER, UE) is gratefully acknowledged. The Aragón Government (T43-17R) and the ESF is also gratefully acknowledged. Lorena Paseta would like to express her gratitude to the Spanish MINECO for the predoctoral grant (BES-2014-068287) awarded.

The development of organic solvent nanofiltration (OSN) membranes has been a continuous effort during the past decade. Several groups generated and published experimental results and simulations with either tailor-made membranes or industrial products. The published data space is diverse, with a single publication often focusing on a certain membrane only, a group of specific solutes only, on the effect of solvent only. A comprehensive comparison of all of these is still lacking. An analysis on the reliability of quantified transport parameters is missing, in particular when different analysis methods and different membrane systems are used. The technology is in its incubation phase with a need for reliable data and measurement standards to ground the process design on reliable membrane transport properties. This study uses an unprecedented extensive standard experimental procedure to measure separation characteristics of polymer membranes for the separation of organic solutes from organic solvents. For a variety of different solvents, solutes and membranes, flux and retention measurements are rigorously characterized by round robin tests at different labs using different analytical systems. This extensive collaborative study evaluates for the first time which fluctuations in results occur under comparable conditions of lab-scale experiments at different locations and which influence these have on the design of OSN processes. Utilizing the variance in the membrane transport data, a process design study and optimization is presented. For the first time ever, we report how variance in membrane transport properties can influence the process design ranging from a simple single stage system for values for the upper transport limits, to a two stage system with a permeate recirculation for mean values, to a complex three stage system for the lower limits.

Thin film composite (TFC) membranes is the dominant type of desalination in the field of membrane technology. Most of the TFC membranes are fabricated via interfacial polymerization (IP) technique. The ingenious chemistry of reacting acyl chlorides with diamines at the interface between two immiscible phases was first suggested by Cadotte back in the 1980s, and is still the main chemistry employed now. Researchers have made incremental improvements by incorporating various organic and inorganic additives. However, most of the TFC membrane literature are focused on improving the water desalination performance. Recently, the application spectrum of membrane technology has been expanding from the aqueous environment to harsh solvent environments, now commonly known as Organic Solvent Nanofiltration (OSN) technology. In this work, some of the main additives widely used in the desalination TFC membranes were applied to OSN TFC membranes. It was found that tributyl phosphate (TBP) can improve the solubility of diamine monomer in the organic phase, and sodium dodecyl sulfate (SDS) surfactant can effectively stabilize the IP reaction interface. Employing both TBP and SDS exhibited synergistic effect that improved the membrane permeance and rejection in solvent environments.

Cynara cardunculus (cardoon) leaves are a rich source of bioactive compounds, such as cynaropicrin. In this work, ethanolic pulsed ultrasound assisted extraction (EtPUAE) derived extracts obtained from cardoon leaves were purified by membrane processing and the different fractions obtained were evaluated for their biological potential. A DuraMem® 200 membrane was selected for cynaropicrin recovery and removal of carbohydrates, in a diananofiltration mode. Diananofiltration (after 5 diavolumes) followed by nanofiltration allowed for a removal of 93.0% of glucose and 95.6% of fructose, with a cynaropicrin maximum loss of 13.9%. The fractionated extract revealed a higher biological activity, when tested with a BJ5-ta human normal fibroblast cell line. An integrated process is proposed, comprising an association of EtPUAE with a fractionation by diananofiltration, assuring a pay-back period of 4.58 years, assessed through an economic evaluation., Regional Development European Foundation and Alentejo Region Operational Program (ALENTEJO 2020) for their financial support to “MedCynaraBioTec – Selection of Cynara cardunculus genotypes for new biotechnological applications: the value chain improvement of cardoon, a well-adapted Mediterranean crop Project (ALT20-03-0145-FEDER-039495). The authors acknowledge Fundaç˜ ao para a Ciˆencia e a Tecnologia for the PhD grant to Teresa Bras ´ (SFRH/BD/110969/2015) and for the exploratory project (IF/ 00505/2014/CP1224/CT0004) attributed to Luísa Neves within the 2014 FCT Investigator Programme. This work was supported by the Associate Laboratory for Green Chemistry - LAQV which is financed by national funds from FCT/MCTES (UIDB/50006/2020). This work was also funded through FCT under the Project UIDB/05183/2020 to Mediterranean Institute for Agriculture Environment and Development (MED)and by the ERDF through the COMPETE2020 - programa operacional competitividade e internacionalização (POCI) with the strategic program UID/BIA/04050/2019 (POCI-01-0145-FEDER-007569)

Three commercial spiral-wound membrane modules of different sizes, from 1.8″ × 12″ to 4.0″ × 40″, are used to concentrate a solution of sucrose octaacetate in ethyl acetate under different operating conditions. A mathematical model to describe the batch concentration process is developed, based on a combination of the classical solution diffusion membrane transport model and the film theory, to account for the mass transfer effects. The model was implemented using the “OSN Designer” software tool. The membrane transport model parameters as well as all parameters in the pressure drop and mass transfer correlations for the spiral-wound modules were obtained from regression on a limited number of experimental data at steady state conditions. Excellent agreement was found between the experimental and multi-scale modelling performance data under various operating conditions. The results illustrate that the performance of a large scale batch concentration process with spiral-wound membrane modules can be predicted based on laboratory crossflow flat sheet test data when the fluid dynamics and mass transfer characteristics in the module, and the necessary channel geometry are known. In addition, the effects of concentration polarisation, pressure drop through feed and permeate channels, and thermodynamic non-ideality of the solution at large scale batch concentration are also investigated.

During the past few decades organic solvent nanofiltration has received a great deal of attention and a growing number of studies has been reported on development and optimisation of solvent resistant membranes and their transport mechanism. However, most of these studies have used flat sheet membranes. On the other hand, many researchers studied fluid dynamics and mass transfer in spiral-wound membrane modules, almost exclusively in aqueous solutions. This paper reports the performance of four spiral-wound membrane modules tested in 0–20 wt% solutions of sucrose octaacetate in ethyl acetate under various pressures and retentate flowrates. These modules were made of two different types of membranes (a commercial membrane, PuraMem® S600, and a development product, Lab-1, from Evonik Membrane Extraction Technology Limited) and covered three module sizes (1.8″×12″, 2.5″×40″ and 4.0″×40″). All modules had the same feed and permeate spacers. The classical solution diffusion model was applied to describe the transport of solute and solvent through the membrane and regress the unknown model parameters from flat sheet data. Correlations for characterising the fluid dynamics and mass transfer in the spiral-wound membrane modules, as well as the parameters describing the feed and permeate channels, were determined by performing the regression of experimental data of a 1.8″×12″ PuraMem® S600 membrane module. The classical solution–diffusion model, combined with the film theory, was then successfully applied to predict the performance of other modules of larger size (such as the 2.5″×40″ and 4.0″×40″ module sizes) and/or made of a different membrane material (such as Lab-1). The procedure proposed in this paper predicts the performance of a specific module by obtaining a limited number of experimental data for flat sheets and a 1.8″×12″ spiral-wound membrane module only (necessary to obtain the fitting parameters characteristic of the membrane and the module). Furthermore, with this procedure, it is not necessary to know a priori the spacer geometry, because the necessary information about the spacer geometry will be also obtained by regression of few experimental data.

Organic solvent nanofiltration (OSN) is a promising technology for an energy-efficient separation of organic mixtures. However, due to the lack of suitable models that allow for a quantitative prediction of the separation performance in different chemical systems OSN is rarely considered during conceptual process design. The feasibility of OSN is usually determined by means of an experimental screening of different membranes. Further experiments are conducted for a selected membrane in order to determine membrane specific parameters for a model-based description of the separation performance for a specific mixture. Obviously, this classical approach is experimentally demanding. The effort in identifying a suitable membrane in the first step could be significantly reduced if a theoretical evaluation of the separation performance was possible. The current article proposes an automatic method for the determination of a suitable predictive model for a given membrane, taking into account a limited set of experimental data. Specially, the rejection of different solutes in a specific solvent is modeled based on a set of physical and chemical descriptors. The proposed approach is based on a combination of genetic programming and global deterministic optimization, allowing for the identification of innovative models, including nonlinear parameter regression. The predictive capability of the generated models is validated on a separate data set. The identified models were able to predict the rejection of different components in the considered case studies with a deviation from the experimental values below 5%.

Organic solvent nanofiltration is a convenient method for the recovery of homogeneous transition metal catalysts. The long chain olefin 1-dodecene is hydroformylated continuously, and the commercially available catalyst complex is separated efficiently using a commercially available nanofiltration membrane. An advantage of this method is that both reaction and separation take place in a single liquid phase. Only continuous operation shows interactions of reaction and separation in the long run. Low energy demand, high scalability as well as transferability to other reactions make this method promising for new industrial applications.

In this research paper we report two ways of controlling the molecular weight cut-off (MWCO) of PEEK membranes prepared via phase inversion and subsequent drying. The two methods explored were the change of polymer concentration in the dope solution – 8 wt%, 10 wt% and 12 wt% – and the variation of solvent filling the pores prior to drying – e.g. water, methanol, acetone, tetrahydrofuran and n-heptane. The results show that it is possible to vary the MWCO from 295 g mol −1 to 1400 g mol −1 by varying these parameters. A statistical analysis based on a genetic algorithm showed that the Hansen solubility parameter, polarity and their interactions with molar volume were likely to be the most important parameters influencing the performance of PEEK membranes when drying from different solvents. In addition, the drying temperature also proved to have an effect on the membrane performance – the higher the temperature the higher the rejection and the lower the permeance.

Thesis (Ph.D. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

Organic solvent nanofiltration (OSN) offers great potential as a versatile tool for process intensification in the chemical industry. Nevertheless, the mass transfer mechanism through OSN membranes is not fully understood. The complex interactions between membrane, solvent and solute make it difficult to predict the separation performance of the membrane. In order to increase the fundamental understanding of the underlying transport phenomena systematic experimental investigations were carried out. A matrix of solvents, solutes and membranes was defined, covering a wide range of properties. The selection of the solutes was based on their industrial relevance to cover representative solute properties. Another criterion was their molecular weights, which should be rather low in order to obtain rejection less than 100%, to evaluate potential solute specific impact factors. The separation characteristics of 17 polar to apolar solutes with molecular weights from 114 g/mol to 339 g/mol were investigated. Moreover, five solvents and two membranes were included in the systematic investigation. On the basis of the results different solvent dependent solute sensitivity regions were identified for each membrane which differ by the impact of solute properties on the rejection. Different transport mechanisms seem to dominate within the different solute sensitivity regions. A correlation of the hydrogen bonding capacity of the solvents with the impact of solute properties on the rejection was found. This new insight offers new perspectives for the prediction of membrane rejection behavior in OSN.