Publications
412 results found
Cook M, Gaffney P, Peeva L, et al., 2018, Roll-to-roll dip coating of three different PIMs for Organic Solvent Nanofiltration, Journal of Membrane Science, Vol: 558, Pages: 52-63, ISSN: 0376-7388
PIM-1, PIM-7, and PIM-8 composite membranes have been fabricated for Organic Solvent Nanofiltration (OSN) on two different support membranes. Both support membranes, PAN and crosslinked Ultem 1000, displayed pore sizes within the range of 20–25 nm as characterised by gas liquid porometry. PIM layers of < 500 nm thickness were formed from dip coating on a roll-to-roll pilot line. The resultant composite membranes exhibited typical MWCOs in the region of 500–800 g mol−1. The quality of coating obtained on the crosslinked Ultem 1000 support membrane was consistently higher for all three PIMs than that obtained on the PAN membrane. The PIM composite membranes coated on to crosslinked Ultem 1000 were stable in a wider range of solvents than those on the PAN support. OSN testing in a model system with isomeric alkane solutes verified that manipulated changes to the molecular architecture of the polymer backbone resulted in a higher separation factor between straight and branched alkane isomers.
Chen W, Sharifzadeh M, Shah N, et al., 2018, Iterative peptide synthesis in membrane cascades: Untangling operational decisions, Computers and Chemical Engineering, Vol: 115, Pages: 275-285, ISSN: 0098-1354
Membrane enhanced peptide synthesis (MEPS) combines liquid-phase synthesis with membrane filtration, avoiding time-consuming separation steps such as precipitation and drying. Although performing MEPS in a multi-stage cascade is advantageous over a single-stage configuration in terms of overall yield, this is offset by the complex combination of operational variables such as the diavolume and recycle ratio in each diafiltration process. This research aims to tackle this problem using dynamic process simulation. The results suggest that the two-stage membrane cascade improves the overall yield of MEPS significantly from 72.2% to 95.3%, although more washing is required to remove impurities as the second-stage membrane retains impurities together with the anchored peptide. This clearly indicates a link between process configuration and operation. While the case study is based on the comparison of single-stage and two-stage MEPS, the results are transferable to other biopolymers such as oligonucleotides, and more complex system configurations (e.g. three-stage MEPS).
Kim JH, Cook M, Park SH, et al., 2018, A compact and scalable fabrication method for robust thin film composite membranes, GREEN CHEMISTRY, Vol: 20, Pages: 1887-1898, ISSN: 1463-9262
Jiang Z, Karan S, Livingston AG, 2018, Water Transport through Ultrathin Polyamide Nanofilms Used for Reverse Osmosis, ADVANCED MATERIALS, Vol: 30, ISSN: 0935-9648
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Levato G, Corcos A, Dichtel W, et al., 2018, Novel thin-film composite nanofiltration membranes with covalent organic framework active layer, 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Kim JH, Moon SJ, Park SH, et al., 2018, A robust thin film composite membrane incorporating thermally rearranged polymer support for organic solvent nanofiltration and pressure retarded osmosis, JOURNAL OF MEMBRANE SCIENCE, Vol: 550, Pages: 322-331, ISSN: 0376-7388
Mitev D, Radeva E, Peshev D, et al., 2018, PECVD modification of nano & ultrafiltration membranes for organic solvent nanofiltration, JOURNAL OF MEMBRANE SCIENCE, Vol: 548, Pages: 540-547, ISSN: 0376-7388
Cook M, Peeva L, Livingston A, 2018, Solvent-Free Coating of Epoxysilicones for the Fabrication of Composite Membranes, Industrial & Engineering Chemistry Research, Vol: 57, Pages: 730-739, ISSN: 0888-5885
Solventless coated epoxysilicone composite membranes have been prepared from a UV curable epoxysilicone polymer for organic solvent nanofiltration. Coatings were conducted solventless on a roll-to-roll pilot line using a forward gravure coating technique, and applied on a polyacrylonitrile or cross-linked poly(ether imide) support. Cross-linking of the poly(ether imide) support membrane with propanediamine enhanced the adhesion properties of the epoxysilicone selective layer. Penetration of the coating solution into the porous support membrane was confirmed using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Membranes fabricated using two different gravure heads have been studied, with submicrometer siloxane layer thicknesses achieved. The separation performance of the membranes is observed to be independent of the thickness. It has been possible to achieve membranes with a molecular weight cut-off < 500 g mol–1 in hydrocarbon solvents. Benefits of the fabrication include the ability to UV cross-link under air, elimination of solvent-based coating, and the feasibility of achieving uniform, submicrometer coatings at large scale manufacturing. These membranes comprise a further step toward greener and safer membrane production.
Peeva LG, Marchetti P, Livingston AG, 2018, Nanofiltration operations in nonaqueous systems, Comprehensive Membrane Science and Engineering: Second Edition, Pages: 36-78, ISBN: 9780444637963
Nanofiltration is a pressure-driven membrane process used to remove solutes with molecular weight in the range of 200-2000 g mol-1, typically from aqueous streams. A relatively recent innovation is the extension of nanofiltration (NF) processes to organic solvents (OSs)-an emerging technology referred to as organic solvent nanofiltration (OSN). Separation of molecules present in OSs by NF has great potential in industries ranging from refining to fine chemical and pharmaceutical synthesis, and OSN is currently an area of intensive investigation. This article summarizes the most recent developments in the field of OSN.
Vogelsang D, Dreimann JM, Wenzel D, et al., 2017, Continuously Operated Hydroamination - Toward High Catalytic Performance via Organic Solvent Nanofiltration in a Membrane Reactor, Industrial & Engineering Chemistry Research, Vol: 56, Pages: 13634-13641, ISSN: 0888-5885
Still, the hydroamination of dienes to form allylic amines is a challenging task in a continuous operation. Herein, we present the performance of a membrane reactor by the implementation of a continuously operated hydroamination reaction of β-myrcene with morpholine. Via application of a poly ether–ether–ketone (PEEK) membrane, operation at elevated temperatures was possible in an integrated reaction/separation unit. First, the kinetics of the hydroamination reaction and relevant membrane characteristics were determined under optimized reaction conditions. Afterward, these results were incorporated in a reactor/separator model to predict the process behavior. With this, catalyst replenishment was adjusted resulting in stable continuous operation. In the end an increase of the turnover number from 460 to 5135 compared to a batch process was achieved. The desired geranyl amines were obtained in very good yields higher than 80%, while an excellent conversion of β-myrcene above 93% was reached in a long-time stable process.
Dong R, Chen R, Livingston A, 2017, Liquid-phase iterative synthesis with OSN: A flexible and scalable platform for precision synthetic macromolecules, 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Foglia F, Karan S, Nania M, et al., 2017, Neutron Reflectivity and Performance of Polyamide Nanofilms for Water Desalination, ADVANCED FUNCTIONAL MATERIALS, Vol: 27, ISSN: 1616-301X
The structure and hydration of polyamide (PA) membranes are investigated with a combination of neutron and X-ray reflectivity, and their performance is benchmarked in reverse osmosis water desalination. PA membranes are synthesized by the interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC), varying systematically reaction time, concentration, and stoichiometry, to yield large-area exceptionally planar films of ≈10 nm thickness. Reflectivity is employed to precisely determine membrane thickness and roughness, as well as the (TMC/MPD) concentration profile, and response to hydration in the vapor phase. PA film thickness is found to increase linearly with reaction time, albeit with a nonzero intercept, and the composition cross-sectional profile is found to be uniform, at the conditions investigated. Vapor hydration with H2O and D2O from 0 to 100% relative humidity results in considerable swelling (up to 20%), but also yields uniform cross-sectional profiles. The resulting film thickness is found to be predominantly set by the MPD concentration, while TMC regulates water uptake. A favorable correlation is found between higher swelling and water uptake with permeance. The data provide quantitative insight into the film formation mechanisms and correlate reaction conditions, cross-sectional nanostructure, and performance of the PA active layer in RO membranes for desalination.
Chen W, Sharifzadeh M, Shah N, et al., 2017, Implication of Side Reactions in Iterative Biopolymer Synthesis: The Case of Membrane Enhanced Peptide Synthesis, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 56, Pages: 6796-6804, ISSN: 0888-5885
Membrane enhanced peptide synthesis (MEPS) improves conventional liquid phase synthesis by purifying intermediate products via filtration. A challenging aspect of MEPS is the propagation of unreacted materials and byproducts throughout the iterative synthesis. In this study, we first develop and validate a model of MEPS. The model is then applied to investigate the implications of side reactions (i.e., formation of error sequences) due to incomplete reaction and insufficient removal of amino acids after coupling. Sensitivity analysis shows that increasing the reaction extent for all couplings from 90 to 100% reduces the yield of truncated sequences from 29 to 0%. The formation of repeating sequences is found to be negligible in all case studies due to the large diavolume of post-deprotection diafiltration. This study provides useful insights into the operation of MEPS with particular emphasis on the control of error sequence formation. These insights are transferable to other sequence-controlled biopolymer syntheses.
Song Q, Wang A, Zhang TH, et al., 2017, Polymer Membranes of Intrinsic Microporosity for Molecular Separations, 13th International Conference on Materials Chemistry (MC13)
Marchetti P, Peeva L, Livingston A, 2017, The Selectivity Challenge in Organic Solvent Nanofiltration: Membrane and Process Solutions, ANNUAL REVIEW OF CHEMICAL AND BIOMOLECULAR ENGINEERING, VOL 8, Vol: 8, Pages: 473-497, ISSN: 1947-5438
Li Y, Klosowski MM, McGilvery CM, et al., 2017, Probing flow activity in polyamide layer of reverse osmosis membrane with nanoparticle tracers, JOURNAL OF MEMBRANE SCIENCE, Vol: 534, Pages: 9-17, ISSN: 0376-7388
We investigate the flow activity of the nanostructured polyamide layer in reverse osmosis (RO) membrane, using gold nanoparticle (NP) tracers of 1–40 nm diameter. Following a detailed structural examination of a commercial SW30RH membrane selected for this study, NP solutions were infiltrated from either the polyamide front or the polysulfone support side. The permeate was then analyzed spectroscopically while the entrapment of NPs within the membrane was mapped by high resolution electron microscopy. Results show that back-filtered NPs exhibited a fractionated distribution according to size: 1 nm nanoparticles permeate across the polyamide-polysulfone interface reaching the interior of the polyamide corrugations, while the larger ones (>10 nm) are retained within the polysulfone and gradually arrested at approximately 100 nm below the polyamide-polysulfone interface. Intermediate-sized 5 nm nanoparticles reached the undulating folds just below the polyamide layer. Permeation pathways across polyamide layer appear to exclude all tracers above 1 nm, which become selectively distributed across the polyamide layer: positively charged NPs label the outer surface of the polyamide film (expected to be carboxylate-rich), while negatively charged particles are uniformly distributed within the layer. Diafiltration measurements quantify the transient kinetics of NP retention and permeation. Overall, our results establish the flow activity of the polyamide nodular surface and provide estimates for the dimensions of permeation pathways.
Valentino L, Matsumoto M, Dichtel W, et al., 2017, Covalent organic frameworks as novel membrane materials, 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Gaffney P, Livingston A, Chen R, et al., 2017, Defined Monomer Sequence Polymers, WO/2017/042583
Processes of preparing defined monomer sequence polymers are disclosed, in which a backbone portion of the polymer is first prepared by performing one or more sequential monomeric coupling reactions with intervening membrane diafiltration purification/isolation steps, followed by a step of decorating the backbone portion with one or more side chains at predetermined positions along its length. The process represents an improvement on prior art techniques, which impose limitations on the size of the side chains that may be present. Defined monomer sequence polymers that are obtainable by the processes are also disclosed.
Song Q, Liu TY, Jelfs KE, et al., 2017, Advanced Microporous Membranes for Molecular Separations, British Zeolite Association 40th Annual Meeting
Livingston A, Baker R, 2017, Membranes from academia to industry, Nature Materials, Vol: 16, Pages: 280-282, ISSN: 1476-1122
Livingston A, 2016, Researchers develop “designer”chemical separation membranes, Membrane Technology, Vol: 2016, ISSN: 0958-2118
In the UK, researchers at Imperial College London have developed a synthetic method for producing molecularly designed polymer membranes which, they say, has the potential to make chemical separation processes up to two orders of magnitude more efficient than is achievable using conventional membranes. This brief feature highlights what is involved.
Yeo BJL, Goh S, Livingston AG, et al., 2016, Controlling biofilm development in the extractive membrane bioreactor, SEPARATION SCIENCE AND TECHNOLOGY, Vol: 52, Pages: 113-121, ISSN: 0149-6395
Peeva LG, Da Silva Burgal J, Heckenast Z, et al., 2016, Continuous consecutive reactions with inter-reaction solvent exchange by membrane separation, Angewandte Chemie International Edition, Vol: 55, Pages: 13576-13579, ISSN: 1433-7851
Pharmaceutical production typically involves multiple reaction steps with separations between successive reactions. Two processes which complicate the transition from batch to continuous operation in multistep synthesis are solvent exchange (especially high‐boiling‐ to low‐boiling‐point solvent), and catalyst separation. Demonstrated here is membrane separation as an enabling platform for undertaking these processes during continuous operation. Two consecutive reactions are performed in different solvents, with catalyst separation and inter‐reaction solvent exchange achieved by continuous flow membrane units. A Heck coupling reaction is performed in N,N‐dimethylformamide (DMF) in a continuous membrane reactor which retains the catalyst. The Heck reaction product undergoes solvent exchange in a counter‐current membrane system where DMF is continuously replaced by ethanol. After exchange the product dissolved in ethanol passes through a column packed with an iron catalyst, and undergoes reduction (>99 % yield).
Burgal JDS, Peeva L, Livingston A, 2016, Negligible ageing in poly(ether-ether-ketone) membranes widens application range for solvent processing, JOURNAL OF MEMBRANE SCIENCE, Vol: 525, Pages: 48-56, ISSN: 0376-7388
Shi B, Marchetti P, Peshev D, et al., 2016, Will ultra-high permeance membranes lead to ultra-efficient processes? Challenges for molecular separations in liquid systems, JOURNAL OF MEMBRANE SCIENCE, Vol: 525, Pages: 35-47, ISSN: 0376-7388
Mazlan NM, Marchetti P, Maples HA, et al., 2016, Organic fouling behaviour of structurally and chemically different forward osmosis membranes – A study of cellulose triacetate and thin film composite membranes, Journal of Membrane Science, Vol: 520, Pages: 247-261, ISSN: 0376-7388
The HTI cellulose triacetate (CTA) and novel thin film composite (TFC) membranes are used to study the multifaceted interactions involved in the fouling and cleaning of forward osmosis (FO) membranes, using calcium alginate as a model foulant. Results show that fouling on the TFC membrane was more significant compared to CTA, arising from a variety of factors associated with surface chemistry, membrane morphology and structural properties. Interestingly, it was observed that in FO mode, membrane surface properties dominated over fouling layer properties in determining fouling behaviour, with some surface properties (e.g. surface roughness) having a greater effect on fouling than others (e.g. surface hydrophilicity). In pressure retarded osmosis (PRO) mode, structural properties of the support played a more dominant role whereby fouling mechanism was specific to the foulant size and aggregation as well as the support pore size relative to the foulant. Whilst pore clogging was observed in the TFC membrane due to its highly asymmetric and porous support structure, fouling occurred as a surface phenomenon on the CTA membrane support layer. Besides pore clogging, the severe fouling observed on the TFC membrane in PRO mode was due to a high specific mass of foulant adsorbed in its porous support. It was observed that a trade-off between enhanced membrane performance and fouling mitigation is apparent in these membranes, with both membranes providing improvement in one aspect at the expense of the other. Hence, significant developments in their surface and structural properties are needed to achieve high anti-fouling properties without compromising flux performance. Measured fouling densities on the studied surfaces suggest that there is not a strong correlation between foulant-membrane interaction and fouling density. Cleaning results suggest that physical cleaning was more efficient on the CTA membrane compared to the TFC membrane. Further, they implied that despite diff
Klosowski MM, McGilvery CM, Li Y, et al., 2016, Micro-to nano-scale characterisation of polyamide structures of the SW30HR RO membrane using advanced electron microscopy and stain tracers, Journal of Membrane Science, Vol: 520, Pages: 465-476, ISSN: 1873-3123
The development of new reverse osmosis (RO) membranes with enhanced performance would benefit from a detailed knowledge of the membrane structures which participate in the filtration process. Here, we examined the hierarchical structures of the polyamide (PA) active layer of the SW30HR RO membrane. Scanning electron microscopy combined with focused ion beam milling (FIB-SEM) was used to obtain the 3-D reconstructions of membrane morphology with 5 nm cross-sectional resolution (comparable with the resolution of low magnification TEM imaging in 2D) and 30 nm slice thickness. The complex folding of the PA layer was examined in 3 dimensions, enabling the quantification of key structural properties of the PA layer, including the local thickness, volume, surface area and their derivatives. The PA layer was found to exhibit a much higher and convoluted surface area than that estimated via atomic force microscopy (AFM). Cross-sectional scanning transmission electron microscopy (STEM) was used to observe the distribution of a tracer stain under various conditions. The behaviour of stain in dry and wet PA indicated that the permeation pathways have a dynamic nature and are activated by water. High resolution STEM imaging of the stained PA nano-films revealed the presence of <1 nm pore-like structures with a size compatible with free volume estimations by positron annihilation lifetime spectroscopy (PALS). This study presents a comprehensive map of the active PA layer across different length scales (from micro- to sub-nanometre) and mechanistic insight into their role in the permeation process.
Kim JF, Gaffney PRJ, Valtcheva IB, et al., 2016, Organic Solvent Nanofiltration (OSN): A New Technology Platform for Liquid-Phase Oligonucleotide Synthesis (LPOS), Organic Process Research and Development, Vol: 20, Pages: 1439-1452, ISSN: 1083-6160
Organic solvent nanofiltration (OSN) technology is a membrane process for molecular separation in harsh organic media. However, despite having well-documented potential applications, development hurdles have hindered the widespread uptake of OSN technology. One of the most promising areas of application is as an iterative synthesis platform, for instance for oligonucleotides or peptides, where a thorough purification step is required after each synthesis cycle, preferably in the same working solvent. In this work, we report a process development study for liquid-phase oligonucleotide synthesis (LPOS) using OSN technology. Oligonucleotide (oligo) based drugs are being advanced as a new generation of therapeutics functioning at the protein expression level. Currently, over 100 oligo based drugs are undergoing clinical trials, suggesting that it will soon be necessary to produce oligos at a scale of metric tons per year. However, there are as yet no synthesis platforms that can manufacture oligos at >10 kg batch scale. With the process developed here, we have successfully carried out eight iterative cycles of chain extension and synthesized 5-mer and 9-mer 2′-O-methyl oligoribonucleotide phosphorothioates, all in liquid phase media. This paper discusses the key challenges, both anticipated and unexpected, faced during development of this process and suggests solutions to reduce the development period. An economic analysis has been carried out, highlighting the potential competitiveness of the LPOS-OSN process and the necessity for a solvent recovery unit.
Jimenez-Solomon M, Song Q, Jelfs K, et al., 2016, Polymer nanofilms with enhanced microporosity by interfacial polymerization, Nature Materials, Vol: 15, Pages: 760-767, ISSN: 1476-4660
Highly permeable and selective membranes are desirable for energy-efficient gas and liquid separations.Microporous organic polymers have attracted significant attention in this respect owing to their highporosity, permeability, and molecular selectivity. However, it remains challenging to fabricate selectivepolymer membranes with controlled microporosity which are stable in solvents. Here we report a newapproach to designing crosslinked, rigid polymer nanofilms with enhanced microporosity bymanipulating the molecular structure. Ultra-thin polyarylate nanofilms with thickness down to 20 nmwere formed in-situ by interfacial polymerisation. Enhanced microporosity and higher interconnectivityof intermolecular network voids, as rationalised by molecular simulations, are achieved by utilisingcontorted monomers for the interfacial polymerisation. Composite membranes comprising polyarylatenanofilms with enhanced microporosity fabricated in-situ on crosslinked polyimide ultrafiltrationmembranes show outstanding separation performance in organic solvents, with up to two orders ofmagnitude higher solvent permeance than membranes fabricated with nanofilms made from noncontortedplanar monomers.
Schaepertoens M, Didaskalou C, Kim JF, et al., 2016, Solvent recycle with imperfect membranes: A semi-continuous workaround for diafiltration, Journal of Membrane Science, Vol: 514, Pages: 646-658, ISSN: 1873-3123
For separation of a two-component mixture, a three-stage organic solvent nanofiltration (OSN) process is presented which comprises of a two-stage membrane cascade for separation with a third membrane stage added for integrated solvent recovery, i.e. solvent recycling. The two-stage cascade allows for increased separation selectivity whilst the integrated solvent recovery stage mitigates the otherwise large solvent consumption of the purification. This work explores the effect of washing the solvent recovery unit at intervals in order to attain high product purities with imperfect solvent recovery membranes possessing less than 100% rejection of the impurity. This operation attains a purity of 98.7% through semi-continuous operation with two washes of the solvent recovery stage, even when imperfect membranes are used in a closed-loop set-up. This contrasts favourably with the 83.0% maximum purity achievable in a similar set-up with a single continuous run. The process achieves slightly lower (−0.7%) yield of around 98.2% compared to a continuously operated process without solvent recovery but consumes approx. 85% less solvent (theoretical analysis suggests up to 96% reduction is possible). 9 different membranes, both commercial (GMT, Novamem, SolSep) and in-house fabricated, are screened and tested on a separation challenge associated with the synthesis of macrocycles – amongst the membrane materials are polyimide (PI), polybenzimidazole (PBI) and, polyetheretherketone (PEEK).
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