398 results found
He A, Jiang Z, Wu Y, et al., 2022, A smart and responsive crystalline porous organic cage membrane with switchable pore apertures for graded molecular sieving, Nature Materials, Vol: 21, Pages: 463-470, ISSN: 1476-1122
Membranes with high selectivity offer an attractive route to molecular separations, where technologies such as distillation and chromatography are energy intensive. However, it remains challenging to fine tune the structure and porosity in membranes, particularly to separate molecules of similar size. Here, we report a process for producing composite membranes that comprise crystalline porous organic cage films fabricated by interfacial synthesis on a polyacrylonitrile support. These membranes exhibit ultrafast solvent permeance and high rejection of organic dyes with molecular weights over 600 g mol-1. The crystalline cage film is dynamic, and its pore aperture can be switched in methanol to generate larger pores that provide increased methanol permeance and higher molecular weight cut-offs (1,400 g mol-1). By varying the water/methanol ratio, the film can be switched between two phases that have different selectivities, such that a single, 'smart' crystalline membrane can perform graded molecular sieving. We exemplify this by separating three organic dyes in a single-stage, single-membrane process.
Yeo J, Peeva L, Chung S, et al., 2021, Liquid Phase Peptide Synthesis via One‐Pot Nanostar Sieving (PEPSTAR), Angewandte Chemie, Vol: 133, Pages: 7865-7874, ISSN: 0044-8249
Yeo J, Peeva L, Chung S, et al., 2021, Liquid phase peptide synthesis via one‐pot nanostar sieving (PEPSTAR), Angewandte Chemie International Edition, Vol: 60, Pages: 7786-7795, ISSN: 1433-7851
Herein, a one‐pot liquid phase peptide synthesis featuring iterative addition of amino acids to a ‘nanostar’ support, with organic solvent nanofiltration (OSN) for isolation of the growing peptide after each synthesis cycle is reported. A cycle consists of coupling, Fmoc removal, then sieving out of the reaction by‐products via nanofiltration in a reactor‐separator, or synthesizer apparatus where no phase or material transfers are required between cycles. The three‐armed and monodisperse nanostar facilitates both efficient nanofiltration and real‐time reaction monitoring of each process cycle. This enabled the synthesis of peptides more efficiently while retaining the full benefits of liquid phase synthesis. PEPSTAR was validated initially with the synthesis of enkephalin‐like model penta‐ and decapeptides, then octreotate amide and finally octreotate. The crude purities compared favorably to vendor produced samples from solid phase synthesis.
Kim JH, Cook M, Peeva L, et al., 2020, Low energy intensity production of fuel-grade bio-butanol enabled by membrane-based extraction, Energy and Environmental Science, Vol: 13, Pages: 4862-4871, ISSN: 1754-5692
Widespread use of biofuels is inhibited by the significant energy burden of recovering fuel products from aqueous fermentation systems. Here, we describe a membrane-based extraction (perstraction) system for the recovery of fuel-grade biobutanol from fermentation broths which can extract n-butanol with high purity (>99.5%) while using less than 25% of the energy of current technology options. This is achieved by combining a spray-coated thin-film composite membrane with 2-ethyl-1-hexanol as an extractant. The membrane successfully protects the micro-organisms from the extractant, which, although ideal in other respects, is a metabolic inhibitor. In contrast to water, the extractant does not form a heterogeneous azeotrope with n-butanol, and the overall energy consumption of for n-butanol production is 3.9 MJ kg-1, substantially less than other recovery processes (17.0 – 29.4 MJ kg-1). By (a) extracting n-butanol from the fermentation broth without a phase change, (b) breaking the heterogeneous azeotrope relationship (less energy consumption for distillation), and (c) utilizing a small volume ratio of extractant : fermentation broth (1:100, v/v), the need for high energy intensity processes such as pervaporation, gas stripping or liquid-liquid extraction is avoided. The application of this perstraction system to continuous production of higher alcohols is developed and shown to be highly favourable.
Thompson KA, Mathias R, Kim D, et al., 2020, N-Aryl-linked spirocyclic polymers for membrane separations of complex hydrocarbon mixtures, Science, Vol: 369, Pages: 310-315, ISSN: 0036-8075
The fractionation of crude-oil mixtures through distillation is a large-scale, energy-intensive process. Membrane materials can avoid phase changes in such mixtures and thereby reduce the energy intensity of these thermal separations. With this application in mind, we created spirocyclic polymers with N-aryl bonds that demonstrated noninterconnected microporosity in the absence of ladder linkages. The resulting glassy polymer membranes demonstrated nonthermal membrane fractionation of light crude oil through a combination of class- and size-based “sorting” of molecules. We observed an enrichment of molecules lighter than 170 daltons corresponding to a carbon number of 12 or a boiling point less than 200°C in the permeate. Such scalable, selective membranes offer potential for the hybridization of energy-efficient technology with conventional processes such as distillation.
McGilvery CM, Abellan P, Klosowski MM, et al., 2020, Nanoscale chemical heterogeneity in aromatic polyamide membranes for reverse osmosis applications, ACS Applied Materials & Interfaces, Vol: 12, Pages: 19890-19902, ISSN: 1944-8244
Reverse osmosis membranes are used within the oil and gas industry for seawater desalination on off-shore oilrigs. The membranes consist of three layers of material: a polyester backing layer, a polysulfone support and a polyamide (PA) thin film separating layer. It is generally thought that the PA layer controls ion selectivity within the membrane but little is understood about its structure or chemistry at the molecular scale. This active polyamide layer is synthesized by interfacial polymerization at an organic/aqueous interface between m-phenylenediamine and trimesoyl chloride, producing a highly cross-linked PA polymer. It has been speculated that the distribution of functional chemistry within this layer could play a role in solute filtration. The only technique potentially capable of probing the distribution of functional chemistry within the active PA layer with sufficient spatial and energy resolution is scanning transmission electron microscopy combined with electron energy-loss spectroscopy (STEM-EELS). Its use is a challenge because organic materials suffer beam-induced damage at relatively modest electron doses. Here we show that it is possible to use the N K-edge to map the active layer of a PA film using monochromated EELS spectrum imaging. The active PA layer is 12 nm thick, which supports previous neutron reflectivity data. Clear changes in the fine structure of the C K-edge across the PA films are measured and we use machine learning to assign fine structure at this edge. Using this method, we map highly heterogeneous intensity variations in functional chemistry attributed to N—C═C bonds within the PA. Similarities are found with previous molecular dynamics simulations of PA showing regions with a higher density of amide bonding as a result of the aggregation process at similar length scales. The chemical pathways that can be deduced may offer a clearer understanding of the transport mechanisms through the membrane.
Jiang Z, Karan S, Livingston AG, 2020, Membrane Fouling: Does Microscale Roughness Matter?, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 59, Pages: 5424-5431, ISSN: 0888-5885
Casanova S, Liu T-Y, Chew Y-MJ, et al., 2020, High flux thin-film nanocomposites with embedded boron nitride nanotubes for nanofiltration, JOURNAL OF MEMBRANE SCIENCE, Vol: 597, ISSN: 0376-7388
Butler EL, Petit C, Livingston AG, 2020, Poly(piperazine trimesamide) thin film nanocomposite membrane formation based on MIL-101: Filler aggregation and interfacial polymerization dynamics, JOURNAL OF MEMBRANE SCIENCE, Vol: 596, ISSN: 0376-7388
Livingston AG, Jiang Z, 2020, Proteins tailor pore geometry, NATURE MATERIALS, Vol: 19, Pages: 257-258, ISSN: 1476-1122
Abdulsalam Ebrahim M, Karan S, Livingston AG, 2020, On the influence of salt concentration on the transport properties of reverse osmosis membranes in high pressure and high recovery desalination, Journal of Membrane Science, Vol: 594, ISSN: 0376-7388
In this work, we investigate the effect of varying the concentration of sodium chloride up to 70 g L−1 - equivalent to a recovery of approximately 50% in seawater desalination-on the transport properties of different reverse osmosis membranes. The study was performed using five commercial thin film composite (TFC) membranes and an analogue TFC membrane fabricated via the interfacial reaction of m-phenylenediamine and trimesoyl chloride. The surface properties of the membranes as measured by atomic force microscopy (AFM), zeta potential, and X-ray photoelectron spectroscopy (XPS) are presented. The solution diffusion model coupled with film theory was used to calculate the permeance of water and salt through the membranes, to account for the effect of concentration polarisation. The mass transfer coefficient in the test cells was estimated independently using the dissolution rate of benzoic acid; and was found to be approximately . A linear reduction in salt permeance was observed in some of the RO membranes, while it remained constant for other membranes, including the analogue membrane. All the tested membranes maintained constant water permeance below 45 g L−1 NaCl. However, when the salt concentration at the membrane surface exceeded 45 g L−1, water permeance either increased, remained constant or decreased. The results demonstrate the dependence of water and salt transport on the concentration of sodium chloride at the membrane surface.
Corcos AR, Levato GA, Jiang Z, et al., 2019, Reducing the Pore Size of Covalent Organic Frameworks in Thin-Film Composite Membranes Enhances Solute Rejection, ACS MATERIALS LETTERS, Vol: 1, Pages: 440-446
Szekely G, Livingston A, 2019, Sustainable nanoscale engineering: From materials design to chemical processing, ISBN: 9780128146811
Sustainable Nanoscale Engineering: From Materials Design to Chemical Processing presents the latest on the design of nanoscale materials and their applications in sustainable chemical production processes. The newest achievements of materials science, in particular nanomaterials, opened new opportunities for chemical engineers to design more efficient, safe, compact and environmentally benign processes. These materials include metal-organic frameworks, graphene, membranes, imprinted polymers, polymers of intrinsic microporosity, nanoparticles, and nanofilms, to name a few. Topics discussed include gas separation, CO2 sequestration, continuous processes, waste valorization, catalytic processes, bioengineering, pharmaceutical manufacturing, supercritical CO2 technology, sustainable energy, molecular imprinting, graphene, nature inspired chemical engineering, desalination, and more.
Livingston A, Trout BL, Horvath IT, et al., 2019, Challenges and directions for green chemical engineering-role of nanoscale materials, Sustainable Nanoscale Engineering: From Materials Design to Chemical Processing, Pages: 1-18, ISBN: 9780128146811
Sultan Z, Graça I, Li Y, et al., 2019, Membrane fractionation of liquors from lignin-first biorefining, ChemSusChem, Vol: 12, Pages: 1203-1212, ISSN: 1864-5631
For the purposing of each lignin fraction in the lignin liquors, the development of separation strategies to fractionate the lignin streams by MW ranges constitutes a timely challenge to be tackled. Herein, membrane separation was applied to the refining of lignin streams obtained from a lignin-first biorefining process based on H-transfer reactions catalyzed by Raney Ni, using 2-propanol as a part of the lignin extraction liquor and as an H-donor. A two-stage membrane cascade was considered to separate and concentrate the monophenol-rich fraction from the CUB liquor. Building on the experimental results, an economic evaluation of the potential of membrane separation for the refining of lignin streams was undertaken. The membrane performance represents the bottleneck of the costs associated with the separation process. Accordingly, we present a detailed analysis of future developments in the performance required to debottleneck the utilization of membrane separation for lignin refining.
Dong R, Liu R, Gaffney P, et al., 2019, Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving, Nature Chemistry, Vol: 11, Pages: 136-145, ISSN: 1755-4330
Synthetic chemists have devoted tremendous effort towards the production of precision synthetic polymers with defined sequences and specific functions. However, the creation of a general technology that enables precise control over monomer sequence, with efficient isolation of the target polymers, is highly challenging. Here, we report a robust strategy for the production of sequence-defined synthetic polymers through a combination of liquid-phase synthesis and selective molecular sieving. The polymer is assembled in solution with real-time monitoring to ensure couplings proceed to completion, on a three-armed star-shaped macromolecule to maximize efficiency during the molecular sieving process. This approach is applied to the construction of sequence-defined polyethers, with side-arms at precisely defined locations that can undergo site-selective modification after polymerization. Using this versatile strategy, we have introduced structural and functional diversity into sequence-defined polyethers, unlocking their potential for real-life applications in nanotechnology, healthcare and information storage.
Dong R, Liu R, Gaffney PRJ, et al., 2019, Author Correction: Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving, Nature Chemistry, Vol: 11, Pages: 184-184, ISSN: 1755-4330
Correction to: Nature Chemistry https://doi.org/10.1038/s41557-018-0169-6, published online 3 December 2018.
Dong R, Chen R, Livingston A, 2018, Iterative synthesis of sequence-defined, multifunctional, biocompatible PEGs for biomedical applications, 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Butler E, Reid B, Petit C, et al., 2018, Extended DLVO interactions of a metal-organic framework: Implications on colloidal dispersion, 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
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
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 L, Livingston A, 2018, Nanofiltration in the pharmaceutical and biopharmaceutical technology, Current Trends and Future Developments on (Bio-) Membranes: Membrane Processes in the Pharmaceutical and Biotechnological Field, Pages: 97-121, ISBN: 9780128136072
Separation processes account for up to 40%-70% of both capital and operating costs in many industries including fine chemical, pharmaceutical, and biopharmaceutical industries, and there is a constant search for efficient and economical separation methods. Membrane separations have been investigated already for many years as an alternative to conventional separation processes (e.g., distillation). Despite many proven success stories, multiple challenges still remain, hampering wider application of membranes. One such challenge is the imperfect separation provided by membranes and their inability to fully discriminate between solutes even with significant differences in their molecular size. In this chapter, we will focus our attention on how the imperfect separation gridlock might be resolved via multistage membrane processes operated in batch and continuous mode. Examples will be presented for typical separation challenges faced by the pharmaceutical industry such as purification, fractionation, solvent recovery, and solvent exchange.
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.
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