Andrew G Livingston

Queen Mary, University of London | QMUL

2D covalent organic frameworks (2D COFs) are attractive candidates for next‐generation membranes due to their robust linkages and uniform, tunable pores. Many publications have claimed to achieve selective molecular transport through COF pores, but reported performance metrics for similar networks vary dramatically, and in several cases the reporte...

Hydrocarbon separation relies on energy-intensive distillation. Membrane technology can offer an energy-efficient alternative but requires selective differentiation of crude oil molecules with rapid liquid transport. We synthesized multiblock oligomer amines, which comprised a central amine segment with two hydrophobic oligomer blocks, and used the...

Fouling is one of the major obstacles to successful membrane-based separations. In aqueous systems, fouling is well characterised and fouling reduction techniques are established. However, in organic solvents, membrane fouling is not well understood. In this work we manufactured anti-fouling organic solvent stable polybenzimidazole (PBI) membranes...

Polymer membranes are widely used in separation processes including desalination ¹ , organic solvent nanofiltration 2,3 and crude oil fractionation 4,5 . Nevertheless, direct evidence of subnanometre pores and a feasible method of manipulating their size is still challenging because of the molecular fluctuations of poorly defined voids in polymers...

While polyamide (PA) membranes are widespread in water purification and desalination by reverse osmosis, a molecular-level understanding of the dynamics of both confined water and polymer matrix remains elusive. Despite the dense hierarchical structure of PA membranes formed by interfacial polymerization, previous studies suggest that water diffusi...

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 composi...

In this work the selectivity of crosslinked organic solvent stable PBI membranes is tuned by varying the molar ratio of two grafting agents: a long flexible polymer modifier (Elastamine RE-1-1000, 1000 g mol⁻¹) and a small molecule modifier (2-methoxyethylamine, 75 g mol⁻¹). Grafting exclusively with the long chain modifier provided a membrane with...

PEPSTAR, a „rising star“ in peptide synthesis, features a „nanostar“ support to grow peptides with organic solvent nanofiltration for isolation. The three‐armed and monodisperse nanostar enables efficient nanofiltration and real‐time reaction monitoring. A cycle consists of coupling, Fmoc removal and nanofiltration, which all performed continuously...

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...

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%...

Separating organics without distillation Hydrocarbon distillation is a widespread and energy-intensive process. Membranes might offer an alternative approach, but few can survive immersion in organic solvents nor are they able to extract relatively small molecules. Thompson et al. developed a series of polymers of intrinsic microporosity that they...

Reverse osmosis membranes are used within the oil and gas industry for sea water 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 membra...

Using organic solvent shortens formation time of membrane nanosheets comprising proteins and copolymers, while tuning protein structure tailors the pore geometry, resulting in superior water permeation.

Nanotechnology and nanomaterials are among the most significant scientific and industrial research breakthroughs of the 21st century. With the rapid globalization of science, chemists, materials scientists, and chemical engineers are synergistically working together worldwide to understand how to manipulate matter for the benefit of humankind. The...

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 effici...

The surface of thin film composite membranes used for reverse osmosis appears to be rough, known as a peak-valley morphology, and this is believed to cause more severe fouling than would occur for a smooth surface. In this study, polyamide nanofilms were made by interfacial polymerization on a sacrificial layer or at a free aqueous-organic interfac...

The goal of this work was to enhance membrane performance by achieving high, well-dispersed loadings of a metal-organic framework: MIL-101. Thin film nanocomposite (TFN) membranes fabricated using n-hexane as an organic phase demonstrated significant aggregation, which reduced selectivities and stochastically increased permeances. Solution-phase me...

Three imine-linked covalent organic framework (COF) films are incorporated as active layers into separate thin-film composite (TFC) membranes and tested for their ability to reject an organic pollutant surrogate and salt from water. The synthesized membranes consist of a polyacrylonitrile (PAN) membrane supporting a TAPB-PDA-H, TAPB-PDA-Me, or TAPB...

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 memb...

Three imine-linked covalent organic framework (COF) films are incorporated as active layers into separate thin-film composite (TFC) membranes and tested for their ability to reject an organic pollutant surrogate and salt from water. The synthesized membranes consist of a polyacrylonitrile (PAN) membrane supporting a TAPB-PDA-H , TAPB-PDA-Me , or TA...

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 str...

In the version of this Article originally published, the authors inadvertently cited ref. 10 in two places in the first paragraph. They would like to clarify that it should not have been cited in the sentence that starts “Polymer chemists have employed strategies such as single monomer insertion..” as it mistakenly implied that the IEG+ method desc...

For the utilization of each lignin fraction in the lignin liquors, the development of separation strategies to fractionate the lignin streams by molecular weight ranges constitutes a timely challenge to be tackled. Herein, membrane filtration was applied to the refining of lignin streams obtained from a lignin‐first biorefining process based on H‐t...

Ultrathin, freestanding, and highly crosslinked polymer films with controllable thickness are fabricated by Andrew G. Livingston and co‐workers in article number 1705973. The independent impact of film thickness and support materials on the membrane performance is explored, revealing that ultrathin films (6.5 nm) transferred onto porous support sub...

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 op...

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 coatin...

Membrane-based liquid filtration has been highlighted as a key green process engineering platform for process intensification. While these systems have been successfully commercialized in desalination and micro/ultra/nanofiltration, it is yet challenging to expand the limited operating conditions (ambient temperature in aqueous environment) of curr...

Thin film composite (TFC) polymer membranes are ubiquitous in membrane-based liquid separation processes, especially in reverse osmosis (RO). While the ultrathin polyamide separating layer employed in TFC membranes has exhibited excellent performance in many liquid separation processes, the polymer support has been identified as a bottleneck to pra...

Thin-film composite membranes comprising a polyamide nanofilm separating layer on a support material are state of the art for desalination by reverse osmosis. Nanofilm thickness is thought to determine the rate of water transport through the membranes; although due to the fast and relatively uncontrolled interfacial polymerization reaction employed...

With the present research we describe several alternative approaches aimed at polymer-on-polymer coatings, produced by Plasma Enhanced Chemical Vapour Deposition (PECVD) technique. The depositions were made using two different plasma systems: plasma chamber unit B 30.2 (precursor pentane, hexamethyldisiloxane, perfluorhexane) and PECVD system “Oxfo...

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). Sep...

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). Se...

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 crosslinked polyetherimide support. Crosslinking of the...

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...

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 rea...

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 by-products throughout the iterative synthesis. In this study, we first develop and validate a model of MEPS. The model is then applied...

Recent development of organic solvent nanofiltration (OSN) materials has been overwhelmingly directed toward tight membranes with ultrahigh permeance. However, emerging research into OSN applications is suggesting that improved separation selectivity is at least as important as further increases in membrane permeance. Membrane solutions are being p...

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 suppo...

The extractive membrane bioreactor can be used as a treatment of difficult organics in hostile wastewater. In this study it was applied to phenol-contaminated saline water where phenol is extracted from the feed stream through a dense membrane to the bioprocess, which is principally a biofilm on the downstream side of the membrane. Our study shows...

Given the recent advances in organic solvent nanofiltration (OSN) membranes for the separation of organic mixtures, this paper investigates the design of OSN membrane cascades for hydrocarbon mixtures. A superstructure optimization approach based on mixed-integer nonlinear programming (MINLP) is considered to determine the most promising cascade co...

The invention relates to branched sol. polymeric supports for membrane enhanced peptides synthesis (MEPS) , and their use in MEPS.

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...

Supplementary

An increasing number of reports in the scientific literature describe membranes with ultra-high permeance which might revolutionise molecular separations in liquid systems by making separation processes dramatically more efficient. Many of these reports relate to breakthroughs in materials science, including fabrication of new 2-D materials such as...

Organic solvent nanofiltration membranes have been prepared from poly(ether-ether-ketone) (PEEK) by phase inversion. Remarkably, these membranes undergo negligible ageing, even under extreme conditions of high temperature air annealing, and high temperature solute filtration with agressive solvents. This negligible ageing of PEEK membranes is contr...

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 membra...

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 inte...

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 inte...

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 membra...

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...

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 in...

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...

Given the recent advances in organic solvent nanofiltration (OSN) membranes for the separation of organic mixtures, this paper investigates the design of OSN membrane cascades for hydrocarbon mixtures. A superstructure optimization approach based on mixed-integer nonlinear programming (MINLP) is considered to determine the most promising cascade co...

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 high porosity, permeability and molecular selectivity. However, it remains challenging to fabricate selective polymer membranes with controlled micro...

Three commercial spiral-wound membrane modules of different sizes, from 1.8“x12” to 4.0“x40”, 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 membr...

One of the main challenges in the field of organic solvent nanofiltration (OSN) is to improve the selectivity of membranes, allowing the separation of closely related solutes. This objective might be achieved by constructing membranes with uniform porous structures. Hybrid Polymer/Metal Organic Framework (MOF) membranes were prepared by in-situ gro...

Reverse osmosis (RO) is now the most ubiquitous technology for desalination, with numerous seawater RO plants being built in water-stressed countries to complement existing water resources. Despite the development of highly permeable RO membranes, energy consumption remains a major contributor to total cost. Forward osmosis (FO) is receiving much a...

In this work it is shown that PEEK membranes are “green” from the production point of view when compared with commercial polyimide (PI) based organic solvent nanofiltration (OSN) membranes. Green metrics (E-factor and solvent intensity) and waste cost were used in order to assess the environmental burden of PEEK membranes: the solvent intensity of...

CPSE Major Research Programmes and Proposals: Towards Isothermal Refining Using Membranes Cascades

Thin film composite membranes were prepared through a facile single-step wire-wound rod coating procedure in which internally crosslinked poly(styrene-co-butadiene) polymer nanoparticles self-assembled to form a thin film on a hydrophilic ultrafiltration support. This nanoparticle film provided a defect-free separation layer 130-150 nm thick, which...

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 f...

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. w...

Organic pollutants which are commonly discharged by the 21 industrial groups identified by the US EPA are regulated under the toxic and priority pollutants list. Novel membrane bioreactor (MBR) systems developed in the last 2 decades, such as the high-retention MBRs (HR-MBRs) and extractive MBRs (EMBR), could be applied in the retention / extractio...

Recently, polybenzimidazole (PBI) membranes crosslinked with dibromoxylene (DBX) were shown to retain their molecular separation performance in the harsh conditions characteristic of organic solvent nanofiltration (OSN). This work is focused on better understanding of the crosslinking reaction between PBI and DBX, and finding the parameters importa...

Membranes with unprecedented solvent permeance and high retention of dissolved solutes are needed to reduce the energy consumed by separations in organic liquids. We used controlled interfacial polymerization to form free-standing polyamide nanofilms less than 10 nanometers in thickness, and incorporated them as separating layers in composite membr...

Due to the discovery of RNAi, oligonucleotides (oligos) have re-emerged as a major pharmaceutical target that may soon be required in ton quantities. However, it is questionable whether solid-phase oligo synthesis (SPOS) methods can provide a scalable synthesis. Liquid-phase oligo synthesis (LPOS) is intrinsically scalable and amenable to standard...

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In-situ growth (ISG) of metal organic frameworks (MOFs) within the pores of integrally skinned asymmetric polymer membrane supports has previously been shown to outperform mixed matrix membranes (MMMs) for organic solvent nanofiltration (OSN) applications. However these membranes have the disadvantage of low flux performances. In order to improve s...

From feasibility tests at laboratory scale to large industrial scale processes, modelling can be applied to Organic Solvent Nanofiltration (OSN) for two purposes: (i) parameter estimation, when experimental data for standard solute + solvent systems are available, and it is desired to estimate relevant parameters for as yet uncharacterised systems,...

Separation processes consume over 40% of energy used in refining, petrochemical and other chemical industries. For bulk separation processes, such as filtration, the energy consumption is generally low due to the simplicity of the separation. However, when separation occurs at a molecular level by distillation, subli-mation or crystallization, high...

In this work a poly(ether ether ketone) (PEEK) membrane is presented for its suitability for organic solvent nanofiltration (OSN) applications using polar aprotic solvents, such as DMF and THF, high temperatures, and basic/acidic conditions. Four grades of PEEK polymer were tested and it was verified that different grades produced membranes with di...

Improved integrally skinned asymmetric membranes for organic solvent nanofiltration, and their methods of preparation and use are disclosed. Membranes are formed from polyimides by phase inversion and are then crosslinked by addition of amine crosslinking agents that react with the imide groups of the polyimide, creating amide bonds. These stabiliz...

Poly(ethylene glycol) [1, PEG~4(OH)2, Mn ~ 200], glycerol ethoxylate [2, PEG~21(OH)3, Mn ~ 1000] and pentaerythritol ethoxylate [3, PEG~15(OH)4, Mn ~ 797] react directly with phenyl-C61-butyric acid methyl ester (PCBM), in the presence of dibutyltinoxide (DBTO) catalyst at 140oC, to give a mixture of fullerene [C60] end capped PEGs via transesterif...

Separation processes play a remarkable role in the chemical and pharmaceutical industries, where they account for 40-70% of both capital and operating costs.1 Organic syntheses in the chemical and pharmaceutical industry are frequently performed in organic solvents and consist of products with high added value that should be removed from the organi...

Reducing solvent consumption in the chemical industries is increasingly becoming a topic of interest. The field of organic solvent nanofiltration (OSN) has markedly evolved in the past decade, and effective membranes are now available that can withstand aggressive solvents while completely rejecting small solutes at the lower end of the nanofiltrat...

Downstream processing accounts for a large fraction of the production costs in pharmaceutical manufacturing. Organic solvent nanofiltration performed in a membrane cascade offers an interesting possibility for a continuous downstream processing unit operation. This work demonstrates continuous purification of Active Pharmaceutical Ingredient (API)...

A new strategy to access highly monodisperse, heterobifunctional linear polyethylenglycols (PEGs) has been designed. This was built around unidirectional, iterative chain extension of a 3-arm PEG homostar. A mono-(4,4′-dimethoxytriphenylmethyl) octagol building block, DmtrO-EG8-OH, was constructed from tetragol. After six rounds of chain extension,...

Organic solvent nanofiltration (OSN) membranes with ultrathin separation layers down to 35 nm in thickness fabricated from a polymer of intrinsic microporosity (PIM-1) are presented. These membranes exhibit exceptionally fast permeation of n-heptane with a rejection for hexaphenylbenzene of about 90%. A 35 nm thick PIM-1 membrane possesses a Young'...

Can Organic Solvent Nanofiltration (OSN) be considered green? Is OSN greener than other downstream processing technologies? These are the two main questions addressed critically in the present review. Further questions dealt with in the review are as follows: What is the carbon footprint associated with the fabrication and disposal of membrane modu...

For thin film composite (TFC) reverse osmosis (RO) membranes, a trade-off is evident between water permeance and salt rejection; and yet to improve their RO performance it is desirable to increase flux without sacrificing selectivity. This paper describes the fabrication of polyamide TCF membranes on highly solvent stable cross-linked polyimide UF...

Variation of the electronic nature of the tetraphenylcyclopentadienone ligand in organoruthenium complexes influences their utility for racemisation of model chiral amines. Our study highlights the need to balance reactivity and selectivity in the design of racemisation catalysts. Electron-poor Shvo-type catalysts are, at first sight, more effectiv...

Hybrid polymer/metal organic framework (MOF) membranes have been prepared using either a mixed matrix membrane (MMM) or in situ growth (ISG) approach and were evaluated for application in organic solvent nanofiltration (OSN). MMMs were produced by dispersing pre-formed particles of the MOF HKUST-1 in polyimide P84 dope solutions. MMMs demonstrated...

Organic solvent nanofiltration (OSN) is suggested as a method for enhancing crystallization in the pharmaceutical industry. OSN crystallization has the potential to reduce energy and/or chemical inputs and allows for control of process conditions and crystal morphology. This work focuses on the crystallization of the pharmaceutical compound griseof...

According to the present invention, there is provided a process for the preparation of a first compound selected from peptides, oligonucleotides and peptide nucleic acids. The process comprises synthesizing the first compound and then separating the first compound formed in step (i) from a second compound, which is a reaction by-product of the synt...

Highly monodisperse, heterobifunctional poly(ethylene glycol) (PEG) was prepared by iterative chain extension of a PEGylated homostar using an octagol (EG8) building block to give MeO–EG24–OH in high purity. The branched structure facilitated purification of intermediates by chromatography, and mono-functionalization of the chain termini. This appr...

If continuous processing is to be employed in pharmaceutical production, it is essential that continuous crystallization techniques can meet the purity and yield achievable in current batch crystallization processes. Recycling of mother liquor in steady state MSMPR crystallizations allows the yield in the equivalent equilibrium batch process to be...

Membrane processes suffer limitations such as low product yield and high solvent consumption, hindering their widespread application in the pharmaceutical and fine chemicals industries. In the present work, the authors propose an efficient purification methodology employing a two-stage cascade configuration coupled to an adsorptive solvent recovery...

The development of OSN Designer is presented: a software tool, which enables commercially available and open source suites of chemical process simulation software for organic solvent nanofiltration (OSN) process modelling and simulation. A modelling framework, comprising state of the art membrane transport models, membrane module flow dynamics, and...

For the development of thin film composite (TFC) OSN membranes the choice of the ultrafiltration (UP) support is as important as the selection of the separating layer. The support should be as smooth as possible (crucial to the formation of a defect free separating layer), and be stable in organic solvents. Other important support parameters that i...

Organic liquids are ubiquitous in chemical science based industries, which range in scale from refining to pharmaceutical production. It is generally accepted that 40-70% of capital and operating costs in these industries are dedicated to separations; and a substantial fraction of this cost is related to processing of organic liquids, both as produ...