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  • Journal article
    Shi B, Marchetti P, Peshev D, Zhang S, Livingston AGet 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
  • Journal article
    Mazlan NM, Marchetti P, Maples HA, Gu B, Karan S, Bismarck A, Livingston AGet 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

  • Journal article
    Klosowski MM, McGilvery CM, Li Y, Abellan P, Ramasse Q, Cabral JT, Livingston AG, Porter AEet 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.

  • Journal article
    Kim JF, Gaffney PRJ, Valtcheva IB, Williams G, Buswell AM, Anson MS, Livingston AGet 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.

  • Journal article
    Jimenez-Solomon M, Song Q, Jelfs K, Munoz-Ibanez M, Livingston AGet 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.

  • Journal article
    Shi B, Peshev D, Marchetti P, Zhang S, Livingston AGet al., 2016,

    Multi-scale modelling of OSN batch concentration with spiral-wound membrane modules using OSN Designer

    , Chemical Engineering Research & Design, Vol: 109, Pages: 385-396, ISSN: 1744-3563

    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.

  • Journal article
    Campbell J, Burgal JDS, Szekely G, Davies RP, Braddock DC, Livingston Aet al., 2016,

    Hybrid polymer/MOF membranes for Organic Solvent Nanofiltration (OSN): chemical modification and the quest for perfection

    , Journal of Membrane Science, Vol: 503, Pages: 166-176, ISSN: 1873-3123

    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 growth (ISG) of HKUST-1 within the pores of polyimide membranes. To improve the performances of ISG membranes, chemical modification was performed. Aryl carboxylic acid moieties were introduced to polyimide P84 ultrafiltration membranes allowing coordination of the HKUST-1 directly on to the polymer. Chemically modified ISG membranes outperformed non-modified ISG membranes in both solute retentions and permeance. Retentions of polystyrene solute in acetone were used to calculate theoretical pore size distributions for each of the membranes tested. It was found that the chemically modified ISG membrane had he narrowest calculated pore size distribution.

  • Conference paper
    Marchetti P, Shi B, Peshev D, Livingston AGet al., 2016,

    Membrane performance characterization and process prediction in OSN: Challenges, achievements and perspective

    , Pages: 104-105
  • Conference paper
    Jimenez-Solomon MF, Song Q, Jelfs KE, Munoz-Ibanez M, Livingston AGet al., 2016,

    Polymer nanofilms with enhanced microporosity by interfacial polymerisation for molecular separations

  • Book chapter
    Adi VSK, Cook M, Peeva LG, Livingston AG, Chachuat Bet al., 2016,

    Optimization of OSN Membrane Cascades for Separating Organic Mixtures

    , Editors: Kravanja, Bogataj, Publisher: ELSEVIER SCIENCE BV, Pages: 379-384
  • Journal article
    Marchetti P, Mechelhoff M, Livingston A, 2015,

    Tunable-porosity membranes from discrete nanoparticles

    , Scientific Reports, Vol: 5, ISSN: 2045-2322

    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 was highly permeable and able to withstand aggressive pH conditions beyond the range of available commercial membranes. The nanoparticles were found to coalesce to form a rubbery film when heated above their glass transition temperature (Tg). The retention properties of the novel membrane were strongly affected by charge repulsion, due to the negative charge of the hydroxyl functionalized nanoparticles. Porosity was tuned by annealing the membranes at different temperatures, below and above the nanoparticle Tg. This enabled fabrication of membranes with varying performance. Nanofiltration properties were achieved with a molecular weight cut-off below 500 g mol⁻¹ and a low fouling tendency. Interestingly, after annealing above Tg, memory of the interstitial spaces between the nanoparticles persisted. This memory led to significant water permeance, in marked contrast to the almost impermeable films cast from a solution of the same polymer.

  • Journal article
    Shi B, Marchetti P, Peshev D, Zhang S, Livingston Aet al., 2015,

    Performance of spiral-wound membrane modules in organic solvent nanofiltration – Fluid dynamics and mass transfer characteristics

    , Journal of Membrane Science, Vol: 494, Pages: 8-24, ISSN: 1873-3123
  • Journal article
    Mazlan NM, Peshev D, Livingston AG, 2015,

    Energy consumption for desalination - a comparison of forward osmosis with reverse osmosis, and the potential for perfect membranes

    , Desalination, Vol: 377, Pages: 138-151, ISSN: 0011-9164

    Reverse osmosis (RO) is now the most ubiquitous technology for desalination, with numerous seawater ROplants being built in water-stressed countries to complement existing water resources. Despite the developmentof highly permeable RO membranes, energy consumption remains a major contributor to total cost. Forward osmosis(FO) is receiving much attention as a potentially lower energy alternative to RO. However, the draw solution(DS) recovery step in FO requires significant energy consumption. The present study is a modellingapproach, simulating FO and RO desalination under various process conditions and process flow schemesusing the Aspen Plus environment. Results suggest that there is practically no difference in specific energy consumption(SEC) between standalone RO, and FO with nanofiltration (NF) DS recovery; this can be generalised forany pressure-driven membrane process used for the DS recovery stage in a hybrid FO process. Furthermore, evenif any or all of the membranes considered, FO, RO or NF, were perfect (i.e. had infinite permeance and 100%rejection), it would not change the SEC significantly. Hence, any advantage possessed by the FO with NF recoveryprocess derives from the lower fouling propensity of FO, which may reduce or eliminate the need for pretreatmentand chemical cleaning

  • Journal article
    Valtcheva IB, Marchetti P, Livingston AG, 2015,

    Crosslinked polybenzimidazole membranes for organic solvent nanofiltration (OSN): Analysis of crosslinking reaction mechanism and effects of reaction parameters

    , Journal of Membrane Science, Vol: 493, Pages: 568-579, ISSN: 0376-7388

    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 important for achieving higher degrees of crosslinking. A statistical approach based on Design of Experiments was used to identify the most significant parameters and interactions affecting the crosslinking reaction. High gain in weight and high bromine content after the reaction are expected to be indirectly related to membranes with high crosslinking degrees. Hence, these two responses were measured as a function of reaction temperature, reaction time, excess of DBX, concentration of DBX and reaction solvent (acetonitrile and toluene). All parameters were found to have a positive effect on both responses, and the reaction was found to be faster in acetonitrile than in toluene. All obtained results were statistically evaluated using Analysis of Variance, and a physical interpretation of the statistical models was attempted.Keywords Polybenzimidazole (PBI); Crosslinking reaction; Alkylation; Design of Experiments (DoE); Organic solvent nanofiltration (OSN)

  • Journal article
    Da Silva Burgal J, Peeva L, Marchetti P, Livingston Aet al., 2015,

    Controlling molecular weight cut-off of PEEK nanofiltration membranes using a drying method

    , Journal of Membrane Science, Vol: 493, Pages: 524-538, ISSN: 0376-7388

    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.

  • Journal article
    Gaffney PRJ, Kim JF, Valtcheva IB, Williams GD, Anson MS, Buswell AM, Livingston AGet al., 2015,

    Liquid-phase synthesis of 2′-methyl-RNA on a homostar support through organic-solvent nanofiltration

    , Chemistry-A European Journal, Vol: 21, Pages: 9535-9543, ISSN: 1521-3765

    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 industrial batch synthesis techniques. However, most reported LPOS strategies rely upon at least one precipitation per chain extension cycle to separate the growing oligonucleotide from reaction debris. Precipitation can be difficult to develop and control on an industrial scale and, because many precipitations would be required to prepare a therapeutic oligonucleotide, we contend that this approach is not viable for large-scale industrial preparation. We are developing an LPOS synthetic strategy for 2′-methyl RNA phosphorothioate that is more amenable to standard batch production techniques, using organic solvent nanofiltration (OSN) as the critical scalable separation technology. We report the first LPOS-OSN preparation of a 2′-Me RNA phosphorothioate 9-mer, using commercial phosphoramidite monomers, and monitoring all reactions by HPLC, 31P NMR spectroscopy and MS.

  • Journal article
    Marchetti P, Livingston AG, 2015,

    Predictive membrane transport models for Organic Solvent Nanofiltration: How complex do we need to be?

    , JOURNAL OF MEMBRANE SCIENCE, Vol: 476, Pages: 530-553, ISSN: 0376-7388
  • Journal article
    Yau HC, Bayazit MK, Gaffney PRJ, Livingston AG, Steinke JHG, Shaffer MSPet al., 2015,

    Synthesis and characterization of branched fullerene-terminated poly(ethylene glycol)s

    , POLYMER CHEMISTRY, Vol: 6, Pages: 1056-1065, ISSN: 1759-9954
  • Journal article
    Bismarck A, Li K, Livingston A, 2015,

    Editorial "Polymers for membrane applications"

    , REACTIVE & FUNCTIONAL POLYMERS, Vol: 86, Pages: 87-87, ISSN: 1381-5148
  • Conference paper
    Marchetti P, Mechelhoff M, Livingston AG, 2015,

    Tunable-porosity membranes for water treatment by discrete nanoparticle assembly

    , Pages: 196-197

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