Chemical and Biomolecular Engineering - Research Publications

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    Application of mechanistic modelling in membrane and fiber chromatography for purification of biotherapeutics - A review
    Qu, Y ; Baker, I ; Black, J ; Fabri, L ; Gras, SL ; Lenhoff, AM ; Kentish, SE (ELSEVIER, 2024-02-08)
    Mechanistic modelling is a simulation tool which has been effectively applied in downstream bioprocessing to model resin chromatography. Membrane and fiber chromatography are newer approaches that offer higher rates of mass transfer and consequently higher flow rates and reduced processing times. This review describes the key considerations in the development of mechanistic models for these unit operations. Mass transfer is less complex than in resin columns, but internal housing volumes can make modelling difficult, particularly for laboratory-scale devices. Flow paths are often non-linear and the dead volume is often a larger fraction of the overall volume, which may require more complex hydrodynamic models to capture residence time distributions accurately. In this respect, the combination of computational fluid dynamics with appropriate protein binding models is emerging as an ideal approach.
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    Composite nanofibrous membranes with two-dimensional ZIF-L and PVDF-HFP for CO2 separation
    Kim, S ; Hou, J ; Choudhury, NR ; Kentish, SE (ELSEVIER SCIENCE SA, 2024-01-15)
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    Equilibrium Sorption of Monovalent and Divalent Organic Ions in Anion Exchange Membranes
    Sim, SSG ; Wang, Q ; Kentish, SE ; Chen, GQ (AMER CHEMICAL SOC, 2023-11-15)
    Ion transport in ion exchange membranes (IEMs) involving weak electrolytes such as organic acid species can exhibit considerably different behavior compared to the transport of inorganic species, partly due to their pH-dependent dissociation behavior. In this work, the concentration-dependence of the equilibrium sorption of sodium co-ions and organic counterions in a strongly basic anion exchange membrane (AEM) is systematically studied for organic acids with one and two carboxylic acid groups, namely, lactic acid and tartaric acid, with the AEMs being equilibrated in organic salt solutions containing predominantly the highest valency of the organic ions. It is discovered that up to ∼28% of total lactic acid within the membrane phase exists as neutral lactic acid molecules and up to ∼30% of total tartaric acid exists as monovalent bitartrate ions, over the range of external salt concentration investigated (0.1-1 equiv/L). This indicates a shift in the acid dissociation equilibria from the external solution to the membrane phase, which appears to be more significant at higher salt concentrations. Our quantification of organic ion speciation in AEMs will contribute to future fundamental studies of organic ion transport in IEMs, enabling a rational design of polymer chemistry and development of electromembrane processes to maximize separation performance.
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    Electrical Conductivity of Pipeline Deposits Under Pressure and Their Impacts on Sales-Gas Pipeline Cathodic Protection Systems
    Macario, E ; Carroll, F ; Xu, X ; Brown, J ; Stella, D ; Kentish, SE (Society of Petroleum Engineers (SPE), 2023-10-11)
    Natural gas pipelines are critical for safe and efficient energy transport across large distances. To maintain operational safety, pipelines use cathodic protection systems that minimize the rate of external corrosion. This work characterizes the effects of black powder deposits, a widely experienced operational hazard across the natural gas industry, on the failure of pipeline cathodic protection systems due to electrical "shorting"of isolation devices. Black powder sludgy deposits from coal seam gas (CSG) pipelines were analyzed, revealing electrical conductivity values within the range of 580 to 5400 μS/cm when under pipeline pressure. These values were used to calculate the internal resistances of monolithic isolation joints (MIJs), a type of electrical isolation device, to show that electrical shorting (internal resistance of < 100 Ω) can occur for black powder sludgy deposit thicknesses in the range of millimeters. To reduce the frequency of such shorting events, it is recommended that upstream dehydration systems be designed to reduce carry-over of triethylene glycol (TEG), that internal nonconductive coatings be applied to isolation devices, and that these devices are installed in ways that facilitate regular cleaning.
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    Crosslinked PVA based polymer coatings with shear-thinning behaviour and ultralow hydrogen permeability to prevent hydrogen embrittlement
    Lei, Y ; Liu, L ; Scholes, CA ; Kentish, SE (Elsevier, 2024-02-07)
    An economic transition from natural gas to a hydrogen economy will require redeployment of steel pipelines and other infrastructure. Mechanisms are urgently needed to prevent embrittlement of the steel in hydrogen service. In this work, we show that poly vinyl alcohol (PVA) and poly (ethylene glycol) diglycidyl ether (PEGDGE) crosslinked polymer materials can be used as internal coatings to dramatically reduce hydrogen permeation to the steel surface. Unlike other crosslinked PVA systems, these materials are shear-thinning and thixotropic, which is an essential requirement for facile, in situ application onto existing infrastructure. A hydrogen permeability of 0.01 Barrer is achieved, which is up to 100 times lower than commercially available coating materials. Experiments show that increasing concentrations of the alkali catalyst (KOH) do not impact the permeability of the crosslinked films but can benefit the rheology by shortening the reaction time. Higher reaction ratios of PVA to PEGDGE give lower hydrogen permeability due to a higher degree of polymer crystallinity, but less favorable rheology due to slower reaction kinetics. PVA with higher molecular weight gives lower hydrogen permeability and promotes shear-thinning behaviour, while PEGDGE with higher molecular weight increased the film permeability but enhances the shear-thinning behavior with shorter reaction times.
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    The Transition from Resin Chromatography to Membrane Adsorbers for Protein Separations at Industrial Scale
    Qu, Y ; Bekard, I ; Hunt, B ; Black, J ; Fabri, L ; Gras, SLL ; Kentish, SEE (TAYLOR & FRANCIS INC, 2023-01-01)
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    Economic optimization of antibody capture through Protein A affinity nanofiber chromatography
    Qu, Y ; Bekard, I ; Hunt, B ; Black, J ; Fabri, L ; Gras, SL ; Kentish, SE (ELSEVIER, 2024-01)
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    Financial and environmental impacts of using oxygen rather than air as a ventilator drive gas
    Balmaks, E ; Kentish, SE ; Seglenieks, R ; Lee, JH ; McGain, F (WILEY, 2022-12)
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    The effect of pH on the fat and protein within cream cheese and their influence on textural and rheological properties
    Ong, L ; Pax, AP ; Ong, A ; Vongsvivut, J ; Tobin, MJ ; Kentish, SE ; Gras, SL (Elsevier BV, 2020-12-01)
    The effect of variation in acid gel pH during cream cheese production was investigated. The gel microstructure was denser and cheese texture firmer, as the pH decreased from pH 5.0 to pH 4.3, despite the viscoelasticity of these gels remaining similar during heating. Protein hydration and secondary structure appeared to be key factors affecting both cheese microstructure and properties. Proteins within the matrix appeared to swell at pH 5.0, leading to a larger corpuscular structure; greater β-turn structure was also observed by synchrotron-Fourier transform infrared (S-FTIR) microspectroscopy and the cheese was softer. A decrease in pH led to a denser microstructure with increased aggregated β-sheet structure and a firmer cheese. The higher whey protein loss at low pH likely contributed to increased cheese hardness. In summary, controlling the pH of acid gel is important, as this parameter affects proteins in the cheese, their secondary structure and the resulting cream cheese.
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    Effects of shredding on the functionality, microstructure and proteolysis of low-moisture mozzarella cheese
    Pax, AP ; Ong, L ; Kentish, SE ; Gras, SL (ELSEVIER SCI LTD, 2021-06)
    Low-moisture mozzarella cheese (LMMC) is commonly shredded before packaging, however, the effects of shredding are not fully understood. Industrially-produced block and shredded LMMC were studied during 8 weeks of storage at 4 °C. Cheese shredded on 15 d and at 8 weeks of age, coated with microcrystalline cellulose and stored in a modified atmosphere (70% N₂ and 30% CO₂), had an altered microstructure after 8 weeks compared with vacuum-packed block cheese. In the latter case the fat formed a more dispersed phase. Proteolysis was higher in shredded samples and a higher level of two bacterial proteases was detected. Despite these differences, the meltability and stretchability of the block and shredded LMMC were similar. The microstructure and functionality of cheese shredded at 15 d and stored for a further 6 weeks was similar to cheese shredded at 8 weeks, suggesting there is a flexible period for performing cheese shredding processes.