Engineering and Information Technology Collected Works - Research Publications
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ItemGas separation performance of copolymers of perfluoro(butenyl vinyl ether) and perfluoro(2,2-dimethyl-1,3-dioxole)(Elsevier BV, 2021-09)Amorphous glassy perfluorinated polymers have high gas permeability, are chemically inert, thermally stable and known for their superior separation performance for several gas pairs. In the current study, the gas separation performance of copolymers of perfluoro(butenyl vinyl ether) (PBVE) and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) with two different monomer ratios, commercially known as CyclAFlor™, was studied for the first time, both at 35 °C and at higher temperatures below their glass transition temperature. For comparison, the temperature dependence of Cytop® (a homopolymer of PBVE) was studied. The higher the mole percentage of PBVE, the lower gas permeability and the higher selectivity for all gas pairs of interest. All permeability coefficients in Cytop® were lower than those reported in the literature except for helium and hydrogen due to the annealing protocol used, enhancing He/gas and H2/gas selectivity. The poly(PBVE-co-PDD) copolymers exhibited separation performance in the vicinity of the Robeson 2008 upper bound for many gas pairs, including He/H2, He/CH4, He/N2 and N2/CH4. In particular, poly(50%PBVE-co-50%PDD) was more permeable than Hyflon® AD 60 but more selective for most gas pairs of interest. Both copolymers showed increasing H2/CO2 selectivity with temperature. While permeability was stable with pressure up to 10 bar at 35 °C, a change in the activation energy of permeation of CO2 at higher temperatures suggested that changes to the polymer structure had occurred, possibly reducing the glass transition temperature. Mixed gas measurements confirmed the suitability of CyclAFlor™ copolymers for CO2/CH4 separation compared to Cytop.
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ItemEngineering Principles of Ultrasound Technology(Elsevier, 2017-07-01)The book also contains how the technology could be launched in industry. Part I discusses ultrasound for food preservation, with topics like advances on thermo-sonication and nanothermosonication. This Chapter describes how ultrasonic waves are formed in ultrasonic baths, with horn transducers and in other acoustic devices. The range of acoustic frequencies and powers relevant to sonoprocessing are outlined. The concept of acoustic cavitation is explained as the formation of a field of small bubbles within a liquid exposed to ultrasound. It is the repetitive collapse of these bubbles under the influence of the acoustic field that is the dominant cause of most effects used in food processing, as it causes fluid turbulence and microjetting. The extent to which it is effective is a function of the system temperature and pressure, as well as fluid properties such as the surface tension, density and viscosity. The concept of acoustic nebulisation, which is the formation of a fine mist, is also explained.
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ItemIsolation of lactoferrin and immunoglobulins from dairy whey by an electrodialysis with filtration membrane process(Elsevier, 2020-02-15)Isolation of high value minor proteins such as lactoferrin and immunoglobulins from crude dairy streams is a major challenge for the dairy industry. Here we investigate an electrodialysis with filtration membrane (EDFM) approach to separate lactoferrin (LF) and immunoglobulins (Ig) from other dairy proteins. A polyvinyl alcohol (PVA) membrane is prepared using phase inversion in a coagulation bath with 80% ethanol to serve as the filtration membrane. A range of treatment times and two electric field strengths (38.5 and 77 V/cm) were then investigated within the electrical cell. The results show that the filtration membrane prepared in-house can offer strong rejection for LF and Ig while allowing a high flux of other proteins. The separation of LF and Ig from a simulated whey solution can be achieved. The use of a partially demineralised whey reduces protein loss, but there is a tradeoff between the energy consumption and the protein removal rate as the extent of this demineralisation is increased.
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Item110th Anniversary: Process Developments in Carbon Dioxide Capture Using Membrane Technology(American Chemical Society, 2019-07-17)Carbon capture and storage has declined in prominence as a large scale response to climate change, but carbon dioxide capture will remain important into the future for the hydrogen economy, and for steel and cement as well as chemical production. Membrane technology can be a significant component of this industry if it is cost competitive. While most scientific research is focused on developing novel materials for this application, it is the process design of the membrane operations that is much more critical in reducing these costs. In postcombustion capture, this involves optimization of the pressure driving force across the membrane, either through feed compression or permeate vacuum pumping, integration of downstream cryogenic purification, and the use of combustion air sweeps. In precombustion capture, integration of the membrane into the steam reformer or water gas shift reactor is key. Membrane contactors can also play a role but must be carefully engineered to ensure pressure drop control and to minimize capillary condensation of water.
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ItemMembrane Separations in the Dairy Industry(Academic Press, 2019-03-15)Membrane filtration is widely used in the dairy industry. This chapter provides an overview of the various applications of reverse osmosis, nanofiltration, ultrafiltration, and microfiltration in the processing of milk, and dairy waste streams. A summary of milk composition and chemistry is provided in relation to membrane processing. Applications of membrane filtration in milk processing are then discussed, including on-farm concentration of milk, removal of microorganisms, and fractionation of protein and fat. Coverage also includes the use of membranes for standardizing the composition of cheese milk, processing and concentration of whey and whey proteins, and purification and treatment of dairy wastes. Recent progress in the understanding of flux decline and fouling in dairy membrane filtration is outlined, along with the potential application of ultrasound.
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ItemMEMBRANE TECHNOLOGY Embedded enzymes catalyse capture(NATURE PUBLISHING GROUP, 2018-05)
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ItemSolubility of Calcium Phosphate in Concentrated Dairy Effluent Brines(AMER CHEMICAL SOC, 2017-05-24)The solubility of calcium phosphate in concentrated dairy brine streams is important in understanding mineral scaling on equipment, such as membrane modules, evaporators, and heat exchangers, and in brine pond operation. In this study, the solubility of calcium phosphate has been assessed in the presence of up to 300 g/L sodium chloride as well as lactose, organic acids, and anions at 10, 30, and 50 °C. As a neutral molecule, lactose has a marginal but still detectable effect upon calcium solubility. However, additions of sodium chloride up to 100 g/L result in a much greater increase in calcium solubility. Beyond this point, the concentrations of ions in the solution decrease significantly. These changes in calcium solubility can readily be explained through changes in the activity coefficients. There is little difference in calcium phosphate speciation between 10 and 30 °C. However, at 50 °C, the ratio of calcium to phosphate in the solution is lower than at the other temperatures and varies less with ionic strength. While the addition of sodium lactate has less effect upon calcium solubility than sodium citrate, it still has a greater effect than sodium chloride at an equivalent ionic strength. Conversely, when these organic anions are present in the solution in the acid form, the effect of pH dominates and results in much higher solubility and a calcium/phosphate ratio close to one, indicative of dicalcium phosphate dihydrate as the dominant solid phase.
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ItemMinimising oil droplet size using ultrasonic emulsification(ELSEVIER, 2009-08)The efficient production of nanoemulsions, with oil droplet sizes of less than 100nm would facilitate the inclusion of oil soluble bio-active agents into a range of water based foods. Small droplet sizes lead to transparent emulsions so that product appearance is not altered by the addition of an oil phase. In this paper, we demonstrate that it is possible to create remarkably small transparent O/W nanoemulsions with average diameters as low as 40nm from sunflower oil. This is achieved using ultrasound or high shear homogenization and a surfactant/co-surfactant/oil system that is well optimised. The minimum droplet size of 40nm, was only obtained when both droplet deformability (surfactant design) and the applied shear (equipment geometry) were optimal. The time required to achieve the minimum droplet size was also clearly affected by the equipment configuration. Results at atmospheric pressure fitted an expected exponential relationship with the total energy density. However, we found that this relationship changes when an overpressure of up to 400kPa is applied to the sonication vessel, leading to more efficient emulsion production. Oil stability is unaffected by the sonication process.