Chemical and Biomolecular Engineering - Research Publications
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ItemInternal polymeric coating materials for preventing pipeline hydrogen embrittlement and a theoretical model of hydrogen diffusion through coated steel(PERGAMON-ELSEVIER SCIENCE LTD, 2022-08-26)This work develops a theoretical analysis of the coating permeability necessary for use as internal coatings of transmission pipelines to prevent hydrogen embrittlement. Internal coating materials suitable to be applied in situ on existing steel pipelines are also evaluated. Twelve different commercially available coatings; crosslinked poly (vinyl alcohol) (PVA), poly (vinyl chloride) and bisphenol A diglycidyl ether (DGEBA)/polyetheramine (D-400) epoxy coatings prepared in-house were tested. Films fabricated from two commercial epoxies had hydrogen permeability of 0.40 Barrer and 0.35 Barrer respectively, which show potential as coating materials. A hydrogen permeability of 0.0084 Barrer was achieved with a crosslinked poly (vinyl alcohol) coating, indicating that this material shows the highest potential of all coatings tested. Unsteady-state hydrogen diffusion through coated steel was then modeled to evaluate the effect of the coating film in reducing hydrogen embrittlement. The result shows that with a 2 mm PVA coating, hydrogen permeation inside the coating will take seven years to reach equilibrium and the final hydrogen concentration on the steel surface will be 44% lower than that without a coating. Greater protection can be provided if coatings can be developed with lower hydrogen permeability.
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ItemEfficient degumming of crude canola oil using ultrafiltration membranes and bio derived solvents(Elsevier BV, 2020-01-01)Vegetable oils derived from rapeseed and its genetic variant canola, are conventionally extracted from oilseeds by means of an organic solvent, typically hexane. Concerns regarding the toxicity of hexane have meant safer and more environmentally friendly solvents such as terpenes are becoming attractive. In this research, the degumming of canola oil/terpene mixtures using ultrafiltration is considered as a critical step in such an extraction process. Polysulfone (PSF) and polyethersulfone (PES) membranes were found to be ineffective in this application, as the oil appeared to cause swelling of the membrane structure. This meant that the original flux could not be restored after cleaning. Conversely, a ceramic membrane (MWCO 5 kDa) provided stable behaviour over several cycles of operation when cleaned with pure solvent at high cross velocity at 40 °C. This membrane showed high phospholipid retention (95 ± 2%), although some oil was also retained (16 ± 3%). Cymene emerged as the most attractive of the three terpenes tested, with higher permeate flux and phospholipid rejection than limonene or pinene.
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ItemOrganic solvent nanofiltration of binary vegetable oil/terpene mixtures: Experiments and modelling(ELSEVIER, 2019-03-01)Bio-derived solvents such as ρ-cymene, d-limonene and α-pinene represent feasible alternatives to n-11 hexane for the extraction of vegetable oils. However, the large-scale utilization of these solvents is 12 still limited mainly owing to their high boiling points and latent heats of vaporization. In this work, the 13 performance of composite polydimethylsiloxane/polyacrylonitrile (PDMS/PAN) organic solvent 14 nanofiltration membranes in the recovery of these solvents from their binary mixtures with canola oil 15 is investigated. The sorption isotherms of the mixtures were first studied using free-standing PDMS 16 films and the multicomponent Flory-Huggins model used to determine the resulting interaction 17 parameters. The partial solvent uptake decreased with increasing oil concentration in the mixture. On 18 the other hand, the partial oil uptake in the solvent mixture was higher than that of the pure oil which 19 was attributed to the swelling effects induced by solvents. The effects of feed concentration (10-30 20 wt. % oil), feed temperature (25-40 °C), transmembrane pressure (5-30 bar), and cross-flow velocity 21 (18-52 cm s-1) on the membrane performance were then studied in a cross-flow membrane setup. 22 Maxwell-Stefan formulations were combined with the ternary Flory-Huggins solubility model to 23 successfully describe these flux data.
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ItemTransport of terpenes through composite PDMS/PAN solvent resistant nanofiltration membranes(ELSEVIER SCIENCE BV, 2018-12-22)
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