School of Chemistry - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 17
-
Item
-
ItemMechanisms for the ultrasonic enhancement of dairy whey ultrafiltration(ELSEVIER SCIENCE BV, 2005-08-01)
-
ItemThe use of ultrasonic cleaning for ultrafiltration membranes in the dairy industry(ELSEVIER SCIENCE BV, 2004-10-01)
-
ItemMinimising oil droplet size using ultrasonic emulsification(ELSEVIER, 2009-08-01)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.
-
ItemTHE FUNDAMENTALS OF POWER ULTRASOUND - A REVIEW(SPRINGER SINGAPORE PTE LTD, 2011-08-01)
-
ItemSpray Assembled, Cross-Linked Polyelectrolyte Multilayer Membranes for Salt Removal(AMER CHEMICAL SOC, 2014-07-29)The present study reports the synthesis of spray-coated cross-linked polyelectrolyte multilayer membranes. Membrane cross-linking was performed using alkyne-azide "click" chemistry, where alkyne and azide functional groups were used to modify the poly(acrylic acid) (PAA) and the poly(allylamine) hydrochloride (PAH) polyelectrolytes. The results demonstrate that deposition at lower ionic strength produced smoother and denser membrane structures. Pore size analysis using neutral poly(ethylene glycol) revealed a decrease in the membrane pore size as the degree of cross-linking was increased, resulting in the membrane rejecting divalent CaCl2 at levels of up to 80%, and 50% rejection of monovalent NaCl. When poly(sodium-4-styrenesulfonate) (PSS) was combined with small amounts of cross-linkable PAA, significant flux increases were observed in the multilayer membranes with no observable reduction in ion rejection.
-
ItemNo Preview AvailableSurface Engineering of Polypropylene Membranes with Carbonic Anhydrase-Loaded Mesoporous Silica Nanoparticles for Improved Carbon Dioxide Hydration(AMER CHEMICAL SOC, 2015-06-09)Carbonic anhydrase (CA) is a native enzyme that facilitates the hydration of carbon dioxide into bicarbonate ions. This study reports the fabrication of thin films of active CA enzyme onto a porous membrane substrate using layer-by-layer (LbL) assembly. Deposition of multilayer films consisting of polyelectrolytes and CA was monitored by quartz crystal microgravimetry, while the enzymatic activity was assayed according to the rates of p-nitrophenylacetate (p-NPA) hydrolysis and CO2 hydration. The fabrication of the films onto a nonporous glass substrate showed CO2 hydration rates of 0.52 ± 0.09 μmol cm(-2) min(-1) per layer of bovine CA and 2.6 ± 0.7 μmol cm(-2) min(-1) per layer of a thermostable microbial CA. The fabrication of a multilayer film containing the microbial CA on a porous polypropylene membrane increased the hydration rate to 5.3 ± 0.8 μmol cm(-2) min(-1) per layer of microbial CA. The addition of mesoporous silica nanoparticles as a film layer prior to enzyme adsorption was found to increase the activity on the polypropylene membranes even further to a rate of 19 ± 4 μmol cm(-2) min(-1) per layer of microbial CA. The LbL treatment of these membranes increased the mass transfer resistance of the membrane but decreased the likelihood of membrane pore wetting. These results have potential application in the absorption of carbon dioxide from combustion flue gases into aqueous solvents using gas-liquid membrane contactors.
-
ItemNo Preview AvailableMembranes: chlorine resistant glutaraldehyde crosslinked polyelectrolyte multilayer membranes for desalination (adv. Mater. 17/2015).(Wiley, 2015-05)Novel membranes are fabricated for use in desalination and water purification applications by F. Caruso, S. E. Kentish, and co-workers, described on page 2791. The crosslinked polyelectrolyte multilayer membranes are synthesized on a porous polysulfone support within aqueous media and are crosslinked with glutaraldehyde. This leads to NaCl rejections of up to 97%. The incorporation of a highly sulfonated polysulfone polyanion results in outstanding chlorine resistance.
-
ItemChlorine Resistant Glutaraldehyde Crosslinked Polyelectrolyte Multilayer Membranes for Desalination(WILEY-V C H VERLAG GMBH, 2015-05-06)Crosslinked polyelectrolyte multilayer membranes are synthesized with salt rejection values approaching those of commercial desalination membranes, but with increased chlorine resistance. The membranes are fabricated directly onto porous commercial substrates. Subsequent crosslinking of the polycation layers with glutaraldehyde leads to NaCl rejections of up to 97%, while the incorporation of a highly sulfonated polysulfone polyanion leads to high chlorine resistance.
-
ItemNo Preview AvailableClick poly(ethylene glycol) multilayers on RO membranes: Fouling reduction and membrane characterization(ELSEVIER SCIENCE BV, 2012-08-01)