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488 results on '"Duke, Mikel"'

165. The fabrication and surface functionalization of porous metal frameworks – a review

Author

Dumée, Ludovic F., primary, He, Li, additional, Lin, Bao, additional, Ailloux, Francois-Marie, additional, Lemoine, Jean-Baptiste, additional, Velleman, Leonora, additional, She, Fenghua, additional, Duke, Mikel C., additional, Orbell, John D., additional, Erskine, Gilbert, additional, Hodgson, Peter D., additional, Gray, Stephen, additional, and Kong, Lingxue, additional

Published
2013
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166. Hybrid Processes Combining Photocatalysis and Ceramic Membrane Filtration for Degradation of Humic Acids in SalineWater.

Author

Lili Song, Bo Zhu, Gray, Stephen, Duke, Mikel, and Muthukumaran, Shobha

Subjects
HUMIC acid, ACIDS, MEMBRANE separation, FILTERS & filtration, CATALYSIS
Abstract

This study explored the combined effects of photocatalysis with ceramic membrane filtration for the removal of humic acid in the presence of salt; to simulate saline wastewater conditions. The effects of operating parameters, such as salinity and TiO2 concentration on permeate fluxes, total organic carbon (TOC), and UV absorbance removal, were investigated. The interaction between the humic acids and TiO2 photocatalyst played an important role in the observed flux change during ceramic membrane filtration. The results for this hybrid system showed that the TOC removal was more than 70% for both without NaCl and with the 500 ppm NaCl concentration, and 62% and 66% for 1000 and 2000 ppm NaCl concentrations. The reduction in UV absorbance was more complete in the absence of NaCl compared to the presence of NaCl. The operation of the integrated photoreactor-ceramic membrane filter over five repeat cycles is described. It can be concluded that the overall removal performance of the hybrid system was influenced by the presence of salts, as salt leads to agglomeration of TiO2 particles by suppressing the stabilising effects of electrostatic repulsion and thereby reduces the effective surface contact between the pollutant and the photocatalyst. [ABSTRACT FROM AUTHOR]

Published
2016
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189. Properties of acid whey as a function of pH and temperature.

Author

Chandrapala, Jayani, Duke, Mikel C., Gray, Stephen R., Zisu, Bogdan, Weeks, Mike, Palmer, Martin, and Vasiljevic, Todor

Subjects
*WHEY, *HYDROGEN-ion concentration, *CALCIUM, *PHOSPHATES, *PROTEIN research, *LACTIC acid, *DENATURATION of proteins
Abstract

Compositional differences of acid whey (AW) in comparison with other whey types limit its processability and application of conventional membrane processing. Hence, the present study aimed to identify chemical and physical properties of AW solutions as a function of pH (3 to 10.5) at 4 different temperatures (15, 25, 40, or 90°C) to propose appropriate membrane-processing conditions for efficient use of AW streams. The concentration of minerals, mainly calcium and phosphate, and proteins in centrifuged supernatants was significantly lowered with increase in either pH or temperature. Lactic acid content decreased with pH decline and rose at higher temperatures. Calcium appeared to form complexes with phosphates and lactates mainly, which in turn may have induced molecular attractions with the proteins. An increase in pH led to more soluble protein aggregates with large particle sizes. Surface hydrophobicity of these particles increased significantly with temperature up to 40°C and decreased with further heating to 90°C. Surface charge was clearly pH dependent. High lactic acid concentrations appeared to hinder protein aggregation by hydrophobic interactions and may also indirectly influence protein denaturation. Processing conditions such as pH and temperature need to be optimized to manipulate composition, state, and surface characteristics of components of AW systems to achieve an efficient separation and concentration of lactic acid and lactose. [ABSTRACT FROM AUTHOR]

Published
2015
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190. Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H2 concentrations.

Author

Zheng, Hang, Zeng, Raymond J., Duke, Mikel C., O'Sullivan, Cathryn A., and Clarke, William P.

Abstract

ABSTRACT It is well established that metabolic pathways in the fermentation of organic waste are primarily controlled by dissolved H2 concentrations, but there is no reported study that compares observed and predicted shifts in fermentation pathways induced by manipulating the dissolved H2 concentration. A perfusion system is presented that was developed to control dissolved H2 concentrations in the continuous fermentation of glucose by a culture highly enriched towards Thermoanaerobacterium thermosaccharolyticum (86 ± 9% relative abundance) from an originally diverse consortia in the leachate of a laboratory digester fed with municipal solid waste. Media from a 2.5 L CSTR was drawn through sintered steel membrane filters to retain biomass, allowing vigorous sparging in a separate chamber without cellular disruption. Through a combination of sparging and variations in glucose feeding rate from 0.8 to 0.2 g/L/d, a range of steady state fermentations were performed with dissolved H2 concentrations as low as an equivalent equilibrated H2 partial pressure of 3 kPa. Trends in product formation rates were simulated using a H2 regulation partitioning model. The model correctly predicted the direction of products redistribution in response to H2 concentration changes and the acetate and butyrate formation rates when H2 concentrations were less than 6 kPa. However, the model over-estimated acetate, ethanol and butanol productions at the expense of butyrate production at higher H2 concentrations. The H2 yield at the lowest dissolved H2 concentration was 2.67 ± 0.08 mol H2/mol glucose, over 300% higher than the yield achieved in a CSTR operated without sparging. Biotechnol. Bioeng. 2015;112: 1177-1186. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Published
2015
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