Rheology of flocculated kaolinite dispersions

McFarlane A.J.,Addai-Mensah J.,Bremmell K. The Korean Society of Rheology 2005 Korea-Australia rheology journal Vol.17 No.4

Rheological characterisation of flocculated kaolinite pulps has been undertaken to elucidate particle interactions underpinning the dewatering behaviour induced by flocculation with polyethylene oxide (PEO), anionic polyacrylamide (PAM A) and their blends. Shear yield stress $(\tau_y)$ analysis indicated that polymer mediated particle interactions were markedly amplified upon shear of PEG based pulps. In contrast, PAM A based pulps showed a significant decrease in yield values upon shear. Steady stress measurements analysed using a modified Ellis model indicated subtle differences between the respective linear viscoelastic plateaus of the pulps. Furthermore, modified shear thinning behaviour was evident in PEG based pulps. Estimation of elastic and viscous moduli (G', G') was made using dynamic stress analysis for comparison with values determined from vane measurements. Despite a noticeable difference in the magnitude of G' between the two methods, similar trends indicating sheared PEG-based pulps to be more elastic than PAM based pulps, were observed. Floc microstructural observations obtained in support of rheological properties indicate that PEG flocculant induces significantly more compact particle aggregation within the clay pulps under shear consistent with the yield stress data, in contrast to PAM A, or indeed unsheared PEG based pulps. Consequentially, sheared PEG based pulps show significantly improved dewatering behaviour. The implications of the results, potential benefits and drawbacks of flocculation with PEG and PAM A are discussed with respect to improvements in current dewatering processes used in the minerals industry.

Rheology of flocculated kaolinite dispersions

J. Addai-Mensah,A.J. McFarlane,K. Bremmell 한국유변학회 2005 Korea-Australia rheology journal Vol.17 No.4

Rheological characterisation of flocculated kaolinite pulps has been undertaken to elucidate particle interactions underpinning the dewatering behaviour induced by flocculation with polyethylene oxide (PEO), anionic polyacrylamide (PAM A) and their blends. Shear yield stress (y) analysis indicated that polymer mediated particle interactions were markedly amplified upon shear of PEO based pulps. In contrast, PAM A based pulps showed a significant decrease in yield values upon shear. Steady stress measurements analysed using a modified Ellis model indicated subtle differences between the respective linear viscoelastic plateaus of the pulps. Furthermore, modified shear thinning behaviour was evident in PEO based pulps. Estimation of elastic and viscous moduli (G', G'') was made using dynamic stress analysis for comparison with values determined from vane measurements. Despite a noticeable difference in the magnitude of G' between the two methods, similar trends indicating sheared PEO-based pulps to be more elastic than PAM based pulps, were observed. Floc microstructural observations obtained in support of rheological properties indicate that PEO flocculant induces significantly more compact particle aggregation within the clay pulps under shear consistent with the yield stress data, in contrast to PAM A, or indeed unsheared PEO based pulps. Consequentially, sheared PEO based pulps show significantly improved dewatering behaviour. The implications of the results, potential benefits and drawbacks of flocculation with PEO and PAM A are discussed with respect to improvements in current dewatering processes used in the minerals industry.

Contrast in Life Histories of Exploited Fishes and Ecosystem Structures in Coastal Waters off West Canada and East Korea

Gordon A. McFarlane,장창익,Jacquelynne R. King,김수암,Richard J. Beamish,오재호 한국해양과학기술원 2009 Ocean science journal Vol.44 No.1

By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by shortlived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late- 1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations. By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by shortlived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late- 1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations.

Contrast in Life Histories of Exploited Fishes and Ecosystem Structures in Coastal Waters off West Canada and East Korea

McFarlane, Gordon A.,Zhang, Chang Ik,King, Jacquelynne R.,Kim, Su-Am,Beamish, Richard J.,Oh, Jae-Ho 한국해양학회 2009 Ocean science journal Vol.44 No.1

By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by shortlived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late-1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations.

Amorphous calcium silicate as a chemisorbent for phosphate

T. W. Lewis,D. C. Southam,A. J. McFarlane,J. H. Johnston 한국물리학회 2004 Current Applied Physics Vol.4 No.2-4

Amorphous calcium silicate (ACS), a novel silicate material developed as ller for use in paper manufacture, has shown ananity for the chemisorption of orthophosphate from an aqueous solution obeying a Freundlich isotherm. Removal eciencies ofup to 100% were achieved at environmental- and waste-scale concentrations of phosphate of between 0.01 and 100 mg P l. 1.Chemisorption studies indicated loadings up to 1.9 mmol HxPOð3. xÞ.4 g. 1 ACS were achievable. Kinetics studies comparing the rateof consumption of phosphate have shown that H2PO.4 is kinetically favoured and chemisorbed with higher loadings, and hencegreater eciency. This is a signicant improvement on other adsorbent-based methods for the removal of phosphate.

Calcium silicate-carbon nanotube composites

T. Borrmann,K. Edgar,J. L. Spencer,A. J. McFarlane,J. H. Johnston 한국물리학회 2004 Current Applied Physics Vol.4 No.2-4

Composites of calcium silicate and carbon nanotubes have been generated. The nanotubes are multi-walled and grow on catalytichematite particles, which have been deposited on the calcium silicate carrier previously. Randomly curled as well as straightnanotubes have been observed.The nano-structured calcium silicate crystallizes at the elevated temperature and reaction conditions used in the formation of thecarbon nanotubes. The silicate forms wollastonite, therefore reducing the high surface area of the amorphous material. Variouscarbon sources have been explored, which allow catalysis at lower temperatures.