Adhesion of Escherichia coli onto quartz, hematite and corundum: Extended DLVO theory and flotation behavior |
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Authors: | Mohsen Farahat Tsuyoshi Hirajima Keiko Sasaki Katsumi Doi |
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Institution: | aDepartment of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan;bDepartment of Genetic Resources Technology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan |
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Abstract: | The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigated. A strain of E. coli was used that had the genes for expressing protein for silica precipitation. The maximum cell adhesion was observed at pH <4.3 for quartz and at pH 4.5–8.5 for corundum. For hematite, cell adhesion remained low at all pH values. The microbe–mineral adhesion was assessed by the extended DLVO theory approach. The essential parameters for calculation of microbe–mineral interaction energy (Hamaker constants and acid–base components) were experimentally determined. The extended DLVO approach could be used to explain the results of the adhesion experiments. The effect of E. coli on the floatability of three oxide minerals was determined and the results showed that E. coli can act as a selective collector for quartz at acidic pH values, with 90% of the quartz floated at 1.5 × 109 cells/ml. However, only 9% hematite and 30% corundum could be floated under similar conditions. By using E. coli and no reagents, it was possible to separate quartz from a hematite–quartz mixture with Newton's efficiency of 0.70. Removal of quartz from the corundum mixture was achieved by E. coli with Newton's efficiency of 0.62. |
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Keywords: | Adhesion Biosurface modification Extended DLVO theory Flotation Mineral processing |
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