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Keiko Sasaki - One of the best experts on this subject based on the ideXlab platform.
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adhesion of ferroplasma acidiphilum onto pyrite calculated from the extended DLVO Theory using the van oss good chaudhury approach
Journal of Colloid and Interface Science, 2010Co-Authors: Mohsen Farahat, Tsuyoshi Hirajima, Keiko SasakiAbstract:Abstract The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated experimentally and theoretically . F. acidiphilum showed high affinity to adhere to pyrite surface at acidic regions, however low affinity was observed at neutral and alkaline regions. The microbe–mineral adhesion was assessed by the extended DLVO Theory. Hamaker constants, electron donors, electron acceptors and surface charges for the microbe and the mineral were experimentally determined. The extended DLVO Theory was used to explain the adhesion results. Significant changes to the pyrite surface properties after being treated with the microbial cells were observed. Pyrite lost its hydrophobic nature and became hydrophilic, the contact angle of untreated pyrite was 61° and this decreased to 36° after the treatment. As a consequence, the flotation experiment results showed that F. acidiphilum strain could act as a good depressant for pyrite in xanthat flotation; where in absence of F. acidiphilum cells, over 95% of pyrite can be recovered as a float. However, when the mineral was pretreated with F. acidiphilum cells, less than 20% can be recovered as a float.
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Adhesion of Ferroplasma acidiphilum onto pyrite calculated from the extended DLVO Theory using the van Oss-Good-Chaudhury approach.
Journal of colloid and interface science, 2010Co-Authors: Mohsen Farahat, Tsuyoshi Hirajima, Keiko SasakiAbstract:The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated experimentally and theoretically. F. acidiphilum showed high affinity to adhere to pyrite surface at acidic regions, however low affinity was observed at neutral and alkaline regions. The microbe-mineral adhesion was assessed by the extended DLVO Theory. Hamaker constants, electron donors, electron acceptors and surface charges for the microbe and the mineral were experimentally determined. The extended DLVO Theory was used to explain the adhesion results. Significant changes to the pyrite surface properties after being treated with the microbial cells were observed. Pyrite lost its hydrophobic nature and became hydrophilic, the contact angle of untreated pyrite was 61 degrees and this decreased to 36 degrees after the treatment. As a consequence, the flotation experiment results showed that F. acidiphilum strain could act as a good depressant for pyrite in xanthat flotation; where in absence of F. acidiphilum cells, over 95% of pyrite can be recovered as a float. However, when the mineral was pretreated with F. acidiphilum cells, less than 20% can be recovered as a float.
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adhesion of escherichia coli onto quartz hematite and corundum extended DLVO Theory and flotation behavior
Colloids and Surfaces B: Biointerfaces, 2009Co-Authors: Mohsen Farahat, Tsuyoshi Hirajima, Keiko Sasaki, Katsumi DoiAbstract: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 x 10(9)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.
Sharon L Walker - One of the best experts on this subject based on the ideXlab platform.
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effect of hydration repulsion on nanoparticle agglomeration evaluated via a constant number monte carlo simulation
Nanotechnology, 2015Co-Authors: Sharon L Walker, Jacob Lanphere, Yoram CohenAbstract:The effect of hydration repulsion on the agglomeration of nanoparticles in aqueous suspensions was investigated via the description of agglomeration by the Smoluchowski coagulation equation using constant number Monte?Carlo simulation making use of the classical DLVO Theory extended to include the hydration repulsion energy. Evaluation of experimental DLS measurements for TiO2, CeO2, SiO2, and ?-Fe2O3 (hematite) at high IS (up to 900 mM) or low |?-potential| (?1.35 mV) demonstrated that hydration repulsion energy can be above electrostatic repulsion energy such that the increased overall repulsion energy can significantly lower the agglomerate diameter relative to the classical DLVO prediction. While the classical DLVO Theory, which is reasonably applicable for agglomeration of NPs of high |?-potential| (?>35 mV) in suspensions of low IS (?<1 mM), it can overpredict agglomerate sizes by up to a factor of 5 at high IS or low |?-potential|. Given the potential important role of hydration repulsion over a range of relevant conditions, there is merit in quantifying this repulsion energy over a wide range of conditions as part of overall characterization of NP suspensions. Such information would be of relevance to improved understanding of NP agglomeration in aqueous suspensions and its correlation with NP physicochemical and solution properties.
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escherichia coli o157 h7 transport in saturated porous media role of solution chemistry and surface macromolecules
Environmental Science & Technology, 2009Co-Authors: Hyunjung Kim, Scott A Bradford, Sharon L WalkerAbstract:The transport and deposition behavior of Escherichia coli O157:H7 was investigated in saturated packed-bed columns and micromodel systems over a range of ionic strength (IS) (1, 10, and 100 mM) and pH (5.8, 8.4, and 9.2) conditions. At a given IS, elevated solution pH resulted in decreased deposition as a result of the increase in the measured zeta potential of the quartz sand. This deposition trend was consistent with predictions from classic Derjaguin−Landau−Verwey−Overbeek (DLVO) Theory. Conversely, the E. coli O157:H7 deposition was inversely proportional to IS (1−100 mM) at high pH conditions (8.4 and 9.2), whereas no effect of IS was observed at pH 5.8. This deposition trend was not consistent with DLVO Theory, but could be explained by pH-associated electrosteric stabilization. This phenomenon is driven by the pH-dependent protonated state of functional groups on E. coli O157:H7 surface macromolecules and the corresponding conformational state of the bacterial polymers. Results from this study de...
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role of cell surface lipopolysaccharides in escherichia coli k12 adhesion and transport
Langmuir, 2004Co-Authors: Sharon L Walker, Jeremy A Redman, Menachem ElimelechAbstract:The influence of bacterial surface lipopolysaccharides (LPS) on cell transport and adhesion has been examined by use of three mutants of Escherichia coli K12 with well-characterized LPS of different lengths and molecular composition. Two experimental techniques, a packed-bed column and a radial stagnation point flow system, were employed to investigate bacterial adhesion kinetics onto quartz surfaces over a wide range of solution ionic strengths. Although the two systems capture distinct deposition (adhesion) mechanisms because of their different hydrodynamics, similar deposition kinetics trends were observed for each bacterial strain. Bacterial deposition rates were directly related to the electrostatic double layer interaction between the bacteria and quartz surfaces, in qualitative agreement with classic Derjaguin−Landau−Verwey−Overbeek (DLVO) Theory. However, DLVO Theory does not fully explain the deposition behavior for the bacterial strain with the lengthy, uncharged O-antigen portion of the LPS. Ne...
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role of cell surface lipopolysaccharides in escherichia coli k12 adhesion and transport
Langmuir, 2004Co-Authors: Sharon L Walker, Jeremy A Redman, Menachem ElimelechAbstract:The influence of bacterial surface lipopolysaccharides (LPS) on cell transport and adhesion has been examined by use of three mutants of Escherichia coli K12 with well-characterized LPS of different lengths and molecular composition. Two experimental techniques, a packed-bed column and a radial stagnation point flow system, were employed to investigate bacterial adhesion kinetics onto quartz surfaces over a wide range of solution ionic strengths. Although the two systems capture distinct deposition (adhesion) mechanisms because of their different hydrodynamics, similar deposition kinetics trends were observed for each bacterial strain. Bacterial deposition rates were directly related to the electrostatic double layer interaction between the bacteria and quartz surfaces, in qualitative agreement with classic Derjaguin-Landau-Verwey-Overbeek (DLVO) Theory. However, DLVO Theory does not fully explain the deposition behavior for the bacterial strain with the lengthy, uncharged O-antigen portion of the LPS. Neither the length nor the charge characteristics of the LPS molecule directly correlated to deposition kinetics, suggesting a complex combination of cell surface charge heterogeneity and LPS composition controls the bacterial adhesive characteristics. It is further suggested that bacterial deposition behavior is determined by the combined influence of DLVO interactions, LPS-associated chemical interactions, and the hydrodynamics of the deposition system.
Mohsen Farahat - One of the best experts on this subject based on the ideXlab platform.
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adhesion of ferroplasma acidiphilum onto pyrite calculated from the extended DLVO Theory using the van oss good chaudhury approach
Journal of Colloid and Interface Science, 2010Co-Authors: Mohsen Farahat, Tsuyoshi Hirajima, Keiko SasakiAbstract:Abstract The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated experimentally and theoretically . F. acidiphilum showed high affinity to adhere to pyrite surface at acidic regions, however low affinity was observed at neutral and alkaline regions. The microbe–mineral adhesion was assessed by the extended DLVO Theory. Hamaker constants, electron donors, electron acceptors and surface charges for the microbe and the mineral were experimentally determined. The extended DLVO Theory was used to explain the adhesion results. Significant changes to the pyrite surface properties after being treated with the microbial cells were observed. Pyrite lost its hydrophobic nature and became hydrophilic, the contact angle of untreated pyrite was 61° and this decreased to 36° after the treatment. As a consequence, the flotation experiment results showed that F. acidiphilum strain could act as a good depressant for pyrite in xanthat flotation; where in absence of F. acidiphilum cells, over 95% of pyrite can be recovered as a float. However, when the mineral was pretreated with F. acidiphilum cells, less than 20% can be recovered as a float.
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Adhesion of Ferroplasma acidiphilum onto pyrite calculated from the extended DLVO Theory using the van Oss-Good-Chaudhury approach.
Journal of colloid and interface science, 2010Co-Authors: Mohsen Farahat, Tsuyoshi Hirajima, Keiko SasakiAbstract:The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated experimentally and theoretically. F. acidiphilum showed high affinity to adhere to pyrite surface at acidic regions, however low affinity was observed at neutral and alkaline regions. The microbe-mineral adhesion was assessed by the extended DLVO Theory. Hamaker constants, electron donors, electron acceptors and surface charges for the microbe and the mineral were experimentally determined. The extended DLVO Theory was used to explain the adhesion results. Significant changes to the pyrite surface properties after being treated with the microbial cells were observed. Pyrite lost its hydrophobic nature and became hydrophilic, the contact angle of untreated pyrite was 61 degrees and this decreased to 36 degrees after the treatment. As a consequence, the flotation experiment results showed that F. acidiphilum strain could act as a good depressant for pyrite in xanthat flotation; where in absence of F. acidiphilum cells, over 95% of pyrite can be recovered as a float. However, when the mineral was pretreated with F. acidiphilum cells, less than 20% can be recovered as a float.
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adhesion of escherichia coli onto quartz hematite and corundum extended DLVO Theory and flotation behavior
Colloids and Surfaces B: Biointerfaces, 2009Co-Authors: Mohsen Farahat, Tsuyoshi Hirajima, Keiko Sasaki, Katsumi DoiAbstract: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 x 10(9)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.
Ned Djilali - One of the best experts on this subject based on the ideXlab platform.
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predicting the interaction between nanoparticles in shear flow using lattice boltzmann method and derjaguin landau verwey overbeek DLVO Theory
Physics of Fluids, 2020Co-Authors: Mohammad Rahnama, Ned DjilaliAbstract:The functionality and performance of colloidal suspensions used in catalyst layer preparation and biomedical applications are largely dependent on the interaction between nanoparticles in colloidal suspension systems. Previous models (e.g., collision model) usually rely on an artificial repulsive force as the sole interaction between nanoparticles to prevent overlapping, but fail to capture the agglomeration or reveal the effect of solvents. In this study, the Derjaguin–Landau–Verwey–Overbeek (DLVO) Theory is implemented in conjunction with a lattice Boltzmann-smoothed profile method developed to simulate the dynamic solid–fluid and particle–particle interactions between nanoparticles in shear flow. Both aqueous and non-aqueous solvents are considered. The model consists of an attractive van der Waals force and repulsive electrostatic and Born forces in aqueous solvents and is modified for non-aqueous solvents by replacing the repulsive electrostatic force by Coulombic repulsion. The numerical model is validated against a benchmark analytic solution for the motion of one nanoparticle in shear flow. For two-particle systems, physically representative simulations are obtained with the DLVO models, resulting in nanoparticles that remain attached or eventually detach depending on a critical particle Reynolds number. Furthermore, the DLVO models properly resolve the effect of solvents on nanoparticle motion. The improved representation of inter-particle interactions achieved with the DLVO and modified-DLVO models provides a physically consistent approach to simulate and investigate agglomeration and dispersion in colloidal suspensions.
I Plaza - One of the best experts on this subject based on the ideXlab platform.
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humic acid adsorption and its role in colloidal scale aggregation determined with the zeta potential surface free energy and the extended DLVO Theory
European Journal of Soil Science, 2017Co-Authors: J Calero, A Ontiverosortega, V Aranda, I PlazaAbstract:Summary The effect of colloidal forces involved in the adsorption of commercial humic acids (HAs) and particle cohesion was studied in the soil of an organic olive grove with the extended Derjaguin, Landau, Verwey and Overbeek (extended-DLVO) Theory. Total interaction energy was determined from the zeta potential (ζ) and surface free energy, measured under different experimental conditions [natural and hydrogen peroxide (H2O2) organic matter-free mineral surfaces]. The soil was clayey, dominated by illite and vermiculite. It showed electron-donor behaviour, with negatively charged surfaces and zeta potential 2.5 mg C g−1). Because the isotherms showed no relation with temperature, adsorption would be better attributed to weak physical interactions. On natural surfaces with HA, soil particle attraction forces increased slightly (≈50 kT) through decreasing soil wettability. However, this effect on total surface energy was overcome largely by increasing electrostatic repulsive energy caused by the adsorption of negatively charged HA (> 300 kT). The DLVO-extended model showed that natural surfaces without H2O2 treatment or added HA seem to be the most favourable state for colloidal aggregate stability. We recommend some caution about the type and quality of organic matter added to increase organic carbon in soil. Highlights We applied the extended DLVO model to study humic acid adsorption and its effects on soil structure. Adsorption on soil surfaces with their natural organic matter was mostly by weak physical forces. Adsorption increased the total particle interaction energy through an increase in electrostatic repulsion. Adsorption of some types of organic matter might decrease the colloidal stability of aggregates.