Solution Chemistry

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K.m. Webb - One of the best experts on this subject based on the ideXlab platform.

  • An improved computer model of struvite Solution Chemistry.
    Talanta, 1992
    Co-Authors: T.j. Wrigley, William D. Scott, K.m. Webb
    Abstract:

    The computer model of the Solution Chemistry of struvite has been improved. Firstly, with ammonia as the prime calculation point in the liquid phase, the algorithm is smaller and faster. Secondly, the incorporation of distilled magnesium hydrogen phosphate in the model significantly increased the concentrations in Solution. Thirdly, estimates of the activity coefficients are included. These improvements have but a marginal (5–10%) improvement in the fit. However, proceeding with this flexible modelling procedure using the symbolic manipulator, Maple, easily allows the inclusion of all possible species. The addition of associated ammonium phosphates improves the fit. The relative standard deviation of the fit of both Taylor's data and the data of Webb is improved from 0.5 to 0.2. Estimates of the association constants are included.

  • A computer model of struvite Solution Chemistry
    Talanta, 1991
    Co-Authors: William D. Scott, T.j. Wrigley, K.m. Webb
    Abstract:

    A computer model is developed to describe struvite Solution Chemistry; this includes the electroneutrality equation and allows greater variability in the input components. Relationships between the major ions are retained without approximation. The model results fit data derived both in our laboratory and from the literature. Equilibrium constants which markedly affect the output are identified and solubility constants are derived. Applications of the model include studies of waste-water treatment and of the formation of kidney stones.

Sharon L Walker - One of the best experts on this subject based on the ideXlab platform.

  • mechanisms of tio2 nanoparticle transport in porous media role of Solution Chemistry nanoparticle concentration and flowrate
    Journal of Colloid and Interface Science, 2011
    Co-Authors: Indranil Chowdhury, Yongsuk Hong, Ryan J Honda, Sharon L Walker
    Abstract:

    Abstract The role of Solution Chemistry, nanoparticle concentration and hydrodynamic effects in the transport and deposition of TiO2 nanoparticles through porous media has been systematically investigated. Two Solution Chemistry variables, pH and ionic strength (IS), showed a significant influence on the transport due to their involvement in the aggregation of the nanoparticles and interaction with quartz sand. An electrostatically unfavorable condition for deposition existed at pH 7, at which the greatest retention occurred in the column, likely due to aggregation (>1000 nm) and straining effects. Under electrostatically favorable conditions (pH 5) significant elution from the column was observed and attributed to smaller aggregate size (∼300 nm) and blocking effects. Nanoparticle concentration was found to contribute to the increased breakthrough of nanoparticles at pH 5 due to blocking and subsequent particle–particle repulsion. Increased flowrate resulted in greater elution of nanoparticles due to hydrodynamic forces acting on aggregates and subsequently contributed to blocking. Overall, a combination of mechanisms including straining, blocking, and DLVO-type forces were involved over the range of Solution Chemistry and nanoparticle concentrations tested. Consideration of these mechanisms is necessary for improved removal of TiO2 nanoparticles via filtration and reliable prediction of transport of these potentially problematic nanoparticles through the subsurface.

  • Container to characterization: Impacts of metal oxide handling, preparation, and Solution Chemistry on particle stability
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2010
    Co-Authors: Indranil Chowdhury, Yongsuk Hong, Sharon L Walker
    Abstract:

    Abstract A study has been conducted to investigate the impact of experimental handling approaches on the state of model nanoparticles, from the container of dry particles to the characterization of suspended particles. Specifically, the effects of sonication, nanoparticle concentration, and ionic strength upon the size, electrophoretic mobility, and stability of the model metal oxides (TiO2, CeO2 and ZnO) were investigated. For initial breakup of dried nanoparticles in water, results indicate 30 min is the optimum sonication duration (120 W) all three metal oxide nanoparticles over the Solution Chemistry tested. Since aggregation is evident in metal oxide nanoparticles, sonication to achieve a proper dispersion of nanoparticles in Solution is necessary prior to further experimentation. No more than 30 s sonication is needed for preparing well-dispersed test sample from the diluted stock suspension. Effects of nanoparticle concentration on the Solution Chemistry were also studied. TiO2 or CeO2 addition can reduce pH with increase of nanoparticle concentration; whereas pH increases with ZnO concentration. Consideration of these parameters (effects of sonication, nanoparticle concentration, and Solution Chemistry) is necessary to ensure successful subsequent toxicity and transport studies.

  • role of Solution Chemistry and ion valence on the adhesion kinetics of groundwater and marine bacteria
    Langmuir, 2007
    Co-Authors: Gexin Chen, Sharon L Walker
    Abstract:

    The role of Solution Chemistry on bacterial adhesion has been investigated using a radial stagnation point flow (RSPF) system. This experimental system utilized an optical microscope and an image-capturing device to directly observe the deposition kinetics of a groundwater bacterium, Burkholderia cepacia G4g, and a marine bacterium, Halomonas pacifica g. Experiments were carried out under well-controlled hydrodynamic and Solution Chemistry conditions, allowing for the sensitivity of bacterial adhesion behavior to be examined under a range of ionic strength and valence (KCl vs CaCl2) simulating groundwater and marine environments. Complimentary cell characterization techniques were conducted to evaluate the electrophoretic mobility, hydrophobicity, surface charge density, and viability of the bacteria under the same range of conditions. Solution Chemistry was found to have a marked effect on the electrokinetic and surface properties of bacteria and the quartz collector, as well as on the resulting rate of ...

  • Role of Solution Chemistry and ion valence on the adhesion kinetics of groundwater and marine bacteria.
    Langmuir : the ACS journal of surfaces and colloids, 2007
    Co-Authors: Gexin Chen, Sharon L Walker
    Abstract:

    The role of Solution Chemistry on bacterial adhesion has been investigated using a radial stagnation point flow (RSPF) system. This experimental system utilized an optical microscope and an image-capturing device to directly observe the deposition kinetics of a groundwater bacterium, Burkholderia cepacia G4g, and a marine bacterium, Halomonas pacifica g. Experiments were carried out under well-controlled hydrodynamic and Solution Chemistry conditions, allowing for the sensitivity of bacterial adhesion behavior to be examined under a range of ionic strength and valence (KCl vs CaCl2) simulating groundwater and marine environments. Complimentary cell characterization techniques were conducted to evaluate the electrophoretic mobility, hydrophobicity, surface charge density, and viability of the bacteria under the same range of conditions. Solution Chemistry was found to have a marked effect on the electrokinetic and surface properties of bacteria and the quartz collector, as well as on the resulting rate of bacterial deposition. Comparable adhesion trends were observed for B. cepacia G4g and H. pacifica g. Specifically, the deposition rates of the two bacteria species in both KCl and CaCl2 Solutions increased with ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which considers the combination of van der Waals and electrostatic double-layer interaction forces. However, in some cases, experimental results showed bacterial deposition behavior to deviate from DLVO predictions. On the basis of the systematic investigation of bacterial cell characteristics, it was found that Ca2+ ions play a distinct role on bacterial surface charge, hydrophobicity, and deposition behaviors. It is further suggested that bacterial adhesion is determined by the combined influence of DLVO interactions, electrosteric interactions associated with Solution Chemistry, and the hydrodynamics of the deposition system.

Funda Savasci - One of the best experts on this subject based on the ideXlab platform.

  • An analysis of 16–17-year-old students' understanding of Solution Chemistry concepts using a two-tier diagnostic instrument
    International Journal of Science Education, 2012
    Co-Authors: Emine Adadan, Funda Savasci
    Abstract:

    This study focused on the development of a two-tier multiple-choice diagnostic instrument, which was designed and then progressively modified, and implemented to assess students' understanding of Solution Chemistry concepts. The results of the study are derived from the responses of 756 Grade 11 students (age 16–17) from 14 different high schools who participated in the study. The final version of the instrument included a total of 13 items that addressed the six aspects of Solution Chemistry, and students' understandings in the test were challenged in multiple contexts with multiple modes and levels of representation. Cronbach alpha reliability coefficients for the content tier and both tiers of the test were found to be 0.697 and 0.748, respectively. Results indicated that a substantial number of students held an inadequate understanding of Solution Chemistry concepts. In addition, 21 alternative conceptions observed in more than 10% of the students were reported, along with discussion on possible sourc...

Emine Adadan - One of the best experts on this subject based on the ideXlab platform.

  • Investigating the influence of pre-service Chemistry teachers' understanding of the particle nature of matter on their conceptual understanding of Solution Chemistry
    Chem. Educ. Res. Pract., 2014
    Co-Authors: Emine Adadan
    Abstract:

    This mixed method study mainly explored how the extent of pre-service Chemistry teachers' understanding of the particle nature of matter (PNM) affects their understanding of Solution Chemistry in the context of multirepresentational (MR) instruction. The ultimate goal was to describe the levels of understanding of specific Solution Chemistry concepts of a group of participants with a high understanding of the PNM and a group with a low understanding of the PNM before and immediately after MR instruction. Data sources included questionnaires about the PNM and interviews on Solution Chemistry. Data from these sources were coded and analyzed using quantitative and qualitative methods. There was a statistically significant difference between the results obtained for the understanding of Solution Chemistry before MR instruction for participants with a high understanding of the PNM and those with a low understanding of the PNM. Both groups of participants exhibited substantial progress towards the scientific understanding of Solution Chemistry from pre- to post-instruction; however, the participants with a high understanding of the PNM still outperformed those with a low understanding of the PNM in terms of developing a more scientific conceptual understanding of the topic after the MR instruction. Moreover, when the participants were provided with an opportunity to view dynamic visual particulate representations of phenomena to support verbal representations, about two-thirds of the participants from both groups were able to develop a scientific understanding of disSolution regardless of the extent of their understanding of the PNM. Yet, the findings suggested that the participants with a high understanding of the PNM were more likely to develop a scientific understanding of a particular concept (e.g., supersaturated Solutions) in Solution Chemistry even without viewing the available visual particulate representations of the phenomenon.

  • An analysis of 16–17-year-old students' understanding of Solution Chemistry concepts using a two-tier diagnostic instrument
    International Journal of Science Education, 2012
    Co-Authors: Emine Adadan, Funda Savasci
    Abstract:

    This study focused on the development of a two-tier multiple-choice diagnostic instrument, which was designed and then progressively modified, and implemented to assess students' understanding of Solution Chemistry concepts. The results of the study are derived from the responses of 756 Grade 11 students (age 16–17) from 14 different high schools who participated in the study. The final version of the instrument included a total of 13 items that addressed the six aspects of Solution Chemistry, and students' understandings in the test were challenged in multiple contexts with multiple modes and levels of representation. Cronbach alpha reliability coefficients for the content tier and both tiers of the test were found to be 0.697 and 0.748, respectively. Results indicated that a substantial number of students held an inadequate understanding of Solution Chemistry concepts. In addition, 21 alternative conceptions observed in more than 10% of the students were reported, along with discussion on possible sourc...

William D. Scott - One of the best experts on this subject based on the ideXlab platform.

  • An improved computer model of struvite Solution Chemistry.
    Talanta, 1992
    Co-Authors: T.j. Wrigley, William D. Scott, K.m. Webb
    Abstract:

    The computer model of the Solution Chemistry of struvite has been improved. Firstly, with ammonia as the prime calculation point in the liquid phase, the algorithm is smaller and faster. Secondly, the incorporation of distilled magnesium hydrogen phosphate in the model significantly increased the concentrations in Solution. Thirdly, estimates of the activity coefficients are included. These improvements have but a marginal (5–10%) improvement in the fit. However, proceeding with this flexible modelling procedure using the symbolic manipulator, Maple, easily allows the inclusion of all possible species. The addition of associated ammonium phosphates improves the fit. The relative standard deviation of the fit of both Taylor's data and the data of Webb is improved from 0.5 to 0.2. Estimates of the association constants are included.

  • A computer model of struvite Solution Chemistry
    Talanta, 1991
    Co-Authors: William D. Scott, T.j. Wrigley, K.m. Webb
    Abstract:

    A computer model is developed to describe struvite Solution Chemistry; this includes the electroneutrality equation and allows greater variability in the input components. Relationships between the major ions are retained without approximation. The model results fit data derived both in our laboratory and from the literature. Equilibrium constants which markedly affect the output are identified and solubility constants are derived. Applications of the model include studies of waste-water treatment and of the formation of kidney stones.