The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform

V S Soldatov - One of the best experts on this subject based on the ideXlab platform.

  • Potentiometric Titration of ion exchangers
    Reactive & Functional Polymers, 1998
    Co-Authors: V S Soldatov
    Abstract:

    Theoretical works on Potentiometric Titration of ion exchangers are reviewed. Most attention is paid to the approach considering this process as a specific case of ion exchange between H+ or OH− and the counterions of the titrant, Mz+ or Az−, accompanied by the neutralization reaction. An equation connecting the most important properties of the ion exchanger–solution system (pH, concentration of the electrolyte in the solution phase and degree of neutralization of the ion exchanger) named `acidity function' is discussed in detail. Practical methods for determination and use of a set of its three constants, sufficient for calculation of ionic equilibria in ion-exchange systems (parameters of acidic–basic strength of ion exchangers), are described and illustrated with experimental examples. The acidity function is used for computer simulation of potentiomertic Titration curves of ion exchangers to observe the influence of different factors on position and shape of the Potentiometric Titration curves and chose the best possible conditions for observing the inflection points. The physical meaning of the constants of the modified Henderson–Hasselbach equation are discussed and their relations with the parameters of acidic–basic strength of ion exchangers are expressed in the quantitative form.

  • quantitative presentation of Potentiometric Titration curves of ion exchangers
    Industrial & Engineering Chemistry Research, 1995
    Co-Authors: V S Soldatov
    Abstract:

    Neutralization of ion exchangers in H + or OH - forms by alkali M(OH) z or acid H z A was considered as a specific case of ion exchange H + -M z+ or OH - -A z- accompanied by the neutralization reaction. An equation connecting pH and the external electrolyte concentration with the ion exchanger neutralization degree was derived. It can be used for presentation of the Potentiometric Titration curves in mathematical form or their calculation at different (not necessarily constant) concentrations of external electrolyte. Applicability of the modified Henderson-Hasselbach equation as one of the possible means for description of Potentiometric Titration curves of ion exchangers was also discussed. The range of its applicability and limitations were established. The physical meaning of its constants was clarified, and the equations of their relations with the apparent ion exchange equilibrium constant have been obtained. The theoretical considerations are illustrated with the example of Potentiometric Titration curves of a carboxylic acid ion exchanger obtained in a wide range of degrees of neutralization and external electrolyte concentrations.

Francois Ravenelle - One of the best experts on this subject based on the ideXlab platform.

  • Potentiometric Titration for determination of amylose content of starch a comparison with colorimetric method
    Food Chemistry, 2012
    Co-Authors: Derek X Duan, Elizabeth Donner, Damon Smith, Francois Ravenelle
    Abstract:

    Amylose, the amount of which varies significantly depending on the source, is one of the key components of starch. The proportion of the essentially linear amylose and the highly branched amylopectin greatly influences the physico-chemical properties of starch. In this study, Potentiometric Titration using an auto-titrator and colorimetric methods were compared for determining amylose contents of a variety of starch samples. Potentiometric Titration results for starches from a variety of botanical sources were within the reported literature ranges while the colorimetric method seemed to overestimate amylose content.

  • Potentiometric Titration for determination of amylose content of starch – A comparison with colorimetric method
    Food Chemistry, 2012
    Co-Authors: Derek X Duan, Elizabeth Donner, Damon Smith, Francois Ravenelle
    Abstract:

    Abstract Amylose, the amount of which varies significantly depending on the source, is one of the key components of starch. The proportion of the essentially linear amylose and the highly branched amylopectin greatly influences the physico-chemical properties of starch. In this study, Potentiometric Titration using an auto-titrator and colorimetric methods were compared for determining amylose contents of a variety of starch samples. Potentiometric Titration results for starches from a variety of botanical sources were within the reported literature ranges while the colorimetric method seemed to overestimate amylose content.

Derek X Duan - One of the best experts on this subject based on the ideXlab platform.

  • Potentiometric Titration for determination of amylose content of starch a comparison with colorimetric method
    Food Chemistry, 2012
    Co-Authors: Derek X Duan, Elizabeth Donner, Damon Smith, Francois Ravenelle
    Abstract:

    Amylose, the amount of which varies significantly depending on the source, is one of the key components of starch. The proportion of the essentially linear amylose and the highly branched amylopectin greatly influences the physico-chemical properties of starch. In this study, Potentiometric Titration using an auto-titrator and colorimetric methods were compared for determining amylose contents of a variety of starch samples. Potentiometric Titration results for starches from a variety of botanical sources were within the reported literature ranges while the colorimetric method seemed to overestimate amylose content.

  • Potentiometric Titration for determination of amylose content of starch – A comparison with colorimetric method
    Food Chemistry, 2012
    Co-Authors: Derek X Duan, Elizabeth Donner, Damon Smith, Francois Ravenelle
    Abstract:

    Abstract Amylose, the amount of which varies significantly depending on the source, is one of the key components of starch. The proportion of the essentially linear amylose and the highly branched amylopectin greatly influences the physico-chemical properties of starch. In this study, Potentiometric Titration using an auto-titrator and colorimetric methods were compared for determining amylose contents of a variety of starch samples. Potentiometric Titration results for starches from a variety of botanical sources were within the reported literature ranges while the colorimetric method seemed to overestimate amylose content.

Staffan Sjoberg - One of the best experts on this subject based on the ideXlab platform.

  • Potentiometric Titration of unbleached kraft cellulose fibre surfaces
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1994
    Co-Authors: Janne Laine, Per Stenius, Lars Lovgren, Staffan Sjoberg
    Abstract:

    Abstract The surface properties of unbleached kraft cellulose fibres in the pH range 2–8 have been investigated using a high precision Potentiometric Titration method. The pulps were digested in various ways, varying both digestion time (level of residual lignin) and the amount of excess alkali. Titrations were made at constant ionic strength (0.1 M NaCl). The results were evaluated by assuming the existence of different types of acidic groups in the surface and adjusting their intrinsic stability constants and the capacitance of the electrical double layer to obtain the best possible fit to experimental data. Fitting was done using the error square sum minimising program fiteql , version 2.0. Distribution diagrams were calculated with the program solgaswater . It was found that the amount of acidic groups decreases with increasing digestion time, while the amount of excess alkali is not important. The pulps contain two types of acidic groups that dissociate in the pH range 2.5–7.5 (intrinsic stability constants pK≈3.4 and pK≈5.5). The pK value of the stronger acid agrees with what could be expected for uronic acids in hemicellulose (xylan), while the amount of the weaker acid correlates directly with the amount of lignin in the pulps.

W Piasecki - One of the best experts on this subject based on the ideXlab platform.

  • influence of electrolyte ion adsorption on the derivative of Potentiometric Titration curve of oxide suspension theoretical analysis
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004
    Co-Authors: Robert Charmas, Piotr Zarzycki, Frederic Villieras, Fabien Thomas, Benedicte Prelot, W Piasecki
    Abstract:

    The theory based on the 1-pK triple layer model of the oxide/electrolyte interface is used to obtain the derivative of a proton adsorption isotherm. The present approach is much more rigorous and complex from a physical point of view compared to our previous paper [J. Phys. Chem. B. 106 (2002) 13280]. In the present work we take into account adsorption of inert electrolyte ions. Also, the present approach takes into consideration the local surface heterogeneity. The aim of this work is not to propose new surface model, but to develop a theoretical basis for obtaining of proton affinity distribution from the derivatives of a Potentiometric Titration curve. We demonstrate how including of electrolyte ion adsorption influences on the shape and behavior of the local derivatives of Potentiometric Titration curves. The influence of the other parameters is also thoroughly investigated. It was found that complete description of the derivative of surface charging curve requires a high number of parameters. Therefore, it is difficult to adopt the obtained peaks for unambiguous decomposition of experimental derivative of a Titration curve onto the parts coming from different patches of the surface.