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Petroleum Geochemical Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Ionic potential is one of the main factors that provides the necessary conditions for the chemical conversion of one mineral to another in aqueous media. The ionic potential of an element is defined as the ion charge (z) divided by ion size (r) in terms of its radius that is (z/r). The ratio (z/r) is a measure of charge density at the surface of the ion. The denser the charge, the stronger the bond formed by the ion with an oppositely charged element. The ionic potential (z/r) or ionic charge density gives the ion the strength that will determine how it will be electro-statically attracted to an opposite charge or how it will be electro-statically repelled by a like charge. Accordingly all the elements are divided into three groups, low, intermediate and high ionic potential. Ionic potentials along with their groups are tabulated in Table 8.2.
The Electron-Phonon Interaction and Strong-Coupling Superconductors
Published in R. D. Parks, Superconductivity, 2018
In the alkali and polyvalent metals the ion-core states are localized about the nuclei over distances small compared to the interatomic separation and are relatively tightly bound on the scale of conduction band energies. This means that to a good approximation the internal dynamics of the core electrons can be neglected. They can be treated as generating an ionic potential rigidly attached to the nuclei. At distances larger than the core radius rc, the bare ionic potential has the simple Coulomb form Ze/r, where Z is the effective ionic charge. This is screened out by the conduction electrons at distances larger than the interatomic spacing. At distances less than rc, the shielding due to the core electrons decreases until near the nucleus, the full positive potential of the nucleus is obtained.
Geochemical Environments
Published in Arthur W. Hounslow, Water Quality Data, 2018
The purpose of this chapter is to acquaint the reader with some of the principles of ion mobility in the aquatic environment. Goldschmidt (1958) used the concept of ionic potential to help explain element behavior. Ionic potential is the ratio of the charge of the ion divided by the ionic radius. A threefold grouping was proposed. The first group consists of those elements with large radii and low charge which included the alkali metals, alkaline earth metals, ferrous iron, manganous iron, copper, and others which occur primarily as simple cations and which are usually mobile. The second group with intermediate ionic potentials are those elements that are readily precipitated as hydroxides, and include aluminum, ferric iron, titanium, and manganic manganese. The third group with high ionic potential occurs as very soluble and mobile oxy-anions and include the elements boron, carbon, phosphorus, and sulfur.
Removal of arsenic from gold processing circuits by use of novel magnetic nanoparticles
Published in Canadian Metallurgical Quarterly, 2018
C. Feng, C. Aldrich, J. J. Eksteen, D. W. M. Arrigan
In order to remove arsenic from the gold processing circuits, numerous efforts have been made. The most commonly used approach is to precipitate the arsenic species with trivalent iron salts and lime (e.g. [8]). Other methods include coagulation and coprecipitation, ion exchange and adsorption [9–12]. Among these techniques, adsorption is considered to be simple but cost-effective for the removal of arsenic from water bodies [11]. Therefore, the development of suitable and efficient arsenic adsorbents has attracted much attention. Recently, [13] proposed a material criterion, i.e. ionic potential, for the selection of potential candidates. Ionic potential is defined as an ion’s charge divided by its radius, indicating how strongly or weakly a specific ion can be repelled electrostatically by ions with like charges or be attracted electrostatically to ions with opposite charges. They claimed that metal oxides/hydroxides with metallic elements’ ionic potentials between approximately four and seven could be used as proper arsenic adsorbents, as shown in Figure 1.
Corrosion, oxidation and high-temperature tribological properties of Ti–B–N coatings
Published in Surface Engineering, 2019
Isaac Asempah, Lihua Yu, Hongbo Ju, Dian Yu, Junhua Xu, Ran Miao
According to [23], the crystal-chemical approach can be used to predict the tribological behaviour of coatings, especially at elevated temperatures. This approach is based on the ionic potential (ϕ) of oxides, which is related to the cationic charge (Z) and the radius of the oxides (r) where . The extent of screening of a cation by neighbouring anion determines the value of the ionic potential. The higher the ionic potential, the higher the degree of screening and vice versa.