Ionic adsorption on variable charge mineral surfaces. Theoretical charge development and titration curves

Bowden, J. W.; Posner, A. M.; Quirk, J. P.

doi:10.1071/sr9770121

Cited by 98 publications

(159 citation statements)

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“…The term ai can be replaced by α γ c, where α is the proportion of the ion, γ is the coefficient of activity and c is the ion concentration in solution. The activity ais is equal to the quantity of occupied sites in relation to available sites, that is θ/ (1-θ), in which θ is the proportion of occupied sites (Bowden et al, 1977). Then: By using FLM, we can obtain adjustable parameters, the ion bonding constant to colloidal surfaces K, and the soil surface electric potential.…”

Section: Four-layer Model (Flm)mentioning

confidence: 99%

“…The neutral surface of FLM is represented by OH-S-OH 2 in which the surface electric potential decreases due to an increase of soil acidity (equation 71), but increases when pH becomes higher (equation 72) (Bowden et al, 1977).…”

Section: Four-layer Model (Flm)mentioning

confidence: 99%

“…The reaction between an ion and a soil charged surface includes a component that reflects a chemical attraction between both. The activity of an ion located close to the surface (ais) can be related to its activity in solution (ai), equation (73) (73) K is the reaction constant, which is related to the ion and to the surface, Zi is the ion valency, øa is the electrostatic potential, F is Faraday constant, R is the gases constant, and T is the absolute temperature (Bowden et al,1977). The term ai can be replaced by α γ c, where α is the proportion of the ion, γ is the coefficient of activity and c is the ion concentration in solution.…”

Section: Four-layer Model (Flm)mentioning

confidence: 99%

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Electrochemical attributes and availability of nutrients, toxic elements, and heavy metals in tropical soils

Fontes¹,

Alleoni²

2006

Sci. agric. (Piracicaba, Braz.)

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Electrochemical properties of soils are very important for the understanding of the physico-chemical phenomena which affect soil fertility and the availability of nutrients for plants. This review highlights the electrochemical properties of tropical soils, the behavior and the availability of nutrients, toxic elements and heavy metals in the soil, especially for soils with predominant variable charge minerals. Availability of the elements is related to ionic exchange, solution speciation, and electrostatic and specific adsorptive soil properties. Empirical and surface complexation models are briefly described, and some results of their application in tropical soils are presented. A better understanding of the role of the double diffuse layer of charges and CEC on nutrient cation availability for highly weathered soils is required, as well as a solid comprehension of surface complexation models, in order to improve the knowledge regarding the behavior of anions in soils. More studies have to be conducted to generate results that enable the use of chemical speciation concepts and calculation of several constants used in surface complexation models, especially for highly weathered soils from the humid tropics. There has to be a continuing development and use of computer softwares that have already incorporated the concepts of chemical speciation and adsorption models in the study of nutrients, toxic elements and heavy metal availability in the soil-plant system. Key words: electric charge, adsorption, model, ionic exchange, speciation ATRIBUTOS ELETROQUÍMICOS E DISPONIBILIDADE DE NUTRIENTES, ELEMENTOS TÓXICOS E METAIS PESADOS EM SOLOS TROPICAISRESUMO: As propriedades eletroquímicas dos solos tropicais são muito importantes para entendimento dos fenômenos físico-químicos que afetam a fertilidade do solo e a disponibilidade dos nutrientes das plantas. Essa revisão destaca os atributos eletroquímicos de solos e o comportamento e a disponibilidade de nutrientes, elementos tóxicos e metais pesados no solo, especialmente aqueles com predominância de minerais com cargas variáveis. A disponibilidade dos elementos é relacionada com a troca iônica, especiação da solução e propriedades adsortivas eletrostáticas e específicas do solo. Modelos empíricos e de complexação de superfície são brevemente descritos, e são apresentados resultados de sua aplicação em solos tropicais. É necessário um melhor entendimento do papel da dupla camada difusa de cargas e da CTC na disponibildade de nutrientes em solos altamente intemperizados, assim como uma melhor compreensão dos modelos de complexação de superfície, a fim de melhorar o entendimento do comportamento dos ânions no solo. Mais estudos devem ser conduzidos para gerar resultados que tornem possível o uso de conceitos de especiação química e o cálculo de diversas constantes usadas em modelos de complexação, especialmente para solos altamente intemperizados do trópico úmido. Deve haver um contínuo desenvolvimento de programas computacionais que já tenham incorporado os conc...

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Section: Four-layer Model (Flm)mentioning

confidence: 99%

Section: Four-layer Model (Flm)mentioning

confidence: 99%

Section: Four-layer Model (Flm)mentioning

confidence: 99%

See 1 more Smart Citation

Electrochemical attributes and availability of nutrients, toxic elements, and heavy metals in tropical soils

Fontes¹,

Alleoni²

2006

Sci. agric. (Piracicaba, Braz.)

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“…The magnitude of the constant charge is independent on pH and the ionic strength of the solution, given that under these conditions there is no decomposition of the crystal lattice of minerals, which likely happens in the case of synthesis of the preparations (Thomas & Hargrove, 1984). The changeable constant-potential charge is also characteristic of aluminum oxides and hydroxides, silica oxides and amphoteric aluminum, and iron oxides and hydroxyoxides (Bowden et al, 1977).…”

Section: Introductionmentioning

confidence: 99%

Electrolytic conductivity of synthetic organomineral complexes

Ksiezopolska

2005

Sci. agric. (Piracicaba, Braz.)

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The mechanism of the formation of organomineral complexes in soils is very complex and still little known. Examination of the complexes in unaltered form, as isolated from the soil, is very difficult due to the dispersing effect of all extraction agents which break the complexes up, destroying their natural properties. It is much easier to perform most of the tests on preparations of organomineral complexes obtained under laboratory conditions. This paper is concerned with model research on the formation of synthetic complexes of humic acids with minerals: Na-montmorillonite, mica, kaolinite at various pH values (3-7) and in the presence of aluminum ions. The aim of the research was to develop an optimum reaction of suspension for the synthesis of organomineral complexes, to study the role of aluminum ions, and to attempt to determine the degree of their complexity on the basis of the electrolytic conductivity (EC). An important influence of the suspension pH value on the value of EC was observed. The greatest correlation was found in the organomineral preparations with kaolinite and with aluminum (r = 0.93 *** ). Generally, it can be stated that the degree of reaction of humic acids with minerals depended most of all on the type of mineral, on the pH value, and on the presence of aluminum.

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“…They were applied to the reaction of synthetic oxides with anions (Bowden et al 1977;Barrow et al 1980a, b;Sposito 1983;Bolan and Barrow 1984;Barrow 1987;Barrow and Bowden 1987;Schindler and Stumm 1987). The surface complexation models differ from each other in two distinct aspects: 1) in the number of planes that are specified and hence in the allocation of ions to the planes, and 2) in the way the surface reaction is modeled.…”

mentioning

confidence: 99%

Increase in Cation Adsorption Induced by Surface Complexation of Sulfate on Andisols and Prediction by “Four-Plane Model”

Kamewada

Takahashi

1996

Soil Science and Plant Nutrition

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Ionic adsorption on variable charge mineral surfaces. Theoretical charge development and titration curves

Cited by 98 publications

References 0 publications

Electrochemical attributes and availability of nutrients, toxic elements, and heavy metals in tropical soils

Electrochemical attributes and availability of nutrients, toxic elements, and heavy metals in tropical soils

Electrolytic conductivity of synthetic organomineral complexes

Increase in Cation Adsorption Induced by Surface Complexation of Sulfate on Andisols and Prediction by “Four-Plane Model”

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