Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-26T02:57:46.207Z Has data issue: false hasContentIssue false
  • English
  • Français

Adsorption of Molybdate Anion (MoO42−) by Sodium-Saturated Kaolinite

Published online by Cambridge University Press:  02 April 2024

Patrick J. Phelan  and
Shas V. Mattigod
Patrick J. Phelan
Affiliation:
Department of Soil and Environmental Sciences, University of California, Riverside, California 92521
Shas V. Mattigod
Affiliation:
Department of Soil and Environmental Sciences, University of California, Riverside, California 92521
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Adsorption of Mo(VI) on 2-0.2-μm size fraction of sodium-saturated kaolinite at 25 ± 2°C and at a constant pH of 7.00 ± 0.05 was studied. The kaolinite sample was pretreated to remove any surface oxide and hydroxide coatings. The initial concentrations of Mo in solution ranged from 1 to 11 mg/liter in a NaClO4 background electrolyte at a constant ionic strength of 0.09 ± 0.01. Calculations of speciation using the GEOCHEM computer program indicated that under experimental conditions Mo(VI) was mainly in the MoO42− form. The experimental conditions were also shown to fulfill the requirements for applying the Langmuir equation in interpreting adsorption data. The Langmuir parameter for the adsorption maximum, n°, and the affinity parameter, KMoO42−−ClO4− were computed to be 3.33 × 10−4 mole/ mole of adsorbent and 5.969 × 105, respectively. The large affinity parameter indicated that the Na-saturated kaolinite surface has a very high affinity for MoO42− ions relative to ClO4− ions.

Резюме

Резюме

Исследовалась адсорбция Mo(VI) на фракции размером 2-0,2 μм каолинита, насыщен-ного натрием при температуре 25 ± 2°C и при постоянной величине рН равной 7,00 ± 0,05. Образец каолинита обработывался так, чтобы удалить все окисные и гидроокисные поверх-ностные покрытия. Начаьные концентрации Мо в растворе распределялись от 1 до 11 мг/литр в электролите NaClO4 при постоянной ионовой силе равной 0,09 ± 0,01. Вычисления количества новых вилов при помощи програмы ГЭОХЕМ указывали на то, что в этих экспериментальных условиях Mo(VI) находился в основном в форме MoO22−. Показано, что экспериментальные условия выполняли необходимые условия для использования уравнения Лангмюра для интерпретации данных адсорбции. Параметр Лангмюра для максимума адсорбции, n0, и параметр подобия, KMoO42−−ClO4−, были вычислены как 3,33 × 10−4 моля/моль адсорбента и 5,969 × 105, соответственно. Значительный параметр подобия указывал на то, что поверхность каолинита, насыщенного Na, имеет очень высокое подобие для ионов MoO42− по отношению к ионом ClO4−. [E.G.]

Resümee

Resümee

Es wurde die Adsorption von Mo(VI) an die 2-0,2 μm Fraktion von Na-gesättigtem Kaolinit bei 25 ± 2°C und einem konstanten pH von 7,00 ± 0.05 untersucht. Die Kaolinitprobe wurde vorbehandelt, um oxidische und hydroxidische Oberflächenbeläge zu entfernen. Die ursprünglichen Konzentrationen an Mo in der Lösung reichten von 1–11 mg/Liter in einer NaClO4 Elektrolytlösung mit einer konstanten Ionenstärke von 0,09 + 0,01. Die Berechnungen mittels GEOCHEM-Programm deuten darauf hin, daß unter den experimentellen Bedingungen Mo(VI) hauptsächlich als MoO42- vorlag. Es zeigte sich auch, daß die experimentellen Bedingungen so waren, daß sie die Anforderungen für die Anwendung der Langmuir-Gleichung bei der Interpretation der Adsorptionsdaten erfüllt haben. Der Langmuir-Parameter für das Adsorptionsmaximum, n°, und der Affinitätsparameter, KMoO42−ClO4−, wurden, auf 3,33 × 10-4 Mole/Mole für den Adsorbenten bzw. mit 5,969 × 105 berechnet. Der große Affinitätsparameter deutete darauf hin, daß die Na-gesättigte Kaolinitoberfläche eine große Affinität für MoO42--Ionen im Vergleich zu ClO4--Ionen hat. [U.W.]

Résumé

Résumé

On a étudié l'adsorption de Mo(VI) sur une fraction de kaolinite saturée de sodium de taille 2-0,2 μm à 25 ± 2°C at à un pH constant de 7,00 ± 0.05. L’échantillon de kaolinite avait été traité à l'avance pour enlever toutes couches oxides et hydroxides. Les concentrations de Mo initiales dans la solution s’étendaient d'l à 11 mg/litre dans un électrolyte d'arrière plan de NaClO4 à une force ionique constante de 0,09 ± 0,01. Des calculs de spéciation employant le programme GEOCHEM ont indiqué que sous les conditions expérimentales Mo(VI) était principalement dans la forme MoO42-. On a aussi montré que les conditions expérimentales ont satisfait les exigences pour appliquer l’équation de Langmuir dans l'interprétation des données d'adsorption. Le paramètre de Langmuir pour le maximum d'adsorption, n°, et le paramètre d'affinité, KMoO42−−ClO4−, ont été computés être 3,33 × 10−4 mole/mole d'adsorbant et 5,969 × 105, respectivement. Le grand paramètre d'affinité a indiqué que la surface de kaolinite saturée de Na a une affinité très élevée pour les ions MoO42− relativement aux ions ClO4− [D.J.]

Keywords

AdsorptionElectrolyteKaoliniteMolybdate ionSpeciation
Type
Research Article
Information
Clays and Clay Minerals , Volume 32 , Issue 1 , February 1984 , pp. 45 - 48
Copyright
Copyright © 1984, The Clay Minerals Society

References

Aubert, H. and Pinta, M., 1977 Trace Elements in Soils New York Elsevier.Google Scholar
Baes, C. F. Jr. and Mesmer, R. E., 1976 The Hydrolysis of Cations New York Wiley.Google Scholar
Barshad, I., 1951 Factors affecting the molybdenum content of pasture plants: I. Nature of soil molybdenum, growth of plants, and soil pH Soil Sci 71 313–327.Google Scholar
Bernas, B., 1968 A new method for decomposition and comprehensive analysis of silicates by AA spectrometry Anal. Chem 40 1682–1686.CrossRefGoogle Scholar
Cotton, F. A. and Wilkinson, G., 1962 Advanced Inorganic Chemistry New York Wiley-Interscience.Google Scholar
Davies, C. W., 1962 Ion Association London Butterworths.Google Scholar
El Prince, A. M. and Sposito, G., 1982 Thermodynamic derivation of equations of the Langmuir type for ion equilibria in soils Soil Sci. Soc. Amer. J 45 277–282.CrossRefGoogle Scholar
Hingston, F. J., Anderson, M. A. and Rubin, A. J., 1981 A review of anion adsorption Adsorption of Inorganics at Solid-Liquid Interfaces 51–90.Google Scholar
Jones, L. H. P., 1957 The solubility of molybdenum in simplified systems and aqueous soil suspensions J. Soil Sci 8 313–327.CrossRefGoogle Scholar
Jorden, R. M., Meglen, R. R. and Hemphill, D. D., 1973 Aqueous release of molybdenum from non-point and point sources: in Trace Substances in Environmental Health VII Colombia, Missouri Univ. Missouri.Google Scholar
Kopp, J. F. and Kroner, R. C., 1970 Trace elements in waters of the United States. Oct. 1, 1962–Sep. 20, 1967 U.S. Dept. Interior, Fed. Wat. Poll. Control Adm., Div. Poll. Sur. .Google Scholar
Mattigod, S. V. and Sposito, G., 1979 Chemical modeling of trace metal equilibria in contaminated soil solutions using the computer program GEOCHEM Chemical Modeling in Aqueous Systems 837–856.CrossRefGoogle Scholar
Sposito, G., 1979 Derivation of the Langmuir equation for ion exchange reactions in soils Soil Sci. Soc. Amer. J 43 197–198.CrossRefGoogle Scholar
Sposito, G. and Thornton, I., 1983 The chemical forms of trace metals in soils: in Applied Environmental Geochemistry London Academic Press.Google Scholar
Vlek, P. L. G., Lindsay, W. L., Chappell, W. R. and Peterson, K. K., 1977 Molybdenum contamination in Colorado pasture soils Molybdenum in the Environment .Google Scholar