Influence of Exchangeable Cation on the Sorption of Trace Amounts of Cadmium by Montmorillonite

García‐Miragaya, J.; Page, A. L.

doi:10.2136/sssaj1977.03615995004100040051x

Cited by 7 publications

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“…The general predominance of specifically adsorbed (Cd-AO) over exchangeable suggests that the Fe oxide may have been present predominantly as a coating on the kaolinite. Increases in Cd adsorption with increase in pH have been observed by several researchers for soils (Garcia-Miragaya and Page 1977;Jarvis and Jones 1980), clays (Farrah and Pickering 1977), and for goethite (Tiller et al 1984). The increase in residual Cd with application rates at all pH values suggests the occlusion of Cd or its diffusion into less accessible sites from which Cd is not displaced by AO or BaCh.…”

Section: Thementioning

confidence: 67%

The influence of pH on the forms of cadmium in four West Australian soils

Mann¹,

Ritchie²

1993

Soil Res.

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The forms of cadmium in soils affect its uptake by plants and hence its potential toxicity to animals and humans. We studied the effect of pH on the forms of native and added Cd in four West Australian soils which differed in their clay, hydrous oxide and organic matter content. The forms of Cd were extracted sequentially by KCl, BaCl2, NaOCl, ammonium oxalate and concentrated acids. The majority of Cd applied to a sandy soil was found in the soluble (KCl) and the exchangeable (BaCl2) forms at all pH values. In the siliceous sand, the proportion of the Cd present in the exchangeable form increased as the soil solution pH increased. However, in the peaty sand, the opposite trend was observed; at pH 5, approximately 50% of the Cd was found in the exchangeable form, while at higher pH values, < 60% was bound to organic matter and 20% was in the soluble form. In soils in which the main adsorption surface was dominated by hydrous oxides (mainly goethite), 50-70% of the Cd was extracted as bound to oxides and as the residual fraction at pH < 5. At pH values > 5, the majority (90%) of it was extracted in these forms. Soils, containing clay (mainly kaolinite) as the major adsorbent, retained Cd mainly in exchangeable form at all pH values and at all the rates of Cd application. At pH > 5, however, some of the Cd was also found in the residual form and bound to organic matter. This work has shown that the form of added Cd in a soil cannot be elucidated by considering the major adsorbing component alone. It is also necessary to know the pH, the presence of other adsorbing surfaces and the rates of applied Cd.

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Section: Thementioning

confidence: 67%

The influence of pH on the forms of cadmium in four West Australian soils

Mann¹,

Ritchie²

1993

Soil Res.

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“…The data cannot be fit to any single exchange equation over a range of ionic strengths and surface ion compositions. Despite the observation that initial adsorption of M s § ions on M+-smectites at low ionic strengths strongly favors M 2+ relative to M § ions as shown by adsorption isotherms (McBride, 1976;Garcia-Miragaya and Page, 1977), Figures 1 and 2 show that KMA is actually smallest at low MS+-adsorption levels. A reasonable explanation of these results can be given when it is realized that greater quantities of adsorbed M 2 § increase tactoid formation from dispersed clay platelets, an explanation that has been developed previously (Banin, 1968).…”

Section: Resultsmentioning

confidence: 82%

Interpretation of the Variability of Selectivity Coefficients for Exchange Between Ions of Unequal Charge on Smectites

McBride

1980

Clays and clay miner.

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Abstract--Ion-exchange experiments in expanding clay minerals conducted over a wide range of surface ionic compositions and ionic strength produce variable mass-action selectivity coefficients. When the exchanging ions are of unequal charge, tactoid structure appears to influence selectivity, although configurational entropy of adsorbed ions may also generate variable selectivity. The degree of deviation from ideal mass-action exchange is related to the dissimilarity of the ions undergoing exchange. Data involving trivalent ion adsorption on smectites suggest that mass-action is a poor approximation when the adsorbing and desorbing ions have different hydration energies and charge. No form of exchange equation is successful in describing ion exchange for a wide range of experimental conditions, although the fluctuation of the selectivity coefficient follows consistent trends with changing experimental conditions. The strong adsorption of high-charge ions on clays is not exothermic, but must be driven by the increasing disorder of ions and/or water.

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“…While addition of clay minerals reduces soluble metal concentration by exchange reactions, one needs to consider the release of adsorbed HM into soil solution due to mass action by other more common cations such as H + , Al 3+ , Ca 2+ , Mg 2+ , and Na + . Many studies demonstrated that the presence of Ca 2+ or Al 3+ ions reduced the efficiency of heavy metals adsorption by clay minerals (Garcia-Miragaya and Page, 1977;Bittel and Miller, 1974), suggesting Ca 2+ or Al 3+ competition for adsorption sites. Cavallaro and McBride (1978) reported that low soil pH has the effect of increasing the fraction of functional groups in soil organic matter that is associated with H + or Al 3+ , thereby reducing the ability of either Cu 2+ or Cd 2+ to be adsorbed.…”

Section: Downloaded By [Uq Library] At 14:23 05 November 2014mentioning

confidence: 99%

Effect of Immobilizing Substances and Salinity on Heavy Metals Availability to Wheat Grown on Sewage Sludge-Contaminated Soil

Usman

Kuzyakov

Stahr

2005

Soil and Sediment Contamination: An International Journal

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The objective of the investigation was to evaluate the effect of immobilizing substances and NaCl salinity on the availability of heavy metals: Zn, Cd, Cu, Ni, and Pb to wheat (Triticum aestivum L.). In greenhouse pot experiment, a sewage sludge amended soil was treated with the following immobilizing substances: three clay minerals (Na-bentonite, Ca-bentonite and zeolite), iron oxides (goethite and hematite), and phosphate fertilizers (superphosphate and Novaphos). The pots were planted with wheat and were irrigated either with deionized or saline water containing 1600 mg L −1 NaCl. Wheat was harvested two times for shoot metal concentrations and biomass measurements. Metal species in soil solution were estimated using the software MINEQL+.The addition of metal immobilizing substances to the soil significantly decreased metal availability to wheat. The largest reduction in metal bioavailability was found for bentonites. The irrigation with saline water (1600 mg L −1 NaCl) resulted in a significant increase in metal chloride species (MCl + and MCl 0 2 ). The highest metal complexation with Cl occurred for Cd, which was about 53% of its total soil solution concentration. The total concentration of Cd (Cd T ) in soil solution increased by 1.6-2.8-fold due to saline water. The NaCl salinity caused a significant increase in uptake and shoot concentration of Cd for two harvests and small but significant increase in shoot Pb concentration for the second harvest. It was concluded that the use of bentonites is the most promising for the reduction of heavy metal availability to plants. Saline water containing 1600 mg L −1 NaCl increased the availability of Cd and Pb to wheat and decreased the efficiency of bentonites to immobilize soluble Cd.

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Influence of Exchangeable Cation on the Sorption of Trace Amounts of Cadmium by Montmorillonite

Cited by 7 publications

References 0 publications

The influence of pH on the forms of cadmium in four West Australian soils

The influence of pH on the forms of cadmium in four West Australian soils

Interpretation of the Variability of Selectivity Coefficients for Exchange Between Ions of Unequal Charge on Smectites

Effect of Immobilizing Substances and Salinity on Heavy Metals Availability to Wheat Grown on Sewage Sludge-Contaminated Soil

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