THE SPECIFIC ADSORPTION OF DIVALENT Cd, Co, Cu, Pb, AND Zn ON GOETHITE

Forbes, E. A.; Posner, A. M.; Quirk, J. P.

doi:10.1111/j.1365-2389.1976.tb01986.x

Cited by 413 publications

(166 citation statements)

References 17 publications

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“…It is also interesting to note that the trend of Pb:Cd NERs of the soils (Oxisol > Ultisol > Mollisol) paralleled the pro portions of variable charged surfaces (oxidic minerals, 1:1 phyllosilicates, and organic matter), and were opposite CEC trends (Table 1). Therefore, on a relative basis, compared to Cd, Pb appeared to have a very high specificity for variable charged surfaces compared to constant surface charge mate rials (Brummer et al, 1983;Forbes et al, 1976;Jenne, 1968;McKenzie, 1980). In Figs.…”

Section: Sites Of CD and Pb Retentionmentioning

confidence: 99%

Sequential sorption of lead and cadmium in three tropical soils

Appel

Lena

Rhue

et al. 2008

Environmental Pollution

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The sorption and desorption of Pb and Cd in tropical soils is strongly influenced by the order in which these metals enter the soil environment. AbstractIt is important to examine mechanisms of Pb and Cd sorption in soils to understand their bioavailability. The ability of three tropical soils to retain Pb, Cd, and Ca was evaluated. The objectives of this study were to (1) determine the extent to which soil sorption sites are metal specific, (2) investigate the nature of reactions between metals and soil surfaces, and (3) identify how metals compete for sorption sites when they are introduced to soils sequentially or concurrently. Lead was shown to be much less exchangeable than Cd and inhibited Cd sorption. Cadmium had little effect on Pb sorption, though both Ca and Cd inhibited the adsorption of Pb at exchange sites. Lead appears to more readily undergo innersphere surface complexation with soil surface functional groups than either Cd or Ca. Thus, regardless of when Pb is introduced to a soil, it should be less labile than Cd.

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Section: Sites Of CD and Pb Retentionmentioning

confidence: 99%

Sequential sorption of lead and cadmium in three tropical soils

Appel

Lena

Rhue

et al. 2008

Environmental Pollution

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“…Increasing amounts of Zn being extracted from natural soils or Zn-treated soils by using acid extracting solutions has been found by HIBBARD (1940), PEECH (1941), BROWN (1950) and others, but has not been interpreted in terms of the competition between Zn and proton to the cation-exchange sites on clay minerals. On the other hand, the specific adsorption of Zn on goethite has been considered as an exchange process against protons on the oxide surface on the basis of its dependence on pH (GRIMME, 1968;FORBES et al, 1976).…”

Section: The Approach Based On the Zn-ca Exchange Equationmentioning

confidence: 99%

Characterization of zinc adsorption sites in two mineral soils

Wada

Abdel-Fattah

1978

Soil Science and Plant Nutrition

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The adsorption of Zn, as compared with Mg, on two mineral soils, which differed in their major cation-exchange materials and with and without Ca-saturation, was measured in the presence of free CaCl a •The adsorption of Zn as well as Mg occurred on cation-exchange sites. The Zn adsorption data conformed to a two-term Langmuir equation. The presence of two kinds of adsorption sites and their numbers and bonding energies were deduced. However, the Langmuir approach was not adopted on the basis of comparison between the total number of the adsorption sites for Zn deduced and the CEC of the soils.As an alternative approach, the selectivity coefficient K~~, as defined by the equation:was calculated for each adsorption equilibrium and plotted against the amount of Zn adsorbed. This K~:-[Zn]80i! plot was used to estimate the capacities of the soil to adsorb Zn with specified affinities. The K~: value varied between 1 and 1,000, whereas the corresponding K~arz value varied only between 0.5 and 1. The K~: value was dependent upon the amount of Zn adsorbed, the status of exchangeable cations, and the major cation-exchange materials (montmorillonite VS. allophane-imogolite) in the soils. The importance of surface OH groups in allophane-imogolite as specific adsorption sites for Zn was suggested.

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“…The observation that certain heavy metal cations tend to adsorb specifically on hydrous oxide and oxyhydroxide surfaces (Kinniburgh et al, 1976;Forbes et al, 1976;McKenzie, 1980) suggests that these minerals play a significant role in the retention of trace metals by soils. Similarly, high surface-area aluminosilicates, such as aUophane and imogolite, should be active metal adsorbents.…”

Section: Introductionmentioning

confidence: 99%

Chemisorption of Cu(II) and Co(II) on Allophane and Imogolite

Clark

McBride

1984

Clays and clay miner.

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Abstract--Adsorption of Cu 2+ and Co 2+ by synthetic imogolite, synthetic allophanes with a range of SiO2/ A1203 ratios, and allophanic clay fractions from volcanic ash soils was measured in an ionic medium of 0.05 M Ca(NO3) 2. The effect ofpH (and metal concentration) on adsorption was qualitatively similar for the synthetic and natural allophanes with relatively minor changes in behavior caused by variable SLOE/ A1203 ratios. Cu and Co were chemisorbed by aUophane at pH 5.0-5.5 and 6.9-7.2 (pH values for 50% adsorption level), respectively, with concomitant release of 1.6-1.9 protons/metal ion adsorbed. Quantitatively, adsorption by imogolite was less than that by the allophanes, presumably because of fewer sites available for chemisorption on the tubular structure of imogolite. Electron spin resonance studies of the imogolite and allophanes revealed that Cu 2 § was adsorbed as a monomer on two types of surface sites. The preferred sites were likely adjacent A1OH groups binding Cu 2+ by a binuclear mechanism; weaker bonding occurred at isolated A1OH or SiOH groups. These chemisorbed forms of Cu E+ were readily extracted by EDTA, CHaCOOH, and metals capable of specific adsorption, but were not exchangeable. In addition, the H20 and/or OH-ligands of chemisorbed Cu E+ were readily displaced by NH3, with the formation of ternary Cu-ammonia-surface complexes.

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THE SPECIFIC ADSORPTION OF DIVALENT Cd, Co, Cu, Pb, AND Zn ON GOETHITE

Cited by 413 publications

References 17 publications

Sequential sorption of lead and cadmium in three tropical soils

Sequential sorption of lead and cadmium in three tropical soils

Characterization of zinc adsorption sites in two mineral soils

Chemisorption of Cu(II) and Co(II) on Allophane and Imogolite

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