Kinetics of Isotopic Exchange of Phosphate Adsorbed on Gibbsite

Kyle, J.; Posner, A. M.; Quirk, J. P.

doi:10.1111/j.1365-2389.1975.tb01927.x

Cited by 57 publications

(24 citation statements)

References 13 publications

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“…Recent theoretical studies with adsorption and desorption in oxide-aqueous solution systems showed that the applicability and method of fitting kinetic data to the Elovich equation require accurate data at short reaction times (Aharoni and Ungarish, 1976). The Elovich equation has described the kinetics of heterogeneous isotopic exchange reactions well on goethite (Atkinson et al .. 1970), but not as well on gibbsite surfaces (Kyle et al .. 1975). Morc recently, a modified form of the Elovich equation has been applied successfully to kinetics of phosphate release and sorption , dissolution of phosphate rocks in soils , and dissolution of P to ethylenediamine tetraacetate (EDT A) (Onken and Matheson, 1982).…”

Section: Elovich Equationmentioning

confidence: 98%

Potassium Dynamics in Soils

Sparks

1987

Advances in Soil Science

336

192

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Section: Elovich Equationmentioning

confidence: 98%

Potassium Dynamics in Soils

Sparks

1987

Advances in Soil Science

336

192

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“…Goethite, a-FeOOH, poorly crystalline goethite, and amorphous Al oxide were synthesized as described by McLaughlin et al (1981). Gibbsite, a-A1(OH)j, was synthesized according to the procedure of Kyle et al (1975) and amorphous Fe oxide was synthesized as described by Sims and Bingham (1968). The oxide mineralogy was verified using x-ray diffraction analysis.…”

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confidence: 99%

Molybdenum Adsorption on Oxides, Clay Minerals, and Soils

Goldberg

Förster

Godfrey

1996

Soil Science Society of America Journal

277

121

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Molybdenum adsorption behavior was investigated on various crystalline and x-ray amorphous Al and Fe oxide minerals, clay minerals, CaC@, and arid-zone calcareous and noncalcareous s soils. Molybdenum adsorption on botb Al and Fe oxides exhibited a maximum at low pH extending to about pH 4 to 5. Above pH 5 adsorption decreased rapidly, with little adsorption occurring above pH 8. Molybdenum adsorption was higher for the oxide minerals having higher specific surface area and lower crystallinity. Molybdenum adsorption on the clay minerals exhibited a peak near pH 3 and then decreased rapidly with increasing pH until adsorption was virtually zero near pH 7. The magnitude of MO adsorption on clays increased in the order: kaolinite < illite < montmorillonite. Shifts in point of zero charge were observed on Al and Fe oxides and kaolinite following M O adsorption, indicating an inner-sphere adsorption mechanism for MO on these surfaces. Molybdenum adsorption behavior on three arid-zone noncalcareous soils resembled that on clays, exhibiting a peak near pH 3 to 4 and decreasing with increasing pH up to pH 7. This behavior is expected since the oxide content of these soils is low. Molybdenum adsorption on calcite and two calcareous arid-zone soils was low, indicating that CaCOJ is not a significant sink for MO in soils.

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“…The isotopic exchange of phosphate adsorbed onto gibbsite was also very slow, and was classified as inert in the pH range 5 to 6, where the exchange half-life was 50 to 4 h, respectively (Kyle et al 1975). The slow desorption and isotopic exchange of phosphate was attributed to the bidentate and binuclear bonding of phosphate on gibbsite edge faces (Hingston et al 1974; Kyle et al 1975). …”

Section: ~A I ( O H ) + N a N T A 2-= -~Aio----n A N T A 2-+ H +mentioning

confidence: 99%

“…The proposed bidentate and binuclear NTA surface complexes are also supported by studies of oxalate and phosphate sorption by gibbsite. The adsorption of oxalate (Parfitt et al 1977) and phosphate (Kyle et al 1975) by gibbsite were described by both bidentate coordination to a single edge site and binuclear coordination between adjacent edge sites. The O-O distance for oxalate was given as 0.28 nm and for phosphate, 0.29 nm (Parfitt et al 1977;Kyle et al 1975).…”

Section: ~A I ( O H ) + N a N T A 2-= -~Aio----n A N T A 2-+ H +mentioning

confidence: 99%

“…The adsorption of oxalate (Parfitt et al 1977) and phosphate (Kyle et al 1975) by gibbsite were described by both bidentate coordination to a single edge site and binuclear coordination between adjacent edge sites. The O-O distance for oxalate was given as 0.28 nm and for phosphate, 0.29 nm (Parfitt et al 1977;Kyle et al 1975). Infrared spectra of oxalate adsorbed to gibbsite was consistent with the bidentate and binuclear coordination (Parfitt et al 1977).…”

Section: ~A I ( O H ) + N a N T A 2-= -~Aio----n A N T A 2-+ H +mentioning

confidence: 99%

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Adsorption of Nitrilotriacetate (NTA), Co and CoNTA By Gibbsite

Girvin

Gassman

Bolton

1996

Clays and clay miner.

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Abstract--Adsorption of Co 2 § nitrilotriacetic acid (NTA) and equal-molar Co 2 § and NTA by a low surface area (LSA) commercial gibbsite (3.5 m 2 g-~) was investigated in batch as a function of pH (4.5 to 10.5), adsorbate (0.5 to 10 txM) and adsorbent (0.5 to 75 g L ~) concentrations and ionic strength (0.01 to 1 M NaC104). The adsorption of Co 2 § (Co-only) and the acid form of NTA (NTA-only) by gibbsite in 0.01 M NaC104 exhibit cation-like and anion-like adsorption edges, respectively. For the equal-molar CoNTA chelate, Co and NTA adsorption edges were similar but not identical to the Co-only and NTAonly edges. Differences suggest the existence of a ternary CoNTA surface complex with the Co in the intact chelate coordinated to surface hydroxyls. NTA-only adsorption was insensitive to ionic strength variation, indicating weak electrostatic contributions to surface coordination reactions. This is consistent with the formation of inner-sphere surface NTA complexes and ligand exchange reactions in which monodentate, bidentate and binuclear NTA surface complexes form. Cobalt adsorption increases (edge shifts to lower pH by 1 pH unit) on LSA gibbsite as ionic strength increases from 0.01 to 1 M NaC104. For the same ionic strength change, a similar shift in the Co-only edge was observed for another commercial gibbsite (16.8 m 2 g 1); however, no change was observed for ~-A1203. Ionic strength shifts in Co 2+ adsorption by gibbsite were described as an outer-sphere CoOH § surface complex using the triplelayer model. Results suggest that, at waste disposal sites where 6~ and NTA have been co-disposed, NTA will not promote ligand-like adsorption of Co for acid conditions, but will reduce cation-like adsorption for basic conditions. Thus, where gibbsite is the dominant mineral sorbent, NTA will not alter 6~ mobility in acidic pore waters and groundwaters; however, NTA could enhance 6~ mobility where alkaline conditions prevail, unless microbial degradation of the NTA occurs.

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Kinetics of Isotopic Exchange of Phosphate Adsorbed on Gibbsite

Cited by 57 publications

References 13 publications

Potassium Dynamics in Soils

Potassium Dynamics in Soils

Molybdenum Adsorption on Oxides, Clay Minerals, and Soils

Adsorption of Nitrilotriacetate (NTA), Co and CoNTA By Gibbsite

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