The Maximum of Phosphate Adsorption at pH 4.0: Why It Appears on Aluminum Oxides but Not on Iron Oxides

Langmuir ◽  
2009 ◽  
Vol 25 (8) ◽  
pp. 4450-4461 ◽  
Author(s):  
Xiao Huang ◽  
Gregory D. Foster ◽  
Robert V. Honeychuck ◽  
John A. Schreifels
Keyword(s):  
Iron Oxides ◽  
Phosphate Adsorption ◽  
Aluminum Oxides

A spectroscopic investigation of phosphate adsorption onto iron oxides

1996 ◽  
Vol 14 (3) ◽  
pp. 1357-1361 ◽  
Author(s):  
M. G. Nooney ◽  
T. S. Murrell ◽  
J. S. Corneille ◽  
E. I. Rusert ◽  
L. R. Hossner ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Spectroscopic Investigation ◽  
Phosphate Adsorption

Influence of organic matter on phosphate adsorption by aluminium and iron oxides in sandy soils

1990 ◽  
Vol 41 (3) ◽  
pp. 443-449 ◽  
Author(s):  
O. K. BORGGAARD ◽  
S. S. JDRGENSEN ◽  
J. P. MOBERG ◽  
B. RABEN-LANGE
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Sandy Soils ◽  
Phosphate Adsorption

Coordination Adsorption of Anions

1997 ◽  
Author(s):  
G. Y. Zhang ◽  
T. R. Yu
Keyword(s):  
Functional Groups ◽  
Ligand Exchange ◽  
Specific Adsorption ◽  
Phosphate Adsorption ◽  
Fluoride Ions ◽  
Aluminum Oxides ◽  
Soil Particles ◽  
Variable Charge ◽  
Iron And Aluminum Oxides ◽  
Variable Charge Soils

In Chapter 4, when the electrostatic adsorption of anions by variable charge soils is discussed, another type of adsorption, specific adsorption, has already been mentioned, although it is not very remarkable for chloride ions and nitrate ions. For some other anions, specific adsorption can be very important. Specific adsorption is determined by the nature of the anions and is also related to the kind of functional groups on the surface of soils. In general, this type of adsorption is more pronounced in soils containing large amounts of iron and aluminum oxides. Therefore, specific adsorption of anions is one of the important characteristics of variable charge soils. Specific adsorption is a common term. For anions, the mechanism of specific adsorption is ligand exchange between these ions and some groups that have already been coordinately linked on the surface of soil particles. Therefore, the term coordination adsorption may be more appropriate than the term specific adsorption. For variable charge soils, phosphate is the strongest specifically adsorbed anion species. Phosphate adsorption is also the most intensively studied anion adsorption in soil science. However, the valence status of phosphate ions is apt to change with the change in environmental conditions. In the adsorption of phosphate by soils, in addition to ligand exchange, other mechanisms, such as chemical precipitation, may also be involved. Therefore, the phenomenon of phosphate adsorption is rather complex, and it is often difficult to make definitive interpretations of experimental results. In the present chapter, the coordination adsorption of anions will be discussed, mainly taking sulfate as the example, because sulfate is only secondary to phosphate in importance for agricultural production among anions capable of undergoing coordination adsorption. For the purpose of comparison, the adsorption of fluoride ions will also be mentioned. On the surface of soil particles there are functional groups such as hydroxyl groups (M-OH) and water molecules (M-OH2) that can participate in ligand exchange with anions. Al-OH, Fe-OH, Al-OH2, and Fe-OH2 groups on the surface of soil particles are the important sites for coordination adsorption of anions. Therefore, when a soil contains large amounts of iron and aluminum oxides, the phenomenon of coordination adsorption of anions will be more pronounced.

scholarly journals Bulk chemical composition of the mountainous meadowy brown soils of the Ukrainian Carpathians and processes of its transformation

2017 ◽  
pp. 11-20
Author(s):  
Andrii Barannyk
Keyword(s):  
Chemical Composition ◽  
Iron Oxides ◽  
Soil Profile ◽  
Alkaline Earth ◽  
Parent Material ◽  
Alkaline Earth Metals ◽  
Bulk Chemical Composition ◽  
Chemical Homogeneity ◽  
Aluminum Oxides ◽  
Bulk Chemical

The features of the bulk chemical composition of mountainous meadowy brown soils and anthropogenically-modified soils of the Svydovets and Chornogora arrays of the Ukrainian Carpathians are investigated. The ratio of the oxides content of the most important chemical elements of the mineral part of mountainous meadowy brown soils and parent material is determined. The basic transformation processes of the mineral part of the studied soils and parent material are established. The peculiarity of the bulk chemical composition of meadow brown soils is the high content of silicon oxides, and the high content of aluminum oxides and iron oxides. Their total content is within 94 %. This indirectly indicates a significant chemical homogeneity of the soil with the parent material. The relative accumulation of SiO2 in the upper genetic horizons of the soil profile is due to the physical disintegration of silicate rocks. Its relative bulk content is gradually reduced from 76.10–77.43 % to 72.28–76.93 % in the transition to a parent material. It was established, that the removal of sesquioxides beyond the boundary of the soil profile leads to the formation of a depleted soil profile on aluminum oxides and iron oxides, as we compare with unchanged parent material. Absolute values of the indicators of leakage factor of alkaline earth metals grow in the direction towards to the parent material. This indicates about intensive development of erosion processes in the upper part of the soil profile. This is due to the physical and chemical disintegration of aluminosilicates and the removal of compounds of disintegration into the lower soil genetic horizons. The analysis of the results of balance of bulk reserves of oxides testified, that during the formation of the mountainous meadowy brown soils of the Ukrainian Carpathians, oxides of trivalent metals (aluminum and iron) and compounds of alkaline earth metals are subjected to removal from the genetic horizons of the soil profile. Quantitative bulk chemical analysis didn’t show any significant differences in the material composition between the mountainous meadowy brown soils and the mountainous meadowy brown anthropogenically altered soil. Key words: mountainous meadow brown soils, bulk chemical composition, Svydovets and Chornogora arrays, Ukrainians Carpathians.

Kinetics of phosphate adsorption on iron oxides formed under the influence of citrate

2000 ◽  
Vol 80 (3) ◽  
pp. 445-454 ◽  
Author(s):  
C. Liu ◽  
P. M. Huang
Keyword(s):  
Activation Energy ◽  
Citric Acid ◽  
Organic Acids ◽  
Surface Chemistry ◽  
Iron Oxides ◽  
Phosphate Adsorption ◽  
Exponential Factor ◽  
Structural Perturbation ◽  
Fe Oxides ◽  
The Impact

The influence of organic acids on the formation of Fe oxyhydroxides and oxides has been intensively studied. However, scant attention has been paid to the subsequent effect on surface chemistry of the Fe oxides formed. The kinetics and mechanisms of phosphate adsorption by the Fe oxides formed in the presence of citrate ligands at initial citrate/Fe(II) molar ratios (MR) of 0, 0.001, 0.01, and 0.1 were investigated using the conventional batch method. The adsorption studies were conducted at the initial phosphate concentration of 0.5 mM and pH 4.0 during the reaction period from 2 min to 56 h at 278, 288, 298, and 313 K. The results show that the phosphate adsorption followed multiple second-order kinetics and had two distinct rates in each reaction system. The amount, rate coefficient, activation energy and pre-exponential factor of phosphate adsorption by the Fe oxides formed greatly varied with their structural and surface properties. These properties, which included crystal structure, specific surface area, surface porosity, surface geometry, and point of zero salt effect (PZSE), differed significantly with the initial citrate/Fe(II) MR at which Fe oxides were formed. The results of this study have cast the light on the role of organic acids such as citric acid in influencing the surface chemistry of naturally occurring Fe oxides through fundamental structural perturbation and the impact on the dynamics of phosphate in terrestrial and aquatic environments. Key words: Kinetics, activation energy, pre-exponential factor, phosphate, iron oxides, citric acid, structural perturbation

Phosphate adsorption performance and mechanisms by nanoporous biochar–iron oxides from aqueous solutions

2020 ◽  
Vol 27 (22) ◽  
pp. 28132-28145
Author(s):  
Zhaoran Zhang ◽  
Haiqin Yu ◽  
Rixin Zhu ◽  
Xue Zhang ◽  
Liangguo Yan
Keyword(s):  
Aqueous Solutions ◽  
Iron Oxides ◽  
Phosphate Adsorption ◽  
Adsorption Performance

Influence of humic substances on phosphate adsorption by aluminium and iron oxides

Geoderma ◽  
2005 ◽  
Vol 127 (3-4) ◽  
pp. 270-279 ◽  
Author(s):  
O.K. Borggaard ◽  
B. Raben-Lange ◽  
A.L. Gimsing ◽  
B.W. Strobel
Keyword(s):  
Humic Substances ◽  
Iron Oxides ◽  
Phosphate Adsorption
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