Effect of Ionic Strength on Specific Adsorption of Ions by Variable Charge Soils: Experimental Testification on the Adsorption Model of Bowden et al.

2010 ◽  
pp. 78-80 ◽  
Author(s):  
Renkou Xu ◽  
Jun Jiang ◽  
Cheng Cheng
Keyword(s):  
Ionic Strength ◽  
Specific Adsorption ◽  
Adsorption Model ◽  
Variable Charge ◽  
Specific Adsorption Of Ions ◽  
Variable Charge Soils

Effects of pH and ionic strength on the cation exchange capacity of soils with variable charge

Soil Research ◽  
1981 ◽  
Vol 19 (1) ◽  
pp. 93 ◽  
Author(s):  
GP Gillman
Keyword(s):  
Ionic Strength ◽  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Surface Soils ◽  
Ph Values ◽  
Variable Charge ◽  
Effects Of Ph ◽  
Variable Charge Soils

The cation exchange capacity of six surface soils from north Queensland and Hawaii has been measured over a range of pH values (4-6) and ionic strength values (0.003-0.05). The results show that for variable charge soils, modest changes in electrolyte ionic strength are as important in their effect on caton exchange capacity as are changes in pH values.

Phosphate adsorption at variable charge soil/water interfaces as influenced by ionic strength

Soil Research ◽  
2009 ◽  
Vol 47 (5) ◽  
pp. 529 ◽  
Author(s):  
Yong Wang ◽  
Jun Jiang ◽  
Ren-kou Xu ◽  
Diwakar Tiwari
Keyword(s):  
Ionic Strength ◽  
Zeta Potential ◽  
Salt Effect ◽  
Phosphate Adsorption ◽  
Adsorption Model ◽  
Net Charge ◽  
Variable Charge ◽  
Opposite Trend ◽  
Variable Charge Soil ◽  
Soil Colloids

The effect of phosphate adsorption on zeta potential of the colloids of variable charge soils and the effect of ionic strength on phosphate adsorption by the soils were investigated using batch experimental method. The presence of phosphate resulted in the decrease in zeta potential and isoelectric point (IEP) of the colloids of the soils, which further suggested that the phosphate was adsorbed specifically by these soils. The effect of phosphate adsorption on zeta potential was correlated with the content of free Fe/Al oxides in the soils; the higher the content of Fe/Al oxides in a soil the greater was the decrease in zeta potential and IEP of the soil colloids. The intersection of phosphate adsorption–pH curves at different ionic strengths (a characteristic pH) was obtained for 2 Oxisols. Above this pH, the adsorption of phosphate increased with increasing ionic strength, whereas below it the reverse trend occurred. The intersect pH was 4.60 for the Oxisol from Guangdong and 4.55 for the Oxisol from Yunnan, which was lower than the values of PZSE (point of zero salt effect) of these soils, but near the PZNC (point of zero net charge) of the soils. The effects of ionic strength and pH on phosphate adsorption by these soils were interpreted with the help of an adsorption model developed previously by Bowden et al. The results of zeta potential suggested that the potential in an adsorption plane became less negative with increasing ionic strength above the soil PZNC and decreased with increasing ionic strength below the soil PZNC. These results support the hypothesis of the adsorption model that the potential in the adsorption plane changed with ionic strength with an opposite trend to the surface charge of these soils. The phosphate adsorption by these soils was related not only to the ionic strength but also to the types of electrolytes present. K+ induced a greater increase in phosphate adsorption than Na+ due to the greater affinity of the soils to K+ than Na+.

Effect of Ionic Strength and pH on Cadmium Adsorption by Brazilian Variable‐Charge Soils

2009 ◽  
Vol 40 (13-14) ◽  
pp. 2132-2151 ◽  
Author(s):  
Marcio Roberto Soares ◽  
José Carlos Casagrande ◽  
Ernesto Rinaldi Mouta
Keyword(s):  
Ionic Strength ◽  
Variable Charge ◽  
Cadmium Adsorption ◽  
Variable Charge Soils

Adsorption of chromate on variable charge soils as influenced by ionic strength

2011 ◽  
Vol 66 (4) ◽  
pp. 1155-1162 ◽  
Author(s):  
Jun Jiang ◽  
Yong Wang ◽  
Renkou Xu ◽  
Chong Yang
Keyword(s):  
Ionic Strength ◽  
Variable Charge ◽  
Variable Charge Soils

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.

Effect of ionic strength on adsorption of As(III) and As(V) on variable charge soils

2009 ◽  
Vol 21 (7) ◽  
pp. 927-932 ◽  
Author(s):  
Renkou XU ◽  
Yong WANG ◽  
Diwakar TIWARI ◽  
Houyan WANG
Keyword(s):  
Ionic Strength ◽  
Variable Charge ◽  
Variable Charge Soils

scholarly journals Nickel adsorption by variable charge soils: effect of pH and ionic strength

2011 ◽  
Vol 54 (1) ◽  
pp. 207-220 ◽  
Author(s):  
Marcio Roberto Soares ◽  
José Carlos Casagrande ◽  
Ernesto Rinaldi Mouta
Keyword(s):  
Ionic Strength ◽  
Effect Of Ph ◽  
Variable Charge ◽  
Nickel Adsorption ◽  
Variable Charge Soils
Sign in / Sign up

Export Citation Format

Share Document