Effects of decalcification on the phosphate sorption characteristics of eight calcareous soils

Soil Research ◽  
1990 ◽  
Vol 28 (6) ◽  
pp. 919 ◽  
Author(s):  
ICR Holford ◽  
M Chater ◽  
GEG Mattingly
Keyword(s):  
Calcareous Soils ◽  
Sorption Isotherms ◽  
Phosphate Sorption ◽  
Surface Equation ◽  
P Sorption ◽  
Surface Areas ◽  
Freundlich Equation ◽  
Sorption Parameters ◽  
Parameter Values ◽  
Sorption Characteristics

Phosphate sorption isotherms and parameter values were determined on eight calcareous soils which were carefully decalcified using a procedure which minimized changes in cation saturation. Calcite content of the original soils varied from 0.8 to 24 2% and calcite surface areas from 4 . 0 to 8.5 m2 g-1. Sorption parameters were derived from the Langmuir 'two-surface' equation. Decalcification increased phosphate sorption at low residual P concentrations (<0.8 mg L-1) but decreased it at higher concentrations. The higher P sorption was associated with an increase in affinity because the calculated sorption capacities of high-affinity surfaces were not increased. These sorption capacities were well correlated with iron oxide contents of the soils, so the increase in phosphate affinity of these surfaces was consistent with the decrease in pH (0.5 to 1.5 units) of the decalcified soils. The lower P sorption at higher concentrations was associated with a substantial decrease in sorption capacity of the postulated low-affinity surfaces. These latter decreases were quantitatively correlated with the calcite surface areas of the original soils. These and other changes in phosphate sorption characteristics support the utility of the Langmuir 'two-surface' equation in providing information, compatible with what would be expected from more complex mechanistic models, and which exceeds what one would expect from other simpler models such as the Freundlich equation. They also support an hypothesis that an important component of low-affinity surfaces of these calcareous soils is calcite on which organic anions are co-adsorbed.

scholarly journals Relationship Between Exchangeable Alumunium and Phosphorus Sorption Parameters of Indonesian Acid Soils

2004 ◽  
Vol 6 (2) ◽  
pp. 70-74
Author(s):  
A Hartono
Keyword(s):  
Acid Soils ◽  
Sorption Isotherms ◽  
Clayey Soils ◽  
Phosphorus Sorption ◽  
General Reaction ◽  
P Sorption ◽  
Hydrous Oxides ◽  
Sorption Parameters ◽  
Main Component

In acid soils, phosphorus (P) sorption is generally attributed to hydrous oxides of Fe and Aluminum (AI) particularly intropical soils with low pH. However, reports concerning the role of exchangeable AI in P sorption mechanism are very liltle.Phosphorus (P) sorption isotherms were studied in fifteen acid upland soils containing different amount of exchangeable AI. Psorption characteristics were satisfactorily described by the Langmuir equation. which was used to determine P sorptionmaxima and bonding energies, with r values ranging from 0.97 to 0.99. The soils varied widely in their capacities to sorb P.P sorption maxima rangedfrom 303 to 1429 mg kg-I (mean 627 mg kg-I) and bonding energies from 0.65 to 8.00 L mtl (mean 2.39 L mg-I). Exchangeable AI was found not correlated with P sorption maxima (r = -0.11) but significantly correlated with P bonding energies (r = 0.68**). This was clearly shown by clayey soils from Java and Sumatra but not in sandy soils fromKalimantan. The results suggested that in general. reaction of exchangeable AI with P increased P bonding energy butexchangeable AI was not the main component in P sorption maximum

scholarly journals Sorption Characteristics and Fraction Distribution Changes of Selenite in Soil

2018 ◽  
Vol 10 (7) ◽  
pp. 2491 ◽  
Author(s):  
Jianxin Fan ◽  
Guoliang Zhao
Keyword(s):  
Linear Regression ◽  
Sequential Extraction ◽  
Multiple Linear Regression ◽  
Sorption Isotherms ◽  
Sorption Kinetics ◽  
Lower State ◽  
Fraction Distribution ◽  
Pseudo Second Order ◽  
Sorption Parameters ◽  
Sorption Characteristics

Sorption properties play a key role in the mobility of selenium (Se) and fraction distribution changes, leading to the bioavailability of Se in the soil environment. Thus, the effect of soil physicochemical properties on the sorption of exogenous selenite was investigated to predict the rate and capacity of sorption. Correlation analysis and multiple linear regression were used to observe the relationship between sorption characteristics and soil properties. Sequential extraction was used to observe the fractions of Se at different ages in soil. Results indicated that sorption isotherms followed the Langmuir equation, and the sorption capacity ranged from 50.7 to 567 mg·kg−1 with pseudo-second-order sorption kinetics. The correlation and multiple linear regression analyses showed that sorption parameters were significantly positively correlated with dithionite–citrate–bicarbonate-extracted Fe (FeDCB), dithionite–citrate–bicarbonate-extracted Al (AlDCB), amorphous Fe (FeOX), and soil organic matter (SOM), whereas pH was negatively correlated. Sequential extraction analyses revealed that the fraction distribution of Se in soil varied with the age, and the content of elemental Se increased with prolonged aging. FeDCB, AlDCB, FeOX, pH, and SOM play important roles in selenite sorption onto soils. Selenite sorption onto soil can be reduced to a lower-state Se, such as elemental Se and selenides, during the aging process. This information on the environmental behavior of Se is used to develop agronomic strategies for increasing Se levels in food crops and improving human health.

scholarly journals Phosphorus exchange in eutrophied coastal brackish water sediments—sorption pattern, potential and factors affecting them

2019 ◽  
Vol 1 (11) ◽  
Author(s):  
Anu Vaalama ◽  
Helinä Hartikainen ◽  
Henry Vallius ◽  
Kaarina Lukkari
Keyword(s):  
Sorption Isotherms ◽  
Particulate Material ◽  
Factors Affecting ◽  
P Sorption ◽  
Fine Sediments ◽  
Surface Areas ◽  
Oxygen Conditions ◽  
High Sorption ◽  
The Baltic ◽  
Sorption Potential

Abstract Phosphorus (P) exchange in clayey mud sediments was investigated with desorption–sorption isotherms at 22 coastal sites in the eutrophied brackish Gulf of Finland, the Baltic Sea. The aim was to gain information on P sorption potential and pattern of oxygenated surface sediments and to elucidate factors explaining them. Modified Freundlich equation was fitted to the isotherm data and used for calculation of the P exchange parameters EPC0 (equilibrium P concentration at zero net sorption), kEPC0, k15 and k100 (P buffering capacities at early, middle and high sorption stages, respectively). They were further used to assess the P sorption potential and pattern of the sediments. Sediment properties explaining the P sorption potential at different sorption stages were identified. The greatest sorption potentials were recorded in originally poorly oxic sediments in the inner archipelago with accumulated fine particulate material, high in adsorbents for P, transported from the watersheds. After oxygenation, they were high in amorphous Fe-oxyhydroxides, which explained their efficient P sorption (kEPC0 > 1.32 l g−1). Poorer P sorption (kEPC0 0.45–0.84 l g−1) was recorded in fine sediments abundant in Al-oxyhydroxides, presumably due to their higher original P occupation degree. The lowest sorption potentials were found in the outer archipelago sediments. Their lowest specific surface areas and highest original P contents referred to scarcity of adsorbents and high occupation degree of the existing ones. These results suggest that the coastal clayey mud sediments investigated possess high P sorption potential, which can be markedly diminished by eutrophication-induced hypoxia but recovered if oxygen conditions improve.

Phosphate sorption characteristics of soils of the north Queensland coastal region

Soil Research ◽  
1988 ◽  
Vol 26 (3) ◽  
pp. 465 ◽  
Author(s):  
BN Toreu ◽  
FG Thomas ◽  
GP Gillman
Keyword(s):  
Clay Fraction ◽  
Coastal Region ◽  
Mineralogical Composition ◽  
Parent Material ◽  
Metamorphic Rocks ◽  
Phosphate Sorption ◽  
Soil P ◽  
P Sorption ◽  
The North ◽  
Sorption Characteristics

Phosphate-sorption curves covering the range of supernatant P concentration, 0-1 �g nil-1, have been determined for a number of agriculturally important soils in the high rainfall (2000-4000 mm) region of tropical Queensland. Where possible, soil samples were taken from both virgin and cultivated sites within a soil series. The soils occur on four major parent materials, namely basaltic, granitic and metamorphic rocks, and on alluvium derived from one or more of these rocks. The shapes of the P-sorption curves and the differences in magnitude of P sorption were related to the mineralogical composition of the clay fraction which, in turn, was determined by parent material. Past applications of phosphatic fertilizer have lessened soil P-sorption capacity, despite a reduction in soil organic matter resulting from clearing and cultivation.

scholarly journals POTASSIUM ADSORPTION IN CALCAREOUS SOILS OF KURDISTAN REGION OF IRAQ

2020 ◽  
Vol 51 (Special) ◽  
Author(s):  
Gh. A. Mam-Rasul
Keyword(s):  
Soil Solution ◽  
Langmuir Isotherm ◽  
Calcareous Soils ◽  
Sorption Isotherms ◽  
Sufficient Information ◽  
Kurdistan Region ◽  
Langmuir Isotherm Model ◽  
Nutrients Availability ◽  
The Difference ◽  
Sorption Parameters

Sorption is one of the most chemical important processes, which determine nutrients availability in soil. Sorption isotherms provide sufficient information about soils sorption’s capacity, and it’s data can be used to determine thermodynamic sorption parameters. The aim of this studyis to evaluate the sorption of potassium onto some soils. An experiment was conducted with four calcareous soils of the Sulaimani province Kurdistan Region of Iraq by using the batch methods. 5g soil samples were equilibrated at 298±1 Kelvin with 50 ml of 0.01M CaCl2 containing 0 to 250 mg L-1 K as KCl. Suspensions were centrifuged, filtered, and concentration of K+ in the clear extract solution was determined. Amount of K+ sorbed by the soil was calculated from the difference between the initial and final concentration of K+ in the equilibrium solution. Sorption of K+ was evaluated using adsorption isotherms. The results showed that K+ sorption was described by linear, Langmuir, Freundlich, and Temkin equations. Langmuir equation gave a better fit of equilibrium K adsorption when it has a higher R2 and lowers SE.  The data indicated that the maximum monolayer coverage capacity (b) from the Langmuir isotherm model ranged between (-113.63 to 2500) mg kg-1. The negative values of (b) for studied locations soils indicated to potassium release instead of adsorption. The Langmuir isotherm constant (KL) ranged from (-0.01 to 0.01) L mg-1. Maximum buffering capacity (MBC) is a capacity factor, which measures the ability of the soil to replenish K ion to soil solution that the ability of a soil to supply K to the soil solution. The value of MBC of the studied soils ranged from 0.453 to 23.75 mg kg-1.The sorption processes for the forth locations are favorable and spontaneous because the value of RL was an equal one.

scholarly journals Radionuclides distribution and its sorption behavior in the Kara sea bottom sediments surface layer

2019 ◽  
Vol 64 (11) ◽  
pp. 1187-1195
Author(s):  
N. V. Kuzmenkova ◽  
V. V. Krupskaya ◽  
E. V. Duriagina ◽  
I. N. Semenkov ◽  
S. E. Vinokurov
Keyword(s):  
Bottom Sediments ◽  
Sea Water ◽  
Sorption Isotherms ◽  
Sorption Kinetics ◽  
Kara Sea ◽  
Sorption Behavior ◽  
Freundlich Equation ◽  
Sea Bottom ◽  
Complexation Mechanism ◽  
Sorption Characteristics

The sorption characteristics of the Kara sea bottom sediments were investigated. The sediments were collected during scientific expedition of the R/V Akademik Mstislav Keldysh (Cruise AMK-66). The mineral and fraction composition of sediments was determined. It has been found that 137Cs sorbed predominantly by an ion exchange mechanism because of the clay minerals presence in the sediments. At the same time, 243Am and 90Sr sorbed from seawater by the surface complexation mechanism. The sorption kinetics for 243Am was established: about 20 hours, 137Cs: 2 hours, 90Sr: less than an hour. The sorption isotherms shows Cs and Am in experiments on marine and distilled water are described by the Henry equation. The Sr behavior in deionized water is described by the Langmuir equation, in the case of sea water, by the Freundlich equation.

Modeling time-dependent phosphate buffering capacity in different soils as affected by bicarbonate and silicate ions

Soil Research ◽  
2008 ◽  
Vol 46 (4) ◽  
pp. 315 ◽  
Author(s):  
Nirmal De ◽  
Samar Chandra Datta
Keyword(s):  
Control System ◽  
Sorption Isotherms ◽  
Buffering Capacity ◽  
Rate Of Change ◽  
Silicate System ◽  
Sorption Data ◽  
P Sorption ◽  
Freundlich Equation ◽  
Practical Implications ◽  
Different Soils

The aim of this paper was to establish a relationship between phosphate buffering capacity and time in the presence of specifically sorbed anions like bicarbonate and silicate. P sorption isotherms were obtained at different times of equilibration for 3 surface soil samples, namely, Typic Haplustept, Calcic Chromustert, and Ultic Paleustalf in 3 different systems namely, bicarbonate (0.001 m), silicate (0.001 m), and a control system without any bicarbonate or silicate and having a common concentration of 0.1 m NaCl. Phosphate sorption data at different times could be fitted very closely to a modified Freundlich equation of the form: X/m = KCntp, where X/m is the amount of phosphate sorbed at solution phosphate concentration C and time t in hours. The values of n and p were positive fractions (mostly) and found to vary with soils and ionic medium. The silicate system was more effective in decreasing P sorption. Phosphate buffering capacity, defined as the first-order partial derivative of X/m with respect to C, KntpCn–1, was calculated at a particular concentration of 0.3 mg/L (usual P concentration of soil solution) at different times from the optimised value of K, n, and p. Phosphate buffering capacity was maximum in the control system and found to increase with time. Bicarbonate and, particularly, silicate ion decreased buffering capacity drastically and also the rate of change of buffering capacity with time. The practical implications of this decrease in buffering capacity by bicarbonate and silicate ions is discussed.

scholarly journals Comparison of adsorption models for the removal of fluorides, nitrates and sulfates by adsorption onto AFN membrane

2016 ◽  
Vol 51 (2) ◽  
pp. 106-116
Author(s):  
Fatma Guesmi ◽  
Islem Louati ◽  
Chiraz Hannachi ◽  
Béchir Hamrouni
Keyword(s):  
Langmuir Isotherm ◽  
Surface Adsorption ◽  
Sorption Isotherms ◽  
Adsorption Parameters ◽  
Sulfate Ions ◽  
Adsorption Models ◽  
Monovalent Ions ◽  
Equilibrium Data ◽  
Sorption Parameters ◽  
Best Fit

The main purpose of this work was to determine adsorption characteristics of fluoride, nitrate and sulfate ions on the AFN membrane. The sorption isotherms for , and ions on the AFN membrane were investigated in the range of 0.05–1 mol.L–1 at 298 K. The suitability of the Langmuir, Dubinin–Astakhov (D-A) and Redlich–Peterson adsorption models to the equilibrium data was investigated. The sorption parameters of the studied models were determined by non-linear regression and discussed. Equilibrium data obtained in this study were found to best fit the Langmuir isotherm. The ΔG° values deduced from the Langmuir isotherm suggest that the affinity order of the AFN membrane for the studied anions is: . In order to improve their selectivity towards monovalent ions, the AFN membrane was modified by adsorption of polyethyleneimine on its surface. Adsorption parameters values of the studied models were determined for the modified AFN membrane. The D-A model provides the best fit to the experimental points. In fact, removal of fluoride and nitrate ions by adsorption on the modified AFN membrane was more effective than the adsorption on the unmodified one. Desorption of fluoride from the modified AFN membrane by nitrate and sulfate ions was investigated.

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