scholarly journals Sorption capacity of phosphate in mineral soils: I Estimation of sorption capacity by means of sorption isotherms

1990 ◽  
Vol 62 (1) ◽  
pp. 1-8
Author(s):  
Raina Niskanen
Keyword(s):  
Ionic Strength ◽  
Sorption Capacity ◽  
Sorption Isotherms ◽  
Clay Content ◽  
Langmuir Equation ◽  
Soil Samples ◽  
Organic Carbon Content ◽  
Sorption Data ◽  
Mineral Soils ◽  
Extractable Al

The sorption capacity of phosphate in seven soil samples (clay content 1—70 %, organic carbon content 0.8—10.7 %, soil pH 4.2—5.3, oxalate-extractable Al 11—222 and Fe 11—202 mmol/kg soil) was studied by means of sorption isotherms. The soils were equilibrated, for two to seven days at +5 and +20°C, with solutions containing phosphate 0—10 mmol/l (0—200 mmol/kg soil) at a constant ionic strength of 0.01 . Prolongation of the reaction time increased the sorption of phosphate only partially. The rise in temperature, from +5 to +20°C, increased the sorption from higher phosphate concentrations. At +20°C, the sorption curves of three soils showed a sorption maximum of 4, 19 and 34 mmol/kg soil. The sorption data of six soils was in accordance with the Langmuir equation; the sorption maximum ranged from 15 to 119 mmol/kg soil, and were of the same magnitude as the maximums determined experimentally.

Extractable iron and aluminium predict the P sorption capacity of Thai soils

Soil Research ◽  
2005 ◽  
Vol 43 (6) ◽  
pp. 757 ◽  
Author(s):  
W. Wiriyakitnateekul ◽  
A. Suddhiprakarn ◽  
I. Kheuruenromne ◽  
R. J. Gilkes
Keyword(s):  
Sorption Capacity ◽  
Stepwise Regression ◽  
Clay Content ◽  
Langmuir Equation ◽  
Soil Types ◽  
Sorption Data ◽  
P Sorption ◽  
P Sorption Capacity ◽  
Freundlich Equation ◽  
Extractable Iron

The objective of this study was to determine if dithionite- and oxalate-extractable Fe and Al can be used to predict the P sorption capacity of Thai soils. Forty-five samples from diverse soil types were taken from surface and subsurface horizons of soils on sandstone, shale/limestone, granite, and basalt. The samples were analysed for P sorption, dithionite- and oxalate-extractable Fe and Al (Fed, Feo, Ald, Alo), specific surface area (SSA), and other soil properties. Generally P sorption data for these soils were slightly better fitted by the Langmuir equation than the Freundlich equation. The Langmuir P sorption maximum ranged from 35 to 1111 μg/g with a median value of 370 μg/g soil. Soils developed on basalt had higher values of P sorption maximum (xm) (range 400–1111 μg/g, median 597 μg/g) than soils on other parent materials. Fed concentrations in soils (4–74 g/kg) were much higher than Feo concentrations (0.2–13.8 g/kg) with values of Feo/Fed ranging from 0.01 to 0.28 (median 0.09), indicating that most of the free iron oxides were crystalline. Amounts of Ald and Alo were about equal with median values of 1.6 and 1.0 g/kg, respectively. About 80% of the samples had SSA values <40 m2/g. Both the P sorption maximum and Freundlich k were linearly related to SSA (R2 = 0.77, 0.74), Ald (R2 = 0.78, 0.79), Alo (R2 = 0.64, 0.74), Fed (R2 = 0.48, 0.41), Feo (R2 = 0.43, 0.72), and clay content (R2 = 0.48, 0.36). Stepwise regression indicated that 81% of the variability in P sorption by these soils could be explained by a combination of dithionite and oxalate Fe and Al, however, Ald alone is almost as effective in predicting the P sorption capacity of Thai soils.

scholarly journals Sorption capacity of phosphate in mineral soils: II Dependence of sorption capacity on soil properties

1990 ◽  
Vol 62 (1) ◽  
pp. 9-15
Author(s):  
Raina Niskanen
Keyword(s):  
Soil Properties ◽  
Sorption Capacity ◽  
Mineral Soil ◽  
Clay Content ◽  
Organic C ◽  
Phosphate Sorption ◽  
P Sorption ◽  
P Sorption Capacity ◽  
Mineral Soils ◽  
Extractable Al

The dependence of the indicator of phosphate sorption capacity on extractable Al and Fe and other soil properties was studied in a material consisting of 102 mineral soil samples. The sum of P adsorbed on soil during two days from a solution containing P 5 mmol/l and P extracted by 0.02 M EDTA (pH 5.3) as an estimate of the initial P content in the soil was used as the indicator of P sorption capacity. In clay and silt soils (n = 51), the Al and Fe extracted by 0.05 M oxalate (pH 2.9) together with the organic C content explained 85 %, the Al and Fe extracted by 0.05 M K4P2O7 (pH 10) together with the clay content 87 %, the Al and Fe extracted by 0.02 M EDTA (pH 5.3) 91 %, and the Al extracted by 1 M CH3COONH4 (pH 4.8) together with the organic C and clay contents 78 % of the variation of the indicator of phosphate sorption capacity. In coarse soils (n = 51), the variation of the indicator was explained well only by oxalate-extractable metals, which together with soil pH and clay content explained 80 % of the variation. Extractable Al was generally the most important explainer of variation. The results suggest that forms of extractable Al and Fe explaining the variation of the indicator of P sorption capacity in clay and silt soils are partially different from those in coarse soils.

Synthesis of kaolinite/iron oxide magnetic composites and their use in the removal of Cd(II) from aqueous solutions

2013 ◽  
Vol 67 (7) ◽  
pp. 1642-1649 ◽  
Author(s):  
Pengfei Zong ◽  
Shoufang Wang ◽  
Chaohui He
Keyword(s):  
Iron Oxide ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sorption Capacity ◽  
Sorption Isotherms ◽  
Entropy Change ◽  
Solution Chemistry ◽  
Standard Entropy ◽  
Iron Oxide Particles ◽  
Magnetic Composites

Kaolinite/iron oxide magnetic composites (kaolinite/MCs) were used as adsorbent for the removal of Cd(II) from aqueous solutions. The influences of pH, ionic strength, solid/liquid ratio and temperature on Cd(II) sorption on kaolinite/MCs were evaluated. The results showed that the removal of Cd(II) on kaolinite/MCs was strongly dependent on pH and ionic strength. An optimal kaolinite/MCs concentration mass per volume for removal of Cd(II) from aqueous solutions was 1.4 g L–1. The Langmuir and Freundlich models were used to simulate sorption isotherms of Cd(II) at three different temperatures of 293, 313 and 333 K. The sorption of Cd(II) on kaolinite/MCs increased with increasing temperature, and thermodynamic parameters (standard entropy change, enthalpy change and Gibbs free energy change) illustrated that this sorption process was spontaneous and endothermic. The sorption behaviors of Cd(II) were mainly dependent on surface properties of kaolinite/MCs and solution chemistry conditions. The sorption capacity of Cd(II) on kaolinite/MCs was lower than that on kaolinite, because iron oxide particles decreased surface charge of kaolinite leading to less sorption capacity. Due to high magnetism, kaolinite/MCs could be easily separated with an external magnetic field. Kaolinite/MCs could therefore be used as potential adsorbent for preconcentration and immobilization of Cd(II) ions from large volumes of aqueous solutions.

scholarly journals Extractable aluminium, iron and manganese in mineral soils: III Comparison of extraction methods

1989 ◽  
Vol 61 (2) ◽  
pp. 89-97
Author(s):  
Raina Niskanen
Keyword(s):  
Organic Carbon ◽  
Soil Ph ◽  
Mineral Soil ◽  
Extraction Methods ◽  
Soil Characteristics ◽  
Organic Carbon Content ◽  
Extractable Metals ◽  
Mineral Soils ◽  
Extractable Al ◽  
Iron And Manganese

The extractability of soil Al, Fe and Mn were studied in 102 mineral soil samples. The extractants were 0.05 M oxalate (pH 2.9), 0.05 M K4P2O7 (pH 10), 0.02 M EDTA (pH 5.3) and 1 M CH3COONH4 (pH 4.8). In the group of clay and silt soils (n = 51), the Al extracted by the four extractants correlated closely; the r values ranged from 0.91*** to 0.96***; in coarser soils (n = 51) the r values ranged from 0.42* to 0.82***. In clay and silt soils, the organic carbon content and soil pH together explained 50 % of the variation in oxalate-extractable Al, 70 % of the variation in pyrophosphate-extractable Al, 53 % of the variation in pyrophosphate-extractable Fe and 56 % of the variation in acetate-extractable Al. The clay and organic carbon contents together with soil pH explained 77 % of the variation in EDTA-extractable Al in clay and silt soils. In coarse soils, the extractable metals were not closely related to the soil characteristics.

scholarly journals Determination of soil specific surface area by water vapor adsorption: I Drying of soil samples

1987 ◽  
Vol 59 (2) ◽  
pp. 63-65
Author(s):  
Raina Niskanen ◽  
Väinö Mäntylahti
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Mineral Soil ◽  
Clay Content ◽  
Fine Sand ◽  
Water Vapor Adsorption ◽  
Soil Samples ◽  
Organic Carbon Content ◽  
Clay Sample

Drying of three mineral soil samples (clay content 4—58 %, organic carbon content 1—5 %) equilibrated at 75.5 % relative humidity was studied. The soils were dried in an oven at +50°C, +70°C and + 105°C for 4 and 8 hours and in a desiccator over pure concentrated H2SO4 and P2O5. Drying over desiccants for 8 hours removed less water than drying at + 50°C. Drying over desiccants for 3—7 days was as efficient as drying at +70°C, for 14—24 days as efficient as 4 hours of drying at + 105°C. Eight hours of drying at + 105°C seemed to be too drastic, because it caused a greater weight loss in the clay sample of 5 % organic carbon content than did prolonged desiccant-drying. Drying at + 70°Cremoved as much water from fine sand which contained 4 % clay as prolonged desiccant-drying.

Structural vulnerability of New Zealand soils

Soil Research ◽  
1997 ◽  
Vol 35 (3) ◽  
pp. 461 ◽  
Author(s):  
A. E. Hewitt ◽  
T. G. Shepherd
Keyword(s):  
New Zealand ◽  
Management Practices ◽  
Clay Content ◽  
Vulnerability Index ◽  
Organic Carbon Content ◽  
Structural Vulnerability ◽  
Phosphate Retention ◽  
Mineral Soils ◽  
Physical Degradation ◽  
The Impact

Some New Zealand soils withstand intensive cultivation and support continuing high production and yet maintain essential soil physical qualities of infiltration, aggregation, and aeration. In other soils, essential soil qualities deteriorate rapidly under the impact of even moderately intensive management practices. Our objective was to estimate the inherent susceptibility of New Zealand soils to physical degradation by focusing on structural vulnerability. We took a deductive approach by reviewing the available information on the structural stability and physical degradation of New Zealand soils. We identified 4 soil attributes that are well represented in the national soils database and are most likely to control structural vulnerability: (i) stabilising short-range-order oxy-hydroxides of aluminium and iron as estimated by phosphate retention, (ii) total organic carbon content, (iii) clay content, and (iv) wetness. The 4 attributes were standardised and transformed and a simple structural vulnerability index (SV) was devised. We determined SV for all mineral soils in the national soils database. The results provide a ranking of soil groups according to their structural vulnerability. We concluded that the index may be used as a first approximation rating of the structural vulnerability of New Zealand soils to aid resource management.

scholarly journals Temperature dependence of phosphate sorption in mineral soils

1990 ◽  
Vol 62 (1) ◽  
pp. 17-20
Author(s):  
Raina Niskanen
Keyword(s):  
Ionic Strength ◽  
Temperature Dependence ◽  
Mineral Soil ◽  
Soil Samples ◽  
Phosphate Sorption ◽  
Mineral Soils

The sorption of phosphate was studied in 33 mineral soil samples at the temperatures of +5°C and +20°C. The soils were equilibrated for 2 days with a solution containing phosphate 0.1 mmol/l at an ionic strength of 0.01. At +5°C, the sorption remained unchanged or increased slightly as compared to the sorption at +20°C. The differences between sorbed amounts ranged from —0.03 to 0.29 mmol/kg soil and were statistically significant in 11 samples.

scholarly journals Removal of Salicylic and Ibuprofen by Hexadecyltrimethylammonium-Modified Montmorillonite and Zeolite

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 898
Author(s):  
Jiyeon Choi ◽  
Won Sik Shin
Keyword(s):  
Sorption Isotherms ◽  
Organic Carbon Content ◽  
Sorption Data ◽  
Maximum Sorption Capacity ◽  
Ideal Adsorbed Solution Theory ◽  
Modified Montmorillonite ◽  
Maximum Sorption ◽  
Competitive Model ◽  
Sorption Mechanisms ◽  
Positively Charged

The removal of salicylic acid (SA) and ibuprofen (IB) by sorption onto HDTMA-modified montmorillonite (HM) and zeolite (HZ) was investigated at pH 7. The single sorption data were fitted well by the Freundlich, Langmuir, Dubinin−Radushkevich (DR), and Polanyi−Dubinin−Manes (PDM) models (R2 > 0.94). The sorption affinity of Freundlich and the maximum sorption capacity of Langmuir and PDM models of pharmaceuticals onto HM were consistently higher than that of HZ mainly owing to the higher organic carbon content. In addition, the KF, qmL, and qm values were in the order of IB > SA owing to higher hydrophobicity and molar volume. Since the predominant speciation of SA and IB is anionic at pH 7 (>pKa), sorption onto HM occurs mainly by the two-dimensional surface adsorption onto the pseudo-organic medium in the HM, whereas the interaction of anionic pharmaceuticals with the positively charged “head” of HDTMA is responsible for HZ. Sorption isotherms were fitted well by the PDM model, which indicated that pore-filling was one of the dominating sorption mechanisms. The extended Langmuir model, modified Langmuir competitive model, and ideal adsorbed solution theory employed with Freundlich and Langmuir sorption models were applied to predict binary sorption. The effect of competition between the solutes was clearly evident in the characteristic curves; the maximum sorbed volume (qv.m) was reduced, and the sorbed volume (qv) had a wider distribution toward the sorption potential density.

Experimental Study and Modeling of Uranium (VI) Sorption onto a Spanish Smectite

2008 ◽  
Vol 1124 ◽  
Author(s):  
Tiziana Missana ◽  
Ursula Alonso ◽  
Miguel Garcia-Gutierrez ◽  
Nairoby Albarran ◽  
Trinidad Lopez
Keyword(s):  
Ionic Strength ◽  
Exchange Process ◽  
Surface Complexation ◽  
Sorption Isotherms ◽  
Sorption Behavior ◽  
Ionic Exchange ◽  
Experimental Conditions ◽  
Sorption Data ◽  
Model Combining ◽  
Wide Range

AbstractAdsorption of uranium onto a Spanish smectite was studied, analyzing the effects of the most important parameters such as pH, ionic strength, radionuclide concentration and solid to liquid ratio. Batch sorption studies, in anoxic conditions under N2 atmosphere, were carried out on the bentonite previously purified and converted into the homoionic Na-form. In the sorption edges, two regions could be clearly distinguished. At pH lower than 5, sorption depended strongly on the ionic strength, possibly indicating the predominance of the uranyl ionic exchange process. At higher pH, sorption did not depend on the ionic strength but only on pH. The sorption behavior in this region suggested the predominance of a surface complexation mechanism. Sorption isotherms showed a non linear behavior in the concentration range used. Sorption data were interpreted using a non electrostatic standard model combining surface complexation, with the weak and strong SOH sites of the clay, and ionic exchange. The acid – base properties of the weak SOH sites were determined by potentiometric titrations. The model used was able to reproduce, in a very satisfactory way, all the data in a wide range of experimental conditions.

Sorption and desorption of orthophosphate and pyrophosphate by mineral fractions of soils, goethite, and kaolinite

1991 ◽  
Vol 71 (3) ◽  
pp. 327-338 ◽  
Author(s):  
T. Al-Kanani ◽  
A. F. MacKenzie
Keyword(s):  
Ammonium Oxalate ◽  
Sorption Isotherms ◽  
Parent Material ◽  
Langmuir Equation ◽  
Particle Sizes ◽  
Sorption Data ◽  
Freundlich Equation ◽  
P Release ◽  
P Fertilizer ◽  
Degree Of Sorption

Sorption-desorption reactions of orthophosphate (OP) and pyrophosphate (PP) were studied in two size fractions of Quebec soils (St. Bernard and Dalhousie) and minerals (goethite and kaolinite). Soil and mineral samples were fractionated into two separates (20.0–2.0 μm and 2.0–0.2 μm). The soils had similar mineral suites, but the St. Bernard have more vermiculite, chlorite, and quartz in the coarser fraction than the Dalhousie soil, perhaps an indication of different origin of parent material. Soil and goethite samples sorbed more OP than PP whereas kaolinite sorbed small but similar amounts of PP and OP. The PP and OP sorption was found to be significantly correlated with acid ammonium oxalate extractable Fe, but not with dithionite extractable Fe. Kaolinite desorbed similar amounts of OP and PP whereas more OP than PP was desorbed from soil and goethite samples. The degree of subsequent desorption seemed to be related to degree of sorption. The lack of similarity between sorption and desorption isotherms may indicate that sorption isotherms are of limited value in P fertilizer studies especially with regard to the estimation of subsequent P release in fertilized soils. Smaller particle sizes and their larger specific surface area resulted in higher OP and PP sorption compared with the coarser particle sizes. For OP sorption, the Langmuir equation yielded the closest fit in comparison to Freundlich and Temkin equations; the Freundlich equation gave the closest fit for PP sorption data. The Langmuir equation failed to fit desorption data. Key words: Orthophosphate, pyrophosphate, sorption, desorption

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