The comparative significance and utility of the Freundlich and Langmuir parameters for characterizing sorption and plant availability of phosphate in soils

Soil Research ◽  
1982 ◽  
Vol 20 (3) ◽  
pp. 233 ◽  
Author(s):  
ICR Holford
Keyword(s):  
Sorption Capacity ◽  
Plant Uptake ◽  
Langmuir Equation ◽  
Plant Availability ◽  
Phosphate Sorption ◽  
Surface Equation ◽  
Highly Correlated ◽  
Two Parameters

In studies using 62 Australian and English soils, the two parameters of the Freundlich sorption equation were compared with phosphate sorption capacity, calculated from the Langmuir 'two-surface' equation, and sorptivity and affinity indices calculated from the simple Langmuir equation applied to an isotherm concentration range of 0-5�g phosphorus/ml. The Freundlich extensive parameter was most highly correlated with sorptivity, and to a decreasing extent with sorption capacity and affinity. It appears to be fundamentally a sorptivity index which reflects the sorption capacity more than the affinity component of sorption, although greatly underestimating sorption capacity. The reciprocal of the Freundlich exponent proved to be an affinity parameter and was most useful in this role on soils of similar sorption capacity. However, conflicting results on different groups of soils showed that this parameter was less distinctive in its role than the others. Studies on two different groups of soils showed that the sorptivity and affinity parameters from the Langmuir equation accounted for more of the variance in plant uptake of labile phosphate than the Freundlich parameters.

scholarly journals The binary gas sorption in the bituminous coal of the Huaibei Coalfield in China

2018 ◽  
Vol 36 (9-10) ◽  
pp. 1612-1628 ◽  
Author(s):  
Lei Zhang ◽  
Zhiwei Ye ◽  
Mingxue Li ◽  
Cun Zhang ◽  
Qingsheng Bai ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Sorption Capacity ◽  
Bituminous Coal ◽  
Gas Adsorption ◽  
Langmuir Equation ◽  
Separation Coefficient ◽  
Gas Sorption ◽  
Langmuir Adsorption ◽  
Gas Molecules ◽  
Huaibei Coalfield

Knowledge of the gas sorption characteristics of a coal not only helps to explain the mechanism of enhanced coalbed methane recovery but also provides an important basis for simultaneous coal and gas extraction. In consequence, the pure and binary gas excess sorption capacity of methane, carbon dioxide, and nitrogen of bituminous coal samples derived from the Xutuan Coal Mine in Huaibei coalfield, in Anhui Province in China, was measured using the volumetric method. The fitting analysis of the pure gas Langmuir adsorption model was carried out. The binary gas excess sorption measurement showed that the final sorption capacity of bituminous samples was the same no matter what the gas adsorption order of competitive adsorption and displacement adsorption. Hence, coal gas adsorption is physical adsorption, i.e. the different adsorption and desorption process of gas molecules does not affect the final adsorption amount of coal to each component of gas. Using the fitting parameters obtained by the Langmuir equation, the extended Langmuir equation was used to predict the adsorption capacity for each component of the binary gas. The comparison between predicted adsorption capacity and measured adsorption capacity showed that the extended Langmuir equation can better describe the trend of the adsorption isotherm curves of a binary gas under different pressures. The separation coefficient and displacement coefficient were defined from Langmuir adsorption theory. The separation coefficient involves the proportion of each component in the free phase and the proportion of each component in the adsorption phase. The displacement coefficient involves the displacement ability of gas molecules at adsorption sites by free gas molecules.

High-Resolution Paleoclimatic Information from Chinese Eolian Sediments Based on Grayscale Intensity Profiles

2000 ◽  
Vol 53 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Stephen C. Porter
Keyword(s):  
Magnetic Susceptibility ◽  
High Resolution ◽  
Digital Camera ◽  
Dune Sand ◽  
Laptop Computer ◽  
Chinese Loess ◽  
Proxy Records ◽  
Eolian Sediments ◽  
Highly Correlated ◽  
Two Parameters

AbstractGrayscale intensity profiles from photographic images offer a rapid means of obtaining paleoclimate proxy records from Chinese loess, dune sand, and paleosols. Although the data can be obtained using conventional 35-mm film images, a digital camera and laptop computer will produce a high-resolution grayscale profile at a field site within minutes. Comparison of grayscale profiles with profiles of magnetic susceptibility measured down loess and dune-sand sections at sites on the Loess Plateau and Tibetan Plateau in a range of altitudes and climatic regimes shows that the two parameters are highly correlated. Therefore, grayscale intensity is a convenient alternative to magnetic susceptibility for generating paleoclimatic data in the loess and desert-margin regions of China. The resolution of both grayscale and susceptibility profiles ultimately is limited by bioturbation, which is most pronounced in paleosols.

Geostatistical assessment of the regional distribution of phosphate sorption capacity parameters (FeOX and AlOX) in northern Belgium

Geoderma ◽  
1995 ◽  
Vol 66 (3-4) ◽  
pp. 285-296 ◽  
Author(s):  
Richard Lookman ◽  
Nadia Vandeweert ◽  
Roel Merckx ◽  
Karel Vlassak
Keyword(s):  
Sorption Capacity ◽  
Regional Distribution ◽  
Phosphate Sorption

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.

Phosphate sorption capacity of European volcanic soils

2010 ◽  
Vol 59 (1) ◽  
pp. 77-84
Author(s):  
Gy. Füleky
Keyword(s):  
Sorption Capacity ◽  
Soil Property ◽  
High Ratio ◽  
Surface Reactivity ◽  
Soil Horizon ◽  
Phosphate Adsorption ◽  
Volcanic Soils ◽  
Phosphate Binding ◽  
Phosphate Sorption ◽  
Sorption Ability

The aim of the presented study was to prepare the phosphate sorption isotherms of 20 European volcanic soil profiles and some other Hungarian and German volcanic soils (n = 114) used in the experiment and to establish the soil characteristics determining the phosphate sorption capacity of these soils. The Langmuir isotherm well describes the phosphate sorption of European volcanic soils at bright concentration interval 0–600 mg·dm -3 P. The calculated phosphate adsorption maximum (P max ) is an excellent soil property for characterizing the surface activity of soils developed on volcanic parent material. The calculated phosphate sorption maxima of soils included in the experiment ranged from 0 to 10.000 mg P·kg -1 . Some of the volcanic soils sorbed a high ratio of the added phosphate at low concentrations, while others sorbed somewhat less. The difference in the phosphate binding affinity of soils caused the differences in the shape of the Langmuir adsorption isotherms. P retention % is a WRB diagnostic requirement of andic soil horizon. It was supposed that the phosphate sorption maximum (P max ) gives a better characterization of the surface reactivity of volcanic soils. As it was predicted, oxalate soluble Al is the most important soil property, which dominantly (in 73%) explained the phosphate sorption ability of European volcanic soils.

Surface-modified apricot pits as biochar feedstock and phosphate sorbent

2020 ◽  
Author(s):  
Gerhard Soja ◽  
Stefan Wyhlidal ◽  
Wolfgang Friesl-Hanl ◽  
Kathrin Zwölfer ◽  
Julia Edlinger ◽  
...  
Keyword(s):  
Surface Modification ◽  
Sorption Capacity ◽  
Vegetable Oils ◽  
Liquid Media ◽  
Phosphate Sorption ◽  
Sorption Dynamics ◽  
Negative Effect ◽  
Screw Reactor ◽  
Surface Modified

&lt;p&gt;Pits from fruit like apricots, peaches and cherries are an under-utilized resource. If there is any use at all, they may be extracted for special vegetable oils. Mostly the pits are combusted or left to rot. However, they are also an appropriate feedstock for pyrolytic carbonization. This study investigated the biochar produced from apricot pits for its potential to sorb phosphate from liquid media and from artificial wastewater.&lt;/p&gt;&lt;p&gt;Shredded apricot pits were pyrolyzed at 450 &amp;#176;C in a lab-scale screw reactor (Pyreka 3.0). Additionally, the impregnation of the feedstock with Mg(OH)&lt;sub&gt;2&lt;/sub&gt; before pyrolysis was studied to test the hypothesis that phosphate sorption to biochar takes advantage of metal bridges on the biochar surface.&lt;/p&gt;&lt;p&gt;The results of isotherm sorption experiments showed that the pre-pyrolysis Mg-surface modification of the pits improved the sorption capacity of the biochar up to 42 mg PO&lt;sub&gt;4&lt;/sub&gt;-P/g whereas the unmodified biochar adsorbed only about one tenth. When KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; was used as the only sorbate, EDX-mapping showed the formation of K-struvite-crystals in the pores of the biochar. Desorption experiments showed a major release of the adsorbed phosphate within a few hours. Sorption competition experiments with phosphate and nitrate showed no negative effect of nitrate on phosphate sorption. Feedstock impregnation with Ca(OH)&lt;sub&gt;2&lt;/sub&gt; resulted in more variable sorption dynamics.&lt;/p&gt;&lt;p&gt;The results could be confirmed by deploying the surface-modified apricot pit biochar for the reduction of the phosphate load in artificial wastewater.&lt;/p&gt;

Sorbed phosphate at standard supernatant concentration as an estimate of the phosphate needs of soils

1965 ◽  
Vol 5 (16) ◽  
pp. 52 ◽  
Author(s):  
RS Beckwith
Keyword(s):  
Sorption Capacity ◽  
Surface Soil ◽  
Equilibrium Concentration ◽  
Solution Concentration ◽  
Small Field ◽  
Surface Soils ◽  
Phosphate Sorption ◽  
Surface Horizon ◽  
Supernatant Solution

Phosphate sorption capacity of soils has meaning only if the equilibrium supernatant solution concentration is specified. Measurements have been made, on a variety of Queensland soils, at an equilibrium concentration of 0.2 p.p.m. P ; reasons for this choice of cencentration are discussed. Phosphate sorption values measured in this way appear to parallel the phosphate needs of legumes growing on a number of the soils examined in the laboratory. The approach is put forward for testing by others on present and future phosphate rate trials. Present phosphate sorption measurements are interpreted as indicating (1) that even where native phosphate is inadequate, or has been depleted by cropping, heavy-textured grey and brown soils of the brigalow lands will only require small field applications of superphosphate. (This statement may not apply to soils containing free carbonate in the surface). (2) that phosphate requirements of krasnozems vary considerably but may exceed 1 ton of superphosphate an acre in some areas. Loss of the surface horizon by erosion, or mixing the subsoil With surface soil, could increase the phosphate requirement of some of these soils. (3) that the phosphate status of soils formed from phyllite in the Gympie district is intermediate between these extremes. Here also the subsoils must be expected to have larger phosphate requirements than the surface soils.

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