On the limitations of the simplified Elovich equation in describing the kinetics of phosphate sorption and release from soils

Polyzopoulos, N. A.; Keramidas, V. Z.; Pavlatou, Athena

doi:10.1111/j.1365-2389.1986.tb00009.x

Cited by 38 publications

(16 citation statements)

References 14 publications

(15 reference statements)

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“…It is apparent that the simple Elovich equation is one of the best kinetic equations that could provide satisfactory fitting of the phosphate sorption kinetic data for both volcanic soils. This result is generally in agreement with other researchers' findings that the Elovich equation was able to describe properly the kinetics of phosphate sorption and desorption on soils and soil minerals (Chien and Clayton 1980;Polyzopoulos et al 1986;Sparks 1989). …”

Section: Sorption Kineticssupporting

confidence: 92%

Phosphorus removal from aqueous solutions by sorption on two volcanic soils

Zeng¹,

Johnson²,

Li³

et al. 2003

Can. J. Soil. Sci.

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, J. 2003. Phosphorus removal from aqueous solutions by sorption on two volcanic soils. Can J. Soil Sci. 83: 547-556. The use of low-cost materials for P removal is of interest for developing cost-effective techniques for preventing P pollution. This paper reports a study on phosphate removal from aqueous solutions by sorption on two volcanic soils. The raw and HCl-treated soils were characterized with respect to oxalate-extractable and dithionite-extractable Al and Fe contents, surface area, and P sorption capacities. The phosphate sorption isotherms, kinetics, pH effects, and desorbability were evaluated in batch tests. The measured isotherm data were well fitted by the Freundlich and Temkin models. Phosphate sorption on these soils was relatively fast and the kinetics could be satisfactorily described by the simple Elovich and power function equations. The two soils had maximum phosphate sorption capacities of approximately 0.85 and 1.35 mg g -1 gram of soil at pH 6.0-6.5. The pH had different effects on phosphate sorption on these soils, likely due to either calcium phosphate precipitation or surface repulsion of the negatively charged phosphate species at a higher pH. Column flow-through tests using both synthetic phosphate solution and liquid swine manure confirmed the phosphate removal ability of the volcanic soils. It was concluded that volcanic soils could be potential low-cost materials for controlling P pollution from agricultural sources. Les deux sols adsorbent relativement vite le phosphore et les équations d'Elovich ainsi que les simples fonctions puissance décrivent de manière satisfaisante la cinétique du mécanisme. La capacité d'adsorption maximale des deux sols s'établit à environ 0,85 et 1,35 mg de phosphate par gramme de sol, à un pH de 6,0 à 6,5. Le pH agit de manière variable sur l'adsorption du phosphate, sans doute à cause de la précipitation du phosphate de calcium ou de la répulsion des phosphates à charge négative en surface quand le pH est plus élevé. Les essais en colonne à renouvellement continu avec une solution de phosphate artificielle et du purin confirment l'extraction du phosphore par les deux sols volcaniques. On en conclut que ces derniers pourraient constituer un matériau bon marché pour lutter contre la pollution attribuable au phosphore d'origine agricole. Mots clés: Extraction du phosphate, sol volcanique, adsorption, isotherme, cinétique, désorptionPhosphorus is an essential nutrient for the growth of organisms in aquatic and terrestrial ecosystems. However, the discharge of P, both organic and inorganic forms, to water bodies may result in accelerated eutrophication, which has negative impacts on ecosystem biodiversity, recreation, and drinking water quality. Public concerns about water contamination by P originating from agriculture have increased. More evidence has linked agriculture to point and nonpoint source pollution of streams, rivers, lakes, and estuaries (Puckett 1995). As an example, land spreading of animal manure is a common practice in Canada and some ot...

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Section: Sorption Kineticssupporting

confidence: 92%

Phosphorus removal from aqueous solutions by sorption on two volcanic soils

Zeng¹,

Johnson²,

Li³

et al. 2003

Can. J. Soil. Sci.

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“…5) and ranged from 0.02-71.1 h. If the data plots linearly against ln(t + t 0 ) then a diffusion release mechanism is assumed (Cox & Joern 1997). The t 0 term accommodates sorption or desorption reactions that do not follow Elovichian behaviour for times preceding t 0 (Polyzopoulos et al 1986) and is estimated by trial and error or by iterative procedures. Only a few soils (e.g., Otiake) produced K release data that fitted the parabolic diffusion equation well.…”

Section: Modelling K Releasementioning

confidence: 99%

Rates of release of non‐exchangeable potassium in New Zealand soils measured by a modified sodium tetraphenyl‐boron method

Carey

Metherell

2003

New Zealand Journal of Agricultural Research

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A modified sodium tetraphenyl-boron method (Na-TPB), which uses an incubation period and boiling with a copper solution to destroy the tetraphenyl-boron-K precipitate (TBK) instead of shaking and resolubilisation with acetone, is proposed as a replacement for Jackson's TBK method. The method as recommended is 1 g soil in 3 ml of 1.7 M NaCl/0.01 M EDTA solution + 0.2 g Na-TPB and incubated at 20°C for between 1 and 168 h. Testing of the method showed it to be a more rapid, accurate, and cost-effective means of routinely testing soil K reserves than Jackson's test. Correlation of TBK values against Jackson's method were good (r 2 = 0.88) for short extraction times (1-4 h) but decreased with increasing extraction time. Regressions of TBK values with K c values, the current method for differentiating K supplying ability between soils, were only fair (r 2 < 0.75). This was due to mechanistic differences between dissolution (Kc-acid extraction) and solubility based (TBK-precipitation) methods.Potassium release curves were established for a range of 24 New Zealand soils for 1-672 h. The bulk of K release (c. 80%) occurred for most soils within the first 48 h with release rates in significant decline after 168 h. Release curves were modelled using a range of simple kinetic models: empirical Elovich, power, exponential, simplified-Elovich, and parabolic diffusion equations were all examined. The quality of fit for each model tended to decrease in that order, although this varied between soil classes.

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“…An anion exchange resin (Amberlite IRA 410) was used as the P-sink in these experiments (Polyzopoulos et al 1986). Shaking periods were 0.…”

Section: Kinetic Experimentsmentioning

confidence: 99%

The role of diffusion in the kinetics of phosphate desorption: the relevance of the Elovich equation

Pavlatou

Polyzopoulos

1988

Journal of Soil Science

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Various kinetic expressions were tested with phosphate desorption data from four contrasting soils and found inadequate, but the data supported a model recently proposed by Aharoni and Suzin. This model assumes that chemisorption reactions are kinetically controlled by diffusion and integration of Fick's equation, under appropriate boundary conditions, results in an expression for the time dependence of adsorption or desorption, that can be approximated by a sequence of equations-parabolic, Elovich and exponential-at small, intermediate and large times, respectively. Thus, full or even partial conformation of data to such a sequence would suggest diffusion control of the rate determining step, a suggestion usually relying on a firelationship alone.Since true rate constants could not be derived from the other expressions tested, calculation of physically meaningful activation energies was not possible. An approach to the calculation of activation energies at different stages of the process, based on the model of Aharoni and Suzin. and the difficulties encountered are also discussed.

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On the limitations of the simplified Elovich equation in describing the kinetics of phosphate sorption and release from soils

Cited by 38 publications

References 14 publications

Phosphorus removal from aqueous solutions by sorption on two volcanic soils

Phosphorus removal from aqueous solutions by sorption on two volcanic soils

Rates of release of non‐exchangeable potassium in New Zealand soils measured by a modified sodium tetraphenyl‐boron method

The role of diffusion in the kinetics of phosphate desorption: the relevance of the Elovich equation

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