Equilibrium and Kinetic Studies of the Adsorption of 2,4-D and Picloram on Humic Acid

Khan, Shahab Ullah

doi:10.4141/cjss73-060

Cited by 100 publications

(59 citation statements)

References 10 publications

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“…The positive correlation between SOC and Kd was stronger for CT (r = 0.89, P < 0.001) than for ZT (r = 0.63, P < 0.001). Other studies have shown that soil organic matter is an important factor in the sorption of 2,4-D by soil and sediment (Khan 1973;Reddy and Gambrell 1987;Stephens et al 2002).…”

Section: Resultsmentioning

confidence: 93%

Evaluating the use of digital terrain modelling for quantifying the spatial variability of 2,4-D sorption by soil within agricultural landscapes

Farenhorst

Florinsky²,

Monreal³

et al. 2003

Can. J. Soil. Sci.

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Farenhorst, A., Florinsky, I. V., Monreal C. M. and Muc, D. 2003. Evaluating the use of digital terrain modelling for quantifying the spatial variability of 2,4-D sorption by soil within agricultural landscapes. Can. J. Soil Sci. 83: 557-564.The most sensitive input parameter in many herbicide fate and transport models is the sorption-partitioning coefficient (Kd), a measure of herbicide sorption by soil. Spatial analyses of Kd are traditionally performed using geostatistics, but this approach requires intensive soil sampling and herbicide analysis. This study examined the use of digital terrain modelling as an alternative tool for quantifying the distribution of herbicide sorption within agricultural fields. Soil samples from a conventional-till (CT) and zero-till (ZT) field were analysed for soil organic carbon (SOC), soil pH, clay content, and the 2,4-D ([(2,4-dichlorophenoxy)acetic acid]) soil-water partitioning coefficient. Digital terrain models were used to calculate topographical variables (elevation, slope gradient, slope aspect, horizontal curvature, vertical curvature, mean curvature, specific catchment area, topographic index and stream power index) for each sampling point. Results indicated that topographic variables were adequate predictors of all soil properties in ZT (R 2 ranging from 0.64 to 0.76), and of SOC in CT (R 2 = 0.65, P < 0.001). For CT, 2,4-D sorption by soil was very well predicted with soil properties alone (R 2 = 0.82, P < 0.001) and with soil properties in combination with topographic variables (R 2 = 0.85, P < 0.001), but was less predicted by topographic variables alone (R 2 = 0.50, P < 0.001). For ZT, the level of prediction of 2,4-D sorption by soil was weak with soil properties alone (R 2 = 0.53, P < 0.001) or when topographical variables alone (R 2 = 0.56, P < 0.001) were used, but a substantial increase in the level of prediction was achieved when both soil properties and topographic variables were used (R 2 = 0.73, P < 0.001). We conclude that digital terrain modelling, in combination with soil properties data, is an appropriate approach for predicting the spatial distribution of 2,4-D sorption within undulating-to-hummocky glacial till landscapes in western Canada.Key words: herbicide sorption, topography, zero-tillage, conventional-tillage, digital terrain modelling.Farenhorst, A., Florinsky, I. V., Monreal, C. M. et Muc, D. 2003. Evaluation de l'utilisation de la modélisation numérique du terrain pour quantifier la variabilité de la sorption du 2,4-D par la terre dans les paysages agricoles. Can. J. Soil Sci. 83: 557-564. Pour beaucoup de modèles sur la dispersion et le transport des herbicides dans le sol le paramètre d'entrée le plus variable est le coefficient de distribution de la sorption (Kd). Les analyses du Kd sont généralement réalisées en utilisant des méthodes géostatistiques, mais cette approche requière d'intensifs échantillonnages de terre avec recherche d'herbicides. Notre étude se propose de vérifier l'utilité de la modélisation numérique du terrain comm...

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Section: Resultsmentioning

confidence: 93%

Evaluating the use of digital terrain modelling for quantifying the spatial variability of 2,4-D sorption by soil within agricultural landscapes

Farenhorst

Florinsky²,

Monreal³

et al. 2003

Can. J. Soil. Sci.

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“…Smaller ∆G 0 values also suggest that carbofuran adsorption by soils is often promoted by weak physical forces (Weber 1993). The attractive forces in physical adsorption involve surface energies that are often less than a few kJ/mol, suggesting a diffusion-controlled mechanism for the adsorption of pesticides (Khan 1973).…”

Section: Resultsmentioning

confidence: 99%

Adsorption and Movement of Carbofuran in Four Different Soils Varying in Physical and Chemical Properties

Singh

Srivastava

2009

Adsorption Science & Technology

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Laboratory studies were conducted to determine the adsorption and movement of carbofuran on four divergent textured Indian soils at a fixed volume fraction (f s = 0.1) of methanol/water mixtures using batch equilibrium and soil thin layer chromatography (soil TLC) techniques. The measured equilibrium adsorption isotherms for silt loam (FSL and ASL) and loam (KL) soils were L-shaped and for sandy loam (BSL) soil S-shaped, all being well fitted by the Freundlich isotherm. A higher adsorption of carbofuran was observed on FSL followed by ASL, KL and BSL soils as anticipated by the values obtained for the Freundlich constant, K F and partition coefficient, K D . The Frontal Retardation factor (FR f ) values obtained from soil TLC studies were inversely proportional to the K F and K D values.The affinity of carbofuran towards organic carbon, organic matter and clay content of the soils was evaluated by calculating the K OC , K OM and K C values. The negative magnitude of the Gibbs' free energy (∆G 0 ) indicated the spontaneity of the adsorption of carbofuran onto the soils studied. The leaching index (LI) of carbofuran calculated for the soils studied indicated its high potential to leach into shallow aquifers and ground water. Pearson's correlations calculated for K F and K D against the soil properties showed a highly significant correlation with the clay + silt content of the soils. Multiple regression of K F and K D against the soil properties indicated that the mineral content of the soils (clay and clay + silt) is the best predictor of carbofuran adsorption, followed by soil pH. Predicted log K OM values were also evaluated by using the aqueous solubility, the 1-octanol/ water partition coefficient (K OW ), the adsorbability index (AI) and the first-order molecular connectivity index ( 1 χ) of carbofuran. Use of the aqueous solubility, and the 1-octanol/water partition coefficient (K OW ) to predict the extent of adsorption gave values which displayed a considerable error in comparison to those measured experimentally, whereas the use of the adsorbability index (AI) and the first-order molecular connectivity index ( 1 χ) of carbofuran improved the predictions considerably.

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“…at 3000 rpm. One ml of the clear supernatant was removed and analyzed for the pesticide concentration (Kahan, 1973;Rounak & Kafia, 2011;Suman & Gajbhiye, 2002).…”

Section: Adsoption -Desorption Experimentsmentioning

confidence: 99%

“…Its adsorption involved ionic interaction with positive charges in soil and also the less energetic Van der Waals forces and charge transfer (Kahan, 1973;Nearpass, 1976). Thus sorption may occur as a result of enthalpy-related and entropy-related forces, hydrophobic bonding is an example of entropy driven processes; it's due to the combination of London dispersion forces.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Adsorption-desorption of Metolachlor and 2,4-D on Agricultural Soils

Shariff¹

2011

IJC

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To investigate the thermodynamics parameters for adsorption-desorption behavior of metolachlor (nonionic herbicides) and 2,4-D (anionic herbicides) on the selected soils by using a kinetic approach. The objective of this study to investigate the rate constants and other kinetic parameters for the adsorption-desorption behavior and to elucidate the effect of temperature, the experiments were done at 10, 25, 40 ±1 ℃. Data from the experiments revealed that the adsorption-desorption of metolachlor and 2,4-D on the selected soil samples followed the first order rate law, and revealed that adsorption of metolachlor and 2,4-D was spontaneous exothermic, a partly physical and partly chemical in nature to some extent. Values of adsorption rate constant k a were in the range 0.853 -2.263 and 0.765 -2.399 for metolachlor and 2,4-D respectively, desorption rate constant k d were in the range 0.744 -1.303 and 0.705 -1.289 for metolachlor and 2,4-D respectively. By using the Arrhenius equation the activation energy of each adsorption-desorption of both pesticides were calculated. The activation energy E a for adsorption processes followed the range 14.667 -17.361 kJ·mol , and -16.292 to -61.292 J·mol -1 ·K -1 for metolachlor and 2,4-D respectively.

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Equilibrium and Kinetic Studies of the Adsorption of 2,4-D and Picloram on Humic Acid

Abstract: KneN, S. U. 1,973. Equilibrium and kinetic studies of the adsorption of 2,4-D and picloram on humic acid. Can. J. Soil Sci. 53: 429-434. Equilibrium and kinetic studies of the adsorption of 2,4-D (2,4-dichlorophenoxy acetic acid) and picloram (4-amino-3,5,6-trichloropicolinic

Cited by 100 publications

References 10 publications

Evaluating the use of digital terrain modelling for quantifying the spatial variability of 2,4-D sorption by soil within agricultural landscapes

Evaluating the use of digital terrain modelling for quantifying the spatial variability of 2,4-D sorption by soil within agricultural landscapes

Adsorption and Movement of Carbofuran in Four Different Soils Varying in Physical and Chemical Properties

Thermodynamic Adsorption-desorption of Metolachlor and 2,4-D on Agricultural Soils

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