Adsorption kinetics of zinc in a calcareous soil as affected by pH and temperature

B., Y.; Liu, J. F.

doi:10.1080/00103629709369859

Cited by 10 publications

(4 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…pollutants by soil constituents and soils (Cooke 1966;Chute and Quirk 1967;Alekseyev and Zyrin 1980;Jardine and Sparks 1984;Simard et al 1992;Mengel and Uhlenbecker 1993;Dang et al 1994;Ma and Liu 1997). Cadmium sorption by HA is well described by the parabolic diffusion equation in the present study, suggesting that its rate is limited by diffusion.…”

Section: Kinetics Of Cadmium Sorption By Humic Acidmentioning

confidence: 48%

Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy

Liu¹,

Frenkel²,

Vairavamurthy³

et al. 2001

Can. J. Soil. Sci.

View full text Add to dashboard Cite

. 2001. Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy. Can. J. Soil Sci. 81: 337-348. Humic acids (HA) constitute a major fraction of the organic matter in soils and sediments. Little is known about the kinetics and mechanisms of Cd sorption by HAs, especially those pertaining to the surface features and structure of the Cd-humate complexes. We investigated Cd sorption by HA using the conventional batch method, N 2 -BET method, atomic force microscopy (AFM), and extended X-ray absorption fine structure (EXAFS) spectroscopy to gain a better understanding of the kinetics and mechanisms. Cadmium sorption by HA can be described by the parabolic diffusion equation. The increase in the apparent diffusion coefficient with an increase in the initial Cd concentration was less pronounced at higher initial Cd concentrations, apparently due to an enhancement in aggregation of the Cd-humate complexes. The HA before and after Cd sorption at Cd concentrations ≤ 10 -6 M in different reaction times was spheroidal in shape. The Cd-humate complexes formed at 10 -4 and 10 -3 M Cd gradually changed to resemble the shape of a bean with increasing reaction time, thereby substantially decreasing their specific surface. Cadmium ions raveled the spheroidal HA particles into a bean-like structure by coordinating to six O atoms from the functional groups of HA, with a Cd-O distance of 2.297(2) Å. The Cd-O bond strength decreased with increasing initial Cd concentration.Key words: Cadmium, humate complexes, conformation, atomic force microscopy, EXAFS Liu, C., Frenkel, A. I., Vairavamurthy, A. et Huang, P. M. 2001. Étude de la mécanique et de la cinétique de la sorption du cadmium par l'acide humique au moyen de la microscopie à force atomique et de la spectroscopie des structures fines par absorption des rayons X. Can. J. Soil Sci. 81: 337-348. Les acides humiques (AH) constituent une bonne partie de la matière organique présente dans le sol et les sédiments. On sait peu de choses sur la cinétique et la mécanique de la sorption du Cd par les AH, surtout en relation avec les propriétés de la surface et la structure des complexes Cd-humate. Les auteurs ont étudié la sorption du Cd par les AH selon la méthode par lots traditionnelle, la technique N 2 -BET, la microscopie à force atomique (MFA) et une variante de la spectroscopie des structures fines par absorption des rayons X (EXAFS) dans l'espoir de mieux comprendre la cinétique et la mécanique du phénomène. L'équation de diffusion parabolique décrit la sorption du cadmium par les AH. La hausse du coefficient de diffusion apparent associée à l'augmentation de la concentration initiale de Cd est moins importante quand la concentration initiale de Cd est plus élevée. On le doit apparemment à une meilleure agrégation des complexes Cd-humate. Les AH présentent une forme sphéroïdale avant et après la sorption du Cd (concentration ≤ 10-6 M) à divers temps de réaction. Les complexes Cd-humate qui voi...

show abstract

Section: Kinetics Of Cadmium Sorption By Humic Acidmentioning

confidence: 48%

Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy

Liu¹,

Frenkel²,

Vairavamurthy³

et al. 2001

Can. J. Soil. Sci.

View full text Add to dashboard Cite

show abstract

“…respectively (Yadava et al, 1991). Ma and Liu (1997), employing a miscible-displacement procedure, studied…”

Section: Sorption Of Ni Onto Al Containing Pyrophyllitementioning

confidence: 99%

Temperature Effects on Nickel Sorption Kinetics at the Mineral–Water Interface

Scheckel

Sparks

2001

Soil Science Soc of Amer J

172

View full text Add to dashboard Cite

spectroscopic and microscopic investigations, determination of basic thermodynamic and kinetic parameters In recent years, innovative studies have shown that sorption of for the formation of these precipitates, such as the metals onto natural materials results in the formation of new minerallike precipitate phases that increase in stability with aging time. While energy of activation, and enthalpy, entropy, and free these findings have demonstrated the usefulness of current state-of-energies of activation, are nonexistent. In view of the the-art molecular-scale methods for confirming macroscopic data and common formation of metal precipitates on natural maelucidating mechanisms, basic kinetic and thermodynamic parameters terials, such information is vital if one is to better predict for the formation of the metal precipitates have not been examined. the fate of metals in the subsurface environment through This study examined Ni-sorption kinetics on pyrophyllite, talc, gibbsreaction models. ite, amorphous silica, and a mixture of gibbsite and amorphous silica The effect of temperature on reaction rates is well over a temperature range of 9 to 35؇C. Using the Arrhenius and known and important in understanding reaction mecha-Eyring equations, we calculated the energy of activation (E a) and nisms. Svante Arrhenius, a Swedish physical chemist enthalpy (⌬H ‡), entropy (⌬S ‡), and free energy of activation (⌬G ‡), who received the 1903 Nobel Prize for chemistry, noted related to the formation of the Ni precipitates. Based on values of E a (93.05 to 123.71 kJ mol Ϫ1) and ⌬S ‡ (Ϫ27.51 to Ϫ38.70 J mol Ϫ1), Ni that for most reactions, the increase in rate with increassorption on these sorbents was surface-controlled and an associative ing temperature is nonlinear. Drawing upon work by mechanism. The ⌬H ‡ values (90.60 to 121.26 kJ mol Ϫ1) suggest, as van't Hoff (1884) for the decomposition of chloracetic indicated by E a values, that an energy barrier was present for the acid in an aqueous solution, Arrhenius (1889) published system to overcome in order for the reaction to occur. Additionally, his famous paper ''Ober die Reacktionsgeschwindigkeit the large, positive ⌬G ‡ values suggest there is an energy barrier for bei der Inversion von Rohrzucker durch Sä uren'' in product formation. Although metal precipitation reactions often occur which he derived an expression for the kinetic temperain the natural environment, this study shows that the rate of these ture dependence of reactions. He concluded that most reactions depends strongly on temperature.

show abstract

“…The results of Ma and Liu (1997) on the adsorption of zinc on a calcareous soil clearly show the existence of binding kinetics. Christensen (1984a) showed that 95% cadmium is bound in the first 10 min on two different natural soils.…”

Section: Introductionmentioning

confidence: 84%

“…Even if only traces of these elements are generally present, they are no less dangerous, contributing to potential problems, such as toxicity of the plants and animals and (Berti and Jacobs 1996;Ma and Liu 1997;Ma et al 2002) consequently a disturbance in terrestrial ecosystems (Stalikas et al 1996;Flynn et al 2002).…”

Section: Introductionmentioning

confidence: 96%