EGU2020-471, updated on 12 Jun 2020
https://doi.org/10.5194/egusphere-egu2020-471
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The adsorption mechanisms of heavy metal ions by meadow soil

Tatiana Bauer1, Tatiana Minkina2, and David Pinskii3
Tatiana Bauer et al.
  • 1Federal Research Centre the Southern Scientific Centre of the Russian Academy of Sciences, Rostov-on-Don, Russian Federation (bauertatyana@mail.ru)
  • 2Southern Federal University, Rostov-on-Don, Russian Federation (tminkina@mail.ru)
  • 3Institute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, Russian Federation (pinsky43@mail.ru)

Soil is one of the key elements for all terrestric ecosystems. The ability of soils to adsorb metal ions from aqueous solution is of special interest and has consequences for agricultural issues as remediation of polluted soils. The aim of this work was to study the mechanisms of copper and zinc adsorption by meadow soil in the Rostov region (Russia). To study the ion-exchange adsorption of the Cu2+ and Zn2+ cations, the soil in the natural ionic form was disaggregated using a pestle with a rubber head and sieved through a 1mm sieve. The soil samples were treated with solutions of Cu2+ and Zn2+ nitrates at the separate presence of metals. The concentrations of the initial solutions were 0.05, 0.08, 0.1, 0.3, 0.5, 0.8 and 1.0 mM L–1. The soil:solution ratio was 1:10. The suspensions were shaken for 1 h, left to stand for 24 h, and then filtered. The contents of the metals in the filtrates were determined by atomic absorption spectrometry. The contents of adsorbed cations were calculated from the difference between the metal concentrations in the initial and equilibrium solutions.  The isotherm of Cu2+ and Zn2+ adsorption by meadow soil from nitrate solutions is described by the Langmuir equation:

Cad = CKlCe / (1 + KlCe),                        (1)

where Cad is the amount of adsorbed cations, C is the maximum adsorption, mM kg–1, Ce is the concentration of the metal in the equilibrium solution, mM L1 and Kl is the Langmuir constant, L mM–1.

According to the binding strength (constant value Кl) to the meadow soil, the studied cations form the series Cu2+ (103.7±6.3) >> Zn2+ (3.9±0.4). The specific interaction with the soil exchangeable complex could be more typical for the adsorption of Cu2+ by the soil than for the adsorption of Zn2+. The obtained regularity also coincides with the order of the change in the electronegativity of the metals. The higher the electronegativity of a metal, the stronger its interaction with the surface of the soil particles, which results in the formation of stronger bonds with the surface functional groups. The values of the maximum adsorption (С) for Cu2+ and Zn2+ decrease in the same order as the constants, but not so significantly: Cu2+ (13.2±0.4) > Zn2+ (3.9±0.4). Thus, the maximum adsorption, an extensive characteristic of the adsorption, is a less sensitive parameter than the equilibrium constant of adsorption Kl, an intensive characteristic of the process.

The reported study was funded by RFBR, project number 19-34-60041.

How to cite: Bauer, T., Minkina, T., and Pinskii, D.: The adsorption mechanisms of heavy metal ions by meadow soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-471, https://doi.org/10.5194/egusphere-egu2020-471, 2019

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