Adsorption Kinetics and Isotherm Modeling of Lead in Calcareous Soils: Insights into Thermodynamics, Desorption, and Soil Properties

ABSTRACT

Since few researches were conducted regarding adsorption kinetics of lead (Pb) especially in calcareous soil therefore, this study has been conducted to determine the Pb adsorption, desorption, and kinetics in two types of calcareous soils. Pseudo-first-order, pseudo-second-order, elovich kinetic models used to determine Pb adsorption. To examine Pb adsorption isotherm, Freundlich, Langmuir, Temkin, and Elovich models were applied at three temperatures (298°, 308°, and 318°K). At three levels of temperatures (298°, 308°, and 318°K), thermodynamic parameters were studied. Desorption was also determined. Pseudo-second-order was the best model for describing the adsorption. Pb adsorption data of all samples were better fitted by Langmuir isotherm. Correlation between Pb adsorption and shaking periods was significantly correlated with soil pH, CCE, clay content, OM, and CEC. ΔG^θ<0 shows Pb adsorption in our samples is thermodynamically possible and spontaneous. ΔS^θ indicated that samples have a high affinity for Pb. Clay with the highest Pb adsorption capacity also has the lowest Pb desorption. Desorption percentage (P_des) were 75% and 93.6% for clay and sandy clay loam, respectively. In other words, over time, sandy clay loam desorbed more Pb.

KEYWORDS:

• Adsorption kinetics
• Calcareous soil
• Langmuir isotherm
• Lead
• Pseudo second order
• Thermodynamic parameters

Acknowledgements

I want to thank my family, who gave me the opportunity to finish this paper (Dr. Farhang Rassaei, Mahdokht Massoud, Dr. Liza Rassaei, Dr. Farshad Rassaei, Dr. Janet Rassaei, and Farhad Rassaei).

Authors’ contributions

Farzad Rassaei: design of the work, the acquisition, analysis, interpretation of data, writing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets during and/or analyzed during the current study available from the corresponding author on reasonable request.

Additional information

Funding

There is no funding regarding this manuscript.