Copper adsorption Behavior in some Calcareous Soils using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich Models

Abstract

This study conducted to characterize copper adsorption behavior and determination sorption thermodynamic parameters in some calcareous soil from Sulaimani Governorate, Iraqi Kurdistan region. Copper adsorption studied in five calcareous soils includes (Sharazor, Qaradagh, Bazian, Mawat, and Surdash) varying in total calcium carbonate, organic matter and a cation exchange capacity of Sulaimani governorate in Iraqi - Kurdistan region. The adsorption isotherms of the Copper metal by the soil carried out using a batch method. One gram of each soil sample, in duplicate, was placed in plastic bottles and equilibrated with 50 ml of solution CaCl2 (0.01M), containing a series of Cu concentrations (0, 2.5, 5, 10, 20, and 40 mg Cu L-1) in the form of (CuSO4). The concentration of Cu determined in a solution using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The amount of Cu adsorbed by the sample determined by subtracting the equilibrium Cu concentration in the solution from the added Cu. The equilibrium isotherm data used to describe Cu adsorption in the five different soils using the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm model. Freundlich model compared to the various models considered as the best model for describing copper adsorption at both temperatures (298 and 318oK) to describe the isotherm models in the studied soils depending on the highest value of the determination coefficient (R2), and the least value of root mean square error (RMSE), and Akaike information criterion (AIC).