Application of thermodynamic characteristics to describe copper adsorption in some calcareous soils

Abstract

This work includes studying the thermodynamic parameters such as Ko, ∆Go, ∆Ho, and ∆So determined in five calcareous soils at two different temperatures (298 oK and 318 oK) include Sharazor, Qaradagh, Bazian, Mawat, and Surdash differing in total calcium carbonate, organic matter, and cation exchange capacity of Sulaimani governorate in the Iraqi-Kurdistan region. One gram of soil samples equilibrated at (298 oK and 318 oK) 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 as (CuSO4). The values of the standard free energy (∆Go) were negative of the five soils ranging from (- 5.026 to - 4.009 kJ mol-1) and (- 5.201 to - 4.075 kJ mol-1) respectively at both 298 oK and 318 oK temperatures. Entropy values (ΔS°) were negative in Sharazor and Bazian soil, while, entropy values (ΔS°) were positive at both temperatures (298 oK and 318 oK) in Qaradagh, Mawat, and Surdash soil.