Thermodynamics of copper desorption from soils as affected by citrate and succinate

The goal of our study was to evaluate the effect of organic ligands citrate and succinate on the kinetics of Cu desorption from contaminated clay and sandy soils at three different temperatures. As shown by our results, the first order equation adequately described the kinetics of Cu desorption from clay and sandy soils under isothermal conditions. The reaction rate constant (kd) values of the first order kinetic equation for Cu desorption increased consistently with temperature, indicating faster Cu release at high temperatures. The desorption rate was more affected by citric than succinic acid at all temperatures studied. The negative values of standard enthalpy of activation suggest that the desorption reactions are not energy-consuming processes. Computation of the free energy of activation yielded values ranging from 87 to 87.9 kJ/mol. The largest value was calculated for the clay soil with succinic acid, the lowest one for the sandy soil with citric acid.