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

摘要：

The first order equation adequately described the kinetics of Cu desorption from clay, calcareous and sandy soil under isothermal conditions. The reaction rate constant (kd) values of the first order kinetic equation for Cu desorption increased consistently with temperature, indicating faster release of Cu at higher temperatures. The Cu desorption rate from the sorbents at all three temperatures was as follows: citric>succinic. The Ea values indicated that Cu desorption from the three soils in the presence of two organic ligands was a diffusion controlled reaction. The negative values of AH suggested that the desorption reactions were not energy consuming processes. The higher negative values of (ΔH-) for Cu desorption from the three soils in the presence of suecinic ligand indicated that the heat energy required to overcome the Cu desorption barrier was greater than in the presence of citric ligand. The free energy of activation (ΔG-) values ranged from 87 to 87. 9kJ/mol. The largest value of ΔG+ for Cu desorption occurred for clay soil in the presence of succinic acid while the lowest value of ΔG- occurred for sandy soil in the presence of citric acid. The information in this study is necessary to contruct fully functional models that will improve understanding of mobility and bioavailability of metals in soils.

关键词： Cu mobility Kinetics organic ligands

作者: E. A. Elkhatib A. M. Mahdy N. H. Barakat

作者单位: Department of Soil and Water, College of Agriculture 21545, Alexandria University, Alexandria, Egypt Department of Soil and Water, College of Agriculture 21545,Alexandria University, Alexandria, Egypt

会议类型: 国际会议

会议名称: 第九届痕量元素生物地球化学国际会议(9th International Conference on the Biogeochemistry of Trace Elements)

会议地点: 北京

会议语种:英文

页码: 692-693

在线出版日期: 2007-07-15（万方平台首次上网日期，不代表论文的发表时间）