Simulation Of Adsorption Of Heavy Metal Ions Onto Ethylenediamine Silica Hybrid Material

Gaussian 09 quantum chemistry software is used to research the corresponding properties of the ethylenediamine silica hybrid material en/SiO₂ adsorbs the metal ions in aqueous solution.which is based on previous experiments in the laboratory.In this paper,the structure of complex formed by the organic ligand ethylenediamine?en?and the metal ions Cu²⁺and Zn²⁺in water are used as research objects.The structural optimization and frequency analysis of the complexes are calculated by the HF?DFT/B3LYP?DFT/M06-2X theoretical methods,the calculation error of the DFT/M06-2X method can be controlled within 3.6%,and this method is used as the calculation method of this study according to the minimum error principle.On this basis,the geometry,frequency,wiberg bond order,natural charge population,and energy changes during the reaction of the eight complexes that may be present in the M???-en-H₂O?M=Cu/Zn?system were calculated and analyzed by the DFT/M06-2X method.By comparison,when Cu²⁺/Zn²⁺and ligand en produce the same form of complexes in aqueous solution,the coordination bond between the coordination atom and Cu²⁺is shorter and the wiberg bond order is larger,the electron cloud overlap between the ligand and the Cu²⁺is greater.Moreover,the thermodynamic calculation results also show that the total energy of the system decreases more when Cu²⁺complexes with the ligand,and the stability of the complexes is higher.The calculation model of the ethylenediamine silica hybrid material?en/SiO₂?was constructed,and the geometric structure,frequency,the frontier molecular orbit and the electrostatic potential were calculated.The properties of en/SiO₂ material adsorbed metal ions Cu²⁺and Zn²⁺in aqueous solution were calculated and analyzed.The results show that the bond length of Cu-N bond formed by the two N atoms on the ethylenediamine group and Cu²⁺are 2.067?and 2.077?respectively,the bond lengths of the Zn-N bond are 2.170?and 2.201?respectively,It shows that the interaction between N atoms and Cu²⁺is stronger.The wiberg bond order of the Cu-N bond are 0.3212 and 0.3354 respectively,and the wiberg bond order of the Zn-N bond are 0.1939 and 0.2059 respectively,It shows that the bonding capacity of N atom and Cu²⁺is stronger.At the same time,en/SiO₂ transferred 0.45 electrons and 0.27 electrons to Cu²⁺and Zn²⁺respectively in the process of adsorption,It indicates that the electron cloud between en/SiO₂ and Cu²⁺is more overlapped and the corresponding coordination bond is stronger.The thermodynamic calculation results show that the energy in the reaction system decreases more when the en/SiO₂adsorbs the Cu²⁺in the aqueous solution,the adsorption reaction is more easily carried out in thermodynamics.It can be seen that compared with Zn²⁺adsorption,the ethylenediamine silica hybrid material has stronger adsorption capacity for Cu²⁺in aqueous solution.