Structure And Properties Of Acidic Phosphate Extractant Molecules And Metal Extraction Composition

Solvent extraction is an important separation technique, and the acidic phosphorus (phosphine) extractant is widely used in industrial solvent extraction. However, as it is difficult to obtain the microstructure information of different kinds of extraction agent molecules by traditional research methods, limiting the further research of the relationship between the microstructure of the extraction agent molecule and extraction properties. Thus, in order to quantitatively describe the relationship between the structure of acidic phosphorus (phosphine) extractant and its properties, it is need to find new, efficient, and more accurate research methods. In this paper, the quantum chemical method was used to research the typical acidic phosphorus (phosphine) extractant molecules and their corresponding extracted complex’s microscopic structure, and get their microstructure information such as geometry, charge distribution, frequency and orbital and so on. On this basis, through data fitting, further research the relationship between the microstructure of the typical acidic phosphorus (phosphine) extractant and properties so that it can provide theoretical basis for guiding the development of new special effect extractants.Using the B3LYP/6-31+G(d, p) method of the density functional theory (DFT) for different chain length acidic phosphorus extractant:dibutyl phosphate, diamyl phosphate, dihexyl phosphate, diheptyl phosphate and di-(2-ethylhexyl) phosphoric acid; dibutyl phosphonic acid, diamyl phosphonic acid, dihexyl phosphonic acid, diheptyl phosphonic acid and bis(2,4,4,trimethylpentyl) phosphinic acid for quantum chemistry calculation, and obtain the microstructure information. From calculated results, it is concluded that there is no imaginary frequency in infrared spectra, the structure of molecules are stability, and there are same functional groups in calculated molecules, their structural is similarity. The results show that the charge of extractant molecules are main focus on the phosphorus atom and an oxygen atom, electron withdrawing group lead the phosphorus atom’s charge density increases extractant, the phosphorus atom and the oxygen atom on the phosphoryl and the hydroxyl is the largest contribution to the HOMO(Highest Occupied Molecular Orbital), LUMO(Lowest Unoccupied Molecular Orbital) orbital, respectively. It is indicates the phosphoryl group and the hydroxyl group are the reactive center of extractant molecules. With the chain length of alkyl in the acidic phosphorus (phosphine) extractant molecule increase, the molecule system become more stable, and the phosphorus molecules easier react with the metal ions in the same state.Density functional theory calculation methods with B3LYP/6-31G basis set were employed to investigate the extraction agent’s dimer molecule structure and properties of di-(2-ethylhexyl)-phosphoric acid (P204),2-ethylexyl phosphonic acid mono2-ethylexhyl ester (P507) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272). The results reveal that the monomer molecules of P204, P507, Cyanex272form non-planar C1configuration dimers through hydrogen bonds. The hydrogen bonding leads to the charge rearrangement, orbital hybridization, restructuring in dimer molecules, It is shows that the bond length in dimmer are longer than that of the monomers and there is big difference of infrared spectrum between dimers and corresponding monmer, especially the bond length of hydroxyl and phosphoryl. Moreover, the role of hydrogen bonding stabilized the dimer molecules. On the basis of stabilization energy of dimer demonstrates three extractant molecules stable order is P204<P507<Cyanex272. From Charge distribution indicate that the number of lone pair electron density of the oxygen atom on phosphoryl group of three extractant moleculese is Cyanex272<P507<P204, the result is match the actual ability to extract metal order Cyanex272<P507<P204. Analysis of frontier orbitals, it is informed that the extractant P204, P507and Cyanex272exists as a dimer molecule is easier to accept or lose electrons, which benefit to improve the extraction ability.The extracted complexes form of extractant molecules P204, P507and Cyanex272have been investigated by B3LYP/LANL2DZ calculation method, and their mcrostructures and properties were analyzed. The results show that extracted complexes have a good structure symmetry, the oxygen atoms that provided by ligand are in the same plane with the metal, forming a planar square. The charge distribution of phosphorus atoms and metal ions in the extracted complexes is Me-P204>Me-P507>Me-Cyanex272(Me is extracted metal), and the charge distribution of ligand oxygen atoms in extracted complexes is Me-P204<Me-P507<Me-Cyanex272. These results demonstrated that the complexing ability with metal ion of three extractant is P204>P507>Cyanex272. According to the stabilization energy AE, frontier orbital energies and the atoms contributions to frontier orbital of the extracted complexes concluded that the extracted complex stability order is zinc extracted complexes>copper extracted complexes>nickel extracted complexes. During the extraction process, these three extraction agent with metal’s binding capability as follows Zn>Cu>Ni. During the extraction process, the oxygen atoms on phosphoryl and hydroxy group of extractant molecule to provide electronics and cooperate with metal and formed complexes. The phosphoryl and hydroxy group in extractant and metal ions are activity center of reaction.In this thesis, the characteristics of solvent extraction and interdisciplinary strengths. In terms of microstructure of extractant molecules, obtained microstructure information by theoretical calculation which traditional research methods can’t get, and lay the foundation for researching the relationship between new extractant microstructure and properties.