Density Functional Theoretical Research On Adsorption Of Heavy Metal Cadmium And Zine Ions And Pfos And Pfoa On Rutile(110)

The natural environment, heavy metals can not be easily metabolized easily bioaccumulated and biomagnificated which is a serious threat to human and aquatic organisms. Cadmium and Zinc ions are two typical heavy metal pollutants, and perfluorinated organic compounds (Perfluorinated Compounds PFCs) which are persistent, bioaccumulative, toxic and long-range transport is a new class of persistent organic pollutants and are widely used in civil and industrial products. These two types of pollutants on mineral surface adsorption-desorption behavior affects its existence state and toxic. Rutile TiO2 is a strong heavy metal adsorbent. In order to understand the effective removal of heavy metal pollutants and perfluorinated compounds in water, Cd(H2O)42+, Zn(H2O)42+ and PFOS,PFOA are carried out a detailed study of chemical adsorption on the rutile (110) surface, and attain their stable adsorption configurations. This paper uses periodic boundary conditions for density functional theory to study bulk rutile (110) plane, in particular, dynamically simulate the adsorption process of this crystal face. Two types of pollutants adsorpted on the rutile (110) surface is a endothermic reaction with higher activation energy.In this paper, the various configurations as well as the adsorption stabilities ofCd(H2O)42+ and Zn(H2O)42+ on slab model of rutile (110) crystal surface are studied by periodic boundary conditional density functional theory (DFT). The results show that on the rutile (110) surface, the adsorption stability order of Cd(H2O)42+ is DC1>SC1>SC2>TC>SE>DC2, not in conformity with Pauling's third rule; the adsorption stability order of Zn(H2O)42+ is DC1>SC1>DC2>SC2>SE>TC, consistent with Pauling's third rule. Also, it attains a series of optimized structures and adsorption potential energy in order to provide a theoretical model of adsorption-desorption behavior, through the dynamic simulation of Cd(H2O)42+ and Zn(H2O)42+ adsorbing on rutile (110). As a result, to adsorb Zn(H2O)42+ is more stable than Cd(H2O)42+ on the rutile(110) surface.From the microscopic point, quantum chemical density functional theory (DFT) B3LYP method with the 6-31G(d, p) and 6-31+G(d, p) are used to calculate the ground state and excited state structure quality of PFOS and PFOA. The results show that at the excited state PFOS and PFOA are more conducive to react, and moreover calculate the different forms of transition to obtain single state transition of PFOS and PFOA in the wavelength 173.95nm and 174.46nm point,where has the strongest oscillator strength.Finally, the adsorption of PFOS and PFOA has been studied on the rutile (110) surface. The variation rule of bond length change before and after adsorption and two configurations of the adsorption potential energy of two kinds of organic pollutantsand was obtained. The results show that, PFOS and PFOA are adsorpted by common oxygen atom on rutile (110) surface. Because of the conjugate, the Ti-O bond lengths are decreasing, regardless of both C-O and S-O tends to form a double bond, then compareing with the adsorption potential energy of two configurations for PFOS, the Stability order of two adsorption configurations is:SC>DC;for PFOA:DC>SC.