Limits...
Study on Synergistic Mechanism of Inhibitor Mixture Based on Electron Transfer Behavior

View Article: PubMed Central - PubMed

ABSTRACT

Mixing is an important method to improve the performance of surfactants due to their synergistic effect. The changes in bonding interaction and adsorption structure of IM and OP molecules before and after co-adsorbed on Fe(001) surface is calculated by DFTB+ method. It is found that mixture enable the inhibitor molecules with higher EHOMO donate more electrons while the inhibitor molecules with lower ELUMO accept more electrons, which strengthens the bonding interaction of both inhibitor agent and inhibitor additive with metal surface. Meanwhile, water molecules in the compact layer of double electric layer are repulsed and the charge transfer resistance during the corrosion process increases. Accordingly, the correlation between the frontier orbital (EHOMO and ELUMO of inhibitor molecules and the Fermi level of metal) and inhibition efficiency is determined. Finally, we propose a frontier orbital matching principle for the synergistic effect of inhibitors, which is verified by electrochemical experiments. This frontier orbital matching principle provides an effective quantum chemistry calculation method for the optimal selection of inhibitor mixture.

No MeSH data available.


Adsorption configurations and electron density differences of OP (a), IM (b) and OP - IM mixtures (c) adsorption on Fe(001) surface. The planes between Fe(001) surface and inhibitor molecules are the cross-sections of electron density differences using Slide function in Material studio software. The red region shows an increase of electrons, while the blue area exhibits a lack of electrons. The deeper the color is, the larger degree it accepts or donates electrons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037402&req=5

f2: Adsorption configurations and electron density differences of OP (a), IM (b) and OP - IM mixtures (c) adsorption on Fe(001) surface. The planes between Fe(001) surface and inhibitor molecules are the cross-sections of electron density differences using Slide function in Material studio software. The red region shows an increase of electrons, while the blue area exhibits a lack of electrons. The deeper the color is, the larger degree it accepts or donates electrons.

Mentions: Figure 2 shows the configurations and properties of OP molecules, IM molecules and OP-IM mixture after adsorbed on Fe(001) surface in aqueous environment through DFTB+ calculation. It is seen that when OP molecules adsorbs on Fe(001) surface, its benzene ring and polyoxyethylene chain adsorb on Fe surface in a parallel way, while the hydrophobic alkyl chain is away from Fe surface and stretches to aqueous solution. For IM molecules, the imidazoline ring and benzene ring adsorb on Fe surface and its hydrophobic alkyl chain is away from Fe surface and stretches to aqueous solution with a certain angle. When OP and IM molecules co-adsorb on Fe(001) surface as mixture, there is no change in the active adsorption sites of the two inhibitor molecules, but the number of adsorption sites in the polyoxyethylene chain of OP molecule decreases. Furthermore, the end of polyoxyethylene chain desorbs and stretches to aqueous solution, as shown in Fig. 2(c). The inclined angle of hydrophobic alkyl chain of IM molecule also increases. These results indicate that the adsorbed groups are the same as the active groups in the frontier orbital distribution calculation.


Study on Synergistic Mechanism of Inhibitor Mixture Based on Electron Transfer Behavior
Adsorption configurations and electron density differences of OP (a), IM (b) and OP - IM mixtures (c) adsorption on Fe(001) surface. The planes between Fe(001) surface and inhibitor molecules are the cross-sections of electron density differences using Slide function in Material studio software. The red region shows an increase of electrons, while the blue area exhibits a lack of electrons. The deeper the color is, the larger degree it accepts or donates electrons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037402&req=5

f2: Adsorption configurations and electron density differences of OP (a), IM (b) and OP - IM mixtures (c) adsorption on Fe(001) surface. The planes between Fe(001) surface and inhibitor molecules are the cross-sections of electron density differences using Slide function in Material studio software. The red region shows an increase of electrons, while the blue area exhibits a lack of electrons. The deeper the color is, the larger degree it accepts or donates electrons.
Mentions: Figure 2 shows the configurations and properties of OP molecules, IM molecules and OP-IM mixture after adsorbed on Fe(001) surface in aqueous environment through DFTB+ calculation. It is seen that when OP molecules adsorbs on Fe(001) surface, its benzene ring and polyoxyethylene chain adsorb on Fe surface in a parallel way, while the hydrophobic alkyl chain is away from Fe surface and stretches to aqueous solution. For IM molecules, the imidazoline ring and benzene ring adsorb on Fe surface and its hydrophobic alkyl chain is away from Fe surface and stretches to aqueous solution with a certain angle. When OP and IM molecules co-adsorb on Fe(001) surface as mixture, there is no change in the active adsorption sites of the two inhibitor molecules, but the number of adsorption sites in the polyoxyethylene chain of OP molecule decreases. Furthermore, the end of polyoxyethylene chain desorbs and stretches to aqueous solution, as shown in Fig. 2(c). The inclined angle of hydrophobic alkyl chain of IM molecule also increases. These results indicate that the adsorbed groups are the same as the active groups in the frontier orbital distribution calculation.

View Article: PubMed Central - PubMed

ABSTRACT

Mixing is an important method to improve the performance of surfactants due to their synergistic effect. The changes in bonding interaction and adsorption structure of IM and OP molecules before and after co-adsorbed on Fe(001) surface is calculated by DFTB+ method. It is found that mixture enable the inhibitor molecules with higher EHOMO donate more electrons while the inhibitor molecules with lower ELUMO accept more electrons, which strengthens the bonding interaction of both inhibitor agent and inhibitor additive with metal surface. Meanwhile, water molecules in the compact layer of double electric layer are repulsed and the charge transfer resistance during the corrosion process increases. Accordingly, the correlation between the frontier orbital (EHOMO and ELUMO of inhibitor molecules and the Fermi level of metal) and inhibition efficiency is determined. Finally, we propose a frontier orbital matching principle for the synergistic effect of inhibitors, which is verified by electrochemical experiments. This frontier orbital matching principle provides an effective quantum chemistry calculation method for the optimal selection of inhibitor mixture.

No MeSH data available.