Organic corrosion inhibitor on the metal surface and the chemical adsorption, which can provide electron pair, also can be provided through a proton to complete, therefore, the chemical adsorption of organic corrosion inhibitor is divided into donor type inhibitor and proton donor type inhibitor.
1. For electronic type corrosion inhibitor:
If the inhibitor of polar groups of the central atom, etc., have not shared the lone pair electrons, and the metal surface are empty orbit, the central atom lone pair electrons will and hollow metal orbital interaction coordination bond formation, the inhibitor molecules adsorbed on the metal surface. The corrosion inhibitor called for electronic type inhibitor. For electronic type inhibitor chemical adsorption is by sharing a pair of electrons to achieve, if the inhibitor with electronic offer and high electron density, chemical adsorption becomes easy, anti-corrosion effect will be better.
2. For proton type corrosion inhibitor:
Chemical adsorption, nonpolar groups arrangement characteristic and physical adsorption is different. In the chemical adsorption, polar groups and metal surface angle is fixed, the nonpolar groups are not free, can only rotate around the axis. If the distance between adjacent molecules, can cover a large area, the covered area is approximately equal to the molecules to bond as the shaft rotates on the metal surface projection area, the adsorption capacity of similar corrosion inhibitor coverage area is greater, the corrosion effect. Chemical adsorption velocity is less than the physical adsorption, and it is not reversible, little temperature influence.
Further, the chemical adsorption is a neutral molecule adsorbed on the metal surface, not as dependent on the charge status of the physical adsorption of the metal surface, it is easier than the physical adsorption of the inhibitor structure affected.
3. π bond adsorption:
The molecular structure containing π electron material generally comprises a double bond, a triple bond, having electron-donating ability. The so-called π bond adsorption of organic inhibitors that have π electronic structure can be formed with a bond to the metal surface to provide electronic empty track, which is called the π adsorption.