Benzotriazole Corrosion Inhibitor Analysis in the Action Mechanism
Abstract: This post introduces the properties and mechanism of benzotriazole corrosion inhibitors. The synergistic action of benzotriazole and imidazole better illustrates the progress of the sustained release. Combined with the corrosion example of copper in sodium chloride solution to illustrate the corrosion inhibition of triazole compounds.
Keywords: benzotriazole corrosion inhibitor, copper corrosion inhibitor, synergistic effect.
1. Benzotriazole Properties and Functions
Benzotriazole, an organic compound. White to light pink needle crystals. It is also a good corrosion inhibitor material. Soluble in alcohol, benzene, toluene, chloroform, dimethylformamide, and most organic solvents, slightly soluble in water, soluble in hot water, soluble in alkaline aqueous solution.
1 2 3-benzotriazole is divided into oil-soluble BTA chemical and water-soluble BTA chemical. The latter can be dissolved in water or a solvent. The solvent may include ethanol, benzene, toluene, chloroform, and N N-dimethylformamide.
In addition, the benzotriazole corrosion inhibitor is used for surface purification of silver, copper, and zinc in electroplating. It has an anti-tarnishing effect. Moreover, it is a good ultraviolet light absorber and can be used as a development antifoggant for black and white film and photographic paper.
Benzotriazole is also a corrosion inhibitor for copper and its alloys widely used in industry, but it is more toxic. However, the imidazole derivatives of benzotriazole are relatively less toxic and can effectively inhibit the copper alloy under acidic conditions.
2. Corrosion Inhibitor Profile and Mechanism
Corrosion inhibitors can prevent or slow the corrosion of materials at specific concentrations and media. The amount of corrosion inhibitor is generally 0.1% to 1%, which can provide significant corrosion inhibitor protection. The medium can use covers acidic, neutral and gaseous. It includes boiler cooling water, descaling and rust removing acid solution and gas phase corrosion inhibitor. The following is explained by the classification of control parts.
2.1 Anode Type Corrosion Inhibitor
The anode type corrosion inhibitor is generally an oxygen-free strong oxidant. Including chromium, molybdenum, tungsten, vanadium and other oxyacid salts and nitrite. The mechanism of action is to form an oxidized coating film with a metal cation in the anode region of the metal surface and to protect it, that is, passivation.
This action inhibits the dissolution of the metal. However, the inhibition depends on the concentration of the corrosion inhibitor. If the concentration is not high enough, the protective film is not fully covered, which may cause pitting.
2.2 Extreme Corrosion Inhibitor
Cathodic corrosion inhibitors are types that inhibit the cathodic reaction on metal surfaces. The types include zinc carbonate, calcium carbonate, zinc phosphate, calcium phosphate, and the like. The mechanism of action of the cathode type corrosion inhibitor is to react with the metal in the cathode region to form a sufficiently thick deposited film, hindering the release of electrons and participating in the reaction.
In practical applications, calcium ions, carbonate ions, and hydroxide ions are naturally present in water. Therefore, it is only necessary to add soluble zinc and phosphate to inhibit corrosion.
2.3 Mixed Corrosion Inhibitor
A mixed corrosion inhibitor is a special organic corrosion inhibitor. The molecular architecture contains two opposite polar groups. The region where the monomolecular film is formed on the metal surface may be either an anode region or a cathode region. The inhibition is to inhibit the diffusion of dissolved oxygen in the water to the metal surface, which hinders the progress of the corrosion reaction. Such corrosion inhibitors include benzotriazole, cetyl amine, and the like.
3. Benzotriazole Corrosion Inhibitor Effect
3.1 Synergistic Synergistic Effect of Imidazole and 1 2 3-Benzotriazole
On the copper metal surface, monovalent copper ions and benzotriazole form an insoluble composite film by adsorption and reaction. It also acts to hinder the corrosion of copper metal.
Moreover, the BTA chemical has a very significant effect on the copper oxide film to promote passivation. The polarization of the anode-anode process after the combination of benzotriazole and imidazole was significantly enhanced. The corrosion potential is negatively shifted. Compounding can increase the inhibition of Cu in the NaCl medium.
From a molecular perspective, benzotriazole and imidazole can act on the oxide film on the surface of Cu and monovalent copper ions. Thereby suppressing corrosion of copper. When imidazole and benzotriazole are used in combination, the imidazole can partially accept electrons from the Cu(d) orbital. Thereby increasing the stability of the complex film.
3.2 Sustained Release of Benzotriazole on Metal Surfaces
In acidic and neutral environments, the effectiveness of corrosion inhibition is multifaceted. As the chemical potential increases, the electrophilic effect decreases and increases. It also increases as the minimum non-occupied orbital energy of the molecule increases.
In particular, in a neutral environment, a nitrogen atom forming a double bond in a molecular structure and an oxygen atom connecting a carbon atom may become active sites. Moreover, the regions of these atoms become regions with a large electron density. It mainly reflects the electronegativity of the whole molecule.
In addition, under acidic conditions, the reactive sites are concentrated in the middle of the nitrogen atom. This is followed by an oxygen atom and plays the same role as the neutral condition.
Therefore, through the above comparison, we can conclude that the triazole compound containing a sulfur atom may be superior to the triazole compound containing an oxygen atom in the inhibition performance.
4. Conclusion
Benzotriazole corrosion inhibitor(BTA) is widely used in metal rust and copper corrosion inhibitors. It can be used as an anti-rust and gas phase corrosion inhibitor. This product can also be used together with a variety of scale inhibitors, bactericidal algaecides for corrosion inhibition and rust prevention of copper and silver equipment.
In electroplating applications, it can be used as a surface for the purification of silver and copper. Prevent oxidative discoloration. For copper corrosion inhibition applications, benzotriazole can form covalent bonds and coordination bonds with surface copper ions. The reaction produces a polymeric protective film. Stopping the progress of the corrosion redox reaction.
The same corrosion inhibition effect can also occur in other metal materials. Such as zinc, lead, cast iron, and nickel.
Benzotriazole can also be used in combination with a variety of other corrosion inhibitors to improve sustained release. In the corrosion inhibition application of the closed circulating cooling water system, the effect is very good.
In addition, the addition of 1 2 3-benzotriazole to the antifreeze mixture of ethylene glycol and water for automobiles can also exert a good sustained release effect, which provides a more promising prospect for extending the life of the device.
Benzotriazole is a commonly used and readily available corrosion inhibitor and chemical raw material. There are quite a few uses in many ways. How to increase its industrial output and how to play its role in life and application more effectively is the current challenge.