Experimental and computational investigation of variamine blue as an inhibitor for copper in chloride solution

Abstract

In this study, the corrosion behavior of copper in chloride solution in the absence and presence of variamine blue has been investigated. In this way, the electrochemical behavior of copper was studied in 3.5% NaCl and 3.5% NaCl +cM variamine blue (c = 0.025 M, 0.05 M, 0.1 M, 0.125 M) solutions under constant temperature (298 K) at a pH value of 3.5 which is about the same as that of conditioned boiler water. The pH value of the solution was adjusted by aqueous HCl and NaOH. Electrochemical techniques such as potentiodynamic polarization, open-circuit potential and electrochemical impedance spectroscopy (EIS) were used. Furthermore, anticorrosive properties of variamine blue against the Cu⁺ and Cu²⁺ metal ions are examined by computational chemistry methods. The optimum concentration of the studied inhibitors showing the highest inhibition efficiency was also evaluated at constant temperature (298 K). The inhibition efficiency (IE) was found to increase with the increase in the concentration of variamine blue. 0.125 M of variamine blue is the optimum concentration and IE% is equal to 91.29 in the mentioned concentration. The thermodynamic parameter $\Delta G$ for the adsorption process was determined. Scanning electron microscopy (SEM) observations of the copper surface confirmed the existence of such an adsorbed film. This study demonstrates that the application of variamine blue will significantly reduce the corrosion rate of copper.

Graphical abstract

Keywords:

• Copper
• corrosion
• variamine blue
• molecular simulations

Acknowledgment

The numerical calculations reported in this paper are performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA Resources).

Disclosure statement

There is no potential conflict of interest in this paper.

Additional information

Funding

The authors are greatly thankful to Cukurova University Research Found for financial support [Project number of FBA-2018-10136].