Development of new three-component BNP-inhibitor for carbon steel in 0.5 mol•dm–3 HCl solution. Thermodynamic, adsorption and electrochemical studies

In this work, the development and investigation of a new in situ synthesised BNP-inhibitor based on boric acid (H3BO3), 1,4-phenylenediamine, and trisodium orthophosphate (Na3PO4) as an effective corrosion inhibitor for carbon steel were reported.The corrosion inhibition properties of the developed BNP-inhibitor were studied using the weight loss assay and electrochemical measurement.It was found that at the components molar ratio of 3:2:1 (×10 -3 mol•dm -3 ) developed inhibitor demonstrates inhibition efficiency up to 93.2% in 0.5 mol•dm -3 HCl solution.Temperature, inhibitor concentration, molar ratio, and nature of the components strongly affect the degree of metal protection.The Langmuir adsorption model turned out to be the most suitable to describe the BNP-inhibitor adsorption mechanism.The free Gibbs energy change corresponds to spontaneous and physical nature of the inhibitor adsorption.Replacing the inhibitor components with similar counterparts does not lead to an increase in protective efficiency.Electrochemical results showed high efficiency of the BNP-inhibitor and are in excellent agreement with gravimetric data.