The prevention of corrosion in mild steel when exposed to groundwater through the use of an aqueous solution of trisodium phosphate

Abstract

An aqueous solution of trisodium phosphate has been utilized to mitigate the corrosion of mild steel in groundwater. The weight loss method has been employed to assess the corrosion rate of mild steel and to determine the corrosion inhibition efficiency of the inhibitor. It has been noted that the inhibitor molecules adhere to the metal surface. The adsorption process follows the Langmuir adsorption isotherm. The mechanism of corrosion inhibition has been investigated through electrochemical studies, including polarization studies and AC impedance spectra. The surface morphology of the protective film has been examined using SEM (scanning electron microscopy) images and FTIR spectra (KBr). The FTIR spectra indicate that the protective film is composed of an iron phosphate complex formed on the anodic sites of the metal surface. The examination of contact angle measurements across different surfaces indicates that when an inhibitor system is present, the contact angle rises, wettability diminishes, hydrophobicity escalates, and corrosion resistance improves. Examination of different AFM images of various surfaces indicates that, when an inhibitor system is present, AFM parameters such as average roughness, RMS roughness, and peak-to-valley height show a reduction. Consequently, the surface attains a smoother texture. Examination of Vickers Hardness across different surfaces indicates that, when an inhibitor system is present, the hardness improves. This suggests that the protective film is both stable and more robust. Consequently, the resistance to corrosion is enhanced. These findings could be applicable in cooling water towers where groundwater may serve as the coolant.