Abstract

The article identifies the minerals that cause salt deposition in various industrial sectors and provides information on reagents used to prevent salt deposition, emphasising a preference for reagents that are multifunctional, environmentally friendly and economically viable. Sodium and potassium salts of mono-, di-, and triisobutylamides of ethylenediaminetetraacetic acid were synthesised for testing as corrosion and scale-forming inhibitors in water systems at 50 ^oC. The structures of the synthesised compounds were confirmed by infrared spectroscopy, and their 10% solutions were prepared to determine the main physicochemical parameters. Inhibition of corrosion and salt deposition experiments were carried out at concentrations of 50, 100 and 150 mg L^-1. At 50 mg L^-1, the trisodium salt of the amide, synthesised from ethylenediaminetetraacetic acid and isobutylamine at a 1:1 molar ratio, exhibited the highest performance, providing 90% protection of the Steel-3 metal plates against corrosion and achieving 90% effectiveness against salt precipitation. Anti-corrosion and anti-scaling evaluations showed that increasing the salt concentration to 100 and 150 mg L^-1 led to a proportional increase in effectiveness. Analysis of the results also indicated that the mono-, di-, and trisodium salts exhibited greater inhibitory activity than their corresponding potassium salts. In terms of activity, both the sodium and potassium salts followed the order: mono- < di- < tri-. It has been established that the inhibition mechanism of steel corrosion in the presence of synthesised salts is due to chemisorption, following the classical Langmuir adsorption isotherm. Additionally, calculations were performed to correlate the electronic properties of the inhibitors with their experimental performance, identifying the carboxylate and amide groups as the primary active centres for adsorption. The theoretical results, including frontier molecular energy-level analysis and electron-transfer fractions, provided a convincing explanation for the superior efficiency of the trisodium salt, consistent with the experimentally observed activity order of mono- < di- < tri-.