INVESTIGATION OF THE INHIBITORY AND COLLOID-CHEMICAL PROPERTIES OF GXMA (GUANIDINE CHLORIDE METHYLACRYLATE) SYNTHESIZED ON THE BASIS OF GUANIDINE

In this study, guanidine chloride methylacrylate (GXMA), a newly synthesized compound based on guanidine, was investigated as an effective corrosion inhibitor for steel in a 15% hydrochloric acid (HCl) solution. Steel grade St-20 was selected for the experiments, and the inhibitory effect of GXMA at various concentrations (100–300 mg/L) was evaluated using the gravimetric method. The tests were conducted over a period of 300 hours within a temperature range of 343–363 K. The experimental results demonstrated that GXMA significantly reduced corrosion rates. Notably, at a concentration of 300 mg/L, GXMA provided a protection efficiency of 93.3% for St-20 steel. The corrosion rate inhibition coefficient was found to be up to 15 times higher compared to the control. Based on weight loss measurements of steel coupons, the effectiveness of GXMA was found to fully comply with the requirements of GOST (RH)39.0-051:2007. To gain deeper insights into the adsorption mechanisms, graphical analyses were conducted using the Langmuir, Temkin, Frumkin, and Flory-Huggins adsorption isotherms. The obtained R² coefficients confirmed that the adsorption of GXMA closely follows the Langmuir model, indicating monomolecular and physico-chemical adsorption on the metal surface. Thermodynamic analyses were carried out based on the Arrhenius equation, and the observed increase in activation energy (Ea), along with a negative entropy change, indicated the predominance of GXMA adsorption processes on the metal surface. The findings revealed that GXMA exhibits maximum inhibitory performance within the concentration range of 250–300 mg/L. This study suggests that GXMA is a promising corrosion inhibitor for protecting metal structures operating in acidic environments, particularly in the oil and gas industry. The results confirm GXMA's potential as a highly efficient, economically viable, and environmentally friendly corrosion inhibitor.