Glucofuranose as corrosion inhibitor in API 5 L X70 steel immersed in NaCl 3 % by different hydrodynamic conditions and theoretical study

The α-D-glucofuranose was synthesized and evaluated by Electrochemical Impedance Spectroscopy (EIS) and Polarization Curves (CP) at different rotation rates, kinetic time and adsorption process onto API 5 L X70 steel in a saline medium with theoretical study. This study demonstrates that α-D-glucofuranose protects the metal surface under static and turbulent flow conditions with ≥95 % inhibition efficiency at 10 ppm. By CP measurements, the inhibitor exhibits a mixed-type control under static conditions. With film persistence of inhibitor at 336 h, reaching an efficiency of 80 %. Also, Langmuir isotherm shows that the glucofuranose presented a chemical adsorption process at different rotation rates. According to the SEM-EDS analysis, the metal's protection is evidenced by the formation of a α-D-glucofuranose monolayer on its surface, which isolates it from the corrosive environment. To explain the interactions and adsorption mechanism between the glucofuranose molecule and the API 5 L X70 steel surface, a computational approach was carried out at the density functional theory level with dispersion correction known as BPW91-D2/6–311++G(2d, 2p). A cluster model was assumed, simulating the metallic surface using the iron cluster Fe6-D2h. The theoretical method was validated through the comparison with IR spectroscopy and XRD experiments performed on α-D-glucofuranose.