Computational simulation, surface characterization, adsorption studies and electrochemical investigation on the interaction of guar gum with mild steel in HCl environment

Guar Gum (GG), a water-soluble hetero polysaccharide is used for the interaction study on mild steel (MS) in 0.5 N HCl by weight loss, electrochemical methods, surface monitoring studies, and DFT and MC based quantum chemical calculations. 200 to 800 ppm of the inhibitor was introduced to the medium at 303 to 323 K. The maximum inhibition efficiency (IE) was obtained for 800 ppm of GG. The surface monitoring including FTIR, XPS, FESEM, and AFM studies reveal that GG effectively forms an adsorbed inhibitive layer on the MS surface by substituting pre-adsorbed water molecules and adsorption phenomenon follows the Langmuir model. The computational correlations (DFT and Monte Carlo simulations) justify the experimental observations. Thermodynamic adsorption parameters confirmed that the GG is adsorbed by spontaneous mixed physisorption and chemisorption with tending to physisorption process.