4‑Chloro-2-((furan-2-ylmethyl) amino)-5-sulfamoylbenzoic Acid (FSM) and N‑(Isopropylcarbamoyl)-4‑(m‑tolylamino) Pyridine-3-sulfonamide (TSM) as Potential Inhibitors for Mild Steel Corrosion in 1 N H2SO4 Medium. Part I

4-Chloro-2-((furan-2-ylmethyl)amino)-5-sulfamoylbenzoic acid (FSM) and N-(isopropylcarbamoyl)-4-(m-tolylamino)pyridine-3-sulfonamide (TSM) drugs were tested as inhibitors for mild steel corrosion in 1 N sulphuric acid solution by weight loss studies and electrochemical methods. The weight loss measurements were carried at different temperatures ranging from 303 to 333 K. In all the studies, Inhibition efficiency increases with increase in concentrations of both FSM and TSM but decreases with rise in the temperature. Potentiodynamic polarization measurements confirmed that the inhibitive action of FSM and TSM is of mixed type. The activation parameters and thermodynamic values responsible for the adsorption were discussed. The adherent film of FSM and TSM formed on metal surface obeyed Langmuir adsorption isotherm. Fourier transform infrared spectroscopy and Ultraviolet–visible absorption spectral analysis were used to validate the mode of inhibition reaction to form complex between metal and inhibitor. The formation of protective layer on the mild steel surface was also confirmed by scanning electron microscopy (SEM) results.