Corrosion inhibition of mild steel by expired pyridoxine hydrochloride in 0.5 M H2SO4 solution

Pyridoxine Hydrochloride (PDH) a water-soluble vitamin that commonly treats B6 deficiency, here has been inspected for corrosion inhibition potential after its invalidity over mild steel in 0.5 M H2SO4 electrolytic solution. Utilization of an expired pharmaceutical compound i.e., PDH for corrosion inhibition introduces a sustainable and cost-effective method for corrosion control. Weight loss, electrochemical impedance spectroscopy (EIS), and polarization measurements were deployed in the experimental evaluation of corrosion potential tests, while surface investigations such as SEM-EDX offered information about the morphology of metallic surfaces. Electrochemical investigations unveiled that charge transfer resistance was found maximum (94.31 cm-2) at higher PDH concentrations (1.2 mM), inhibiting the corrosion with 89.55 % efficacy. Additionally, temperature increase (308 K to 328 K) was profoundly seen to affect corrosion mitigating potential of PDH (90.55 % to 85.65 %) respectively. Activation parameters computed for bare acid and diverse PDH concentrations and explained. Subsequently, studies including contact angle measurement at metal/electrolyte interface and XRD were corroborated to perceive the effect over mild steel surface upon exposure to PDH solution. The adsorption of PDH on mild steel was seen to obey the Langmuir adsorption isotherm, and the efficiency of corrosion inhibition increased with an increase in pyridoxine concentration. Furthermore, the corrosive media have been analyzed to get an idea about the pH and conductivity of electrolytes.