Adsorptive and Inhibitive Potential of Halide Ions and Plant Extracts from <i>Cucurbita Maxima</i> as Stainless Steel Inhibitors

Abstract

By utilizing weight loss measurements and electrochemical technique, the corrosion inhibition efficiency of Cucurbita maxima peel and  seed extracts on Grade 304 austenitic stainless steel in 1 M sulphuric acid solution was examined. The efficacy of C. maxima extracts'  inhibition increased with concentration while decreasing with temperature. At 0.7 g/L extract concentration for 3 hours of immersion, the  inhibitor's greatest efficiency was 95.21% for PCM and 94.26% for SCM. Stainless steel corrosion was successfully inhibited by C. maxima  peel and seed extracts, according to the results, and it was discovered that the presence of halide ions enhanced the efficacy of the  inhibition. The synergistic effect of halide ions was found to follow the order: KI > KCl. According to the polarization curve, C. maxima  functions as a mixed-type inhibitor. Due to the extract components' adsorption on the stainless steel surface, peel and seed extracts  exhibit an inhibitory effect. The activation energy of the corrosion reaction increases by the presence of both extracts. The physical  adsorption is shown by the negative values of ΔGads, which range from -12 kJ/mol to -18 kJ/mol. These values show the spontaneity of  the adsorption process. Adsorption is a physical process that adheres to Langmuir adsorption isotherms. The results of a study using  scanning electron microscopy to examine the surface morphology of stainless steel in inhibited and uninhibited acid solutions revealed  that the presence of extract and halide inhibitors remarkably lowers the corrosion rate. This is as a result of the extract and halide  inhibitor molecules adhering to the surface and forming a barrier that prevents an acid attack.