Investigation of the Adsorptive And Inhibitive Properties Of Cucurbita Maxima Peel Extract And Halide Ions As Inhibitors For Stainless Steel in 1m H2so4 Solution

Abstract

In consideration of the need to populate the research database with information on green corrosion inhibition, the present study investigated the corrosion inhibition efficiency of various concentrations of Cucurbita maxima peel extract on Grade 304 austenitic stainless steel in 1 M  H₂SO₄ using  two basic analytical methods, namely gravimetric and electrochemical methods.  The extract showed a progressive increase in inhibition efficiency with an increase in concentration but with a decrease in temperature, the efficiency was observed to decline.  employment of synergistic combination of the extract with iodide ions extended the maximum inhibition efficiency from 88.27 to 90.20 % for PCM with KI at 0.7 g/L extract concentration for 3 hours’ immersion time and an efficiency of 90.43% at 0.7 g/L concentration with KCl at 30 ⁰C.  Evidences from the  polarization curve indicated that C. maxima peel functions as a mixed-type inhibitor. The inhibition action of the peel extract is due to the adsorption of the extract compounds on the stainless-steel surface. The presence of the extract increased the activation energy of the corrosion reaction. The  evaluated range for the  ΔG_ads values  confirmed that the adsorption is spontaneous and operated through a physical adsorption mechanism that best fitted the Langmuir adsorption model. .  The scanning electron micrograph of the metal surface shows a smooth surface compared to the surface obtained for the control experimental set-up. The greatest efficiency was achieved using the peel extract with KI halide ion which shows that the peel of C. maxima is a very effective corrosion inhibitor on stainless steel in an acidic medium.