Corrosion Inhibition Effect of a Non-toxic Waste Compound on Stainless Steel in 0.5 Molar Concentration of Sulfuric Acid

Abstract

The corrosion of metallic material is a global scientific setback affecting all areas of engineering and technology. Therefore, research on corrosion and its inhibition is of great interest in a wide range of disciplines. The toxic nature and the low inhibition effectiveness of the majority of the conventional organic molecule in inhibiting metals against corrosion in the acid-containing solution have enforced scientists to develop non-toxic compounds. The inhibitive tendency of coconut shell powder (CSP) on stainless steel UNS N08904 (SS) corrosion in 0.5 molar H2SO4 medium at 30 °C was examined in the present study via gravimetric, potentiodynamic polarization, and scanning electron microscopy techniques. The obtained result shows that CSP is an excellent inhibitor for SS against corrosion, CSP adsorption on the surface of SS obeys Langmuir and Freundlich adsorption isotherms. The inhibition efficiency of 98% was obtained using 10 g CSP after 140 h exposure. The potentiodynamic polarization result describes CSP as a mixed-type inhibitor owing to changes in the lateral repulsion effect between the inhibitor molecules. The icorr values for the uninhibited and inhibited (10 g CSP) samples were 0.000172 A/cm2 and 3.09E-05 A/cm2, respectively. The inhibitive action of CSP is also evidence by scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX) analyses. Also, the anodic dissolution mechanism of SS was affected while the hydrogen evolution process did not change the mechanism of stainless steel with CSP due to the presence of heteroatom in the major components of CSP. The CSP can, therefore, serve as a good green inhibitor for SS corrosion in a 0.5 M H2SO4 environment.