Promising Organic Inhibitor of Salak (Salacca zalacca) Peel Extract on AISI 1040

This study investigates the corrosion inhibition properties of Salak (Salacca zalacca) peel extract as a green inhibitor on AISI 1040 steel in a 1M HCl acidic environment and focusing on secondary metabolites such as flavonoids and tannins. The qualitative phytochemical analysis showed antioxidant activity of the inhibitor extract was categorized as moderate with an IC50 value of 105.219 ppm. Functional group analysis using FTIR indicated that the flavonoids and tannins in the extract acted as antioxidants and inhibited corrosion growth. The weight loss test revealed the highest inhibition efficiency 11.13% was achieved at a concentration of 200 ppm after 20 days of immersion. In the potentiodynamic polarization test, the corrosion rate was 0.025 mm/year at the same concentration and immersion time. These results suggest that Salak (Salacca zalacca) peel extract can effectively inhibit corrosion at spesific concentrations but its efficiency diminishes at higher concentrations.