Influence of tannin content in Terminalia catappa leaves extracts resulted from maceration extraction on decreasing corrosion rate for mild steel in 1M H₂SO₄

The ability of natural compounds as corrosion inhibitors is necessary to obtain safe corrosion inhibitors for the environment. The tannin compounds derived from plant extract has the ability to decrease the corrosion rate. The purpose of this research is to find the ability of tannin compounds in Terminalia catappa leaves extracts to decrease corrosion rate on mild steel. Terminalia catappa leaves that have been mashed in ethanol solvent extraction using maceration with the variable time 2.4 and 6 days. Mild steel that has been on the sandpaper and cleaned then soak into the 1 M H2SO4. Terminalia catappa leaves extract concentration used is 0, 250, 500, 500, 750, 1000 ppm, the immersion time is 3.6 and 9 hours. Calculating of corrosion rate is used the weight loss method, the analysis of the tannin concentration using GC-MS. The results indicate that highest tannin content equal to 7.23% in 6 days maceration time. The result showed that the corrosion rate was reduced in the presence of tannin content in Terminalia catappa leaves extract.