Studi Eksperimental Kinerja Lignin dari Tandan Kosong Kelapa Sawit sebagai Inhibitor Korosi pada Baja ST41 dalam Media H₂SO₄ 0,5 M

Abstract

This experimental study was conducted to evaluate the effect of inhibitor concentration and immersion time on weight loss, corrosion rate, inhibition efficiency, and changes in surface roughness of low-carbon steel ST41. The study also aimed to assess the efficiency of lignin extracted from Oil Palm Empty Fruit Bunches (EFB) as a natural corrosion inhibitor for ST41 steel in sulfuric acid (HSO4) medium, and to observe the morphological characteristics of the steel surface with and without the inhibitor. The weight loss method was employed as the primary technique due to its simplicity, by measuring the difference between the initial and final weight of the specimen after immersion in the inhibitor solution. In addition, microscopic and cross-sectional observations were conducted to determine the type and morphology of corrosion formed on the steel surface. The results showed corrosion rate values of 31.6922 mpy. 16.1809 mpy, 15.6787 mpy, and 22.3719 mpy, corresponding to inhibition efficiencies of 34.56%, 82.48%, 67.83%, and 23.85%, respectively, for the 3 g/L inhibitor concentration at immersion times of 1 h. 12 h, 24 h, and 48 h. At a concentration of 7 g/L, the corrosion rates were 26.3358 mpy. 12.2379 mpy, 10.5780 mpy, and 20.2028 mpy, resulting in inhibition efficiencies of 45.62%, 86.75%, 78.30%, and 31.23% for the same immersion durations. These results indicate that the lignin extract acts effectively as a green corrosion inhibitor, with higher concentrations and moderate immersion times producing more stable protective film formation on the ST41 steel surface.