Study on the Use of Jamblang (Syzygium cumini) Pulp Extract as Corrosion Inhibitor for Low-Carbon Steel in 3.5% NaCl Solution

Inhibitor derived from synthetic materials are still the best option to slow down corrosion rate. However, the resulting environmental impact has adverse effects that must be addressed quickly. Among these natural inhibitor, Jamun fruit flesh shows significant potential for use as corrosion inhibitor. Thus, this study aims to investigate the effectiveness of jamblang pulp extract to slow down the corrosion rate of carbon steel in NaCl solution based on the efficiency obtained. Extract was obtained using the solid-liquid extraction method with a Soxhlet extractor. Phytochemical and Fourier-transform infrared (FTIR) spectroscopy tests were conducted on extract. To assess corrosion rate and efficiency, The experiments were designed by mixing inhibitors at variations of 200, 300, 400, 500, and 600 ppm within soaking periods of 120, 240, 360, 480, 600, 720, and 840 h. The results of FTIR spectroscopy and phytochemical test indicated the presence of heteroatom N and O bond compounds, flavonoid content, and tannins inhibiting corrosion rate on the surface of carbon steel. Furthermore, the weight loss method test showed that lowest corrosion rate occurred at an immersion time of 360 h by 0.90 mpy with an efficiency of 76.92%. Jamblang pulp extract showed excellent protection at a concentration of 200 ppm with an average efficiency of 53.52%, so it can be applied as a natural inhibitor on low carbon steel.