Development of an empirical model for predicting carbon steel corrosion rate using Melastoma candidum leaves extract an inhibitor

Giving significant attention to carbon steel corrosion is essential for predicting damage and loss and for determining appropriate protection methods. Several studies have shown that measuring corrosion rate based on weight loss is a simple method, but it is relatively time-consuming. Therefore, this study aims to develop an empirical model for the corrosion rate of carbon steel in a corrosive environment containing 3.5% NaCl, protected by an inhibitor derived from Melastoma candidum leaves. The 18 carbon steel plate samples were immersed in separate containers consisting of inhibitor concentrations of 0, 200, 400, 600, 800, and 1000 ppm, respectively, and in 3.5% NaCl for 30 days. The developed empirical model was based on the relationship between corrosion rate and inhibitor concentration at specific time intervals. The analysis showed that both the experimental testing and the developed empirical model produced valid results, as showed by a trend line graph. This empirical model provided a novel contribution to predicting corrosion protection for carbon steel. The highest corrosion rate obtained for unprotected steel specimens was 0.32 mm/year, and decreased significantly with increasing inhibitor concentration.