Performance of Natural Plant-Based Inhibitors: Effect of Psidium Guajava Extract Concentration and Immersion Time on Corrosion Rate of Boiler Tubes

Abstract

Corrosion in boiler header tubes poses a major operational challenge in steam-based power generation, especially in systems exposed to chloride-rich feedwater. Environmentally benign corrosion inhibitors have gained attention as alternatives to synthetic chemicals. This study examines the effectiveness of tannin-rich Psidium guajava (guava) leaf extract as a natural corrosion inhibitor for boiler tube carbon steel immersed in a 4% NaCl medium. The extract was produced through ethanol maceration and rotary evaporation. Specimens were exposed to inhibitor concentrations of 0, 500, 1000, 1500, and 2000 ppm for 3, 5, 7, and 10 days. Corrosion rates were measured using the weight-loss method, supported by XRF characterization and optical microscopy. Results show a consistent decrease in corrosion rate with increasing inhibitor concentration, with 2000 ppm providing the highest protection. Longer immersion increased mass loss but lowered corrosion rate due to progressive film formation. Maximum inhibition efficiency exceeded 70%, classified as “very good.” Microscopy revealed smoother surfaces and more uniform protective films on treated specimens, indicating strong adsorption of tannin compounds. Overall, Psidium guajava extract demonstrates strong potential as a green, sustainable corrosion inhibitor for boiler applications.