Performance of natural plant-based inhibitors: Effect of Psidium guajava extract concentration and immersion time on corrosion rate of boiler tubes

¹ Department of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Surabaya, Indonesia
² Faculty of Engineering and Quantity Surveying, INTI International University, Negeri Sembilan 71800, Malaysia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

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 Psidium guajava leaf extract as a natural corrosion inhibitor for boiler tube carbon steel immersed in a 4% NaCl medium. Corrosion rates were measured using the gravimetric method supported by optical microscopy. The results showed that increasing inhibitor concentration up to 1500 ppm significantly reduced the corrosion rate and increased inhibition efficiency at all immersion times. The optimum performance was achieved at 1500 ppm after 7 days of immersion, where the corrosion rate decreased and the inhibition efficiency reached 82.7%. A slight decline in performance at 2000 ppm indicated that excessive inhibitor concentration may reduce film stability due to multilayer formation or competitive adsorption. Optical micrographs supported these findings by showing severe pitting on the uninhibited surface and a smoother, more homogeneous morphology on the inhibited specimen. These results demonstrate that Psidium guajava leaf extract is a promising environmentally friendly inhibitor for boiler tube protection in saline media.