Efficiency of ficus sycomorus exudates as corrosion inhibitor for mild steel pipes in acid concentrated water and soil

摘要

Abstract This study investigated the performance of Ficus sycomorus exudates in preventing mild steel exposed to acid concentrated water and soil. The study was performed in order to find an alternative coating substance that can reduce the corrosion of mild steel pipes exposed to corrosive water and soil media. Various mild steel specimens were cut into portions and coated with the exudates at 25–50 μm thickness. To accelerate the rate of corrosion, 0.5 M hydrochloric acid (HCl) was added to tap water in a container. Also, the same concentration of HCl was equally added to soil samples. Uncoated mild steel specimens were immersed in the acid concentrated water and soil, servicing as control sample. The rate of corrosion was monitored for 30 days (720 h). The inhibition efficiency of the exudates for both corrosive media was compared. Results showed that the weight loss and corrosion rate of mild steel decreased with increase in coating thickness. Comparatively, weight loss and corrosion rate in the uncoated specimens were higher than the coated specimens. For uncoated specimens, the corrosion rate was 0.2793 mm per year (mm/yr) and 0.4150 mm/yr for specimen immersed in water and soil respectively, but at 25 μm coating thickness, it decreased to 0.1789 mm/yr and 0.3028 mm/yr for specimens in water and soil. Also, at 50 μm coating thickness, corrosion rate decreased to 0.0036 mm/yr and 0.0335 mm/yr for specimens in water and soil, respectively. The inhibition efficiency increased from 35.93 to 98.72% for specimens immersed in water and 27.04–91.92% for specimens buried in soil at 25 – 50 μm coating thickness. The results demonstrated that Ficus sycomorus can be alternative corrosion inhibitor for steel pipes exposed to corrosive media, but a minimum coating thickness of 35 μm is recommended to attain an excellent performance.