Application of Celtis Zenkeri Exudates as Corrosion Inhibition for Galvanised Steel Exposed to Acidic Media

Abstract

This study investigated the performance of Celtis zenkeri exudates in preventing galvanised 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 galvanised steel pipes exposed to corrosive water and soil media. Various steel specimens were cut into portions and coated with the exudates at 25 - 50µm thickness. To accelerate the rate of corrosion, 0.5M hydrochloric acid (HCl) was added to tap water in a container. Also, the same concentration of HCl was equally added to soil samples. Uncoated 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 hours). The inhibition efficiency of the exudates for both corrosive media was compared. Results showed that the weight loss and corrosion rate of galvanised steel decreased with increase in coating thickness. Comparatively, the weight loss and corrosion rate in the uncoated specimens were higher than the coated specimens. With 25 - 50µm coating thickness, the decrease in corrosion rate ranged from 0.01272 to 0.0027mm/yr for specimens immersed in water and from 0.2226 to 0.0185mm/yr for specimens buried in soil, while for uncoated specimens, the corrosion rate was 0.2793mm/yr and 0.4150mm/yr for specimen immersed in water and soil respectively. The inhibition efficiency of Celtis zenkeri exudates increased with coating thickness, which ranged from 54.46 – 99.03% for specimens immersed in water and 46.36 – 95.54% for specimens buried in soil at 25µm – 50µm coating thickness. The results demonstrated that Celtis zenkeri exudates can be used as corrosion inhibitor for steel exposed to corrosive media.