Investigation of the Anti-Corrosion Activities of Aloe Vera Extract on Iron Metal Sheets

Abstract

The anti- corrosion activities of Aloe Vera extracts were investigated using weight loss method in three corrosive agents (1MHCl, fresh prepared Mango juice and Dashen Beer). The result reveals that the inhibition efficiency of Aloe Vera extract is higher at higher concentration (55.5% at 20 mg/Kg, 65.58% at 40 mg/Kg, 73.59% at 80 mg/Kg, 74.48% at 120 mg/Kg, 83.59% at 200 mg/Kg). The surface coverage area of Aloe Vera extract is also increased with concentration as (0.900 at 20 mg/Kg, 916 at 40 mg/Kg, 0.923 at 80 mg/Kg, 0.991 at 120 mg/Kg, 0.996 at 200 mg/Kg). This is due the fact that as the concentration of inhibitors increased, a larger number of inhibitors molecule is get adsorbed on the metal surface which results more coverage of the corroded metal surface. This makes the metal too difficult from further corrosion by the corrosion agents. In the other hand, the inhibition efficiency and surface coverage area of Aloe Vera are lower at higher temperature.  As temperature increases from 298 to 313 K, the inhibition efficiency decreases from 83.59% to 55.5%. This is due to the fact that at an elevated temperature desorption of pre-adsorbed inhibitor molecules occur from metal surface; decomposition and rearrangement of some inhibitors may take place which increases corrosion rate at uninhibited metal surface. Adsorption of Aloe Vera extract on iron metal sheets are obeyed the Langmuir, Temkin and Frumkin adsorption isotherms. The positive value of activation energy (Ea) and the negative value of free energy of adsorption (?G^oad) support the physical adsorption of Aloe Vera extract by iron metal sheets.

Keywords: Corrosion, Anticorrosion Activities, Metal Sheet, Corrosion Agent, Adsorption and Aloe Vera Extract