ABSTRACT

The inhibition of corrosion of mild steel in Tetraoxosulphate (vi) acid by Lisinopril and the effect of halide ions, have been studied using Thermometric, gasometric. The results obtained shows that the corrosion rate of various concentration of H2SO4 were found to vary with concentration of H2SO4. The highest and least values of corrosion rate were obtained at H2SO4 concentration of 2.5 and 1.0 respectively. It was seen that corrosion of mild steel in 2.5M H2SO4 vary with temperature therefore corrosion rate increase as the temperature increase and with increase in time. The inhibition efficiency of Lisinopril was optimum at 323k with the value range from 60.47 to 76.16%. the values of inhibition efficiency, degree of surface coverage and corrosion rate for the joint effect of halides were found to vary with temperature and concentration. The optimum values of inhibition efficiency were obtained at 323 and 303k showing that this compound functions as an inhibitor at specific temperature. The average value of activation energy (Ea) was found to be higher than the average obtained for the blank indicating that lisinopril retards the corrosion of mild steel in H2SO4. The synergistic combination with KI, KCI, and KBr were all negative indication that absorption of lisinopril antagonized the adsorption of the respective halides. The adsorption inhibition of lisinopril on mild steel surface as revealed by thermodynamic is spontaneous and exothermic. Therefore the use of lisnopril as corrosion inhibitor is recommended.