The inhibition efficiency (IE) of an aqueous extract ofAllamanda blanchetii(Purple) in controlling corrosion of mild steel which has been evaluated by weight loss method in the absence and presence of corrosion inhibitor at different time intervals at room temperature. The result showed that the corrosion inhibition efficiency ofAllamanda blanchetiiwas found to vary with different time interval and different acid concentrations. Also, it was found that the corrosion inhibition behavior ofAllamanda blanchetiiis greater in sulphuric acid than citric acid medium. SoAllamanda blanchettican be used as a good inhibitor for preventing mild steel material. The surface analysis study confirms the corrosion of the mild steel and its inhibition by the inhibitorAllamanda blanchetii.

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The inhibition of corrosion of mild steel usingPiper nigrumL in different acid medium by weight loss method was investigated. The corrosion inhibition was studied in hydrochloric acid and sulphuric acid by weight loss method at different time interval at room temperature. The result showed that the corrosion inhibition efficiency of this compound was found to vary with different time interval and different acid concentration. Also, it was found that the corrosion inhibition behavior ofPiper nigrumL is greater in sulphuric acid than hydrochloric acid. So,Piper nigrumL can be used as a good inhibitor for preventing mild steel material.

Formazan of benzaldehyde (FB) and formazan ofp-dimethyl amino benzaldehyde (FD) were synthesized. These compounds were studied as corrosion inhibitor for mild steel in 1.11 N hydrochloric acid by weight loss method. The result showed that the corrosion inhibition efficiency of these compounds was found to vary with the temperature and acid concentration. Also, it was found that the corrosion inhibition behaviour of FD is greater than that of FB. The kinetic treatment of the results gave first order kinetics. The relative corrosion inhibition efficiency of these compounds has been explained on the basis of structure dependent - electron donor properties of the inhibitors.

In this study, two organic molecues namely, [4-(4-aminobenzoyl)-piperazin-1-yl)] furan − 2-yl) methanone (4-4-ABPFM) and 4-(4-aminophenylpiperazin-1-yl) furan-2-yl) methanone (4-4-APPFM) were synthesized and characterized using FTIR, UV-visible, thin layer chromatography, C-13 and proton NMR. The corrosion inhibition efficiencies of these molecules were tested using weight loss, polarization and AC impedance methods. Quantum chemical calculations (which included local selectivity, global reactivity and Monte Carlo simulation) were also implemented to complement the experimental data. The results obtained provided information confirmed that the synthesized compound has some inherent corrosion inhibition potentials due to the presence of aromatic rings, pi-electron systems, heteroatoms and corrosion structure parameters. The maximum inhibition efficiencies were 95 and 91% for 4,4-ABPFM and 4,4-APPFM respectively. The ideal fitness of the Langmuir isotherm with slope and R2 values approximating unity was also upheld. Theoretical calculation results showed strong accord to experimental values and supported higher efficiency for 4,4-ABPFM than 4,4-APPFM. Monte Carlo simulation showed that the adsorption energy is negative and also supported evidence drawn from the experiment, which is the spontaneous adsorption of the inhibitors on the metal surface.