2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI) were synthesized and characterized by FT-IR and NMR Studies. The corrosion inhibition properties of these compounds on aluminium in 1 M HCl and 0.5 M H 2 SO 4 were investigated by weight loss, potentiodynamic polarization, electrochemical impedance and scanning electron microscopic techniques. The weight loss study showed that the inhibition efficiency increases with increase in the concentration of the inhibitor and was found to be inversely related to time and temperature while it shows no significant change with increase in acid concentration. The effectiveness of these inhibitors were in the order of UDI > NI > PDI > HDI .The values of activation energy, free energy of adsorption, heat of adsorption, enthalpy of activation and entropy of activation were also calculated to elaborate the mechanism of corrosion inhibition. The adsorption of these compounds on aluminium surface follows the Langmuir adsorption isotherm. The potentiodynamic polarization data show that the compounds studied are mixed type inhibitors. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The surface characteristics of inhibited and uninhibited metal samples were investigated by scanning electron microscopy (SEM).

No abstract

The inhibitive effect of four oleo chemicals (namely; 2-Pentadecyl-1,3-imidazoline (PDI), 2-Undecyl-1,3-imidazoline (UDI), 2-Heptadecyl-1,3-imidazoline (HDI), 2-Nonyl-1,3-imidazoline (NI)), regarded as green inhibitors, were studied for the corrosion protection of mild steel in 0.5 M H 2 SO 4 . The methods employed were weight loss, potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy (SEM) was carried out on the inhibited and uninhibited metal samples to characterize the surface. The purity of synthesized inhibitors was checked by FT-IR and NMR studies. The inhibition efficiency increased with increase in inhibitor concentration, immersion time and decreased with increase in solution temperature. No significant change in IE values was observed with increase in acid concentration. The best performance was obtained for UDI possessing 96.2% inhibition efficiency at 500 ppm concentration. The adsorption of the compounds on the mild steel surface in the presence of sulfuric acid obeyed Langmuir's adsorption isotherm. The values obtained for free energy of adsorption and heats of adsorption suggest physical adsorption. The addition of inhibitor decreased the entropy of activation suggesting that the inhibitors are more orderly arranged along the mild steel surface. The potentiodynamic polarization data indicate mixed control. The electrochemical impedance study further confirms the formation of a protective layer on the mild steel surface through the inhibitor adsorption.

No abstract

2-amino-1, 3, 4-thiadiazoles (AT), 2-amino-5-methyl-1, 3, 4-thiadiazoles (AMT), 2-amino-5-ethyl -1, 3, 4-thiadiazoles (AET) and 2-amino-5-propyl -1, 3, 4-thiadiazoles (APT) were synthesized. FT-IR and NMR studies were done in order to confirm the composition of the synthesized inhibitors. These compounds were evaluated as inhibitors for mild steel in 20% formic acid and 20% acetic acid by weight loss, potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopic study (SEM) was also used to investigate the surface morphology of inhibited and uninhibited metal samples. The inhibition efficiency of these compounds was found to vary with the inhibitor concentration, immersion time, temperature and acid concentration. The adsorption of these compounds on the steel surface from both acids were found to obey Langmuir's adsorption isotherm. These compounds are mixed type inhibitors in both acid solutions. Various thermodynamic parameters (E a , ∆G ads , ∆Q, ∆H, ∆S, t 1/2 ) have also been calculated to investigate the mechanism of corrosion inhibition. Electrochemical impedance study was used to investigate the mechanism of corrosion inhibition.

Reaction of ninhydrin with [Cr(histidine)(HzO)3] 2+ 477 of ninhydrin with a [Cr(histidine)-Summary The composition of the N-diketohydrindylidene histidinato chromium(III) complex formed by interaction of ninhydrin with the [Cr(histidine)(H20)3] 2+ complex has been determined using Job's method of continuous variations. The reaction is slow and the kinetic studies were carried out under varying conditions of pH, temperature and [ninhydrin]. The observed pseudo-first order rate constant under these conditions follow the rate equation: 1/kob s = 1/{Ktk3[N ] } + 1/k3Thc reaction has the features of a template mechanism which proceeds through coordination of ninhydrin to the [Cr(histidine)] 2+ complex. The reaction is expected to involve the combination of two ligands (ninhydrin and histidine) attached to the same Cr "* (CLAM reaction). The Cr In ion provides a better opportunity for thc reaction of ninhydrin and histidine by assembling their reactive groups together. On the basis of the observed data the probable mechanism has been proposed.

No abstract

No abstract