Inhibition effect of some aniline compounds on corrosion of mild steel in 3% HF

246-250<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">The corrosion inhibition efficiencies(IE%) of aniline(AL), p-<span style="font-size:11.0pt;line-height: 115%;font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;="" mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:minor-fareast;="" mso-hansi-theme-font:minor-latin;mso-bidi-font-family:arial;mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-style:="" italic"="">toluidine(PTD), <span style="font-size:11.0pt; line-height:115%;font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;="" mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:minor-fareast;="" mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">p-anisidine (PAD), p-<span style="font-size:11.0pt;line-height: 115%;font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;="" mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:minor-fareast;="" mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">phenitidine ( PPD) and N,N-dimethyl aniline(DMA) have been evaluated in 3% HF by weight loss and potentiostatic polarization methods. PAD is the best inhibitor and IE% can be classified in the following order: PAD> PPD > PTD > DMA > AL. The effect of temperature (range 303-333 K) on the corrosion behaviour of mild steel in plain HF solution and inhibited acid was also studied. The corrosion rate increased with increasing temperature both in uninhibited and inhibited acid and the values of IE% of all the inhibitors depend on temperature. The inhibitors act as mixed adsorption type inhibitors. Adsorption of AL, DMA and PTD on mild steel in 3% HF interface corresponds to Langmuir adsorption isotherm model while PAD and PPD appear to adsorb on the metal surface according to Temkin adsorption isotherm.</span

Study on corrosion control of N80 steel in acid medium using mixed

221-227Effects of inhibitor mixtures (TVE-3A, TVE-3B and TVE-3C) containing formaldehyde in combination with phenol or cresol on corrosion behaviour of N80 steel in 15% HCl solution were investigated using weight loss and potentiostatic polarization technique. The influence of temperature (30-115°C) and time interval (6-24 h) in the absence and presence of inhibitors on corrosion of the steel in the acid has been studied. TVE-3B has shown the maximum inhibition of 68.6% at ambient temperature whereas maximum inhibition shown by TVE-3A and TVE-3C was found to be 62.2% and 65.7% respectively. The inhibition efficiency was found to gradually decrease with increase in temperature in the case of TVE-3A while TVE-3B and TVE-3C showed a further increase in the protection at higher temperatures (about 81% at 115°C). The protective efficiency of TVE-3B and TVE-3C is comparable with Grade-III (about 88% at 115°C) commercial inhibitor. Inhibition of corrosion is due to adsorption of inhibitors on the metal surface. The adsorption is found to obey Frumkin isotherm. FTIR study of the metal surface products after the corrosion inhibition tests reveal presence of non-linear poly phenyl species, no free carbonyl group indicating formation of a cross linked and three dimensional networking resulting in novalac resin or bakelite by condensation polymerization (acid catalyzed). Oxygen atom, (of –OH group in phenol or substituted phenol) may coordinate to Fe²⁺ on the metal surface resulting in a protective inhibitor layer. Thermal stability of the inhibitor mixtures was determined by DSC, which has shown that the compounds present in TVE-3A vaporize with increase in temperature while the compounds present in the case of TVE-3B and TVE-3C are thermally stable up to 200°C

Adsorption and corrosion inhibition properties of 5-amino 1,3,4-thiadiazole-2-thiol on the mild steel in hydrochloric acid medium: Thermodynamic, surface and electrochemical studies

International audienceThe inhibition effect of 5-amino 1,3,4-thiadiazole-2-thiol (5-ATT) on the corrosion of mild steel in 1 M HCl solution at 303 K was studied practicing weight loss, electrochemical electrochemical (AC and DC) studies and Xray photoelectron spectroscopy (XPS) methods. The obtained results showed that 5-ATT was an effective inhibitor in HCl medium. The inhibition efficiency, eta(%), increased with the increase in concentration inhibitor but the temperature has almost no effect on the inhibition efficiency of 5-ATT. The activation dissolution thermodynamic parameters were calculated and discussed. Thermodynamic data and XPS analysis clearly show that the adsorption mechanism of 5-ATT on the mild steel surface in 1 M HCl solution is mainly electrostatic-adsorption. Tafel curves reveal that 5-ATT behaves as a mixed-type inhibitor with cathodic predominance and obeyed Langmuir adsorption isotherm. With the aim of extracting the parameters of the electrochemical impedance spectroscopy an appropriate equivalent circuit model was offered