The Inhibited Effect of Cysteine Towards the Corrosion of Copper in Nitric Acid Solution
The detailed study of cysteine (Cys) as corrosion inhibitor for copper in nitric acid solution has been performed through weight loss, electrochemical polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) measurements. The effect of inhibitor concentration, temperature and immersion time against inhibitor action was investigated. Results show that Cys may be used as an efficient inhibitor for copper in nitric acid at higher temperatures (98% at 50°C). Potentiodynamic polarization studies reveal that Cysteine acts as a mixed-type inhibitor without any change in the mechanism of hydrogen evolution. The adsorption of this compound on copper surface obeys Langmuir's adsorption isotherm and has a chemisorptions mechanism.
A study of tetrazoles derivatives as corrosion inhibitors of copper in nitric acid
Purpose – To evaluate the effect of some tetrazole compounds as corrosion inhibitors of copper in HNO3 at various temperatures.Design/methodology/approach – 1‐phenyl‐5‐mercapto‐1,2,3,4‐tetrazole (PMT) was selected as the best inhibitor among the tetrazole compounds tested. Gravimetric and electrochemical techniques were conducted.Findings – PMT was an excellent inhibitor for copper in acid. Its efficiency attained 97.5 per cent and decreased slightly with temperature.Research limitations/implications – The inhibition efficiency increased with the concentration of PMT to reach 97.5 per cent at 10−3 M. Good agreement between the various methods explored was observed. Polarisation measurements also showed that PMT acted as a mixed inhibitor.Practical implications – The efficiency of PMT increased with the concentration but decreased with rise of temperature in the 298‐333 K range. As such, PMT could be used in chemical cleaning and pickling processes.Originality/value – The originality of this work was the f...
Inhibition of copper corrosion by isatin in aerated 0.5 M H2SO4
The corrosion inhibition of commercial copper by means of isatin was studied in aerated 0.5 M H2SO4 in the temperature range 25–55 °C using weight-loss, potentiodynamic and spectrophotometric tests, and determination of double layer capacitance. Inhibition efficiencies up to 94% in the concentration range of 1×10−4–7.5×10−3 M of isatin were obtained. The corrosion rates estimated with weight-loss measurements were higher than those correspondingly determined with the potentiodynamic test, especially at higher concentrations of inhibitor. This is in accord with other researches that have pointed out the limitation of the Tafel line extrapolation method in the determination of corrosion rates. The kinetics of cuprous and cupric ion formation and UV–visible spectra support the formation hypothesis of a complex between copper and isatin. The adsorptive behaviour of isatin on copper 0.5 M H2SO4 was also investigated.