Byline: Roland Tolulope Loto Cleophas Akintoye Loto and Patricia Abimbola Popoola
Summary: The electrochemical behaviour of carbon steel in 0.5 M H2SO4 was studied in the presence of 2-amino-5-ethyl-1 3 4-thiadiazole (TTD) as inhibitor with the aid of weight loss method potentiodynamic polarization and open circuit potential measurement technique. The effect of inhibitor concentrations exposure time corrosion rate and surface coverage on inhibition efficiency was investigated. Results showed that TTD performed excellently in the acid solution with the inhibition efficiency increasing with increase in inhibitor concentration up to a peak value of 80.67% and 90.5% at maximum concentration from weight loss test and potentiodynamic polarization tests. The compound showed cathodic inhibition tendency in solution with the inhibitor molecules been effectively adsorbed onto the steel surface stifling the electrochemical reactions responsible for corrosion through the exposure hours.
Results from statistical analysis through ANOVA software depicts the overwhelming influence of inhibitor concentration on inhibition efficiency compared to exposure time.
Keywords: Corrosion; Thiadiazole; Sulphuric acid; Inhibition and Steel.
The corrosion phenomenon occurs naturally leading to deterioration of metallic alloys and its physical and mechanical properties due to interaction of the alloy with their environment. Corrosion damage cuts across all industries where steel especially carbon steel is applied from pipelines bridges petroleum and chemical processing plants to vehicles wastewater systems and other marine applications. The economic loss due to corrosion is huge and constitutes a significant proportion of virtually every nation's GDP. Mitigation against corrosion varies widely with numerous methods and corrosion control techniques available however most of them are uneconomical or hazardous to the environment. Corrosion prevention with the use of chemical compounds and derivatives known as inhibitors has been one of the most cost effective and practical techniques for corrosion prevention with a number of researches on them worldwide
Since addition of inhibitors does not disrupt industrial processes and operations [1-4]. Currently there are efforts to develop environmentally friendly corrosion inhibitors with the use of organic compounds with molecules containing heteroatoms [5-9]. These compounds have been observed to protect steel against corrosion in acidic conditions through adsorption onto the steel surface. This process results in the separation of the steel surface from the acid solutions through physical physiochemical and or chemical mechanisms . The strength and duration of protection offered by the organic compounds varies with the types of compound and their molecular structure configuration and atomic constituents and combination.
Results and discussion
Weight Loss Analysis
Figs (1 and 2) shows the variation of corrosion rate and percentage inhibition efficiency versus exposure time at specific TTD concentrations while Fig. 3 shows the variation of %IE with TTD concentration. In H2SO4 the steel surface passivates progressively with increase in inhibitor concentration from 0.125% - 0.375% TTD as the cationic molecules of TTD gradually inhibits the corrosive effect of the anionic species (Cl-/ SO4 ) by displacingthem through competitive adsorption thereby forming a physiochemical film which strongly adheres to the steel surface. The film is virtually impenetrable and effective till 0.75% TTD. The...