Corrosion of low-carbon steel in sulphuric acid solution in presence of pyrazole—halides mixture

Corrosion Inhibition of Mild Steel in 1 M H2SO4 by Polyvinyl Pyrrolidone and Synergistic Iodide Additives

“…The decrease in inhibition efficiency with rise in temperature, as illustrated in Tables 1 and 2, suggests possible desorption of some of the adsorbed inhibitor from the metal surface at higher temperatures. Such behavior shows that the additives were physically adsorbed on the metal surface [4,12]. This is further confirmed by the decrease in K values with rise in temperature, as seen in Table 3.…”

“…To further upgrade the performance of such organic inhibitors, extensive studies have been undertaken to identify synergistic effects of other additives. Interestingly, addition of halide ions to sulphuric acid solutions containing some organic compounds has been reported to yield the required enhancement [1][2][3][4][5][6][7][8][9][10][11][12][13]. The inhibitive effects for the halides have been observed to increase in the order Cl -< Br -< I -, with the iodide ion being the most effective.…”

Rothmannia longiflora extract as corrosion inhibitor for mild steel in acidic media

“…The shift towards negative value of entropies (S*) at the optimum concentration imply that the activated complex in the rate determining step represents association rather than dissociation, meaning that disordering decreases on going from reactants to the activated complex [45]. An estimate of the heat of adsorption (Q ads ) was obtained from the trend of surface coverage with temperature as follows [46][47][48]:…”

“…The calculated values of both parameters are given in Table 5. The positive values of heats of adsorption (Q ads ) indicate that the degree of surface coverage increased with rise in temperature again suggesting that the effectiveness of RL with rise in temperature [46][47][48][49][50].…”

Electrochemical passive properties of AlxCoCrFeNi (x = 0, 0.25, 0.50, 1.00) high-entropy alloys in sulfuric acids

“…A rising temperature decreased the Tafel slopes of anode (Table 3), increased I corr , and increased E corr and E t (the transpassive potential) slightly. The corrosion rate is directly related to I corr , according to Arrhenius equation, I corr = A exp(−E a /RT) [13,26], where the pre-exponential factor A is generally independent of temperature and is a constant of alloys, where R denotes the gas constant, T denotes temperature, and E a denotes activation energy for corrosion. In the case of small experimental temperature range, E a is assumed to be independent of T. Consequently, E a can be obtained from ln(I corr ) vs. 1/T plot.…”