Casein as a natural protein to inhibit the corrosion of mild steel in HCl solution

Enhancement of corrosion resistance of the cooling systems in desalination plants by green inhibitor

“…Similar trends were reported for corrosion inhibition using seaweed extract 21 and provitamin B5 41 . On the opposite hand, in the case of Silybum marianum leaves increasing the temperature improved the inhibition efficiency 36 ; similar trend was reported by Rabizadeh et al while using casein as the inhibitor 38 , and by Umoren et al 39 with palm seed ethanolic extract. The Arrhenius plot was used for evaluating the activation energy (E a , kJ mol −1 ) of corrosion for carbon steel in seawater and TOE-treated seawater, using the equation 42 : www.nature.com/scientificreports www.nature.com/scientificreports/ where R is the universal gas constant 8.314 J mol −1 K −1 , T the absolute temperature and A the pre-exponential factor.…”

“…For Aster koraiensis leaves extract the sorption constant reaches 0.71 L mg −1 37 . Casein was also reported for inhibiting mild steel corrosion in acidic solutions with sorption constant ranging between 0.006 and 0.034 L mg −1 (depending on temperature) 38 . For the extracts of date palm leaves and seeds, the sorption constant also varied in a similar range (between 0.004 and 0.18 L mg −1 ) 39 .…”

“…Similar drastic increase in enthalpy change was observed by Rabizadeh and Asl 38 when using casein as an inhibitor of corrosion for mild steel. The positive value of the enthalpy change is associated with the endothermic character of the steel dissolution 38 . The entropy change (deduced from the intercept of ln(C R /T) vs. 1/T) slightly varied from −235 J mol −1 K −1 to −216 J mol −1 K −1 .…”

“…As expected, this inhibition efficiency increases with TOE dosage: there is a strong increase between 100 mg L −1 and 200 mg L −1 , while at higher dosage the enhancement tends to stabilize. It is noteworthy that the range of frequency should be extended to lower frequencies (to 0.01-0.1 Hz) to reach the saturation and to get a better evaluation of corrosion inhibition efficiency 38 . The phase angle plots also confirm a slight increase of the angle and the width of the peak with increasing TOE dosage.…”

Test method and device for evaluation of volatile corrosion inhibitors

“…Moreover, the electrochemical measurement allows for both objective and time-resolved characterization of the surface state (passivity or corrosion-activity). In this respect, numerous studies have established correlations between values obtained from electrochemical measurements in direct current mode or in alternating current mode and the passivity/inhibition or corrosion activity of a metallic surface [9][10][11][12][13][14][15][16]. In any case, the basis for the evaluation is the relation of current density and potential.…”