Abstract
The implementation of corrosion engineering control methods and techniques is crucial to extend the life of urban and industrial infrastructure assets and industrial equipment affected by natural corrosion. Then, the search of stable and environmentally friendly corrosion inhibitors is an important pending task. Here, we provide experimental evidence on the corrosion inhibitory activity of aqueous extracts of Skytanthus acutus Meyen leaf, a native plant from the Atacama Desert in northern Chile. Skytanthus extracts as a powder should be prepared at 55 °C to avoid thermal decomposition and loss of corrosion inhibitory activity. Corrosion of carbon steel AISI1020 immersed in 0.5 M NaCl was evaluated in the presence of different doses of Skytanthus extract by complementary and simultaneous linear polarization, electrochemical impedance spectroscopy, and weight-loss technique under high hydrodynamic conditions. Mixed Potential Theory was applied to confirm the electrochemical activity of the extract inhibitory capabilities. The Skytanthus extracts reached a 90% corrosion inhibitory efficiency when tested at 100 to 1200 ppm in a time span of 48 h, through an electrochemical interaction between the extract inhibitor component and the carbon steel surface. The corrosion inhibition activity observed in Skytanthus dry extracts involves a protective film formation by a mechanism that includes an iron dissolution at the expense of either oxygen reduction and/or hydrogen evolution, followed by a ferrous-ferric iron cycling, the formation of an iron complex and adsorption to the metal surface, and, finally, desorption or degradation of the protecting film. The water-soluble plant extract was subjected to HPLC-MS analyses that rendered 14 major signals, with quinic acid, protocatechuic acid, chlorogenic acid isomers, vanillic acid hexoside, and patuletin 3-methoxy-7-glucoside as the most abundant components. Then, we propose that a phenolic derivative is responsible for the corrosion inhibitory activity found in Skytanthus extracts.
Highlights
Carbon steel has no capacity to develop a protective surface oxide layer against the aggressiveness of the surrounding environment, it is the most widely used steel material in engineering applications
The dried residue (DR) prepared at 80 ◦C showed an anticorrosion activity significantly lower than DR obtained at 60 ◦C, measured as polarization E-I data for carbon steel in solution
It has been reported that thermal decomposition of total phenolic content (TPC) in sweet cherry caused a sequential reduction in TPC in the whole processing temperature range studied, with a variation of 46% at 70–90 ◦C and between 47 to 63% up to 120 ◦C during a 60 min heating compared with untreated extracts [26]
Summary
Carbon steel has no capacity to develop a protective surface oxide layer against the aggressiveness of the surrounding environment, it is the most widely used steel material in engineering applications This is justified by its significant lower cost in comparison to more noble higher-grade alloys, mechanical properties, and its amenability to be safely operated in very corrosive service conditions under a properly designed and implemented control system. The use of corrosion inhibitors for carbon steel in chloride-containing solutions is steadily increasing mainly because the seawater transport and processing is becoming the main alternative to cope with the expanding trend of freshwater scarcity This is true in mineral extracting and processing plants around the world which are facing decreasing lower-grade ores and increasing water consumption rates [2,3]. Given the logistic tasks associated with such standard practice, this method is not normally used at the early corrosion inhibitor research testing; instead, linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy are electrochemical methods mainly preferred which sometimes are complemented with weight-loss testing which consists of immersion of test coupons on quiescent solutions for long predetermined times [4,5,6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
