Corrosion Inhibition in CO2-Saturated Brine by Nd3+ Ions.

This study reports the use of an inorganic corrosion inhibitor to mitigate dissolved CO2-induced corrosion. Using electrochemical techniques (polarization curves, open circuit potential, polarization resistance, and electrochemical impedance), the effect of adding Nd3+ ions on the corrosion resistance of X52 steel immersed in CO2-saturated brine at 20 °C and 60 °C was evaluated. The polarization curves showed that the Icorr values tend to decrease with increasing Nd3+ ion concentration, up to the optimal inhibition concentration, and that the corrosion potential increases at nobler values. Open circuit potential measurements showed a large increase in potential values immediately after the addition of the Nd3+ ions. Similarly, polarization resistance measurements showed similar trends. It was observed that regardless of temperature, Nd3+ ions can reduce the corrosion rate by more than 97% at doses as low as 0.001 M. Electrochemical impedance measurements confirmed the formation of a protective layer on the steel surface, which caused an increase in the magnitude of the impedance module and phase angle, which indicates an increase in the resistance to charge transfer and capacitive properties of the metallic surface. The characterization of the metallic surface showed that the protective layer was formed by Nd carbonates, whose formation was due to a CO2 capture process.

Inhibition of X52 Corrosion in CO2-Saturated Brine by a Dialkyl-Diamide from Coffee Bagasse Oil.

This work reports the performance of a green corrosion inhibitor with double hydrocarbon chain. The evaluated inhibitor was a dialkyl-diamide from coffee bagasse oil and its electrochemical behavior was evaluated on an API-X52 steel in CO2-saturated brine at 60 °C. The electrochemical behavior was determined by measurements of open circuit potential, polarization resistance, and electrochemical impedance spectroscopy. In addition, the thermodynamic parameters of the corrosion process were obtained in the temperature range from 40 °C to 80 °C. Electrochemical studies showed that the inhibitor is capable of suppressing metal dissolution by up to 99% at 25 ppm. On the other hand, the thermodynamic parameters indicate that when adding the inhibitor, there is a strong increase in both Ea and ΔH° values, and that as time increases, they decrease until reaching similar values to those observed in the absence of the inhibitor. Furthermore, ΔS° values tend to become more negative with immersion time because of the formation of a stable film on the metal surface.

Sweet Corrosion Inhibition by CO2 Capture.

The most practical and economical way to combat the problems derived from CO2 corrosion (sweet corrosion) is the use of corrosion inhibitors of organic origin. Its main protection mechanism is based on its ability to adsorb on the metal surface, forming a barrier between the metal surface and the aggressive medium. However, despite its excellent performance, its inhibition efficiency can be compromised with the increase in temperature as well as the shear stresses. In this study, the use of an inorganic inhibitor is proposed that has not been considered as an inhibitor of sweet corrosion. The reported studies are based on using LaCl3 as a corrosion inhibitor. Its behavior was evaluated on 1018 carbon steel using electrochemical measurements, such as potentiodynamic polarization curves, open-circuit potential measurements, linear polarization resistance measurements, and electrochemical impedance. The results showed an inhibition efficiency of the sweet corrosion process greater than 95%, and that the inhibition mechanism was different from the classic corrosion process in CO2-free electrolytes. In this case, it was observed that the inhibitory capacity of the La3+ cations is based on a CO2-capture process and the precipitation of a barrier layer of lanthanum carbonate (La2(CO3)3).

Correction: Mechanochemical enzymatic resolution of N-benzylated-ß3-amino esters.

[This corrects the article DOI: 10.3762/bjoc.13.167.].

Mechanochemical enzymatic resolution of N-benzylated-ß3-amino esters.

The use of mechanochemistry to carry out enantioselective reactions has been explored in the last ten years with excellent results. Several chiral organocatalysts and even enzymes have proved to be resistant to milling conditions, which allows for rather efficient enantioselective transformations under ball-milling conditions. The present article reports the first example of a liquid-assisted grinding (LAG) mechanochemical enzymatic resolution of racemic ß3-amino esters employing Candida antarctica lipase B (CALB) to afford highly valuable enantioenriched N-benzylated-ß3-amino acids in good yields. Furthermore the present protocol is readily scalable.