Synergetic Anticorrosion Mechanism of Main Constituents in Chinese Yam Peel for Copper in Artificial Seawater

Abstract

Active constituents of Chinese yam peel (CYPE), namely, diosgenin (DOG), batatasin-I (BTS-I), batatasin-III (BTS-III), and yam polysaccharide (Y-PS), were extracted via an ultrasonic soaking strategy. The synergetic anticorrosion mechanism among these compounds for copper in artificial seawater (ASW) was clarified by gravimetric measurements, electrochemical evaluations, surface analyses, quantum chemical calculations under a dominant solvent model, and molecular dynamics (MD) simulations. The results of weight loss revealed that CYPE strongly inhibited the corrosion of copper in ASW, and the elevating temperature boosted the anticorrosion efficacy of CYPE. The inhibition efficiency could attain 96.33% with 900 mg/L CYPE in ASW at 298 K due to effective adsorption. CYPE simultaneously suppressed the anodic and cathodic reactions for copper in ASW, which could be categorized as the mixed-type corrosion inhibitor with the predominant anodic effect. Similar electrochemical kinetics was evidenced by electrochemical frequency modulation (EFM). Electrochemical impedance spectroscopy (EIS) indicated that CYPE prominently increased the charge-transfer resistance at the copper/electrolyte interface without altering the corrosion mechanism. Extending the immersion time was also conducive for CYPE to further minimize the corrosion of copper in ASW, which was demonstrated by the time-course polarization, EIS, and EFM tests. Owing to the adsorption of CYPE, the copper surface was well-protected and showed reduced wettability and limited variation of roughness. From the outcomes of quantum chemical calculations, global and local reactive descriptors of DOG implied the cross-linked deposition of actually formed dioscin on the copper surface; otherwise, those of BTS-I/-III showed the propensity for parallel adsorption, which could chemically anchor on the voids uncovered by dioscin and thereby synergistically inhibit the corrosion process. The adsorption orientations of DOG, BTS-I, and BTS-III were also consolidated by MD simulations. The findings of this study might be beneficial to inspire the development of eco-friendly corrosion inhibitors from plant wastes for copper in marine environments.

One-Pot Hydrothermal Synthesized Nitrogen and Sulfur Codoped Carbon Dots for Acid Corrosion Inhibition of Q235 Steel

“…In the spectrum of thiourea, 1608 and 3375 cm –1 peaks agree to shearing and stretching vibrations of NH 2 while the one at 1477 cm –1 agrees to CS stretching . The peaks observed for CDs are the typical peaks of the CN stretching vibration of NH/OH that appeared at 3113 and 1410 cm –1 . The stretching peaks of CS and NCS occur, respectively, at 1476 and 2056 cm –1 .…”

“…24 The peaks observed for CDs are the typical peaks of the CN stretching vibration of NH/OH that appeared at 3113 and 1410 cm −1 . 25 The stretching peaks of CS and NCS occur, respectively, at 1476 and 2056 cm −1 . 26 The CO stretching and CO stretching are observed at 1682 and 1248 cm −1 .…”

Optimized Anticorrosion of Polypyrrole Coating by Inverted-Electrode Strategy: Experimental and Molecular Dynamics Investigations

“…Similar to the aforementioned inference, this derivation of i corr can be due to the intensive charge exchange of PPy coatings with the ambient electrolyte. The maximum β a value was established for PPy-I coated copper (173.53 mV/dec), further supporting that compact protective layer can also efficiently passivate the substrate in ASW [ 29 ]. In addition, the reduced β c modulus for PPy-I-coated specimen compared with those for P-Cu and PPy-T-protected samples arises from the cathodic de-doping process, which can neutralize the excessive charges at the copper–coating interface [ 38 ].…”

“…The adhesive grades and conductivities of the PPy-T and PPy-I coatings on the copper surface are further compared in Figure 3 d. The PPy-I coating (113 S/m) showed greater conductivity than that of the PPy-T analogue (89 S/m). High conductivity renders the favorable anodic protection effect of conductive coatings for the underlying metal [ 18 , 29 , 30 ]. Shahryari et al [ 31 ] also reported that PPy could convert the metal surface into the passivated state.…”

“…As seen, the low magnitude of χ 2 and comparable R s values evidence the effectiveness of equivalent circuits for the fitting procedure. The coated specimens earned higher R f values than P-Cu, which can be attributed to the barrier effect of the PPy layer [ 29 ]. The optimum R f value (71.40 Ω·cm 2 ) is found for the PPy-I-coated specimen, evidencing the compact coating structure and the ensuing strong physical barrier at the copper–coating interface.…”