Ginger-derived carbon quantum dots as sustainable inhibitor of steel corrosion and barite precipitation.

A one-step pyrolysis was used to synthesize ginger carbon quantum dots (G-CDs), which were described using XPS, FTIR, XRD, EDX, and TEM to validate the different integrated functions, particle dimension, morphology, component composition, amorphous construction, and bonding types. The dual action of the synthesized G-CDs as corrosion and scale inhibitors was examined. Scale inhibition characteristics of G-CDs for precipitation of BaSO₄ were investigated using the conductivity technique. Results indicated that G-CDs have an effective inhibition of 84.9% at 200 mg/L. Application of Langmuir and Flory-Huygens isotherms along with the Kinetic-thermodynamic model on the experimental findings demonstrated the suitability and applicability of all of them, yielding a (∆G°_ads) _{precipitation} ≃ - 26.7 kJ/mole, suggesting that G-CD adsorption on the scale particle surface is cooperative, involving both chemical and physical interactions, with the physical aspect being the dominant mechanism. SEM and XRD studies indicated that the scale particles (BaSO₄) were deformed when precipitated in the presence of G-CDs due to their adsorption on the particles' surfaces.On the other hand, the inhibition characteristics for the steel corrosion in NaCl solution (0.5 M) were examined using EIS and mass loss method techniques that revealed that G-CDs act as high-efficiency eco-friendly corrosion inhibitor giving 98.3% at 400 mg/L. However, the PDP results indicated that the G-CDs act as mixed-type inhibitor. Application of the adsorption isotherms on the experimental corrosion inhibition data revealed that the three models are applicable, giving (∆G°_ads) _corrosion values equal to - 28.2 kJ/mole, which means that the adsorption process of the G-CQDs is cooperative (physical/chemical). XPS, XRD, EDX and TEM analysis of the steel's surface upon submersion in a NaCl solution (0.5 M) + 400 mg/L G-CDs solution for 1 h revealed that the corrosion products completely disappeared, the carbon dots were closely attached to the surface of the steel, and the Cl⁻ ions were displaced from the steel surface, which confirms that the G-CDs function as a superior ecologically friendly inhibitor for mitigating the steel corrosion. A mechanism of the inhibition of corrosion of steel in a NaCl solution (0.5 M) by G-CDs was reported, which suggests that in the absence of G-CDs in chloride media, the specific adsorption of the chloride ions on the steel surface and catalyse the charge transfer cathodic and anodic corrosion reactions. However, in the presence of G-CDs in the environment, the strong active absorbable carbon dots surface particles displace the Cl^- ions from the steel surface, mitigating the catalytic effect causing inhibition of the corrosion process.