Bio-nanocoatings based on castor oil enhanced with nanomaterials as corrosion reducers in injection wells pipelines

Corrosion is a recurring problem in the oil and gas industries. The application of coatings has been demonstrated to prevent the corrosion of pipelines and associated infrastructure, reducing maintenance and repair costs. In this study, an alkyd-urethane coating based on castor oil with the addition of alumina (Al₂O₃), carbon quantum dots (CQDs), and silica (SiO₂) nanoparticles as corrosion reducers in injection-well pipelines is evaluated. The use of this bio-based resin combined with nanoparticles represents an innovative approach to develop sustainable anticorrosive coatings. Potentiodynamic polarization (ASTM 59-97) with and without CO₂, electrochemical impedance spectroscopy and corrosion resistance tests were used to evaluate the effect of nanomaterials on the anticorrosive performance of the coatings. The effects on rheological properties were determined using steady and dynamic rheology. Furthermore, the changes in the microstructure coating were observed by scanning electron microscopy (SEM). Based on potentiodynamic analysis, the coating in the presence of nanoparticles increased the corrosion potential and reduced the corrosion rate. Notably, the coating with 100 mg per L CQDs exhibited the best performance with respect to corrosion potential and current corrosion with and without CO₂. In particular, the efficiency of corrosion inhibition of the CQDs coating was 99.9%. However, the coating with 100 mg L^-1 of Al₂O₃ showed better corrosion resistance over time to salt spray exposure and electrochemical impedance test. The resin exhibited Newtonian behaviour, with a viscosity of 150 cP at 25 °C. On the other hand, the resin exhibited viscoelastic behaviour with <i>G</i>'' > <i>G</i>' in the evaluated frequency range. The SEM results confirm the incorporation of nanoparticles resulting in structural changes of coating. Based on these results, nanomaterial enhanced castor oil-based coatings can be a promising alternative to inhibit the corrosion generated in injection wells and promote sustainability using renewable raw materials. This work advances the field of sustainable anticorrosive coatings, with potential applications extending beyond injection wells to marine, infrastructure, automotive, among others underscoring its broad industrial and environmental impact.