Recently, due to the corrosion problem in the petroleum industry and the usage of commercial corrosion inhibitors, which, when released untreated into the environment, are considered to be environmentally unfriendly, green corrosion inhibitors are being researched. In this paper, the results of dandelion-root-extract testing as a green corrosion inhibitor for carbon steel in simulated brine solution saturated with carbon dioxide (CO₂) are shown. The extract’s inhibition efficiency in static and flow conditions was determined by using potentiodynamic polarization with Tafel extrapolation and electrochemical-impedance-spectroscopy methods. In static conditions, the extract was tested at different concentrations. A maximum inhibition efficiency of 98.37% in static conditions at an extract concentration of 12 mL/L and 82.80% in flow conditions at a concentration of 14 mL/L was achieved. Additionally, for the most efficient dandelion-root-extract concentration (12 mL/L), the biodegradability and toxicity were determined. A biodegradability of 0.96 and a toxicity of 2.38% was achieved. Based on the obtained results of the conducted laboratory measurements, it can be concluded that dandelion-root extract has significant potential in terms of its use as a green corrosion inhibitor for carbon steel in a CO₂-saturated brine solution.

Due to issues with the corrosion problem in the petroleum industry and the use of less ecologically acceptable corrosion inhibitors, great emphasis, within research on corrosion inhibitors, is now being put on green corrosion inhibitors (GCIs). In this study, Lady’s mantle flower extract (LMFE) has been observed as a plant-based GCI for carbon steel in a simulated CO₂-saturated brine solution. The effectiveness of the inhibitor in static and flow conditions has been determined using potentiodynamic polarization with Tafel extrapolation and electrochemical impedance spectroscopy (EIS). In static conditions, the inhibitor has been tested at concentrations from 1 g/L to 5 g/L with an increment of 1 g/L per measurement, while, in dynamic (flow) conditions, the inhibitor has been tested at concentrations from 3 g/L to 6 g/L with an increment of 1 g/L per measurement. All measurements were performed at room temperature. EIS and potentiodynamic polarization methods showed that LMFE achieves maximum effectiveness in protecting carbon steel from corrosion when added at a concentration of 4 g/L in static conditions and at a concentration of 5 g/L in flow conditions. The test methods proved that the inhibitory effectiveness of LMFE is greater than 90% in both test conditions (static and flow). The inhibitor efficiency was attributed to the adsorption of LMFE on the carbon steel surface, which was demonstrated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). A biodegradability of 0.96 and a toxicity of 19.34% for LMFE were determined. The conducted laboratory tests indicate that LMFE could be used as an effective corrosion inhibitor for CO₂ carbon steel corrosion.

In production and transportation systems of the oil industry, brine solutions contain high concentrations of chloride and dissolved CO₂, which is a very corrosive medium to which carbon steel is exposed. Therefore, finding new effective and environmentally friendly corrosion inhibitors is of great importance. The effect of CeCl₃ (in concentrations from 5 mg dm⁻³ to 20 mg dm⁻³) and oleic acid imidazoline (IOA) (in concentrations from 5 mg dm⁻³ to 20 mg dm⁻³) separately and their mixtures (in concentrations from 5 mg dm⁻³ to 15 mg dm⁻³ of CeCl₃ and from 5 mg dm⁻³ to 20 mg dm⁻³ of IOA) as corrosion inhibitors of AISI 1018 carbon steel corrosion in simulated brine solution saturated with CO₂ at 60 °C were examined by means of weight-loss testing, electrochemical measurements (polarization resistance, linear polarization with Tafel extrapolation, electrochemical impedance spectroscopy) and surface analyses (scanning electron microscopy with energy-dispersive X-ray spectroscopy analyses, Raman spectroscopy and X-ray diffraction). All test methods showed a higher efficiency of compounds′ mixtures (from 62.77% to 97.94%) and a higher degree of corrosion protection compared to the action of individual compounds (efficiency from 3.43% to 94.61% for IOA and from 57.58% to 96.27% for CeCl₃). Imidazoline, a common corrosion inhibitor in CO₂-saturated systems, most likely forms a surface film with voids via its adsorption on steel surface, while cerium carbonate tends to fill these voids by creating a more compact film. In this way, a denser and thicker surface film is formed.

The decarbonization of European industry will require large-scale underground CO₂ storage. To ensure the long-term safety of storage sites, it is essential to maintain the integrity of both the geological formation and the surface infrastructure. A critical component exposed to elevated risk...