Rosin imidazoline as an eco-friendly corrosion inhibitor for the carbon steel in CO2-containing solution and its synergistic effect with thiourea

•Rosin was used to synthesize a corrosion inhibitor with multiple adsorption sites.•The adsorption sites of RI were determined by quantum chemical calculation.•The adsorption of RI on carbon steel surface follows langmuir adsorption mode.•When RI used in conjunction with TU, inhibition performance is further improved.