Lignin-based corrosion inhibitor via solvent-induced self-assembly for carbon steel in acidic medium

Background With increasing environmental concerns, the development of eco-friendly corrosion inhibitors has gained significant attention. Lignin, the second most abundant natural polymer on Earth, possesses abundant functional groups such as hydroxyl and methoxy groups, which offer considerable potential for use as a green corrosion inhibitor. Methods Solvent-induced self-assembly is a preparation method that utilizes changes in the solvent environment to drive the spontaneous formation of ordered molecular structures. Both sodium lignosulfonate (SLS) and cetyltrimethylammonium bromide (CTAB) possess functional groups, including sulfonic acid and quaternary ammonium groups, respectively, which endow them with excellent self-assembly potential. In this study, SLS and CTAB were employed as raw materials to prepare the novel material, designated as SLS-CTAB, using the solvent-induced self-assembly method. The corrosion inhibition performance and mechanism of SLS-CTAB as a high-efficiency, green corrosion inhibitor for carbon steel in acidic environments were systematically investigated using weight loss measurements, electrochemical tests, and multiscale characterization methods. Significant Findings This method enabled the efficient preparation of SLS-CTAB, achieving a yield of 38.98%. Weight loss measurements showed that the corrosion inhibition efficiency reached 94.22% at 50 mg/L. Mechanistic analysis suggested that SLS-CTAB could act as a hybrid corrosion inhibitor by spontaneously adsorbing onto the carbon steel surface through the physical and chemical adsorptions. This process formed a hydrophobic protective film that effectively inhibited the penetration of corrosive ions, thereby exhibiting superior corrosion inhibition performance.