Cellulose, as a kind of renewable natural polymer, has great potential as green corrosion inhibitor. However, the low inhibition effect is the obstacle to its practical application. Herein we developed a high efficiency green cellulose derivative corrosion inhibitor, levodopa-carboxymethyl cellulose (LDCMC), by modifying carboxymethyl cellulose (CMC) with levodopa (LD) through a simple amidation reaction. The inhibition effect of CMC for mild steel in HCl medium is dramatically improved with an increase in inhibition efficiency from 56.98% of CMC to 97.27% of LDCMC. The intrinsic nature of the dramatically improved inhibition effect is in-depth unraveled by first-principles calculations based on density functional theory (DFT). CMC and LDCMC can adsorb on the mild steel surface through -OH, -COOH and LD fragment by forming the covalent bonds with steel surface. Benefiting from the additional strong adsorption of the benzene ring in LD fragment, the introduction of LD can significantly enhance the adsorption capacity of LDCMC, which is the intrinsic nature of the dramatical improvement in the inhibition effect of LDCMC.

中文翻译：

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左旋多巴改性羧甲基纤维素缓蚀效果显着提高：实验研究和第一性原理计算

纤维素作为一种可再生的天然聚合物，作为绿色缓蚀剂具有巨大的潜力。但抑制效果低，限制了其实际应用。在此，我们通过简单的酰胺化反应用左旋多巴（LD）对羧甲基纤维素（CMC）进行改性，开发了一种高效绿色纤维素衍生物缓蚀剂——左旋多巴羧甲基纤维素（LDCMC）。 CMC在HCl介质中对低碳钢的缓蚀效果显着提高，缓蚀效率从CMC的56.98%提高到LDCMC的97.27%。基于密度泛函理论 (DFT) 的第一性原理计算深入揭示了显着改善的抑制效果的本质。 CMC和LDMCC可以通过-OH、-COOH和LD片段与钢表面形成共价键而吸附在低碳钢表面。受益于LD片段中苯环的额外强吸附作用，LD的引入可以显着增强LDCMC的吸附能力，这也是LDCMC抑制效果大幅提升的内在本质。