The corrosion inhibition efficiency of sodium caprylate (SC) in protecting carbon steel (CS) in aqueous 3.5 wt.% NaCl was studied. SC was found to enable good corrosion protection of CS, yielding a maximum corrosion inhibition efficiency of 80 ± 2%. The inhibition efficiency was shown to be directly proportional to the SC surface coverage, characterized by a two-step adsorption isotherm. The adsorption of SC on CS in the lower SC concentration region was found to follow the Langmuir adsorption isotherm and the first-order reversible adsorption kinetics. The corresponding Gibbs free energy of SC adsorption was determined to be −23.8 kJ · mol⁻¹, indicating a highly spontaneous adsorption process. The scanning electron microscopy imaging of the SC-inhibited CS showed that the surface exhibited good corrosion stability during a 72 h exposure to the test medium.

中文翻译：

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辛酸盐对碳钢在人工海水中的缓蚀作用

研究了辛酸钠 (SC) 在 3.5 wt.% NaCl 水溶液中保护碳钢 (CS) 的缓蚀效率。发现 SC 能够为 CS 提供良好的腐蚀保护，产生的最大腐蚀抑制效率为 80 ± 2%。抑制效率显示与 SC 表面覆盖率成正比，其特征在于两步吸附等温线。在较低的 SC 浓度区域，SC 在 CS 上的吸附被发现遵循 Langmuir 吸附等温线和一级可逆吸附动力学。SC吸附相应的吉布斯自由能为-23.8 kJ·mol ^-1，表明高度自发的吸附过程。SC 抑制 CS 的扫描电子显微镜成像表明，在暴露于测试介质 72 小时期间，表面表现出良好的腐蚀稳定性。