In this study, two tri-cationic surfactants containing two amide functional groups and three positively charged quaternary aminium nitrogens were synthesized. The structures of the synthesized surfactants were proved by various spectroscopic methods (FT-IR, ¹H NMR, and ¹³C NMR). Inhibition activities of two synthesized products against mild steel corrosion were determined using the weight loss method in 1.0 M HCl acidic medium. As a result of corrosion tests performed by immersing metal coupons in acidic solutions with different inhibitor concentrations for 24 h at room temperature, close and effective inhibitions were obtained for both surfactants. It has been found that the number of carbons in the long carbon chain in their structures is an effective factor in corrosion protection. In the acid environment, the corrosion inhibition efficiency of the inhibitor with more carbon in the long chain was found slightly higher than the other. While the compound containing 16 carbon atoms in its long chain showed corrosion inhibition over 92%, the compound containing 12 carbons in its long chain exhibited corrosion inhibition of 90% and below. In addition, some physicochemical parameters such as critical micelle concentration, surface tensions at this concentration, and free energy of micelle formation were calculated for the tri-cationic surfactants in order to correlate them with their anti-corrosion activities. Surface images were also taken by scanning electron microscope, which is an important supporting evidence that surfactants adsorb on the metal surface and protect the surface from corrosion, to determine the roughness conditions on the metal surfaces immersed in the acid solution.

中文翻译：

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含两个酰胺官能团的三阳离子表面活性剂的合成及其在酸性介质中对金属腐蚀的缓蚀作用

在这项研究中，合成了两种含有两个酰胺官能团和三个带正电荷的季铵氮的三阳离子表面活性剂。合成的表面活性剂的结构通过各种光谱方法（FT-IR，¹ H NMR，和¹³C核磁共振）。在 1.0 M HCl 酸性介质中使用失重法测定两种合成产物对低碳钢腐蚀的抑制活性。通过在室温下将金属试片浸入不同抑制剂浓度的酸性溶液中 24 小时进行腐蚀试验，两种表面活性剂均获得了紧密有效的抑制作用。已发现其结构中长碳链中的碳数是防腐蚀的有效因素。在酸性环境中，长链含碳量较多的缓蚀剂的缓蚀效率略高于其他缓蚀剂。而在其长链中含有 16 个碳原子的化合物显示出超过 92% 的腐蚀抑制，在其长链中含有 12 个碳的化合物表现出 90% 及以下的腐蚀抑制。此外，计算了三阳离子表面活性剂的一些物理化学参数，如临界胶束浓度、该浓度下的表面张力和胶束形成的自由能，以便将它们与其抗腐蚀活性相关联。还通过扫描电子显微镜拍摄表面图像，这是表面活性剂吸附在金属表面并保护表面免受腐蚀的重要支持证据，以确定浸入酸溶液中的金属表面的粗糙度情况。计算了三阳离子表面活性剂的胶束形成自由能和自由能，以便将它们与其抗腐蚀活性相关联。还通过扫描电子显微镜拍摄表面图像，这是表面活性剂吸附在金属表面并保护表面免受腐蚀的重要支持证据，以确定浸入酸溶液中的金属表面的粗糙度情况。计算了三阳离子表面活性剂的胶束形成自由能和自由能，以便将它们与其抗腐蚀活性相关联。还通过扫描电子显微镜拍摄表面图像，这是表面活性剂吸附在金属表面并保护表面免受腐蚀的重要支持证据，以确定浸入酸溶液中的金属表面的粗糙度情况。