Abstract

In this study, two surfactants with the same long chain were synthesized. One shows dicationic and the other tricationic properties. Various spectroscopic methods such as FT-IR, ¹H NMR and ¹³C NMR were used to confirm the structures of the synthesized surfactants. The inhibition activities of two synthesized surfactants against mild steel corrosion in 1.0 M HCl solution were determined using the weight loss method. The 24-h corrosion tests on metal coupons immersed in acidic solutions were carried out using different inhibitor concentrations and similar and successful inhibition was obtained for both surfactants. Current density was determined by potentiodynamic polarization at a single inhibitor concentration to compare with the inhibition efficiency results obtained by decrease in weight method. Based on the current density, the inhibition efficiencies of the surfactants were calculated by Tafel extrapolation method. The inhibition efficiency results obtained by both weight loss and Tafel method were close and consistent. According to both methods, the corrosion inhibition of dicationic surfactant was slightly better than that of tricationic surfactant. By determining the critical micelle concentration for the two surfactants, some physicochemical parameters such as surface tensions and free energy of micelle formation at this concentration were calculated and correlated with their corrosion inhibitory activity. Scanning electron microscopy was used to ascertain the surface roughness conditions of metals submerged in an acidic solution, thus visually proving that surfactants protect the metal surface from corrosion.

中文翻译：

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二阳离子和三阳离子表面活性剂的合成及其在 HCl 介质中金属氧化活性的比较

摘要

在本研究中，合成了两种具有相同长链的表面活性剂。一种显示双阳离子性质，另一种显示三阳离子性质。使用FT-IR、¹ H NMR和^{13 C NMR等各种光谱方法来确认合成的表面活性剂的结构。}采用失重法测定了两种合成表面活性剂在 1.0 M HCl 溶液中对低碳钢腐蚀的抑制活性。使用不同浓度的抑制剂对浸入酸性溶液中的金属试片进行 24 小时腐蚀测试，两种表面活性剂均获得相似且成功的抑制效果。在单一抑制剂浓度下通过动电位极化测定电流密度，并与重量减少法获得的抑制效率结果进行比较。根据电流密度，采用塔菲尔外推法计算表面活性剂的缓蚀效率。失重法和塔菲尔法得到的抑制效率结果接近且一致。两种方法均表明，双阳离子表面活性剂的缓蚀效果略好于三阳离子表面活性剂。通过确定两种表面活性剂的临界胶束浓度，计算了该浓度下的一些物理化学参数，例如表面张力和胶束形成的自由能，并将其与它们的腐蚀抑制活性相关联。使用扫描电子显微镜来确定浸没在酸性溶液中的金属的表面粗糙度状况，从而直观地证明表面活性剂可以保护金属表面免受腐蚀。