Carbon steel alloys are the usual materials in petroleum refining facilities. However, poor corrosion resistance of carbon steel is a serious problem for the use of its alloys in the petroleum industries. Herein, we demonstrate the use of pharmaceutical drugs namely; levofloxacin, moxifloxacin, metolazone, and nifedipine for enhancing carbon steel resistance in 2 M HCl solution using mass loss, electrochemical impedance spectroscopy, potentiodynamic polarization, computational studies, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The order of average corrosion inhibition efficiency of the studied compounds are Meto>Levo>Moxi>Nife. This order is in agreement with the polarization, mass loss, and theoretical measurements. The morphological studies from SEM and AFM revealed that the tested compounds could effectively enhance carbon steel resistance through adsorption on the metal surface. The adsorption behavior follows Langmuir, Temkin, El-awady, Frumkin, and Flory- Huggins adsorption isotherms. The computational studies using DFT simulation revealed the mechanisms of inhibition performances of the inhibitors on the carbon steel corrosion. The quantitative structure-activity relationship (QSAR) approach provides a clear definition of some measured quantum chemical parameters needed to align with the inhibitors’ inhibition efficiencies that were determined experimentally. Mulliken population analysis revealed the atoms that are responsible for adsorption on the surface of carbon steel. The present investigation provides new insight into the usefulness of these drugs in corrosion mitigation.

碳钢合金是石油精炼设施中的常用材料。然而，碳钢的耐腐蚀性差是其合金在石油工业中使用的一个严重问题。在这里，我们展示了药物的使用，即；左氧氟沙星、莫西沙星、美托拉宗和硝苯地平使用质量损失、电化学阻抗谱、动电位极化、计算研究、扫描电子显微镜 (SEM) 和原子力显微镜 (AFM) 提高 2 M HCl 溶液中的碳钢电阻。研究化合物的平均缓蚀效率顺序为Meto>Levo>Moxi>Nife。这个顺序与极化、质量损失和理论测量一致。SEM 和 AFM 的形态研究表明，测试化合物可以通过吸附在金属表面上有效地提高碳钢的抵抗力。吸附行为遵循 Langmuir、Temkin、El-awady、Frumkin 和 Flory-Huggins 吸附等温线。使用 DFT 模拟的计算研究揭示了抑制剂对碳钢腐蚀的抑制性能机制。定量构效关系 (QSAR) 方法提供了一些测量的量子化学参数的明确定义，这些参数需要与实验确定的抑制剂的抑制效率保持一致。马利肯布居分析揭示了负责碳钢表面吸附的原子。