Metal corrosion is brought about by the oxidation of atoms on the surface resulting in irreversible damage to structures at staggering costs. Hence, the search for efficient and cost-effective corrosion inhibitors is relevant. In this study, the ethanolic extract of Red Dragon Fruit (Selenicereus costaricensis) waste peels (RDF) has been tested for its anti-corrosion property using the weight loss method at different temperatures (303-343 K). The calculated inhibition efficiency of 2% RDF is 97%. Thermodynamic studies reveal that increasing inhibitor concentration raises the activation parameters of mild steel in acidic media such as activation energy (Ea) and changes in enthalpy (Ho) and entropy (So). Moreover, increased immersion time, inhibitor concentration, and temperature led to increased inhibition efficiency. The spontaneous process (Go ads = -23.47 kJ/mol) of adsorption of RDF on mild steel surfaces obeys the Langmuir isotherm model. Lastly, optical microscopy of the inhibited and uninhibited systems confirms the potential of the RDF against pitting corrosion.

中文翻译：

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红火龙果 (Selenicereus costaricensis) 废皮提取物在酸性环境中对低碳钢的腐蚀抑制、吸附行为和热力学研究

金属腐蚀是由表面上的原子氧化引起的，从而以惊人的成本对结构造成不可逆转的损坏。因此，寻找有效且具有成本效益的缓蚀剂是相关的。在这项研究中，使用失重法在不同温度（303-343 K）下测试了红火龙果（Selenicereus costaricensis）废皮（RDF）的乙醇提取物的防腐性能。2% RDF的计算抑制效率为97%。热力学研究表明，增加抑制剂浓度会提高低碳钢在酸性介质中的活化参数，例如活化能 (Ea) 和焓 (Ho) 和熵 (So) 变化。此外，增加浸泡时间、抑制剂浓度和温度会提高抑制效率。RDF 在低碳钢表面吸附的自发过程（Go ads = -23.47 kJ/mol）遵循 Langmuir 等温线模型。最后，抑制和未抑制系统的光学显微镜证实了 RDF 对抗点蚀的潜力。