Study and Assessment of the Efficiency of the Cocoa Bark Extracted from the Theobroma Cacao as an Inhibitor of the Corrosion of Carbon Steel in Substitution of Benzotriazole

Corrosion represents high losses to the economy, therefore, researches on the minimization of its damages in materials, mainly the metallic ones, are necessary. Among the various alternatives of protection against corrosion, there is the application of corrosion inhibitors that can minimize or even stop the corrosive process of metallic materials. However, at present, substances usually used as corrosion inhibitors present high toxicity, being considered harmful components to the environment and to human health. Therefore, there is an urgent need for studies on viable corrosion inhibitors, by considering not only economic but also environmental costs. The present work studied the use of cocoa bark extract (Theobrama cacao L), for possible replacement of benzotriazole (BTAH) in the corrosion inhibition of ASTM 1020 carbon steel (CS- ASTM 1020) in 18.23 g.L-1 hydrochloric acid media. Weight loss measurements, anodic and cathodic potentiodynamic polarization curves and electrochemical impedance experiments were carried out. The results showed that the addition of the extract to the electrolyte effectively hinder the corrosion process and indicated its adsorption on the electrode surface. In addition, the inhibiting efficiency of the cocoa bark extract was only slightly inferior to BTAH, showing that it can be an environmentally friendly option to toxic inhibitors.腐蚀会给国民经济造成巨额损失，因此针对材料（尤其是金属材料）的腐蚀损伤最小化开展相关研究十分必要。在众多腐蚀防护方案中，缓蚀剂（corrosion inhibitor）的应用可有效减缓乃至阻断金属材料的腐蚀进程。然而当前常用的缓蚀剂大多毒性较强，被视为对环境与人体健康有害的物质。因此，亟需研发兼顾经济效益与环境成本的实用型缓蚀剂。本研究探索了可可树皮提取物（cocoa bark extract，Theobrama cacao L）替代苯并三氮唑（benzotriazole，BTAH）的可行性，以在18.23 g·L⁻¹盐酸介质中对ASTM 1020碳钢（CS-ASTM 1020）实施腐蚀防护。本研究采用重量损失法、阴阳极动电位极化曲线法以及电化学阻抗实验开展表征。结果表明，向电解液中添加该提取物可有效抑制腐蚀进程，且证实提取物会吸附于电极表面。此外，可可树皮提取物的缓蚀效率仅略低于BTAH，证明其可作为有毒缓蚀剂的环保替代方案。