National Center for Education and Research on Corrosion and Materials Performance, NCERCAMP-UA, Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, 302 E Buchtel Ave, Akron, OH 44325-3906, USA.
Molecules. 2022 Dec 10;27(24):8776. doi: 10.3390/molecules27248776.
The inhibiting performance of sodium succinate (NaCHO) was evaluated as an organic environmentally friendly corrosion inhibitor for carbon steel rebars in 0.6 M Cl simulated concrete pore solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements were utilized to evaluate the inhibitor performance at different temperatures and concentrations. The investigated corrosion inhibitor showed strong corrosion inhibition performance as it adsorbs on the surface of the rebar, creating a protective adsorption film. According to PDP, the inhibitor is classified as a mixed-type inhibitor with an inhibitor efficiency of 77, 69, 59, and 54% for 25, 35, 45, and 55 °C, respectively. EIS validated the PDP tests, showing that sodium succinate displaces the water molecules at the interface, creating an adsorption film by complexing with ferrous ions. The film thickness was calculated, and sodium succinate was able to produce a thicker protective film (span of nanometers) relative to the reference at every temperature. The adsorption of sodium succinate follows the Temkin adsorption isotherm. Δ was found to be -32.75 kJ/mol, indicating that the inhibitor adsorption is a combined physisorption and chemisorption process. Different surface characterizations were utilized to substantiate the adsorption of sodium succinate, these include scanning electron microscopy, energy-dispersive X-ray spectroscopy, and micro-Raman spectroscopy. Finally, quantum chemical calculations showed that the delocalized electrons in the carboxyl group have high HOMO energies and electrostatic potential, which facilitates the adsorption of sodium succinate corrosion inhibitor onto the carbon steel rebar surface.
本文研究了琥珀酸钠（NaCHO）作为一种有机环保型缓蚀剂，在 0.6 M Cl-模拟混凝土孔隙溶液中对钢筋的缓蚀性能。采用动电位极化（PDP）和电化学阻抗谱（EIS）测试方法，在不同温度和浓度下评价了缓蚀剂的性能。研究发现，该缓蚀剂在钢筋表面吸附形成保护膜，具有较强的缓蚀性能，属于混合型缓蚀剂，在 25、35、45 和 55°C 时的缓蚀效率分别为 77%、69%、59%和 54%。EIS 测试结果验证了 PDP 测试结果，表明琥珀酸钠取代了界面处的水分子，通过与亚铁离子络合形成吸附膜。计算了膜厚，结果表明，琥珀酸钠在每个温度下都能比参比组产生更厚的保护膜（纳米级范围）。琥珀酸钠的吸附符合 Temkin 吸附等温线，计算得到的吸附自由能变化值（ΔGads）为-32.75 kJ/mol，表明其吸附过程是物理吸附和化学吸附的综合作用。采用扫描电子显微镜、能谱分析和微拉曼光谱等表面分析方法对吸附作用进行了验证。最后，量子化学计算表明，羧基中离域的电子具有较高的 HOMO 能量和静电势能，有利于琥珀酸钠缓蚀剂吸附到钢筋表面。
