Sodium alginate (SA), a polysaccharide biopolymer, has been studied as an effective inhibitor against the corrosion of API X60 steel in neutral 3.5% NaCl using gravimetric and electrochemical techniques (OCP, EIS and EFM). The inhibition efficiency of the SA increased with concentration but was lower at higher temperature (70 °C). Electrochemical measurements showed that the SA shifted the steel corrosion potential to more positive value and reduced the kinetics of corrosion by forming an adsorbed layer which mitigated the steel surface wetting, based on contact angle measurement. SEM-EDAX was used to confirm the inhibition of SA on API X60 steel surfaces. The SA adsorbs on the steel surface through a physisorption mechanism using its carboxylate oxygen according to UV–vis and ATR–IR measurements, respectively. This phenomena result in decreased localized pitting corrosion of the API X60 steel in 3.5% NaCl solution. Theoretical results using quantum chemical calculations and Monte Carlo simulations provide further atomic level insights into the interaction of SA with steel surface.

中文翻译：

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海藻酸钠：一种有前途的生物聚合物，可用于盐介质中的API X60高强度碳钢腐蚀防护

海藻酸钠（SA）是一种多糖生物聚合物，已通过重量分析和电化学技术（OCP，EIS和EFM）研究了作为一种有效的缓蚀剂，用于中性3.5％NaCl中的API X60钢腐蚀。SA的抑制效率随浓度的增加而增加，但在较高温度（70°C）时较低。电化学测量表明，基于接触角测量，通过形成吸附层可减轻钢表面润湿性，SA将钢的腐蚀电位移至更大的正值并降低了腐蚀动力学。SEM-EDAX用于确认SA对API X60钢表面的抑制作用。SA分别根据UV-vis和ATR-IR的测量值，利用其羧酸氧通过物理吸附机制吸附在钢表面。这种现象导致API X60钢在3.5％NaCl溶液中的局部点蚀减少。使用量子化学计算和蒙特卡洛模拟的理论结果为SA与钢表面的相互作用提供了原子级的进一步见解。