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目的 研究吲哚-3-乙酸(IAA)在H2SO4(0. 1 mol/L)溶液中对碳钢(Q235)的缓蚀性能,降低碳钢生产过程对环境的影响. 方法 采用动电位极化曲线测试、交流阻抗实验、失重实验和扫描电镜实验分析缓蚀剂的缓蚀性能及作用机理.结果 IAA的缓蚀效率随着缓蚀剂浓度的增加而逐渐增大,当IAA浓度增加到4×10-3 mol/L 时,缓蚀效率最高达到88. 85%. 温度升高,缓蚀效率降低,说明IAA不宜于高温下使用. IAA是一种混合型缓蚀剂,对阴极反应和阳极反应均有抑制作用,且在缓蚀剂分子吸附过程中,吸附在碳钢表面的水分子和缓蚀剂分子发生竞争吸附作用,能有效阻止H+的穿越,从而抑制腐蚀H+的放电. IAA在碳钢表面的吸附遵循Langmuir吸附等温模型,该吸附自发进行且是物理吸附和化学吸附共同作用. 缓蚀剂通过抑制腐蚀反应的活性点,提高活化能垒,防止碳钢溶解腐蚀. IAA在碳钢表面形成保护膜,减轻了腐蚀. 结论 IAA是一种以抑制阳极反应为主的混合型缓蚀剂,在0. 1 mol/L H2 SO4 溶液中能够对Q235碳钢起到优异的保护作用.

Objective To study the inhibiting effect of indole-3-acetic acid (IAA) for mild steel in H2SO4(0. 1 mol/L) solution so as to reduce the influence of carbon steel production process on the environment. Methods The weight loss experiment, the po-tentiodynamic polarization test, the electrochemical impedance spectroscopy ( EIS) and the scanning electron microscopy ( SEM) were conducted to investigate the inhibition efficiency and the mechanism. Results The inhibition efficiency was enhanced with the increasing inhibitor concentration, and the highest inhibition efficiency reached 88. 85% at the inhibitor concentration of 4×10-3 mol/L. The inhibition efficiency of IAA was lower when the temperature increased, which indicated that IAA was not suitable for high temperature. IAA acted as a mixed-type inhibitor and had a suppressing effect on anodic and cathodic reactions. And there was a competitive adsorption emerged between the adsorbed water molecules and the inhibitor molecules in the process of adsorption effect, which effectively prevented the H+ from crossing, thereby inhibiting the discharge process of the corrosion H+. The adsorp-tion of IAA on carbon steel surface followed the Langmuir adsorption isotherm model, which was spontaneous and was a combination of physical and chemical adsorption. Inhibition of corrosion by inhibiting the active point of the corrosion reaction can improve the activation energy barrier and prevent corrosion of carbon steel. The inhibitor molecules reduced the metal corrosion significantly. Conclusion IAA is a mixed-type corrosion inhibitor, which can inhibit the anodic reaction. It can protect the Q235 carbon steel in 0. 1 mol/L H2 SO4 solution.