Gemini-type imidazoline quaternary ammonium salt is a new type of environmentally friendly corrosion inhibitor has been widely used in engineering materials. However, most of them are hazardous/toxic compounds derived from petroleum-based products, which did harm to environment. In this work, an environmentally friendly Gemini-shaped imidazoline quaternary ammonium salt corrosion inhibitor (G211) was synthesized using cheap fatty acid recycled from dimer acid industry as feedstock. The corrosion inhibition effects of G211 on Q235 steel in 1 M HCl solution were investigated through weight loss experiments, potential polarization curves, and alternating current impedance spectroscopy experiments. The results show that the inhibition rate of G211 as a mixed-type inhibitor is up to 94.4% and the concentration drop as low as 500 ppm at 25 ℃. The adsorption of G211 on Q235 surface follows Langmuir adsorption isothermal curve. The chemical composition of the Q235 steel surface was analyzed through scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Furthermore, the possible corrosion inhibition mechanism of G211 on the surface of Q235 steel is proposed. This article not only presents an outstanding solution for safeguarding Q235 steel against corrosion but also introduces a feasible method for high-value utilization of monomer acid (MA).

双子型咪唑啉季铵盐是一种新型环保型缓蚀剂，已广泛应用于工程材料中。然而，它们大多数是源自石油产品的有害/有毒化合物，对环境造成危害。本工作以二聚酸工业回收的廉价脂肪酸为原料，合成了一种环保型双子座咪唑啉季铵盐缓蚀剂（G211）。通过失重实验、电位极化曲线和交流阻抗谱实验研究了G211对Q235钢在1 M HCl溶液中的缓蚀作用。结果表明，G211作为混合型缓蚀剂，在25℃时缓蚀率高达94.4%，浓度下降低至500 ppm。 G211在Q235表面的吸附遵循Langmuir吸附等温曲线。通过扫描电子显微镜（SEM）和X射线光电子能谱（XPS）分析Q235钢表面的化学成分。进一步提出了G211对Q235钢表面可能的缓蚀机理。本文不仅提出了一种保护Q235钢免受腐蚀的出色解决方案，而且还介绍了一种单体酸（MA）高值化利用的可行方法。