目的 合成一种二苯乙酮咪唑啉季铵盐(PPLB)化合物，研究其在0.5 mol/L HCl溶液中对Q235钢的缓蚀性能，探讨其吸附动力学过程及可能的缓蚀机制。方法 以有机胺、硬脂酸、苯乙酮和氯化苄等为原料，经脱水环化、曼尼希反应和季铵化制备季铵盐。通过腐蚀失重、动电位极化曲线测试、电化学阻抗和表面形貌分析等手段，研究了二苯乙酮咪唑啉季铵盐在HCl介质中对Q235钢的缓蚀性能。结果 HCl溶液中PPLB对碳钢具有优异的缓蚀性能，缓蚀效率随浓度和介质温度的升高而增加。在353 K下，PPLB添加量为4.8×10^–4 mol/L时，缓蚀效率可达98.9%，表明缓蚀剂在高温酸性介质中仍可有效抑制碳钢的腐蚀。电化学研究结果证明，PPLB可同时降低阴阳极的腐蚀电流密度，即抑制了腐蚀的阴阳极过程，是一种通过“几何覆盖效应”起作用的混合型缓蚀剂，其在碳钢表面的吸附遵循Langmuir吸附等温规律，为典型的化学吸附。结论 合成的二苯乙酮咪唑啉季铵盐化合物是一种优异的酸性介质缓蚀剂，独特的分子结构使其通过多中心化学吸附在碳钢表面生成保护性吸附膜，从而有效抑制了HCl对碳钢的腐蚀。

The work aimed to synthesize a new diacetophenone imidazoline quaternary ammonium salt compound (labeled PPLB) and evaluate its corrosion inhibition performance for Q235 steel in 0.5 mol/L HCl solution by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The inhibition mechanism of PPLB was also discussed. The diacetophenone imidazoline quaternary ammonium salt compound was prepared from organic amine, stearic acid, acetophenone and benzyl chloride by dehydration, cyclization, Mannich reaction and quaternization. The weight loss measurement results showed that with the increasing of PPLB concentration and medium temperature, the inhibition efficiency increased gradually, and when the inhibitor dosage was 4.8×10?4 mol/L, the inhibition efficiency reached to 98.9% at 353 K, proving that the PPLB was an excellent corrosion inhibitor for Q235 steel in HCl solution. Electrochemical studies indicated that the inhibitor simultaneously retarded both cathodic and anodic processes and acted as a mixed type inhibitor. The PPLB molecules absorbed on metal surface merely by geometric blocking mechanism and the corrosion reaction mechanism was not changed. Besides, the adsorption behavior of PPLB was in accordance with the Langmuir adsorption isotherm. After the addition of PPLB, the charge transfer resistance and film resistance values obviously enhanced, while the double layer capacitance and film capacitance significantly reduced, suggesting that the inhibitor molecules took effects by adsorbing at the metal/solution interface. The thermodynamic parameters deduced from experimental data revealed that the adsorption of inhibitor PPLB was a spontaneously chemical process. The inhibitor molecules may take effects by adsorbing on mild surface via lone pair electrons of nitrogen and oxygen atoms, which could lead to the increase of surface coverage of PPLB molecules on the Q235 steel surface. The inhibition performance was also evidenced by scanning electron microscope. Compared with the sample in 0.5 mol/L HCl solution, the surface of specimen in the presence of PPLB was much smoother. These results confirmed that the PPLB can effectively protect mild steels from corrosion in 0.5 mol/L HCl solution.