The anti-corrosion activity of a newly synthesized ethylene tetra phosphonic acid (ETPA), namely {Ethylenebis [(2-hydroxy-5,1,3-phenylene) bismethylene]} tetraphosphonic acid, against the corrosion of carbon steel in 0.5-M H2SO4 medium and its synergistic effect with Cu[Formula: see text] ions were studied using potentiodynamic polarizations and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization studies indicate that ETPA acts as a mixed-type inhibitor and inhibition efficiency increases with increasing ETPA concentration. The adsorption of ETPA at the surface of carbon steel follows Langmuir adsorption isotherm. EIS results demonstrated the adsorption of ETPA onto the carbon steel surface, leading to the formation of ETPA overlaying film. Addition of [Formula: see text] M Cu[Formula: see text], at low ETPA concentration ([Formula: see text] M), results in significant increase in inhibition efficiency (88%), superior to that obtained at high ETPA concentration (81% at [Formula: see text] M). SEM and EDAX analyses confirmed the existence of a uniform protective film on the electrode surface attributed to ETPA–Cu[Formula: see text] complex formation.

中文翻译：

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乙烯四膦酸-Cu2+体系在H2SO4溶液中对碳钢的防腐活性

新合成的乙烯四膦酸（ETPA），即{乙烯双[(2-羟基-5,1,3-亚苯基)双亚甲基]}四膦酸对0.5-MH中碳钢腐蚀的抗腐蚀活性2所以4使用动电位极化和电化学阻抗谱 (EIS) 研究了介质及其与 Cu [公式：见正文] 离子的协同效应。动电位极化研究表明，ETPA 作为一种混合型抑制剂，抑制效率随着 ETPA 浓度的增加而增加。ETPA在碳钢表面的吸附遵循朗缪尔吸附等温线。EIS结果表明ETPA吸附在碳钢表面，导致ETPA覆盖膜的形成。添加[公式：见正文] M Cu[公式：见正文]，在低 ETPA 浓度（[公式：见正文] M）下，抑制效率显着提高（88%），优于在高 ETPA 下获得的抑制效率浓度（[公式：见文本] M 时为 81%）。