吡哌酸、左氧氟沙星及环丙沙星在0．5mol／L H2SO4中对碳钢的缓蚀性能与机理研究

Corrosion Inhibition and Mechanisms Study on Pipemidic Acid,Levofloxacin and Ciprofloxacin for Mild Steel in 0.5 mol/L H_2SO_4

利用失重实验、动电位极化曲线测试、交流阻抗测试(EIS)及扫描电子显微镜(SEM)方法对吡哌酸(8-乙基-5-氧代-5,8-二氢-2-(1-哌嗪基)吡啶并[2,3-d]嘧啶-6-羧酸)、左氧氟沙星[(±)-9-氟-2,3-二氢-3-甲基-10-(4-甲基-1-哌嗪基)-7-氧代-7H-吡啶并[1,2,3-de][1,4]苯并恶嗪-6-羧酸]及环丙沙星[l-环丙基-6-氟-1,4-二氢-4-氧代-7-(1-哌嗪基)-3-喹啉羧酸]在303 K时0.5 mol/L H2SO4中对碳钢的缓蚀性能、作用机理进行研究.失重实验得出,303 K时试样浸泡在0.5 mol/L H2SO4溶液中的腐蚀速度随缓蚀剂的浓度增大而减小,同时三种缓蚀剂的缓蚀效率显著增大.电化学测试表明缓蚀剂分子对阴阳极反应均有抑制作用,但对阴极的抑制作用更加明显,其抑制作用与缓蚀剂在金属表面的覆盖有关.303 K时缓蚀剂在金属表面的吸附行为符合Langmuir等温线,且作用过程物理、化学吸附兼有.扫描电子显微镜观察结果表明,添加三种缓蚀剂对碳钢表面的腐蚀起到了显著的保护作用.同种条件下的测试结果表明,环丙沙星缓蚀性能最强.

The corrosion inhibition and mechanisms of pipemidic acid （8-ethyl-5-oxo-5,8-dihydro-2-（1- piperazinyl）pyrido[2,3-d]pyrimidine-6-carboxylic acid）, levofloxacin [（ ±）-9-fluoro-2,3-dihydro-3- methyl-10-（4-methyl-1-piperazinyl）-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid] and ciprofloxacin [1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-（1-piperazinyl）-3-quinoline carboxylic acid） for mild steel in 0.5 mol/L H2SO4 was studied using weight loss experiment, potentiodynamic polarization curves, electrochemical impedance spectroscopy （EIS） and scanning electron microscopy （SEM） at 303 K. The results obtained from weight loss experiment showed the inhibition efficiency was significantly increased with the inhibitor concentration increasing. Electrochemical corrosion experiment revealed the inhibition process was related to the inhibitor molecules covering on the metal surface, which mainly inhibited cathode hydrogen evolution reaction. The inhibitor molecules on the mild steel surface obeyed Langmuir isothermal model and involved physical adsorption and chemical adsorption at 303 K. Scanning electron microscopy observations showed the three inhibitors played a significant protective effect on metal corrosion. All the test results concluded that ciprofloxacin inhibition performance was best under the same conditions.