CO_2体系中咪唑啉季铵盐与十二烷基磺酸钠之间的缓蚀协同效应

Synergistic Inhibition Effect of Imidazoline Ammonium Salt and Sodium Dodecyl Sulfate in CO_2 System

采用失重法、电化学阻抗谱(EIS)、极化曲线、X射线光电子能谱仪(XPS)及扫描电子显微镜(SEM)研究了CO2饱和的3.5%NaCl腐蚀介质中,咪唑啉季铵盐(IAS)与十二烷基磺酸钠(SDSH)对Q235钢的缓蚀协同效应.结果表明,IAS与低浓度SDSH在腐蚀介质中具有较好的缓蚀协同效应,且当二者以1:1(50 mg·L-1:50 mg·L-1)的浓度比例复配时,协同效应最明显,缓蚀率为88.5%;而IAS与高浓度SDSH间会产生拮抗效应.本文通过建立合理的吸附模型,阐述了协同效应及拮抗效应的机理.SDSH与IAS在Q235钢表面的吸附过程均为放热的自发过程,前者符合Frumkin吸附模型,后者符合Temkin吸附模型.单独使用较高浓度的SDSH对Q235钢也有较好的缓蚀作用,缓蚀率接近90%.

The synergistic inhibition effect of the imidazoline ammonium salt （IAS） and sodium dodecyl sulfate （SDSH） on the corrosion of Q235 carbon steel in a CO2 saturated brine solution was studied by weight loss, electrochemical impedance spectroscopy （EIS）, Tafel polarization measurements, X-ray photoelectron spectrometry （XPS）, and scanning electron microscopy （SEM）. We found that in the CO2 saturated brine solution, a good synergistic inhibition effect exists between IAS and low concentrations of SDSH, and the most significant synergistic inhibition occurred at a concentration ratio of 1：1 （50 mg·L^-1：50mg·L^-1） with an inhibition efficiency of 88.5%. However, antagonism occurs upon mixing IAS with a high concentration of SDSH. In this paper, the mechanisms of the synergistic and antagonistic effects are analyzed using a reasonable adsorption model. Good corrosion inhibition on Q235 carbon steel was also found when only using a high concentration of SDSH with an inhibition efficiency of about 90%. Both the adsorption processes of SDSH and IAS on the surface of Q235 carbon steel are spontaneous processes and the former process complies with the Frumkin adsorption model while the later complies with the Temkin adsorption model.