1mol/L HCl中不同浓度维生素B1和B6对碳钢的缓蚀性能及机理

Corrosion Inhibition Effect and Mechanism of Vitamin B1 and B6 with Different Concentration for Carbon Steel in Aqueous Solution of 1 mol/L Hydrogen Chloride

通过研究盐酸硫胺(维生素B1)、吡哆醇(维生素B6)作为缓蚀剂对碳钢的缓蚀行为及其作用机制,可为新型环境友好缓蚀剂的开发和应用提供一定的理论基础。利用失重法、极化曲线法和交流阻抗法、量子化学方法研究了不同浓度维生素B1和B6在1 mol/L盐酸溶液中对Q235碳钢的缓蚀性能及机理。结果表明:碳钢的腐蚀速率随缓蚀剂浓度的增大而减小,维生素B1的缓蚀效率较高,缓蚀效果较好;在298 K下,缓蚀剂在碳钢表面的吸附遵循Langmuir吸附等温规律,其吸附过程包括物理吸附和化学吸附;维生素B1和B6是抑制阴极为主的混合缓蚀剂,腐蚀电流密度Jcorr随缓蚀剂浓度的增加而减小;在298 K下,维生素B1和B6的交流阻抗谱为单一时间常数的容抗弧,同时电荷转移阻抗Rt随缓蚀剂浓度的增加而变大,双电层电容Cdl则相反;维生素B1比B6具有较高的最高占据轨道能量EHOMO和较低的最低空轨道能量ELUMO;维生素B1比B6的缓蚀效果更好。

The corrosion inhibition action and mechanism of thiamine hydrochloride(vitamin B1) and pyridoxine hydrochloride(vitamin B6) with different concentration for carbon steel in 1 mol/L HCl were analyzed by using weight loss,polarization curve,electrochemical impedance and quantum chemical methods.It was found that the corrosion rate of the carbon steel decreased with increasing concentration of the inhibitors,and vitamin B1 had better inhibition effect.At 298 K,the adsorption of the inhibitor molecules on carbon steel surface followed Langmuir adsorption isotherm law and involved both physical adsorption and chemical adsorption.Vitamins B1 and B6 were mixed-type inhibitors and mainly inhibited cathodic corrosion,and the corrosion current density Jcorr decreased with increasing concentration.Corresponding electrochemical impedance spectra appeared as capacitive reactance arc characterized by single time constant,while the charge transfer resistance Rt increased with increasing concentration of the inhibitor,and the double-layer capacitance Cdl decreased therewith.Vitamin B1 had higher energy of the highest occupied molecular orbital(EHOMO) and lower energy of the lowest unoccupied molecular orbital(ELUMO) than vitamin B6.