天然海水中氨基酸复合缓蚀剂对黄铜缓蚀性能的研究

Corrosion inhibition of brass in natural seawater using mixtures of amino acids

采用动电位极化和交流阻抗法测定海水环境中L-半胱氨酸及赖氨酸对黄铜试样的缓蚀性能,然后将这两种氨基酸分别与葡萄糖酸钠复配,研究其缓蚀协同作用。结果表明:单独使用L-半胱氨酸及赖氨酸,缓蚀效率最高分别为87.5%和89.93%;与葡萄糖酸钠复配后,两组复合缓蚀剂的缓蚀性能均显著提高,缓蚀效率分别达到97.35%和98.62%;两种氨基酸缓蚀剂在黄铜表面的吸附均遵从Langmuir吸附等温线。葡萄糖酸钠的加入弥补了单独使用氨基酸缓蚀剂吸附膜致密性差的缺陷,另外扫描电镜实验结果也显示缓蚀剂的加入明显抑制了金属的腐蚀。

The inhibition performance of two amino acids,namely L-cysteine and lysine,on the corrosion behavior of brass in seawater has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）.The synergistic inhibition between the two amino acids and sodium gluconate was also studied.The results show that L-cysteine and lysine are effective corrosion inhibitors for brass corrosion in seawater at 298 K,and the maximum inhibition efficiencies reached 87.5% and 89.9%,respectively.As a result of the synergistic inhibition by different concentrations of sodium gluconate,the inhibition efficiency could be significantly further improved,with the highest values reaching 97.4% and 98.6%,respectively.L-cysteine behaves as a cathodic inhibitor for brass in seawater.In the case of cysteine in seawater,the corrosion current density decreased,and the potential shifted slightly,which indicates that cysteine inhibits the cathode reaction effectively and acts as a mixed type inhibitor.It was found that the adsorption of L-cysteine and lysine on a brass surface in seawater followed the Langmuir adsorption isotherm model.It is proposed that the complexation of mononuclear and binuclear metal complexes adsorbed on the metal surface eliminates defects in the adsorbed film of amino acids and protects the brass from corrosion.Surface observation by scanning electron microscopy was performed in order to confirm the mechanism of inhibition action.