核桃青皮缓蚀剂的提取制备及其缓蚀性能

以乙醇水溶液为提取溶剂,采用回流提取法从核桃青皮中提取制备了核桃青皮缓蚀剂(WGHI),并用失重法、动电位极化曲线、EIS、UV、FTIR和SEM测试了WGHI对冷轧钢在0.5 mol/L HCl溶液中的缓蚀性能。结果表明:乙醇体积分数为40%时,提取制备出的WGHI产率和缓蚀率均较佳,分别为14.2%和90.3%。WGHI对冷轧钢在0.5 mol/L HCl溶液中的腐蚀具有明显抑制作用,且随着WGHI质量浓度的增加缓蚀性能逐渐增强,但随温度的升高有所下降,20℃时100 mg/L WGHI的缓蚀率为90.3%。WGHI通过物理和化学吸附方式在钢表面发生吸附,吸附过程中会释放出热量,同时混乱度减小,该吸附规律遵循Langmuir吸附方程。添加WGHI后同时抑制了钢的阴极和阳极腐蚀反应,为混合抑制型缓蚀剂;Nyquist呈单一弥散容抗弧,其阻抗值随WGHI质量浓度的增加而显著增大。SEM结果显示:WGHI能有效减缓钢表面在HCl溶液中的腐蚀并且降低了其表面粗糙度。

Extraction and Preparation of Walnut Green Hush Inhibitor and its Inhibitive Action

Walnut green husk inhibitor (WGHI) was extracted and prepared by reflux extraction with the solvent of ethanol water solution. The inhibition action of WGHI on the corrosion of cold rolled steel in 0.5 mol/L HCl was studied by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), ultraviolet and visible spectrophotometer (UV), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) methods. The results show that the optimum volume fraction of ethanol solution is 40%, and the corresponding maximum production rate and inhibition efficiency are 14.2% and 90.3%, respectively. WGHI can efficiently inhibit the corrosion of cold rolled steel in 0.5 mol/L HCl. Inhibition performance increases with the concentration of WGHI, but decreases with the increase of temperature. Through both physisorption and chemisorption mechanism, WGHI can adsorb on steel surface spontaneously, in which the heat is released and accompanied by a decrease in chaotic degree, and its adsorption behavior obeys Langmuir adsorption isotherm. The addition of WGHI drastically inhibits both anodic and cathodic reactions for the corrosion of steel, and can be arranged as a mixed-type inhibitor. Nyquist appears an individual depressed capacitive loop, and the impedance increases with the increase of WGHI concentration. Inspection of the micrographs of corroded steel surface reveals that WGHI can efficiently retard the corrosion and decrease the surface roughness of steel surface in HCl solution.