核桃青皮提取物对铝在HNO3溶液中的缓蚀作用

Inhibition Effect of Walnut Green Husk Extract on Aluminum in HNO3 Solution

用10%~60%(体积分数)乙醇溶液从核桃青皮中提取制备了核桃青皮提取物(WGHE),采用失重法、动电位极化曲线和扫描电子显微镜(SEM)等观察研究了WGHE对铝在HNO3溶液中的缓蚀作用。结果表明:采用40%乙醇水溶液提取制备的WGHE的产率和缓蚀率均较高。WGHE对铝在HNO3溶液中的腐蚀有明显的抑制作用,缓蚀率随着WGHE加入量的增加而增大,但随温度的升高而降低。20℃时,1.0g·L-1 WGHE对铝在1.0mol·L-1 HNO3溶液中的缓蚀率达85%以上。随着腐蚀浸泡时间和HNO3浓度的增加,缓蚀率先增加后降低,腐蚀浸泡时间为24h或HNO3浓度为1.0mol·L-1时出现极大值。在20~50℃的1.0mol·L-1 HNO3溶液中,WGHE在铝表面的吸附为放热过程,且服从Langmuir吸附等温式。WGHE作为阳极型缓蚀剂在HNO3中对铝起到缓蚀作用。

Walnut green husk extract(WGHE)was prepared from walnut skin with 10%~60%(volume fraction)ethanol solution.The corrosion inhibition effect of WGHE on aluminum in HNO3 solution was studied by weight loss method,potentiodynamic polarization curve and scanning electron microscopy(SEM).The results showed that the yield and inhibition rate of WGHE prepared by 40%ethanol aqueous solution were relatively higher.WGHE had a significant inhibitory effect on the corrosion of aluminum in HNO3 solution.The corrosion inhibition rate increased with the increase of WGHE addition,while decreased with the increase of temperature.The inhibition rate of 1.0 g·L-1 WGHE for Al in 1.0 mol·L-1 HNO3 at 20℃was higher than 85%.With the increase of corrosion immersion time and HNO3 concentration,the corrosion inhibition rate first increased and then decreased.When the corrosion immersion time was 24 hor the concentration of HNO3 was 1.0 mol·L-1,the maximum value of corrosion inhibition rate appeared.In 1.0 mol·L-1 HNO3 solution at 20~50℃,the adsorption of WGHE on the aluminum surface was an exothermic process and obeyed the Langmuir adsorption isotherm.WGHE acted as an anode-type corrosion inhibitor to inhibit the corrosion of aluminum in HNO3 solution.