核桃青皮提取物与碘化钾对钢在柠檬酸中的缓蚀协同效应  

Synergistic Inhibition Effect of Walnut Green Husk Extract and Potassium Iodide on Corrosion of Steel in Citric Acid Solution

作　　者：王丽姿 黄苗 李向红 WANG Lizi;HUANG Miao;LI Xianghong(College of Chemical Engineering,Southwest Forestry University,Kunming 650224,China)

机构地区：[1]西南林业大学化学工程学院,昆明650224

出　　处：《中国腐蚀与防护学报》2021年第6期819-827,共9页Journal of Chinese Society For Corrosion and Protection

基　　金：国家自然科学基金(51761036);云南省农业基础研究联合专项(2017FG001(-004));云南省基础研究计划杰出青年项目(202001AV070008);云南省万人计划青年拔尖人才专项(51900109)。

摘　　要：以农林废弃物核桃青皮为原料,采用乙醇水溶液为提取剂进行回流提取制得核桃青皮提取物(WGHE);通过全浸失重法研究了WGHE与碘化钾(KI)对冷轧钢在1.0 mol/L柠檬酸(H_(3)C_(6)H_(5)O_(7))溶液介质中的缓蚀协同性能,并采用动电位极化曲线探究了电化学作用机理;借助扫描电子显微镜(SEM)和原子力显微镜(AFM)研究了钢表面的微观形貌和表面粗糙度。结果表明,WGHE及KI单独使用具有中等程度的缓蚀作用,最大缓蚀率分别为67.4%和69.3%;当WGHE与KI混合复配使用后,缓蚀性能显著上升,25℃时缓蚀协同效应系数大于1,两者之间存在缓蚀协同效应,200 mg/L WGHE与100 mg/L KI复配后的缓蚀率高达85.3%。WGHE、KI混合使用前后在冷轧钢的表面吸附规律均遵循Langmuir吸附等温方程式,协同缓蚀剂WGHE/KI在钢表面的吸附平衡常数(K)进一步增大至0.0382 L/mg,而标准吸附Gibbs自由能(ΔG^(0))降低为-28.9 kJ/mol。WGHE、KI单独使用时对阴极反应产生了抑制作用,而WGHE与KI的复配物为混合抑制型缓蚀剂。SEM和AFM分析得出WGHE与KI混合使用后更能有效减缓柠檬酸介质对钢表面的腐蚀。Walnut green husk extract(WGHE) was obtained from the raw materials of forestry and agricultural residue of walnut green husk by circulation reflux method with ethanol water solution as extractive solvent. The synergistic inhibition performance and mechanism of WGHE and potassium iodide(KI) on the corrosion of a cold rolled steel(CRS) in 1.0 mol/L citric acid(H_(3)C_(6)H_(5)O_(7)) solution were assessed by means of immersion test, potentiodynamic polarization curve measurement, and electrochemical impedance spectroscopy(EIS), as well as scanning electron microscope(SEM) and atomic force microscope(AFM). The results showed that either individual WGHE or KI was a moderate inhibitor, and the maximum inhibition efficiency was 67.4% for WGHE and 69.3% for KI respectively. When WGHE was mixed with KI, the complex could promote the inhibitive action, and the synergism parameter was higher than 1 for the solution at 20 ℃. There was a synergism between WGHE and KI, and the maximum inhibition efficiency for the mixture of 200 mg/L WGHE with 100 mg/L KI was 85.3%. No matter when WGHE was mixed with KI, the adsorption of inhibitor molecules on CRS surface obeys Langmuir isotherm. The incorporation of WGHE with KI further increases the adsorption equilibrium constant(K) up to 0.0382 L/mg,while the standard Gibbs adsorption free energy(ΔG^(0)) shifts more negatively to-28.9 kJ/mol. Potentiodynamic curves indicate that individual WGHE or KI mainly retards the cathodic reaction, while the mixture of WGHE/KI acts as a mixed-type inhibitor. SEM and AFM microphotographs confirm that the synergistic of WGHE and KI can more efficiently alleviate the citric acid induced corrosion of the cold rolled steel.

关 键 词：缓蚀剂 缓蚀协同效应 吸附 钢 核桃青皮 碘化钾 柠檬酸 

分 类 号：TG174[金属学及工艺—金属表面处理]