阳离子木薯淀粉接枝共聚物对钢在HCl中的缓蚀性能

Corrosion Inhibition of Cationic Cassava Starch Graft Copolymer for Steel in HCl solution

摘要:

将木薯淀粉（CS）与丙烯酰胺（AA）及二甲基二烯丙基氯化铵（DMDAAC）进行反应制备出阳离子木薯淀粉接枝共聚物（CCSGC）；采用失重法、开路电位（OCP）-时间曲线、动电位极化曲线、电化学阻抗谱（EIS）和扫描电子显微镜（SEM）研究了CCSGC对冷轧钢在HCl介质中的缓蚀性能。结果表明：CCSGC在1.0 mol/L HCl溶液中对冷轧钢具有优良的缓蚀作用，20 ~ 50 oC下当CCSGC添加量为50 mg/L时最大缓蚀率均能超过92%。CCSGC的缓蚀性能明显高于反应物CS、AA、DMDAAC或CS/AA/DMDAAC混合物。CCSGC在钢表面的吸附符合Langmuir吸附等温式，且为伴随混乱度增加、放热的混合吸附过程。CCSGC为通过“几何覆盖效应”同时抑制阴极和阳极的混合抑制型缓蚀剂；EIS呈存在弥散效应的容抗弧，电荷转移电阻随CCSGC浓度的增加而增大，但双电层电容值却反而下降。SEM表明添加CCSGC能有效地抑制钢在盐酸中的腐蚀。

Abstract:

Cationic cassava starch graft copolymer (CCSGC) was prepared by reacting cassava starch (CS) with acryl amide (AA) and dimethyl diallyl ammonium chloride (DMDAAC). The corrosion inhibition of CCSGC on the corrosion of cold rolled steel in HCl was studied by weight loss, open circuit potential (OCP)-time curves, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM) methods. The results show that CCSGC exhibits outstanding inhibition effect for cold rolled steel in 1.0 mol/L HCl, and the inhibition efficiency values are higher than 92% at 20 ~ 50 oC even when the additive CCSGC concentration is as low as 50 mg/L. The inhibitive performance of CCSGC is better than the reactants of AA, CS, DMDAAC or AA/CS/DMDAAC mixture. The adsorption of CCSGC on steel surface obeys Langmuir adsorption isotherm, and it is an exothermic process that involves mixed adsorption accompanied by an increase of chaotic degree. CSGC is a mixed-type inhibitor that retards both anodic and cathodic reactions simultaneously, and the electrochemical mechanism is caused by "geometric blocking effect". EIS exhibits the depressed capacitive loop, and the charge transfer resistance increases with the concentration of inhibitor, while double layer capacitance decreases. SEM reveals that the corrosion of steel is prominently retarded after adding CCSGC to the media.