橙子皮提取物对HCl溶液中铝的缓蚀作用研究

Inhibition Effect of Orange Peel Extract on Aluminum in Hydrochloric Acid Solution

通过乙醇水溶液回流提取法制得橙子皮提取物,用红外光谱测定橙子皮提取物的官能团结构组成,首次采用静态失重法、电化学法及表面微观形貌观察系统分析了橙子皮提取物对1.0 mol/L HCl溶液中铝的缓蚀性能及作用机理。结果表明:缓蚀性能随橙子皮提取物浓度增大而不断增强,但随温度增大而减弱;20℃时橙子皮提取物浓度处于300~900 mg/L范围内,缓蚀率处于稳定值,且最高缓蚀率高达98%以上;橙子皮提取物在铝表面的吸附符合Langmuir吸附等温式,吸附作用类型为以物理吸附为主的混合型吸附,且加入橙子皮提取物使得表观反应活化能升高。橙子皮提取物明显抑制了铝的阴极析氢反应,而对阳极抑制作用较为微弱,且加入后腐蚀电流密度急剧减小;电化学阻抗谱包含2个时间常数,在高频区呈容抗弧,而在低频区呈感抗弧,加入橙子皮提取物后铝的电荷转移电阻值增大;从扫描电子显微镜和原子力显微镜可以看出,铝的缓蚀表面腐蚀程度急剧降低,且表面粗糙度明显减小。

Orange peel extract(OPE)was prepared by reflux extraction method with ethanol aqueous solution,and its functional groups were characterized by infrared spectrum(FTIR).The inhibition effect of OPE on aluminum in 1.0 mol/L HCl solution was studied in detail for the first time by weight-loss,electrochemical technique,and surface analysis methods.The results showed that inhibitive performance increased continuously with the increase of OPE concentration,but turned to be lower with at higher temperature.When the OPE concentration is in the range of 300 mg/L–900 mg/L at 20℃,its inhibitive action is in stable state,and the maximum inhibition efficiency is as high as 98%.The adsorption of OPE was in accordance with Langmuir adsorption isotherm,and its adsorption mode was the mixed adsorption while mainly the physisorption.Polarization curves indicated that the presence of OPE significantly retarded the cathodic reaction of aluminum electrode in HCl solution,while slightly inhibited the anodic reaction,and then leaded to lower corrosion current.Electrochemical impedance spectroscopy(EIS)contained 2 time constants,and Nyquist appears a capacitive loop at high frequencies followed by an inductive one at low frequency values,and the charge transfer resistance increases with the addition of OPE.Scan-ning electron microscope(SEM)and atomic force microscope(AFM)revealed the corrosion degree and surface roughness of aluminium surface was sharply dropped to more extent after adding OPE to the media.