滇润楠叶提取物对铝在HCl中的缓蚀性能

Inhibition Action of Machilus yunnanensis Leaves Extract on Corrosion of Al-plate in HCl Medium

采用失重法、电化学法、电感耦合等离子发射光谱仪(ICP-OES)、金相显微镜、扫描电子显微镜(SEM)及接触角测试研究了滇润楠叶提取物(MYLE)在1.0 mol·L^(-1)HCl溶液中对Al的缓蚀性能。结果表明:20℃时,1000 mg·L^(-1)MYLE的最大缓蚀率可达93.5%,MYLE浓度越高,缓蚀性能越强;而温度越高,缓蚀性能越弱。MYLE在Al表面的吸附主要以化学吸附为主,在低温时符合Langmuir吸附等温式,高温时符合Freundlich吸附等温式。Al在添加MYLE前后的HCl中腐蚀动力学规律符合Arrhenius公式和过渡态理论方程,添加MYLE后表观活化能(E_(a))、指前因子(A)、表观活化焓(ΔH_(a))、表观活化熵(ΔS_(a))均增大。MYLE为混合型缓蚀剂,其电化学缓蚀作用机理为“几何覆盖效应”,Nyquist图主要由高频区的容抗弧和低频区的感抗弧组成,且随着MYLE浓度增大,电荷转移电阻和电感电阻均增大。添加MYLE后,缓蚀体系中Al^(3+)浓度明显降低,SEM观察进一步证实了MYLE有效减缓了Al表面的腐蚀程度。

The inhibition action of Machilus yunnanensis leaves extract(MYLE)on Al-plate in 1.0 mol·L^(-1)HCl solution were studied by means of mass loss method,electrochemical tests,inductively coupled plasma optical emission spectrometer(ICP-OES),metallographic microscope,scanning electron microscope(SEM)and contact angle measurements.The results show that the maximum inhibition efficiency of 1000 mg·L^(-1)MYLE at 20℃ can reach as high as 93.5%.The inhibition efficiency increases with the increase of MYLE concentration,while the higher the temperature,the weaker the inhibition performance.The adsorption of MYLE on Al surface is mainly based on chemisorption,which conforms to Langmuir isotherm at lower temperatures and Freundlich isotherm at higher temperatures.The corrosion kinetic reaction of Al in HCl solutions without or with MYLE is in accordance with Arrhenius formula and transition state theory equation.In the presence of MYLE,the relevant apparent activation energy(E_(a)),pre-exponential factor(A),apparent activation enthalpy(ΔH_(a))and apparent activation entropy(ΔS_(a))are all increased.MYLE is a mixed inhibitor through“geometric blocking effect”.Nyquist diagram is mainly composed of a capacitive reactance arc in high frequency region and an inductive reactance arc in low frequency region.With the increase of MYLE concentration,both the charge transfer resistance and inductance resistance increase.After the addition of MYLE,the concentration of Al^(3+) in HCl solutions is significantly dropped,and SEM morphology further confirms that MYLE can efficiently slow down the corrosion degree of Al-plate.