A new inhibitor, 6-bromo-(2,4-dimethoxyphenyl)methylidene]imidazo [1,2-a]pyridine-2-carbohydrazide (DMPIP) was evaluated as a corrosion inhibitor for Mild Steel (MS) in 0.5 M HCl solution at 303-323 K using potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) techniques. Both the techniques confirmed an increase in inhibition efficiency with the concentration of DMPIP but decrease with temperature. The highest inhibitive action (96.7%) was registered at 303 K for 500 ppm of DMPIP concentration. Polarization study revealed mixed inhibition action by DMPIP. Nyquist plot obtained for MS using EIS technique showed two capacitive loops on addition of inhibitor to HCl solution confirmed the inhibitory action of DMPIP via adsorption at the metal/solution interface. The surface morphology analysis was carried out by SEM, EDX and FTIR techniques. The adsorption process was demonstrated using Langmuir's adsorption isotherm model. The thermodynamic parameters (∆G^o_ads, ∆H^o_ads) indicated that the adsorption was spontaneous and done by physisorption. Further, quantum chemical studies using Density Functional Theory (DFT) elucidated that the formation of Fe-DMPIP complex presumably due to the interaction of protonated form of DMPIP with the empty d orbitals of the iron atom.

一种新的抑制剂6-溴-（2,4-二甲氧基苯基）亚甲基]咪唑[1,2- a使用电位动力学极化和电化学阻抗谱（EIS）技术，在303-323 K的0.5 M HCl溶液中，对]吡啶-2-甲酰肼（DMPIP）作为低碳钢（MS）的腐蚀抑制剂进行了评估。两种技术均证实，随着DMPIP浓度的增加，抑制效率提高，但随着温度的降低而降低。对于500 ppm DMPIP浓度，在303 K时具有最高的抑制作用（96.7％）。极化研究显示DMPIP的混合抑制作用。使用EIS技术获得的MS奈奎斯特图显示，在向盐酸溶液中添加抑制剂后，出现了两个电容性环，证实了DMPIP的抑制作用是通过在金属/溶液界面的吸附实现的。通过SEM，EDX和FTIR技术进行表面形态分析。使用Langmuir的吸附等温线模型演示了吸附过程。热力学参数（∆G^o _ads，∆H ^o _ads）表示吸附是自发的，是通过物理吸附完成的。此外，使用密度泛函理论（DFT）进行的量子化学研究阐明了Fe-DMPIP络合物的形成可能是由于DMPIP的质子化形式与铁原子的空d轨道相互作用所致。