Study On Corrosion Inhibition Effect Of Zinc By Benzimidazole, 6-nitrobenzimidazole And PbCl₂ In KOH Solution

This article gives an overview about the type of alkaline zinc-based batteries and the present research about it, also analyses the property and the existing problems of zinc electrode in alkaline solution, and summarizes the main method and approach of solving the anodic problems of alkaline zinc-base battery. On this basis of investigation, we have researched the electrochemical behavior of zinc electrode with three corrison inhibitors which including two kinds of imidazoles compounds and lead (II) chloride (PbCl2) in alkaline medium.In this thesis, two kinds of imidazolium compounds (Benzimidazole, 6-Nitrobenzimidazole) and a lead salt (PbCl2) have been used as inhibitors for Zinc in KOH solution. we have applyed the methods of weight loss method, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electronic microscope (SEM), current-time curves, and quantum chemical calculations to study the electrochemical performance of the above three inhibitors for zinc in alkaline solution. The main results of the study are as follows:In the room temperature, when the two imidazolium compounds at low concentration, the inhibitors exhibit a poor inhibition performance in the low concentration KOH solution, while the concentrations are above a certain value, they exhibit a good inhibition effect, then we could conclude that the inhibition efficiency of the imidazolium compounds increase with the inhibitor concentration increasing. Both of the two imidazolium compounds are belong to anodic corrosion inhibitors, and the compounds adsorb on to the surface of zinc obey the Langmiur isothermal adsorption in the alkaline solution.This article also studied the relationship between the inhibition effect and the experimental temperature. The results shown that, the inhibition efficiency of benzimidazole could not be affected distinctly by temperature, but the corrosion inhibition efficiency of 6-Nitrobenzimidazole reduced with the increasing of temperature. However, the two kinds of inhibitors can not show perfect inhibition efficiency when the concentration of alkaline solution increasing. This would not affect the charging efficeiency of alkaline znic electrode significantly.Through the current-time measuring technique, we can see that Pb2+ could effectively inhibit the generation of zinc dendrite in the charging process when Pb2+ concentration is less than 0.1g/L, and this will not affect the charging efficiency. When the cathode polarization overpotentialη≥-100mV, 6-Nitrobenzimidazole has better inhibition effect at lower concentration, and Benzimidazole improve its inhibition effect on zinc dendrite generation when its concentration is increasing.Adsorption thermodynamics and adsorption kinetics showed that the adsorption of 6-Nitrobenzimidazole on the surface of zinc is through the joint action of physical adsorption and chemical adsorption, apparent activation energy increased with the increasing of 6-Nitrobenzimidazole concentration. The adsorption of benzimidazole on the surface of zinc is dominated by the chemical adsorption of covalent bond interactions, the activation performance showed a trend of first increase and then decrease with the increase in the concentration of benzimidazole. Imidazole compounds of zinc electrode in alkaline zinc adsorption changed the process of corrosion, inhibitor concentration can cause changes in the nature of the adsorption layer, which is the process of change leading to corrosion of zinc decisive factor.Quantum chemical calculations indicate that both of the imidazolium compounds can form a stable adsorption film on the surface of zinc. The results of density functional of lead on zinc electrode shows that, The energy of lead atoms adsorpted with zinc atoms is overall lower than the energy of zinc atom adsorpted with zinc atoms, which indicating that the surface adsorption of lead atoms in zinc atoms is more stable than zinc formed, without considering the impact of external environment.