Study On Preparation, Corrosion Inhibition Effect And Mechanism Of Nitrogenous Organic Corrosion Inhibitor Based On Hydrochloric Pickling

Metal corrosion exists throughout all sectors of the national economy and department of industrial processes. The problems of corrosion not only cost valuable resources of the state, cause huge losses of economic, but also decrease the quality of the product, result in adverse effects on the environment, and even cause major accidents; it has become a stumbling block to the advancement of industries and development of science and technology. Acid solutions are widely used in many industrial processes, such as industrial cleaning, acid descaling, oil-well acidification, and petroleum processes, in which corrosion inhibitor occupies an important position in metal protection engineering, which can prevent corrosion of metals effectively, to protect the role of metal materials. With the increasing of the people environmental protection consciousness and the concept of green chemistry, low toxicity, high efficiency and environmental friendly has become new trend of development of corrosion inhibitor technology in the future. Based on the above ideas, in order to slove the problems of metal corrosion in hydrochloric acid pickling process, this paper synthesized and selected five acyl hydrazone compounds and four kinds of aromatic aldehyde amine Schiff base compounds and a Gemini surfactant as corrosion inhibitors. The corrosion inhibition of the studied compounds in 1 mol/L hydrochloric acid solution of carbon steel were investigated by the weight loss method and electrochemical techniques. The surface of the metal was also analyzed by scanning electron microscopy. In addition, quantum chemical calculations were carried out to explore the relationship between the molecular structure and the corrosion inhibition efficiency. This paper is of great significance to enrich the types of synthetic high-efficiency corrosion inhibitor. Some results were drawn as follows:1. A new kind of hydrazone compounds were synthesized. And the optimal experimental conditions were considered. The experimental results show that these five hydrazone compounds show good inhibition efficiency for carbon mild steel in 1 mol/L HC1 solution. The inhibition efficiency of these five hydrazone compounds increase with the increasing inhibitor concentration and decrease with higher temperature and longer exposure period. These compounds act as a mixed-type inhibitor. They can not only inhibit the anodic dissolution of carbon steel but also inhibit cathodic hydrogen evolution reaction. Select CBH and 4BBH which corrosion effect better as an example to continue their studies. It was found that adsorption of the synthesized compounds on carbon mild steel surface in 1 mol/L HC1 solution obeyed the Langmuir adsorption isotherm. Schiff base compounds can form self-assembled monolayers on metal surface which can inhibit corrosion on metal to achieve the purpose of protecting metal. Both physical and chemical adsorption were involved in the adsorption process, with chemical adsorption predominating. CBH corrosion effect the best inhibition efficiency can reach more than 96%, is a kind of efficient corrosion inhibitor. The study on the mechanism of corrosion inhibitors was carried on.2. Preparations of four aromatic aldehyde amine Schiff base compounds. The experimental results show that these four Schiff base compounds show good inhibition efficiency for carbon mild steel in 1 mol/L HC1 solution. The inhibition efficiency of these four Schiff base compounds increase with increasing inhibitor concentration. These compounds act as a mixed-type inhibitor. They can not only inhibit the anodic dissolution of carbon steel but also inhibit cathodic hydrogen evolution reaction. It was found that adsorption of the synthesized compounds on carbon mild steel surface in 1 mol/L HC1 solution obeyed the Langmuir adsorption isotherm. Schiff base compounds can form self-assembled monolayers on metal surface which can inhibit corrosion on metal to achieve the purpose of protecting metal. Both physical and chemical adsorption was involved in the adsorption process, with chemical adsorption predominating.3. Select Gemini surfactants DSH as the research object. Quantum chemistry calculation shows DSH is coplanar parallel reverse structure. The inhibition efficiency of DSH increased with increasing inhibitor concentration and decrease with higher temperature. It was found that adsorption of thesynthesized compounds on carbon mild steel surface in 1 mol/L HC1 solution obeyed the Langmuir adsorption isotherm. Inhibitor can form self-assembled monolayers on metal surface which can inhibit corrosion on metal to achieve the purpose of protecting metal. Both physical and chemical adsorption were involved in the adsorption process, with physical adsorption predominating. Varieties of test methods for corrosion inhibition results have a good consistency. Experimental data obtained through weight loss, such as the Gibbs free energy thermodynamic parameters change, entropy, enthalpy and other related, based on the analysis of these parameters, the mechanism of corrosion inhibition and adsorption of Gemini surfactants were analyzed.