Synthesis and properties of imidazoline corrosion inhibitor for hydraulic support concentrate

In order to effectively alleviate the corrosion of the filter element and column of the hydraulic support, five-membered nitrogen heterocyclic imidazoline group was introduced on the basis of sebacic acid and L-glutamic acid by acylation-cyclization reaction, and xylene was used as solvent and water-carrying agent. Two kinds of corrosion inhibitor of bicyclic imidazoline quaternary ammonium sebacate GM-1 and L-glutamic acid bicyclic imidazoline quaternary ammonium salt LM-1 were synthesized with excellent corrosion inhibition performance for hydraulic support concentrate. The water solubility is enhanced by using sodium chloroacetate as a quaternary ammonium salting agent. Its structure was confirmed by infrared spectroscopy. The corrosion inhibition performance of two additives on HT300 gray cast iron in 330 mg/L NaCl corrosion medium was studied by corrosion weight loss, water contact angle, electrochemical and quantum chemical methods. Adsorption mode and corrosion inhibition mechanism of two additive molecules on the surface of HT300 gray cast iron. The research results show that both additives have good corrosion inhibition performance on HT300 gray cast iron immersed in 330 mg/L NaCl corrosive medium. The corrosion rate reached 95.89% and 85.79% respectively. Electrochemistry shows that both additives are anodic corrosion inhibitors and inhibit the transfer of charge between the graphite electrode and gray cast iron. The adsorption mode of additives on the surface of cast iron satisfies the Langmuir monolayer adsorption, and the Gibbs free energies are −35.361 kJ/mol and −31.093 kJ/mol respectively. It shows that the adsorption is a spontaneous physical adsorption and chemical adsorption process, and chemical adsorption is the main. When adding additives with a mass concentration of 0.5%, the water contact angles on the surface of HT300 gray cast iron soaked in GM-1 and LM-1 reached 86.24° and 82.34°, respectively, indicating that the corrosion of Cl⁻ was isolated through the presence of additive molecules in the hydrophobic film is formed on the surface of HT300 gray cast iron.Quantum chemistry shows that adsorption films are formed through coordination and feedback bonds. Compared with LM, GM is easier to adsorb on the surface of HT300 gray cast iron because the empty 3d orbital of metal is easier to give electrons to form coordination bonds and the energy barrier required for adsorption is smaller.