Synthesis And Corrosion Inhibition Performance Of Diacetophenone Imidazoline Quaternary Ammonium Salts In HCl Solution

Acid solutions,especially hydrochloric acid solution and citric acid,are widely used in quantities of industrial processes like in the oil and gas well acidizing,acid cleaning,descaling,etc.These operations generally induce the serious equipment corrosion which will lead to enormous economic losses and even cause severe safety accidents.In order to avoid unnecessary losses and ensure the safety during operation,corrosion inhibitor are often added into the medium to retard corrosion in the industrial process.In recent years,the main research interests in the field of inhibitors are focused on the developing of high efficiency and environmentally friendly inhibitors.The work aimed to synthesize three new diacetophenone imidazoline quaternary ammonium salt compounds(labeled PPLA PPLB and PPLC)and to evaluate their corrosion inhibition performances for Q235 steel in 0.5 M HCl solution by weight loss,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS)and scanning electron microscope(SEM).The purpose is to explore the dependence of inhibition performance on the concentration and temperature,and the possible inhibition mechanism of the compound for the carbon steel in acidic solution.Based on the experimental data,some thermodynamic and kinetic parameters were estimated,and the adsorption kinetic process of the inhibitor on the surface of carbon steel was also discussed.The main results were drawn as follows:(1)Three kinds of diacetophenone imidazoline quaternary ammonium salt compounds(PPLA PPLB and PPLC)were successfully designed and synthesized.In order to further confirm the structure of these compunds,PPLA PPLB and PPLC were characterized by FT-IR.(2)The results of weight loss measurements showed that PPLA PPLB and PPLC inhibitors all exhibited the excellent inhibition property for carbon steel in 0.5 M HCl solution,and the inhibition efficiency increased with the increasing concentration of inhibitors.The order of inhibition efficiency was PPLC>PPLB>PPLA,when the applied concentration of inhibitors was the same.The three inhibitors also showed outstanding corrosion inhibition performance at high temperature.(3)Electrochemically experimental results demonstrated that three inhibitors acted as the mixed type inhibitors by a geometric blocking mechanism to simultaneously retard the anodic iron dissolution and the cathodic hydrogen evolution reaction.And their adsorption behaviors on the carbon steel surface in the HCl solution obeyed the Langmuir isotherm model and presented a spontaneous chemisorption process.(4)The comprehensive analysis of XPS and SEM results showed that the synthesized inhibitor molecules formed a protective adsorption film on the surface of carbon steel through multi-center chemical adsorption,which could effectively inhibit the corrosion of carbon steel in the HCl solution.