Synthesis Of Imidazoline Corrosion Inhibitor And Study On Its Inbihition Performance And Mechanism

With the improvement of material conditions of people and the level ofindustrial technology, environmental pollution is becoming more and moreserious. Then, a new concept was brought out, that is "green chemistry". Fromthe raw materials to the processing of intermediate products, as well as the entireprocess should be uesd for minimizing the harm to the environment, evenharmless. It requires that the chemical production technology should avoid theuse of toxic raw materials or produce large amounts of toxic byproducts as muchas possible. In the process of developing corrosion inhibitors, it not only needsthe new types, high-performance, more importantly, friendly to environmental.Because of excellent environmental protection and corrosion properties,imidazoline corrosion inhibitors are widely used in various chemical processes.The fatty acids and amines are usually used to synthesize the imidazolinecorrosion inhibitor. There are fewer reports in using the grease to synthesizeimidazoline corrosion inhibitors and preventing corrosion. In this paper,imidazoline intermediate was synthesized by solvent method using rapeseed oiland2-(aminoethylamino) ethanol. And then it was modified by benzyl chlorideand sulfamic acid to obtain cationic and amphoteric derivates IM-1and IM-2respectively. The products were analyzed with IR spectrum and1HNMRspectrum. And then the optimal inhibitor was selected from two products bystatic weight-loss measurement. The amphoteric derivate IM-2was selected outto the following tests. A sample selected from them was mixed with KI (20:1),finally a complex system (IM-3) was gained. Its inhibition performance wasevaluated by weight-loss measurement and electrochemical test. Thenfilm-forming performance was explored in the surface of A3steel in differentconcentrations and different time with inhibitor IM-3. Scanning electronmicroscope was applied to investigate the shape patterns on the surface of A3steel in hydrochloric acid before and after corroding. And the IM-3was compared with other common inhibitors, such as thiourea andhexamethylenetetramine in inhibition performance. The results show that theIM-3has stronger corrosion inhibiting ability than other inhibitors for A3carbonsteel in hydrochloric acid, and the static loss result is better than the dynamicresult. The best time of film-forming is4h and the optimal concentration of IM-3is100mg/L. Its static corrosion inhibition efficiency reaches88.62%~98.98%and dynamic corrosion inhibition efficiency reaches86.76%~95.85%inhydrochloric acid. The polarization curve result shows that IM-3belongs tomixed inhibitor dominated by anodic inhibition.Using maize oil as raw materials, imidazoline quaternary ammonium salt(IM) was synthesized through aminolysis with diethylenetriamine andquartemarization with benzyl chloride, and then it was modified by urea andthiourea to obtain IM-O and IM-S respectively. The products were analyzed withIR spectrum and1HNMR spectrum. The inhibition performance of A3steel inhydrochloric acid was evaluated by weight-loss measurement. The compareresearch in the concentration of corrosion inhibitor, the concentration ofhydrochloric acid, the temperature of acid pickling, the time of pickling and theconcentration of Fe3+were done. The results show that IM-O and IM-S are goodinhibitors for A3steel in hydrochloric acid, and IM-O has stronger corrosioninhibiting ability than IM-S. The best time of inhibition is6h and the optimalconcentration of IM-O and IM-S is100mg/L in5%HCl at55℃.To determine the corrosion inhibition effects of corrosion inhibitor structureby the quantum chemistry calculation method, imidazoline quaternaryammonium salt was synthesized through oleic acid, diethylenetriamine andbenzyl chloride, and then it was modified by urea and thiourea to obtainoleic-acid imidazoline inhibitor IM-O and IM-S respectively. The products wereanalyzed with IR spectrum and1HNMR spectrum. The inhibition performance ofA3steel in hydrochloric acid was evaluated by weight-loss measurement.Additionally, quantum chemistry calculation was carried out to analyze thecorrosion inhibition mechanism. Global and local activity indices, such asHOMO energy, LUMO energy, charge distribution and Fukui function, suggestedthat oleic-acid imidazoline inhibitor IM-O has stronger corrosion inhibitingability than IM-S, and the results of the quantum chemical calculation are equal to the experimental tests.