Synthesis And Evaluation Of New Type Polysaccharide Inhibitors

At present,CO₂ is used in the oil industry to enhance oil recovery.Inevitably,when carbon dioxide is dissolved in the formation water,CO₂ solution will corrode the carbon steel pipeline,which affects the normal production of oil fields and causes huge losses.Many inhibitors have been developed to prevent carbon dioxide from corroding steel pipes,but they are toxic,the development of new environmentally-friendly inhibitors is current requirements and future trend.In this thesis,chitosan oligosaccharides,glycidyltrimethylammonium chloride,propionaldehyde and benzaldehyde were used as raw materials to synthesize non-toxic chitooligosaccharide derivatives?PHC and BHC?as green corrosion inhibitors.Infrared spectroscopy and nuclear magnetic resonance analysis showed that the chitosan oligosaccharide derivatives were successfully prepared.The inhibition effect of chitosan oligosaccharide derivatives?PHC and BHC?on P110 carbon steel corrosion in 3 wt.%NaCl CO₂-saturated solution was researched by gravimetric measurement,scanning electron microscope?SEM?,atomic force microscopy?AFM?,electrochemical studies and quantum chemical calculations.The results show that:as inhibitor concentration increases,the inhibition efficiency was increased.The weight loss test results showed that the inhibition efficiency of 100 mg/L PHC was 86%,and the inhibition efficiency of 100 mg/L BHC was 89%.The inhibition efficiency of 100 mg/L PHC and 100 mg/L BHC measured by Tafel were 88%and 92%,respectively.All test results show that BHC molecules have better corrosion inhibition than PHC.Potentiodynamic polarization results indicated that both compounds are mixed type inhibitors.Energy dispersive X-ray?EDX?and electrochemical impedance spectroscopy?EIS?measurements show that the inhibitors adsorbed on P110 steel surface successfully.The adsorption ability on the P110 steel surface was evaluated by calculating the quantum chemical parameters of inhibitor molecules.The results show that BHC moleculars have a stronger adsorption capacity on the steel surface than PHC moleculars.At the same time,compared with the field corrosion inhibitors ZH-1 and TA801,the experiments show that the chitosan oligosaccharide derivatives have the same corrosion inhibition efficiency as the oil field corrosion inhibitors in use,but the chitosan oligosaccharide derivatives have the advantages of non-toxicity.