Synthesis Of Benzimidazole Derivatives And The Research On The Corrosion Inhibition Of Carbon Steel In Hydrochloric Acid Solution

Hydrochloric acid was used to clean the scale of equipment and pipelines in theindustrial production.Picking often cause corrosion of metallic materials and corrosioninhibitor is added to reduce metal metal corrosion and acid consumption and it will be a moreeffective method.Recently, the corrosion inhibitor with low toxicity, water-soluble,biodegradable, stable and efficient guadually become a research hotspot.In this thesis, three benzimidazole derivatives with surface activity, respectively calledBDC6T, BDC8T, BDC12T, have been synthesized, using1,3,5-trichloro-2,4,6-triazine,aliphatic amines,2-amino-benzimidazol and N, N-dimethyl-1,3-propanediamine as rawmaterials, and the structures have been characterized by FT-IR, ESI-MS,1H-NMR.The surface activity of aqueous solution of the products has been studied by surfacetension method. The results indicated that BDC6T and BDC8T had good surface activity at20℃. The lowest surface tension（γcmc）were32.7mN/m,29.9mN/m and the critical micelleconcentration (cmc) were4.2×10-3mol/L,2.3×10-3mol/L.And the adsorption efficiency ofBDC8T was higher than BDC6T and the adsorption area is relatively large.The corrosion rate of DC6T and BDC8T has been studied by weight loss method. Theresults indicated that the corrosion rate are increased with the increasing of concentration ofall three kinds of inhibitor. When the temperature is lower than30℃, corrosion rate does notchange with temperature changes significantly and when the temperature is above30℃,corrosion rate is reduced significantly with the temperature changes.A polarization curves, electrochemical impedance and SEM have been used to researchon the corrosion inhibition of45#carbon steel in hydrochloric acid solution and the corrosionrate was calculated with fitting parameters by impedance and polarization. The results can befound the two compounds are belong to mixed corrosion inhibitor of based on cathode andhave a significant inhibition effect of carbon steel. Also the inhibition rate of two compounds increases as the concentration increases.Adsorption thermodynamics showed that the two compounds adsorb on to the surface ofcarbon steel obey the Langmiur isothermal adsorption in the acid solution and the adsorptionon the surface of carbon steel is through the joint action of physical adsorption and chemicaladsorption.