Study On The Synthesis And The Corrosion Inhibition Performance Of Thiadiazole Derivatives With Surface Activity

Carbon steel is a widely used metal material,but its easily to corrosion in the useage,due to its actively chemical properties.Therefore,the corrosion protection of carbon steel has been given close attention for scholars in the field of corrosion science.Addition inhibitors reasonably is regarded as an economic and efficient means of protection.Two thiadiazole derivatives with surface active properties were synthesized.The main results obtained are as follows:Two thiadiazole derivatives with surface activity,called MTC₆T and MTC₈T,had been synthesized using cyanuric chloride,Hexylamine,octylamine,2-Mercapto-5-methyl-1,3,4-thiadiazole?MMTD?and N,N-dimethyl-1,3-propanediamine as raw materials,and their structures were characterized by ESI-MS,1H-NMR and FT-IR.The ability of MTC₆T and MTC₈T to reduce the surface tension of 0.5 M H2SO4 solution is obviously better than that of MMTD.When the amount of MTC₆T and MTC₈T reached 0.2mM and 0.1 mM,the surface tension changed little with the increase of corrosion inhibitor concentration,and the concentration was called critical micelle concentration at this time.Weight loss method,electrochemical test,quantum chemical calculation and SEM test showed that the corrosion inhibition efficiency increased with the increase of the inhibitor concentration,while decreased with the increase of the temperature.The three inhibitors had obvious inhibition effect for both cathodic and anodic corrosion reaction,which belongs to a mixed type inhibitor.The addition of them had changed the structure of electric double layer on the carbon steel surface,increased the corrosion reaction resistance.MTC₈T had higher EHOMO and lower ELUMO.Therefore,MTC₈T was more easily to adsorbed on the carbon steel surface than MTC₆T.In the SEM study,the metal surface were smooth under the protect of MTC₆T and MTC₈T,which significantly inhibited the occurrence of pitting corrosion.Adsorption thermodynamic and corrosion kinetic studies showed that,the adsorption of MMTD on the carbon steel surface in sulfuric acid solution was subjected to Freundlichadsorption isotherm.While for MTC₆T and MTC₈T,the adsorption were spontaneous exothermic process and subjected to langmuir adsorption model,the rise of temperature were not favorable for the adsorption process.Both of them on the carbon steel surface were mainly chemical adsorption.The index factors Ar and apparent activation energy Ea all increase with the increasing of inhibitior concentration.The value of Ea follows the order:Ea?MTC₈T?>Ea?MTC₆T?>Ea?MMTD?,which further confirmed the corrosion effect was optimal for MTC₈T.