Synthesis Of The N-acyl Amino-acid Compounds And Study On The Corrosion Inhibition Performance

Metal material is the most widely used engineering materials in modern society, moreattention is paid to the problems of its corrosion and corrosion inhibition. Adding corrosioninhibitor is a convenient and low cost method, it has become one of the most widely usedmethod of anticorrosion technology, because it has good effect and high economicefficiency. With the strengthening of environmental protection consciousness and the ideaof sustainable development is thorough, there are more and more restrictions for the toxic,poor biological degradation ability corrosion inhibitors. Therefore, it is an urgent problemfor researching and developing efficiency, low toxicity and environmental friendlycorrosion inhibitor. For having source widely, non-toxic, easily bio-degradable, Amino acidcompounds have become an important direction of inhibitor development.Some N-acyl amino acid compounds were syntheszied with the raw material ofL-glutamic、glycine、methylglycinate and undecylenic acid、decylic acid、lauric acid、oleic acid、octanoic acid、benzoic acid by using condensation method process route ofSchotten-Baumann: N-(1-oxo-10-undecenyl)-L-glutamic(S1)、 N-(1-oxo-10-undecenyl)-glycine(S2)、 N-decanoyl-L-glutamic(G1)、 N-decanoyl-glycine(G2). The inhibitoryperformance of corrosion inhibitor for corrosion of Q235steel in neutral water medium wasinvestigated by weight loss and electrochemical method and SEM.The inhibitors show excellent inhibition efficiency for inhibiting corrosion of Q235steel in neutral water medium. The inhibition efficiency of S1is up to90%when itsconcentration is200mg/L, others need300mg/L. The corrosion potential moves to positivevalue after adding inhibitors, the four inhibitors belong to anodic type inhibitor. Thecorrosion current density decreases and charge transfer resistance increases with increase ininhibitor concentration, the existence of corrosion inhibitors inhibit electrochemicalcorrosion process, reduce the corrosion rate and increase the inhibition efficiency. Theadsorption model of four inhibitors on Q235steel obey the Langmuir adsorption isotherm,and the adsorption process is proved to be spontaneous and the typical physical adsorption.The apparent activation energy becomes higher after adding the inhibitor, which shows thatthe energy barrier is increased and the inhibitor plays a negative catalytic role.