Study On Synthesis&Corrosion Inhibitory Property Of The Derivatives Of Nicotinic Acid&Isonicotinic Acid

Presently,95%of the metal used in industry is steel all over the world. However, thesteel is oxidized by air easily and the oxidation layer will appear on the surface of the steel.So it is necessary to use the method of hydrochloric acid pickling to clean up the oxidationlayer. But the hydrochloric acid pickling is difficult to be controlled. The hydrochloric acidcan not only clean up the oxidation layer but also corrode the steel. In that situation thecorrosion inhibitor is used to inhibit acid corrosion on steel.This project studied the synthesis of the derivatives of nicotinic acid and isonicotinicacid, and analyzed their physical properties and IR spectra.Then the effects of corrosioninhibition of these derivatives on Q235steel in6mol/L HCl had been studied by weight lossmethod, electrochemical polarization curves, EIS, SEM, FTIR and etc.This research indicated that these inhibitors in HCl had good corrosion inhibitioneffects on Q235steel. The inhibition efficiency of nicotinic acid amide A1reached93.49%at70℃when the concentration of the compound was700mg/L; The inhibition efficiency ofisonicotinic acid amide A2reached92.78%at70℃when the concentration of thecompound was1000mg/L. The inhibition efficiency of the quaternary ammonium salt ofnicotinic acid amide Y1reached96.63%at70℃when the concentration was300mg/L; Theinhibition efficiency of the quaternary ammonium salt of isonicotinic acid amide Y2reached91.60%at70℃when the concentration was500mg/L.These inhibitors all were cathodic corrosion inhibitors by the method of electrochemicalpolarization curves. And we have known the type of corrosion of Q235steel in HCl withthe inhibitors was general corrosion from the pictures of SEM.The adsorption models of these inhibitors were all in line with Langmiur isothermmodel, and their adsorption process was spontaneous exothermic process.